British Medical Bulletin Advance Access published November 25, 2012
Placenta as a reservoir of stem cells: an underutilized resource? Caterina Pipino1, Panicos Shangaris1,2, Elisa Resca1,†, Silvia Zia3, Jan Deprest3, Neil J. Sebire4, Anna L. David2, Pascale V. Guillot5, and Paolo De Coppi1,6* 1
Introduction: Both embryonic and adult tissues are sources of stem cells with therapeutic potential but with some limitations in the clinical practice such as ethical considerations, difficulty in obtaining and tumorigenicity. As an alternative, the placenta is a foetal tissue that can be obtained during gestation and at term, and it represents a reservoir of stem cells with various potential. Sources of data: We reviewed the relevant literature concerning the main stem cells that populate the placenta. Areas of agreement: Recently, the placenta has become useful source of stem cells that offer advantages in terms of proliferation and plasticity when compared with adult cells and permit to overcome the ethical and safety concern inherent in embryonic stem cells. In addition, the placenta has the advantage of containing epithelia, haematopoietic and mesenchymal stem cells. These stem cells possess immunosuppressive properties and have the capacity of suppress in vivo inflammatory responses.
*Correspondence address. Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK. E-mail: p.
[email protected] † Present address: CEIADepartment of Laboratories, Pathological Anatomy and Forensic Medicine, University of Modena and Reggio Emilia, Modena, Italy.
Areas of controversy: Some studies describe a subpopulation of placenta stem cells expressing pluripotency markers, but for other studies, it is not clear whether pluripotent stem cells are present during gestation beyond the first few weeks. Particularly, the expression of some pluripotency markers such as SSEA-3, TRA-1-60 and TRA-1-81 has been reported by us, but not by others. Growing points: Placenta stem cells could be of great importance after delivery for banking for autologous and allogeneic applications. The beneficial effects of these cells may be due to secretion of bioactive molecules that act through paracrine actions promoting beneficial effects. Areas timely for developing research: Understanding the role of placenta stem
British Medical Bulletin 2012; 1–25 DOI:10.1093/bmb/lds033
& The Author 2012. Published by Oxford University Press. All rights reserved. For permissions, please e-mail:
[email protected]
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Surgery Unit, Institute of Child Health, University College London, London, UK; 2Prenatal Cell and Gene Therapy Group, Institute for Women’s Health, University College London, London, UK; 3 Department of Development and Regeneration, Faculty of Medicine, and Division Woman and Child, University Hospital Gasthuisberg, Leuven, Belgium; 4Department of Paediatric Pathology, Great Ormond Street Hospital for Children, London, UK; 5Institute of Reproductive and Developmental Biology, Imperial College London, London W12 0NN, UK, and 6Department of General Surgery, Great Ormond Street Hospital for Children, London, UK
C. Pipino et al.
cells during pregnancy and their paracrine actions could help in the study of some diseases that affect the placenta during pregnancy.
Keywords: placenta/amniotic epithelial cells/mesenchymal stem cells/ haematopoietic stem cells Accepted: October 9, 2012
Introduction
Page 2 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Placenta is one of the most important organs in the uterine environment. It is short lived by design, enabling the mammalian embryo/ foetus to survive and develop within the confines of the intrauterine environment. Placenta plays such an important role during mammalian embryogenesis that, not only it is the first structure to form, but without a placenta the embryo cannot survive.1 Targeted mutations in the mice that are associated with placental defects are eventually lethal for the embryo.1 Placenta assumes multiple roles during gestation, including providing nutrients and removing waste products, to secretory and immunomodulatory functions. The placenta is a vital source for a wide range of hormones, growth factors, cytokines and transcription factors2 and is involved in the protection of the foetus from various chemical, infections and immune assaults, arising from the maternal circulation or from the cervix3. As with all organs, it performs these functions via multiple specialized cell types derived from lineage-committed precursors that either proliferate or differentiate. This process depends on a coordinated interaction among genetic, epigenetic and physiological cues that are differentially interpreted as a function of gestational age.4 The human placenta, as shown in Figure 1,5 can be conceptually visualized as having two components: a foetal part (amniotic and chorionic structures) and a maternal part originating from the decidual basalis.6 The amnion represents the inner layer, and the amniotic epithelial (AE) cells create a continuous lining adjacent to the amniotic fluid, whereas on the other side of the amniotic epithelium is a thin layer of amniotic mesoderm.7 AE cells and amniotic mesenchymal cells are derived from the epiblast and hypoblast, respectively. The timing of the derivation of amnion from the epiblast is important because it has been suggested that tissues that form prior to gastrulation may retain stem cell or stem cell-like capabilities.8 Chorionic structures are composed of chorionic mesoderm and a highly variable trophoblast layer, forming both chorionic villi and extravillus trophoblast. Chorionic trophoblast differentiates towards cytotrophoblast, syncytiotrophoblast
Placenta as a reservoir of stem cells
and various types of intermediate trophoblastic cells, all arising from the trophectoderm of the implanting blastocyst.9 The development of the human placenta begins as early as 12 days post conception. The proliferation of the trophoblastic trabeculae leads to the formation of primary villi, surrounded by maternal circulation.10 These villi are then transformed into secondary villi by the invasion of extra-embryonic mesenchyme in subsequent days. The development of the tertiary villi is marked by the formation of the first foetal capillaries in the mesenchyme. These mesenchymal villi are essential in the formation of the villous trees that form the placenta proper. Additionally, extravillous trophoblast invades the maternal spiral arterial walls in the decidua and myometrium converting these to low resistance uteroplacental vessels.2,10 The first cell lineage, which appears during placental development, is, therefore, trophoblast and it gives rise to many subsequent structures. Chorionic trophoblastic cells represent stem cells that in the appropriate growth factors environment may have unlimited proliferation potential.11 These cells provide the required components that allow the efficient and controlled interface of the foetal and maternal vascular systems. The foetal part is derived from allantoic mesoderm and the maternal from vessels and decidua.1 Towards the end of the first trimester in normal pregnancies, there is partial regression of chorionic villi,12 and the remainder of the gestation sac is made up of the chorion laeve or smooth chorion. The chorion laeve and the British Medical Bulletin 2012
Page 3 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Fig. 1 Schematic structure of human placenta showing both the foetal component (amnion and chorion) and the maternal one (decidua). The chorionic villi emerge from the chorion and allow exchanges from maternal to foetal blood (modified from Sood et al. 5)
C. Pipino et al.
Placental stem cells The placenta has gained more interest recently because it may potentially represent an important source of a variety of stem cells, including trophoblastic, haematopoietic, epithelial and mesenchymal stem cells (MSCs).18 – 20 Although it remains uncertain whether pluripotent stem cells persist during development beyond the first few weeks,21 the placenta has been demonstrated to contain various stem cell niches that may reflect the different embryonic origin of its components. Of relevance, the placenta has been reported to contain a population of broadly multipotent stem cells that also show expression of embryonic stem (ES) cells markers such as c-KIT, OCT4, SOX2, SSEA3, SSEA4, TRA-1-60 and TRA-1-81.22,23 These cells have a mesodermal phenotype, but demonstrate a broad differentiation potential that is not limited to mesenchymal lineages, but extends also to hepatocytes, vascular endothelial, pancreatic and neuronal differentiation.22,23 Mesodermal cells may also be responsible, in vivo, for the immunomodulatory function of the placenta. They are phenotypically similar to those present in adult bone marrow, although they are easy to distinguish from the latter using gene and protein profiling and may have greater potential to respond to injuries. For example, renin and flt-1 are expressed uniquely in placental MSCs.24 Other cell types also populate the placenta and may be relevant for therapy, including for example, mature and immature haematopoietic progenitors giving rise to erythroid and myeloid lineages25 (Table 1). Page 4 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
amnion make up the amniotic membranes (AMs). The differences among various layers are also revealed by gene expression analysis and may vary among individuals and be associated with specific placenta diseases.5 The placenta is, however, also a filter and its role may change during pregnancy. Foetal-derived cells do in fact migrate to the mother through the placenta during pregnancy and can engraft and persist in maternal organs.13 CD34þ or CD34þCD38þ cells, of foetal origin, were found in maternal circulation 27 years after a previous pregnancy.14 Those progenitors could indeed have regenerative properties and benefit the mother in case of organ and/or tissue damage.15 Conversely, because such foetal cells represent ‘foreign’ tissue, they may provoke an immune response with resultant autoimmune disease.13,16,17 Additional studies are required to understand the reasons of the persistence of foetal cells only in the organs of some women affected with autoimmune disease and also to understand how these cells are related to the disease process.17
Placenta as a reservoir of stem cells
Table 1 Types of stem cells that populate the placenta. The differentiation potential and the main expressed markers are shown. Differentiation potential
Markers
Isolation protocol
References
Haematopoietic
Haematopoietic
Parolini et al. 18
Gekas et al. 127; Ottersbach & Dzierzak124
AE
Mesenchymal, haematopoietic, hepatic, cardiac, pancreatic and neural cells
Miki et al.26; Murphy et al. 33; Pratama et al. 35
Parolini et al. 18; Miki et al. 26; Pratama et al. 35
Chorionic mesenchymal
Adipogenic, chondrogenic, osteogenic, skeletal myogenic and neurogenic
CD34, c-Kit, Sca-1, Gata-2, Gata-3 and Runx-1 OCT-4, Nanog, SOX-2, TRA-1-60, TRA-1-81, EpCAM, E-cadherin, CD49d, CD49f, CK7 CD105, CD90, CD73, CD44, CD29, CD13, CD166, CD49e, CD10, HLA-ABC
Parolini et al. 18; Portmann-lanz et al.69; Soncini et al. 70
AM mesenchymal
Adipose, chondrogenic, osteogenic, skeletal myogenic, angiogenic, neurogenic, pancreatic and myogenic
Pasquinelli et al. 58; Sakuragawa et al. 85; Portmann-lanz et al. 69; Schoeberlein et al. 109; Hennerbichler et al. 86; Zhang X et al. 87; Soncini et al. 70 Pasquinelli et al. 58; Sakuragawa et al. 85; Portmann-lanz et al. 69; Schoeberlein et al. 2006; Hennerbichler et al. 86; Zhang et al. 87; Soncini et al. 70
CD105, CD90, CD73, CD44, CD29, HLA-A,B,C, CD13, CD10, CD49c, CD49d, CD54, CD166
Hennerbichler & Griensven86; Portmann-lanz et al. 69; Sakuragawa et al. 85
The main stem cell populations are discussed in detail.
Placental AE cells
Human AE cells develop from the epiblast by 8 days post fertilization26 and can be isolated from the amnion after delivery (Fig. 2)27. Because amnion can be obtained from the delivered placenta without invasive procedures and ethical issues, AE cells represent a potential source of cells to be used for both autologous and allogenic applications and their banking has been explored.28 Characterization
AE cells are heterogeneous for the expression of stem cells markers, and some studies have described the presence of subpopulations of stem cells expressing markers of pluripotency such as OCT-4, British Medical Bulletin 2012
Page 5 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Type of stem cells
C. Pipino et al.
NANOG, SOX-2, TRA-1-60 and TRA-1-81.18,26 They can give rise, in vitro, to committed cells belonging to the three germ layers: ectoderm, mesoderm and endoderm. Under appropriate conditions, AE cells form spheroid structures, and, by immunofluorescence and confocal microscopy, the expression of pluripotent markers in the spheroid structure attenuates when the cells are adherent to the culture dish, whereas it is possible that the cells of the middle layer retain their pluripotency because of their support by the outer cells.26 The latter has been suggested as potential application for AE cells that could be used as feeder layers to support the growth, while preserving the pluripotency of ES cells.29 Their function could be mediated by secreted factors and/or membrane proteins in the culture medium that could facilitate the growth and the maintenance of undifferentiated ES cells.29 In this regard, the presence of high levels of several growth factors such as TNF-a, NGF, BDNF, noggin and activin in AE cells has been demonstrated by RT-PCR, immunohistochemistry and western blot.30,31 Although AE cells have been demonstrated to have pluripotent characteristics and can differentiate beyond the three standard mesoderm lineages, unlike ES cells, they have the advantage of not forming teratomas when transplanted into immunodeficient mice.26,32 Finally, they do not require feeder layers to be maintained in culture26 and can be Page 6 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Fig. 2 Schematic representation of foetal membrane structure at term showing amnion and chorion layers and the extracellular matrix composition (modified from Parry and Strauss27).
Placenta as a reservoir of stem cells
Applications
AE cells properties have been recognized for many years and have been used in skin transplantation and ocular diseases such as corneal transplantation, particularly as a scaffold to promote epithelialization.18,36,37 It is also possible to create an artificial amnion using human AE cells on a mechanically enhanced collagen scaffold containing encapsulated human amniotic stromal fibroblasts. AE cells have also been shown to promote healing and regeneration in animal models of disease.38 When transplanted in both mouse and sheep models of lung injury, AE cells improved lung function and reduced pulmonary fibrosis.39 – 42 Importantly, not only the membrane, but also the AE cells, generated a minimal immunological response because they British Medical Bulletin 2012
Page 7 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
isolated and cultured in xenogenic free conditions, which is required for clinical use.33 While various protocols have been described for the isolation of AE cells, refrigeration of the placenta after delivery and proceeding with the isolation of the cells within 3 h is required.34 Briefly, the amnion is separated from the chorion, washed and subjected to enzymatic digestion steps. The resulting cells can be used fresh or cryopreserved and, if desired, can be purified and sorted by fluorescentactivated cell sorting, using an appropriate antibody cocktail composed of anti-EpCAM-PE, anti-CD90-PeCy5 and anti-CD105-APC.33 DMEM supplemented with 10% of foetal bovine serum and 10 ng/ml epidermal growth factor is most commonly used. In this setting, the cells attach easily to the culture dish and display a typical cuboidal epithelial shape.26 In one detailed protocol for isolation of AE cells from human term placenta, Murphy and colleagues33 use EpiLife growth medium, an animal free culture medium for AE cells expansion that could allow the therapeutic use of the cells. They also described a step by step method for freezing and thawing the cells, again using animal free products, required for cell banking. A density separation method can also be used to enrich the SSEA-4 cell population.34 Recent evidence suggests that AE cells cultured in serum-free medium show differences at passage 5 in the immunosuppressive properties and in the secretion of immunomodulatory factors, when compared with the cells at passage 0.35 In addition, the epithelial markers EpCAM, E-cadherin, CK7, CD49f are down regulated at passage 4– 5 and some mesenchymal markers, such as CD44, CD146, CD105, are increased. After passage 5 in a serum-free medium, the AE cells lose their ability to differentiate into chondrocytes, hepatocytes and pancreatic cells, but retain their ability to differentiate into osteocytes and lung cells.35 These data suggest that AE cells at different passages could be used for a range of therapeutic applications and could be cultured in a serum-free medium until passage 5 without losing their epithelial properties.
C. Pipino et al.
express low levels of MHC antigens (class I and II), representing a further advantage for a possible allogenic application.18,39 Differentiation
Placental MSCs
Human MSCs or stromal53 cells were firstly described by Friedenstein in the bone marrow in 1968.54 These cells were subsequently isolated from many other tissues, including the lung, foetal liver, foetal blood, adipose tissue, umbilical cord blood, muscle, dental and placenta.55 – 57 MSCs have a high capacity of self-renewal in culture and their plasticity may vary according to their origin.58 These characteristics have Page 8 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Therefore, under certain conditions, these cells can be differentiated into a range of tissue such as hepatic, cardiac, pancreatic and neural cells.26 Specifically, AE cells in particular culture conditions express a range of neural markers,18,43 are able to produce catecholamines in vitro and their transplantation in a rat model of Parkinson’s disease leads to the production of dopamine in vivo.44 Along the same lines, human AE cells, when transplanted in animal models of spinal cord injury, lead to beneficial results, without inflammation and rejection.18,45 AE cells, transplanted in monkeys that had a transection of their spinal cord, had a reparative and regenerative effects and prevented the death of axotomized neurons, which became evident after 60 days from injection.45 Furthermore, in a similar rat model, AE cells release neurotrophic factors and improve hind limb function 8 weeks post transplantation.46,47 AE cells were shown also to repair damaged cholinergic neurons, as they express choline acetyltransferase and acetylcholine, detected by HPLC, RT-PCR and western blot.48 When transplanted into the brain of rats with cerebral artery occlusion, human AE cells colonize the ischaemic site and reduce the infarct area.49 Human or rat AE cells have also been used in the model of liver injury because they express hepatic specific genes such as albumin and a-fetoprotein. Human AE cells transfected with the Lac Z gene, transplanted into the liver of severe combined immunodeficiency (SCID) mice treated with retrorsine, were identified in the liver50 and were able to differentiate into cells expressing hepatic specific genes and showing functional enzymatic activity.51 Finally, AE cells under in vitro nicotinamide stimulation can differentiate in pancreatic cells and can normalize the blood glucose level after transplantation in a model of streptozotocin (STZ)-induced diabetic rat.52 For these reasons listed above, AE cells represent a promising source to be used for clinical application.
Placenta as a reservoir of stem cells
British Medical Bulletin 2012
Page 9 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
made them attractive in the field of regenerative medicine and tissue engineering,59 particularly if they are derived from foetal or neonatal tissue such as the placenta.60 – 64 Placental MSCs, first described in 2004, are plastic-adherent cells, share a similar immunophenotype to that of bone marrow MSCs and have lineage differentiation potential.65 They express stromal markers such as CD166, CD105, CD73, CD90 and others, whereas they are negative for the haematopoietic markers CD14, CD34 and CD45.66,67 Additionally, according to some of the studies, they express pluripotency markers such as SSEA3, SSEA4, OCT4, NANOG, TRA-1-60 and TRA-1-81.19,68 The amnion membrane contains two cell types: the AE cells, discussed above, that are derived from the epiblast and the amniotic MSCs (AMSCs) derived from the hypoblast. The chorion that consists primarily of trophoblast derived from the outer layer of the blastocyst (trophectoderm), also contains chorionic MSCs (CMSCs).9 MSCs have been successfully isolated from first-, second- and third-trimester placental compartments, including amnion, chorion, decidua parietalis and decidua basalis,65,69 – 71 and during ongoing pregnancy using minimally invasive techniques such as chorionic villus sampling (CVS), but represent ,1% of cells present.72,73 MSCs from amnion,18,28,74,75 chorion69,70 and chorionic villi24,66,76 have been described as having a more limited life span than the MSCs population obtained from the maternal part of the extraembryonic membranes or decidua.69,70,77 First-trimester placental stem cells generally grow faster than those found in the third trimester, and the majority of term placenta-derived stem cells are found at the quiescent G0/G1 phase of the cell cycle.69 Such cells derived from the foetus and its annexes display a number of ontological translationally advantageous properties when compared with their adult MSCs counterparts: they have greater expansion capacity with a considerably faster doubling time than adult MSCs and yet do not form teratomas, characteristic of ES cells or induced pluripotent stem cells56,78 – 80 (Table 2). In this context, it is should be emphasized that the placental tissue can be foetal (amnion and chorion) or maternal (decidua) in origin, requiring the type of tissue to be individually characterized with respect to MSCs function. We have focused our attention to the foetal stem cells derived from the chorion (trophectoderm) and the amnion (epiblast) embryo.81 Amniotic and CMSCs share common characteristics, such as plastic adherence and, despite limited proliferation capacity, show in vitro differentiation towards osteogenic, adipogenic, chondrogenic, skeletal myogenic lineages (mesoderm) and neurogenic lineage (ectoderm). AMSCs may also differentiate towards angiogenic, cardiomyogenic (mesoderm) and pancreatic (endoderm) lineages, while some reports show also in vivo multiorgan engraftment capacity.65,69,70,73,82 – 84
C. Pipino et al.
Table 2 Summary of animal model diseases treated with placenta MSCs of different origins. MSCs
Origin
Animal model
Disease treated
Outcome
References
AMSC
Human & Rat
Rat
Normal and infarcted cardiac tissue
Ameliorate ventricular function, capillary density and scar tissue
AMSC
Human & Mouse Human
Mouse
Bleomycin-induced lung injury
Reduction in severity of lung fibrosis
Fujimoto et al. 103; Ventura et al. 102; Zhao et al. 98 Cargnoni et al. 105
Nude rat
Cartilage defects
Rat
IBD
Differentiation into chondrocytes and deposition of collagen type II Useful for treating IBD
AMSC
AMSC chorionic plate and villous-chorion derived cells
Human
Mouse
Duchenne muscular dystrophy
Placental MSCs
Human
Rat
Ischaemic stroke
Hypoxia-ischaemia and inflammation
Placental MSCs from chorionic villi of term placenta
Human
Mouse
Diabetes mellitus
Angiogenic potential: may be beneficial in inducing re-epithelialization; to correct balance between inflammatory cell activation/ suppression; to prevent further damage Expression of muscle-specific genes during differentiations in vitro Expression of human dystrophin and laminin in vivo Stimulation and migration of stem cells and progenitor cells in the host Survival of the graft after 4 weeks Possible autologous cell graft Reduction of hyperglycemia, restoration of normoglycemia, increase in body weight, indicating sign of diabetes reversal (undifferentiated cells and newly formed ILCs) No teratoma in vivo after xenotransplantations
Ishikane et al. 113
Kawamichi et al. 83
Yarygin et al. 107; Yu et al. 108 Schoeberlein et al. 109
Kadam et al. 110
Continued
Page 10 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
AMSC
Wei et al. 84
Placenta as a reservoir of stem cells
Table 2 Continued MSCs
Origin
Human Placenta-derived mesenchymal- like stromal cells (PLX)
Human
Placental chorionic villi
Human
Disease treated
Outcome
Mouse
Acute chronic ischaemia
Improve blood flow and Prather capillary density et al. 115
Nude rat
Cartilage defects-articular osteochondral defects Engineered heart valve
Deciduas and chorionic villi-stromal cells
Human
Rat
Ischaemic stroke
Foetal membrane
Rat
Rat
Hindlimb ischaemia
References
Reduced oxidative stress and endothelial damage with an increase in limb function Hyaline cartilage Zhang et al. 87 appearance
Postnatal applications
Repairing congenital cardiac malformations Increase in functional recovery in treated animals Reduced infarct ratio and improvement in astroglial reactivity (cell from deciduas) Improvement in blood perfusion Higher capillary/muscle fibre ratio Paracrine mechanism
Schmidt et al. 104; Weber, Zeisberger, & Hoerstrup, 2011
Kranz et al. 106
Ishikane et al. 113
Isolating protocols
AMSCs and CMSCs have been isolated using various protocols.58,69,70,85 – 87 To minimize maternal cell contamination, AMSCs are isolated by dissection of a term amnion from the deflected part of the foetal membranes.18 The tissue is then minced and trypsinized to remove the epithelial cells and digested with collagenase, collagenase and DNase18 or dispase.88 AMSCs express mesenchymal stem cell markers such as CD166, CD105, CD90, CD73, CD49e, CD44, CD29, CD13 and haematopoietic stem cell markers such as CD14, CD34, CD45.63,69,85,86 To isolate CMSCs, mesodermal tissue is digested with collagenase or collagenase and DNase, after a mechanical and enzymatic removal of the trophoblastic layer with dispase.69,70 Alternatively, MSCs may also be isolated from chorionic foetal villi through explants British Medical Bulletin 2012
Page 11 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Chorionic villi
Animal model
C. Pipino et al.
Immunology of placental-derived MSCs
Both AMSCs and CMSCs express low levels of HLA-ABC and no HLA-DR, indicating their immunoprivileged status, and, therefore, it is not a surprise that placenta MSCs could successfully engraft in neonatal swine, sheep and rats, without a xenogenic response.94 They also have immunomodulatory properties that may involve direct cell-to-cell contact or secretion of soluble factor.95,96 They block maturation of monocytes into dendritic cells, preventing the expression of the dendritic cells marker CD1a and reducing the expression of CD80, CD83 and HLA-DR.95,96 Despite this in vitro finding, in vivo multiple distinct cell populations act together in the immune reaction. Isolation and Page 12 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
culture at term. Isolated cells have characteristics that resemble haematopoietic progenitors and some tumours like Ewing’s sarcoma58 and they may show expression of markers of multipotency such as CD105, CD90, CD73, CD44, CD29, HLA-A,B,C, CD13, CD166, CD49e and CD10.69,70 MSCs can be successfully isolated from chorionic villi from the 9th to 12th week of gestation during routine CVS. Chorionic villus cytotrophoblast contains a population of cells that express markers typical of multipotent stem cells both in vitro as in vivo, but do not expresses typical MSCs surface antigens. A subset of cells expressing the pluripotency markers OCT4, NANOG, SOX2, c-MYC, KLF4, SSEA3, SSEA4, TRA-1-60 and TRA-1-81 are able to differentiate not only into lineages of the three germ layers, but also into cells with some characteristics of hepatocytes in vitro with the ability to store glycogen.75,89 – 91 When cultured in permissive conditions, they can also form embryoid bodies containing cells of the three germ layers (data unpublished). Both expanded AMSCs and CMSCs, similarly to adult bone marrow MSCs, are negative for CD34, CD45 (haematopoietic markers) and CD14 (monocytic marker).65,69,70,82 The expression of markers of pluripotency is, however, more controversial because markers such as SSEA-3 and SSEA-4 have been reported and it is also the experience of the authors (data unpublished), but it has not been detected by others.92 Similarly, AMSCs from term placenta express RNA for OCT4, SOX2, NANOG, CFC1, DPPA3, ROM1 and PAX632 and mRNA for Oct-4, NANOG, and REX-1 has been reported in CMSCs.93 Human AMSCs and CMSCs adhere and proliferate in culture and can be kept until passages 5 –10.63 CD49d, EpCAM, E-cadherin, CD49f, CK7 are expressed by epithelial cells that can be used to distinguish them from AMSCs and CMSCs.28,35 Transmission electron microscopy of AMSCs showed features of both mesenchymal and epithelial differentiation.58 This hybrid phenotype is interpreted as a sign of multipotentiality and was not found in CMSCs that show simpler cytoplasmic organization than AMSCs.58
Placenta as a reservoir of stem cells
Preclinical studies in animal models
Progress in understanding the biology and the properties of placentaderived MSCs has encouraged researchers to explore their potential effects in animal models of various diseases, in the hope of developing future clinical applications.18,42 Muscle
Studies on human and native rat AMSCs showed similar findings: cells were able not only to express cardiac specific genes under certain culture conditions, but also to integrate into normal and infarcted rat cardiac tissue, where they differentiated into cardiomyocyte-like cells.98 This improved ventricular function, capillary density and scar tissue.102,103 Stem cells derived from prenatal chorionic villi have also been successfully engineered into a living autologous heart valve that could have postnatal applications for repairing congenital cardiac malformations.104 Recently, human AMSCs, chorionic-plate-derived cells and villous chorion-derived cells have been used to treat a Duchenne muscular dystrophy murine model.83 These cells were able to express muscle-specific genes during differentiation in vitro (myotubes). When human AMSCs were transplanted into a mouse model of Duchenne muscular dystrophy, myofibres expressing human dystrophin and laminin were found in the muscle tissue.83 Lung
In a mouse model of bleomycin-induced lung injury, transplantation of a mixed population of AMSCs, CMSCs and AE cells from either human or mouse was associated with a reduction in severity of lung fibrosis. The cell source (allogenic or xenogenic) and the administration route (systemic, intravenous or intraperitoneal; local, intratracheal) did British Medical Bulletin 2012
Page 13 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
expansion protocols for placental cells might also influence their immunomodulatory properties: for example, expansion of AMSCs without previous removal of the HLA-DRþ subpopulation may result in partial abrogation of the immunosuppressive effects of these cells.82 However, no evidence of immunological rejection of human-placenta derived cells were reported in several preclinical studies, after xenogenic transplantation into immunocompetent animals such as rats, swine and bonnet monkeys.47,49,94,97,98 Furthermore, co-transplantation of cord blood and placental MSCs in non-obese diabetic/severe combined immune-deficient mice has been shown to result in enhanced cord blood cells engraftment and improve homing of CD34þ cells.99,100 Human placenta-derived MSCs undergoing in utero transplantation into foetal rats demonstrated migration to various organs and differentiation similar to that of human bone marrow-derived MSCs.101
C. Pipino et al.
not affect the outcome.105 A decrease in neutrophil infiltration was observed, despite only sparse donor cells in the host lungs: these effects were probably not only related to engraftment and differentiation of transplanted cells, but more to paracrine actions of soluble molecules secreted by mesenchymal cells. Stroke
Diabetes mellitus
Human placenta-derived MSCs isolated from chorionic villi of full term placenta110 expressed transcripts of insulin, glucagon, somatostatin, Ngn3 and Isl1. Transplantation of such undifferentiated MSCs under the renal capsule of STZ-induced diabetic mice resulted in a reduction of hyperglycemia and restoration of normoglycemia and increased body weight, all indicating signs of diabetes reversal. Similar results were reported after transplantation of biocompatible macrocapsules (to avoid immune rejection) packed with human MSCs differentiated into islet-like cell clusters (ILCs) in diabetic mice. Transplantation of undifferentiated human MSCs, or newly formed ILCs, into STZinduced diabetic mice also appeared safe and did not cause teratoma formation.111 This study indicates that human placental MSCs are a promising source for insulin-producing cells. Intestinal disease
Chronic relapsing and remitting inflammation of the intestinal tract are the characteristic features of ulcerative colitis and Crohn’s disease, collectively termed inflammatory bowel disease (IBD). Human AMSCs possess trophic effects on intestinal epithelial cells, stimulating Page 14 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
CMSCs, transplanted intravenously in a rat model of experimental ischaemic stroke, significantly improved functional recovery when compared with non-injected control animals. Those treated with MSCs demonstrated a reduced infarct ratio and an improvement in astroglial reactivity.106 In a similar model, intravenous transplantation of placental MSCs stimulated the proliferation of stem cells and progenitor cells in the host and migration in the site of injury.107 It has been suggested that a paracrine action of the transplanted cells, through modulation of peripheral and local immunoreactions, and/or a secretion of soluble factor by transplanted cells with anti-apoptotic, neurogenic and angiogenic effects may be important.108 Similarly, intracerebral MSCs injection into neonatal rat brain (2.56 days old) showed survival of the graft cells at 4 weeks after their injection into the left lateral ventricle.109 This is probably related to the fact that hypoxia –ischaemia and inflammation during preterm intrauterine and extrauterine life frequently coexist.
Placenta as a reservoir of stem cells
architectural organization and polarized differentiation,112 therefore, suggesting their potential use for treating IBD. Their angiogenic potential may aid in improving perfusion and healing, whereas the paracrine activity of these cells may be beneficial in inducing ulcer re-epithelialization, restoring a correct balance between inflammatory cell activation/suppression in the intestinal mucosa and preventing further damage. Vascular disease
Tissue engineering
Placenta-derived MSCs are able to differentiate in vitro towards a chondrogenic lineage, and use of these cells has been investigated for repair of cartilage defects in vivo. These defects have been treated87 using human CMSCs, pre-embedded in a collagen sponge and cultured in a chondrogenic medium for 2 weeks, inserted into the articular osteochondral defect of nude rats. After 6 weeks, the original defects were covered, and the tissue showed a hyaline cartilage appearance. The edge of the reparative tissue, however, showed hypertrophic cartilage formation, suggesting that it would be necessary to set up appropriated transplantation conditions to avoid side effects. Human AMSCs, when implanted with collagen scaffold into the cartilage defects of nude rats, also differentiated into chondrocytes, with deposition of collagen type II.84 British Medical Bulletin 2012
Page 15 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
Atherosclerosis-related peripheral vascular disease can cause either acute or chronic ischaemia that in advanced stage is represented by critical limb ischaemia. Allogenic injection of MSCs isolated from the foetal membranes of pregnant rats demonstrated a therapeutic effect in a rat model of hind limb ischaemia. Three weeks following injection, rats showed an improvement in perfusion and a higher capillary/muscle fibre ratio of ischaemic muscle, but there was no evidence of endothelial differentiation or cellular fusion of transplanted cells with the host ones. This beneficial effect could, therefore, be explained by a paracrine mechanism whereby transplanted MSCs might act as a source of cytokines, to exert angiogenic effects, mobilize host stem/progenitor cells and accelerate angiogenesis.113,114 The possibility to treat acute and chronic ischaemia using human placenta-derived MSCs has also been investigated [ placental expanded peripheral artery disease (PLX-PAD)]. Injection of PLX-PAD into a mouse hind limb ischaemia model, expanded in a 3D bioreactor, significantly improved blood flow, increased capillary density, reduced oxidative stress and endothelial damages with a slight increase in limb function, probably due to a paracrine mechanism.115
C. Pipino et al.
Fragments of entire AM
Placental haematopoietic stem cells
Haematopoietic stem cells (HSCs), which are found in the bone marrow during postnatal life, are able to give rise to all blood cell lineages during the blood cell production of an individual’s lifetime. Before engrafting in the bone marrow, HSCs are generated from the yolk sac (YS) and later from the dorsal aorta in the developing aortagonad mesonephros (AGM) region during foetal development.119 Subsequently, they proliferate and colonize first the foetal liver and spleen, then the thymus for expansion and differentiation prior to migration in the bone marrow, which is where they are confined postnatally.120,121 Haematopoietic activity was firstly observed in the YS in the 1970s, in mouse embryo experiments.122 This is the site where the production of erythroid cells and the emergence of macrophage and megakaryocyte progenitors begin. HSCs from the YS expand later in the bloodstream and foetal liver, to give rise to the definitive cells.123 Initially, the YS was considered the only site of early haematopoietic activity. Subsequently, another source of HSCs was found in mice, in the AGM region at embryonic day E10.5, a day before their appearance in the YS.121,124 HSCs are also found, later in gestation, in the umbilical cord blood125 and in both amniotic fluid and membranes that contain c-kitþ Lin-cells that display multilineage haematopoietic ability.126 Experiments carried out in the mouse embryo suggest the presence of HSCs in the placenta,127 and, indeed the placenta may represent a large reservoir of HSCs. Formation of haematopoietic colonies Page 16 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
AM has anti-inflammatory and anti-bacterial properties, wound protection, anti-fibroblastic and epithelialization effects providing absent or low immunogenicity. These features have led to the use of AM as a dressing to promote healing of burned skin or leg ulcers and to treat ophthalmic disorders.116 The value of using fragments of the entire AM for the treatment of biliary fibrosis in a rat model of bile duct ligation has also been reported, with treated cases exhibiting reduced severity of liver fibrosis and slowed progression of damage when used as a patch onto the surface of the model. These effects might not be due to a replacement mechanism because no human cells were detected in the animals treated, but rather to a release of soluble factors by cells of the AM patch with paracrine effects on host tissue.117 The possible utility of fragments of human AM as a bile duct substitute has also been investigated in a dog model of bile duct damage, and in the absence of vascularized support, amniotic fragments were associated with improved outcome.118
Placenta as a reservoir of stem cells
British Medical Bulletin 2012
Page 17 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
in the spleen of irradiated mice occurs after transplantation of mouse placental tissue,127 and other studies in mice confirmed that the placenta is a source of hematopoietic precursors, beginning around E9.121 HSC numbers increase dramatically up to E12.5, and few HSCs are found in the placenta after E15.5, when these stem cells begin to migrate in the foetal liver.128 Recently, it was reported in the mouse that the two precursor tissues of the placenta, the chorion and the allantois, possess haematopoietic potential.129 Grafting experiments in avian embryos demonstrate that cells derived from the avian allantois contribute to adult haematopoietic activity.130 After the discovery of HSCs in the placenta, many studies have been performed to better understand, if these cells are functionally and phenotypically similar to the other HSCs present in other sites.120 Placental HSCs express many of the same markers as foetal liver and adult bone marrow-derived HSCs, including CD34 and c-KIT.127 Moreover, mouse placenta HSCs express Sca-1 that is also expressed in adult bone marrow HSCs. Sca-1 HSCs are localized within the vasculature of the placental labyrinth, and the umbilical vessels and mouse placenta also expresses important haematopoietic transcription factors such as Gata-2, Gata-3 and Runx-1.124 The localization of haematopoietic factors in the placental labyrinth vasculature suggests that this site might be a niche for HSCs. Probably, the growth factors and hormones from the vascularized placental niche contribute to the HSCs migration from the AGM region to the foetal liver, through the umbilical vessels.124 In humans, blood production starts at Day 16 of gestation in the YS and at Day 19, the intra-embryonic splanchnopleura becomes haematopoietic. The development of the splanchnopleura/AGM region begins at Day 27.131 Primitive erythroblasts expressing GATA-4 and c-KIT, but not CD34 and CD45, are found in the human placental vessels around Day 24.60 Initially, progenitors are found from Week 6 in CD34þ and CD342 fractions, but by Week 8 all progenitors are CD34þ.25 Haematopoietic activity in the human placenta is similar to the one observed in the murine placenta, but in contrast to the mouse, human HSCs can still be found in the placenta at term suggesting that this tissue is an important source of potential medical use.60 Chorionic villi are analogous to the labyrinth of the mouse placenta, and together with the chorionic plate have haematopoietic potential.132 It has been shown that the human placenta contains most of the haematopoietic progenitors, and human-SCID repopulating cells (hu-SRCs) are also described.132 Haematopoietic engraftment in SCID mice, indeed, is an assay for detection of human HSCs.133 In this study, cells from either human placenta vessels or tissues were injected into SCID mice. Cells derived from the placental vessels successfully engrafted to the SCID recipient, whereas tissue cells did not, demonstrating that placental
C. Pipino et al.
hu-SRCs accumulate in the placental labyrinth, probably attached to the vascular endothelium.132 In addition, MSCs derived from human placenta may act as pericyte-like cells involved in supporting human haematopoiesis.132 These findings indicate that although the placenta is normally discarded following delivery, it participates in HSC development and could be of major importance in haematological clinical applications and regenerative medicine.120
Advantages and clinical applications of placental stem cells
Page 18 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
In the last few years, the placenta has become a very attractive source for the isolation of stem cells. Chorionic villous-derived stem cells can be obtained in early gestation during prenatal diagnosis and from term placenta following delivery. Stem cells derived from the placenta, together with amniotic fluid stem cells and other foetal cells, therefore, represent an easy to obtain alternative source of stem cells23,134 that offer advantages in terms of proliferation and plasticity.135,136 Ethical and safety concerns still limit the clinical use of ES cells. Adult stem cells are difficult to expand, have a limited plasticity, their number is relatively low and even decreases with age137 and they require invasive procedures for their collection. In addition, human placenta MSCs have higher expansion and engraftment properties than bone marrow MSCs.138,139 The placenta may represent a valid alternative with intermediate characteristics59 with expression of markers of pluripotency, but the inability to form teratomas in permissive conditions.68,140 The placenta usually can be disposed off, whereas the umbilical cord blood may be stored for many years already because of its haematopoietic potential. The placenta has the advantage of containing haematopoietic and MSCs, the latter not being consistently present in amniotic fluid. While the placenta has been traditionally regarded as important for maintaining and regulating foeto-maternal exchange, it has become apparent that it may also act as a reservoir of progenitors, although the role of these cells during gestation remains incompletely understood. These cells could be of major importance postnatally when banked, both for autologous and allogenic applications. The latter may be particularly relevant because placental MSCs have more marked immunosuppressive properties than bone marrow MSCs137 and are particularly efficacious in not inducing allogenic lymphocytes proliferation and suppressing in vivo inflammatory responses.141 It is clear that the range of potential clinical applications of placentaderived stem cells is continuously widening and evolving. Furthermore, the general perception is that many of the beneficial effects of these cells are likely be due to secretion of bioactive molecules that act on
Placenta as a reservoir of stem cells
other cells and the microenvironment that they occupy to promote endogenous tissue repair or eliciting other beneficial effects through paracrine actions.116
Conclusion
Funding J.P.D. was beneficient from a fundamental clinical research grant of the Fonds Wetenschappelijk Onderzoek Vlaanderen (1.8.012.07.N.02). P.D.C. was supported by the Great Ormond Street Hospital Charity. P.S. was supported by a UCL/UCLH Comprehensive Biomedical Research Centre Entry Level Fellowship. C.P. was supported by the University G. D’Annunzio Chieti, Italy.
References 1 Rossant J, Cross JC. Placental development: lessons from mouse mutants. Nat Rev Genet 2001;2:538– 48. 2 Regnault TRH, Galan HL, Parker TA et al. Placental development in normal and compromised pregnancies—a review. Placenta 2002;23(Suppl A):S119– 29. 3 Gude NM, Roberts CT, Kalionis B et al. Growth and function of the normal human placenta. Thrombosis Res 2004;114:397–407. 4 Maltepe E, Bakardjiev AI, Fisher SJ. Review series the placenta: transcriptional, epigenetic, and physiological integration during development. Comp Gen Pharmacol 2010; 120:1016– 25. 5 Sood R, Zehnder JL, Druzin ML et al. Gene expression patterns in human placenta. Proc Natl Acad Sci USA 2006;103:5478– 83. 6 Sadler TW. Langman’s medical embryology. In: Sun B (ed). Langman’s Medical Embryology. 9th edn. Philadelphia, PA, USA: Lippincott Williams & Wilkins, 2009,385.
British Medical Bulletin 2012
Page 19 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
The human placenta potentially offers a large number of stem cells that are relatively easy to isolate, expand and differentiate into different cell types.23,68,140 Placenta-derived cells, aside from their relative ease of isolation and the lack of ethical concerns for their procurement, are viable candidates for a range of cell-based therapeutic approaches. They successfully engraft and survive in various organs and tissue. Their absent or low immunogenicity and immunomodulatory properties suggest their utility in an allogenic transplantation setting, and their multilineage differentiation capacity in vitro and ability to successfully engraft and survive in various organs and tissue94,116 suggest their utility in tissue regeneration approaches. However, additional studies are required to understand in more detail the cellular and molecular mechanisms involved in the development and activity of these placental stem cells and to optimize their therapeutic potential.
C. Pipino et al.
Page 20 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
7 Parolini O, Soncini M. Human placenta: a source of progenitor/Stem Cells? J Reprod Med Endocrinol 2006;3:117– 26. 8 Pera MF, Reubinoff B, Trounson A. Human embryonic stem cells. J Cell Sci 2000;113(Pt 1):5–10. 9 Abdulrazzak H, Moschidou D, Jones G et al. Biological characteristics of stem cells from foetal, cord blood and extraembryonic tissues. J R Soc Interface 2010;7(Suppl 6): S689– 706. 10 Castellucci M, Kosanke G, Verdenelli F et al. Villous sprouting: fundamental mechanisms of human placental development. Hum Reprod Update 2000;6:485–94. 11 Cross J. Genes, development and evolution of the placenta. Placenta 2003;24:123– 30. 12 Ilancheran S, Moodley Y, Manuelpillai U. Human fetal membranes: a source of stem cells for tissue regeneration and repair? Placenta 2009;30:2– 10. 13 Johnson KL, Bianchi DW. Fetal cells in maternal tissue following pregnancy: what are the consequences? Hum Reprod Update 2004;10:497–502. 14 Bianchi DW, Zickwolf GK, Weil GJ et al. Male fetal progenitor cells persist in maternal blood for as long as 27 years postpartum. Proc Natl Acad Sci USA 1996;93:705– 8. 15 Bou-Gharios G, Amin F, Hill P et al. Microchimeric fetal cells are recruited to maternal kidney following injury and activate collagen type I transcription. Cells Tissues Organs 2011;193:379– 92. 16 Bianchi DW. Fetal cells in the mother: from genetic diagnosis to diseases associated with fetal cell microchimerism. Euro J Obstet Gynecol Reprod Biol 2000;92:103– 8. 17 Khosrotehrani K, Johnson KL, Lau J et al. The influence of fetal loss on the presence of fetal cell microchimerism: a systematic review. Arthritis Rheum 2003;48:3237–41. 18 Parolini O, Alviano F, Bagnara GP et al. Concise review: isolation and characterization of cells from human term placenta: outcome of the first international Workshop on Placenta Derived Stem Cells. Stem Cells 2008;26:300– 11. 19 Yen BL, Huang H-I, Chien C-C et al. Isolation of multipotent cells from human term placenta. Stem Cells 2005;3–9. 20 Tsagias N, Koliakos I, Lappa M et al. Placenta perfusion has hematopoietic and mesenchymal progenitor stem cell potential. Transfusion 2011;51:976–85. 21 Shin D-M, Liu R, Klich I et al. Molecular signature of adult bone marrow-purified very small embryonic-like stem cells supports their developmental epiblast/germ line origin. Leukemia 2010;24:1450–61. 22 Miki T, Strom SC. Amnion-derived pluripotent/multipotent stem cells. Stem Cell Rev 2006;2:133–42. 23 Delo DM, De Coppi P, Bartsch G et al. Amniotic fluid and placental stem cells. Methods Enzymol 2006;419:426–38. 24 Fukuchi Y, Nakajima H, Sugiyama D et al. Human placental derived cells have mesenchymal stem/progenitor cell potential. Cells 2004;649–58. 25 Ba´rcena A, Muench MO, Kapidzic M et al. A new role for the human placenta as a hematopoietic site throughout gestation. Reprod Sci 2009;16:178– 87. 26 Miki T, Lehmann T, Cai H et al. Stem cell characteristics of amniotic epithelial cells. Stem Cells 2005;23:1549–59. 27 Parry S, Strauss JF. Premature rupture of the fetal membranes. N Engl J Med 1998; 338:663–70. 28 Wolbank S, van Griensven M, Grillari-Voglauer R et al. Alternative sources of adult stem cells: human amniotic membrane. Adv Biochem Eng Biotechnol 2010;123:1–27. 29 Miyamoto K, Hayashi K, Suzuki T et al. Human placenta feeder layers support undifferentiated growth of primate embryonic stem cells. Stem Cells 2004;22:433– 40. 30 Uchida S, Inanaga Y, Kobayashi M et al. Neurotrophic function of conditioned medium from human amniotic epithelial cells. J Neurosci Res 2000;62:585– 90. 31 Koyano S, Fukui A, Uchida S et al. Synthesis and release of activin and noggin by cultured human amniotic epithelial cells. Dev Growth Differ 2002;44:103–12. 32 Ilancheran S, Michalska A, Peh G et al. Stem cells derived from human fetal membranes display multilineage differentiation potential. Biol Reprod 2007;77:577–88. 33 Murphy S, Rosli S, Acharya R et al. Amnion epithelial cell isolation and characterization for clinical use. Curr Protoc Stem Cell Biol 2010;13:1E.6.1– 6.25.
Placenta as a reservoir of stem cells
British Medical Bulletin 2012
Page 21 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
34 Miki T, Marongiu F, Dorko K et al. Isolation of amniotic epithelial stem cells. Curr Protoc Stem Cell Biol 2010;12:1E.3.1– 3.10. 35 Pratama G, Vaghjiani V, Tee JY et al. Changes in culture expanded human amniotic epithelial cells: implications for potential therapeutic applications. PLoS One 2011;6:e26136. 36 Dua H, Gomes J, King A et al. The amniotic membrane in ophthalmology1. Surv Ophthalmol 2004;49:51–77. 37 Ishino Y, Sano Y, Nakamura T et al. Amniotic membrane as a carrier for cultivated human corneal endothelial cell transplantation. Invest Ophthalmol Vis Sci 2004;45:800– 6. 38 Mi S, David AL, Chowdhury B et al. Tissue engineering a fetal membrane. Tissue Eng A 2011;18:373– 81. 39 Vosdoganes P, Hodges RJ, Lim R et al. Human amnion epithelial cells as a treatment for inflammation-induced fetal lung injury in sheep. Am J Obstet Gynecol 2011; 205:156.e26–33. 40 Murphy S, Lim R, Dickinson H et al. Human amnion epithelial cells prevent bleomycin-induced lung injury and preserve lung function. Cell Transplant 2011; 20:909– 23. 41 Moodley Y, Ilancheran S, Samuel C et al. Human amnion epithelial cell transplantation abrogates lung fibrosis and augments repair. Am J Respir Crit Care Med 2010;182:643–51. 42 Parolini O, Alviano F, Bergwerf I et al. Toward cell therapy using placenta-derived cells: disease mechanisms, cell biology, preclinical studies, and regulatory aspects at the round table. Stem Cells Dev 2010;19:143– 54. 43 Sakuragawa N, Thangavel R, Mizuguchi M et al. Expression of markers for both neuronal and glial cells in human amniotic epithelial cells. Neurosci Lett 1996;209:9–12. 44 Kakishita K, Elwan MA, Nakao N et al. Human amniotic epithelial cells produce dopamine and survive after implantation into the striatum of a rat model of Parkinson’s disease: a potential source of donor for transplantation therapy. Exp Neurol 2000;165:27– 34. 45 Sankar V. Role of human amniotic epithelial cell transplantation in spinal cord injury repair research. Neuroscience 2003;118:11–7. 46 Wu Z-yuan, Hui G-zhen, Lu Y et al. Transplantation of human amniotic epithelial cells improves hindlimb function in rats with spinal cord injury. Chin Med J 2006;119:2101–7. 47 Meng X-T, Li C, Dong Z-Y et al. Co-transplantation of bFGF-expressing amniotic epithelial cells and neural stem cells promotes functional recovery in spinal cord-injured rats. Cell Biol Int 2008;32:1546– 58. 48 Sakuragawa N, Misawa H, Ohsugi K et al. Evidence for active acetylcholine metabolism in human amniotic epithelial cells: applicable to intracerebral allografting for neurologic disease. Neurosci Lett 1997;232:53– 6. 49 Liu T, Wu J, Huang Q et al. Human amniotic epithelial cells ameliorate behavioral dysfunction and reduce infarct size in the rat middle cerebral artery occlusion model. Shock 2008;29:603– 11. 50 Sakuragawa N, Enosawa S, Ishii T et al. Human amniotic epithelial cells are promising transgene carriers for allogeneic cell transplantation into liver. J Hum Genet 2000;45:171– 6. 51 Marongiu F, Gramignoli R, Dorko K et al. Hepatic differentiation of amniotic epithelial cells. Hepatology 2011;53:1719– 29. 52 Wei JP, Zhang TS, Kawa S et al. Human amnion-isolated cells normalize blood glucose in streptozotocin-induced diabetic mice. Cell Transplant 2003;12:545–52. 53 Dominici M, Le Blanc K, Mueller I et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy 2006;8:315– 7. 54 Afanasyev BV, Elstner EE, Zander AR et al. A. J. Friedenstein, founder of the mesenchymal stem cell concept. Transplantation 2010;1:35–8. 55 Heey O, Paulal U. A population of cells isolated from rat heart capable of differentiating into several mesodermal phenotypes. J Surg Res 1996;62:233–42. 56 Campagnoli C. Identification of mesenchymal stem/progenitor cells in human first-trimester fetal blood, liver, and bone marrow. Blood 2001;98:2396– 402. 57 Bieback K, Kern S, Klu¨ter H et al. Critical parameters for the isolation of mesenchymal stem cells from umbilical cord blood. Stem Cells 2004;22:625– 34.
C. Pipino et al.
Page 22 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
58 Pasquinelli G, Tazzari P, Ricci F et al. Ultrastructural characteristics of human mesenchymal stromal (stem) cells derived from bone marrow and term placenta. Ultrastruct Pathol 2007;31:23–31. 59 Baksh D, Song L, Tuan RS. Adult mesenchymal stem cells: characterization, differentiation, and application in cell and gene therapy. J Cell Mol Med 2004;8:301–16. 60 Dzierzak E, Robin C. Placenta as a source of hematopoietic stem cells. Trends Mol Med 2010;16:361– 7. 61 Amos T, Gordon M. Sources of human hematopoietic stem cells for transplantation—a review. Cell Transplant 1995;4:547– 69. 62 Matikainen T, Laine J. Placenta—an alternative source of stem cells. Toxicol Appl Pharmacol 2005;207(2 Suppl):544–9. 63 Kaviani A. The placenta as a cell source in fetal tissue engineering. J Pediatr Surg 2002;37:995– 9. 64 Gucciardo L, Lories R, Ochsenbein-Ko¨lble N et al. Fetal mesenchymal stem cells: isolation, properties and potential use in perinatology and regenerative medicine. BJOG 2009;116:166– 72. 65 Anker PS In’t, Scherjon SA, Kleijburg-van der Keur C et al. Isolation of mesenchymal stem cells of fetal or maternal origin from human placenta. Stem Cells 2004;22:1338– 45. 66 Igura K, Zhang X, Takahashi K et al. Isolation and characterization of mesenchymal progenitor cells from chorionic villi of human placenta. Cytotherapy 2004;6:543– 53. 67 Sudo K, Kanno M, Miharada K et al. Mesenchymal progenitors able to differentiate into osteogenic, chondrogenic, and/or adipogenic cells in vitro are present in most primary fibroblast-like cell populations. Stem Cells 2007;25:1610–7. 68 Battula VL, Bareiss PM, Treml S et al. Human placenta and bone marrow derived MSC cultured in serum-free, b-FGF-containing medium express cell surface frizzled-9 and SSEA-4 and give rise to multilineage differentiation. Differentiation 2007;75:279–91. 69 Portmann-lanz CB, Schoeberlein A, Huber A et al. Placental mesenchymal stem cells as potential autologous graft for pre- and perinatal neuroregeneration. Am J Obstet Gynecol 2006;664–73. 70 Soncini M, Vertua E, Gibelli L et al. Isolation and characterization of mesenchymal cells from human fetal membranes. J Tissue Eng Regen Med 2007;1:296–305. 71 Poloni A, Rosini V, Mondini E et al. Characterization and expansion of mesenchymal progenitor cells from first-trimester chorionic villi of human placenta. Cytotherapy 2008;10:690– 7. 72 Zhang Y, Li C, Jiang X. Human placenta-derived mesenchymal progenitor cells support culture expansion of long-term culture-initiating cells from cord blood CD34 þ cells. Exp Hematol 2004;32:657–64. 73 Alviano F, Fossati V, Marchionni C et al. Term amniotic membrane is a high throughput source for multipotent mesenchymal stem cells with the ability to differentiate into endothelial cells in vitro. BMC Dev Biol 2007;7:11. 74 Marcus AJ, Coyne TM, Rauch J et al. Isolation, characterization, and differentiation of stem cells derived from the rat amniotic membrane. Differentiation 2008;76:130– 44. 75 Tamagawa T, Oi S, Ishiwata I et al. Differentiation of mesenchymal cells derived from human amniotic membranes into hepatocyte-like cells in vitro. Hum Cell 2007;20:77– 84. 76 Chang C-M, Kao C-L, Chang Y-L et al. Placenta-derived multipotent stem cells induced to differentiate into insulin-positive cells. Biochem Biophys Res Commun 2007; 357:414–20. 77 Okamoto K, Miyoshi S, Toyoda M et al. ‘Working’ cardiomyocytes exhibiting plateau action potentials from human placenta-derived extraembryonic mesodermal cells. Exp Cell Res 2007;313:2550– 62. 78 Sarugaser R, Lickorish D, Baksh D et al. Human umbilical cord perivascular (HUCPV) cells: a source of mesenchymal progenitors. Stem Cells 2005;23:220–9. 79 Fong C, Richards M, Manasi N et al. Comparative growth behaviour and characterization of stem cells from human Wharton’s jelly. Reprod Biomed Online 2007;15:708– 18. 80 Guillot PV, Gotherstrom C, Chan J et al. Human first-trimester fetal MSC express pluripotency markers and grow faster and have longer telomeres than adult MSC. Stem Cells 2007;25:646– 54.
Placenta as a reservoir of stem cells
British Medical Bulletin 2012
Page 23 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
81 Crane JP, Cheung SW. An embryogenic model to explain cytogenetic inconsistencies observed in chorionic villus versus fetal tissue. Prenat Diagn 1988;8:119–29. 82 Wolbank S, Peterbauer A, Fahrner M et al. Dose-dependent immunomodulatory effect of human stem cells from amniotic membrane: a comparison with human mesenchymal stem cells from adipose tissue. Tissue Eng 2007;13:1173–83. 83 Kawamichi Y, Cui C-H, Toyoda M et al. Cells of extraembryonic mesodermal origin confer human dystrophin in the mdx model of Duchenne muscular dystrophy. J Cell Physiol 2010;223:695– 702. 84 Wei JP, Nawata M, Wakitani S et al. Human amniotic mesenchymal cells differentiate into chondrocytes. Cloning Stem Cells 2009;11:19– 26. 85 Sakuragawa N, Kakinuma K, Kikuchi A et al. Human amnion mesenchyme cells express phenotypes of neuroglial progenitor cells. J Neurosci Res 2004;78:208– 14. 86 Hennerbichler S, Griensven MVAN. Dose-dependent immunomodulatory effect of human stem cells mesenchymal stem cells from adipose tissue. Tissue Eng 2007;13:1173–83. 87 Zhang X, Mitsuru A, Igura K et al. Mesenchymal progenitor cells derived from chorionic villi of human placenta for cartilage tissue engineering. Biochemical and Biophys Res Commun 2006;340:944–52. 88 Bacˇenkova´ D, Rosocha J, To´thova´ T et al. Isolation and basic characterization of human term amnion and chorion mesenchymal stromal cells. Cytotherapy 2011;13:1047–56. 89 Trimester F, Villi C, Spitalieri P et al. Identification of multipotent cytotrophoblast cells from human first trimester chorionic villi. Cloning Stem Cells 2009;11:535–56. 90 Chien C-C, Yen BL, Lee F-K et al. In vitro differentiation of human placenta-derived multipotent cells into hepatocyte-like cells. Stem Cells 2006;24:1759– 68. 91 Huang H-I. Isolation of human placenta-derived multipotent cells and in vitro differentiation into hepatocyte-like cells. Curr Protoc Stem Cell Biol 2007;1:1E.1.1–1.9. 92 Miki T, Mitamura K, Ross MA et al. Identification of stem cell marker-positive cells by immunofluorescence in term human amnion. J Reprod Immunol 2007;75:91– 6. 93 Fariha M-MN, Chua K-H, Tan G-C et al. Human chorion-derived stem cells: changes in stem cell properties during serial passage. Cytotherapy 2011;13:582– 93. 94 Bailo M, Soncini M, Vertua E et al. Engraftment potential of human amnion and chorion cells derived from term placenta. Transplantation 2004;78:1439–48. 95 Banas A, Teratani T, Yamamoto Y et al. IFATS collection: in vivo therapeutic potential of human adipose tissue mesenchymal stem cells after transplantation into mice with liver injury. Stem Cells 2008;26:2705–12. 96 Magatti M, De Munari S, Vertua E et al. Human amnion mesenchyme harbors cells with allogeneic T-cell suppression and stimulation capabilities. Stem Cells 2008;26:182– 92. 97 Kong X-Y, Cai Z, Pan L et al. Transplantation of human amniotic cells exerts neuroprotection in MPTP-induced Parkinson disease mice. Brain Res 2008;1205:108– 15. 98 Zhao P, Ise H, Hongo M et al. Human amniotic mesenchymal cells have some characteristics of cardiomyocytes. Transplantation 2005;79:528– 35. 99 Prather WR, Toren A, Meiron M. Placental-derived and expanded mesenchymal stromal cells (PLX-I) to enhance the engraftment of hematopoietic stem cells derived from umbilical cord blood. Expert Opin Biol Ther 2008;8:1241–50. 100 Hiwase SD, Dyson PG, To LB et al. Cotransplantation of placental mesenchymal stromal cells enhances single and double cord blood engraftment in nonobese diabetic/severe combined immune deficient mice. Stem Cells 2009;27:2293–300. 101 Chen C-P, Liu S-H, Huang J-P et al. Engraftment potential of human placenta-derived mesenchymal stem cells after in utero transplantation in rats. Hum Reprod 2009; 24:154–65. 102 Ventura C, Cantoni S, Bianchi F et al. Hyaluronan mixed esters of butyric and retinoic acid drive cardiac and endothelial fate in term placenta human mesenchymal stem cells and enhance cardiac repair in infarcted rat hearts. J Biol Chem 2007;282:14243– 52. 103 Fujimoto KL, Miki T, Liu LJ et al. Naive rat amnion-derived cell transplantation improved left ventricular function and reduced myocardial scar of postinfarcted heart. Cell Transplant 2009;18:477–86. 104 Schmidt D, Mol A, Breymann C et al. Living autologous heart valves engineered from human prenatally harvested progenitors. Circulation 2006;114(1 Suppl):I125–31.
C. Pipino et al.
Page 24 of 25
British Medical Bulletin 2012
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
105 Cargnoni A, Gibelli L, Tosini A et al. Transplantation of allogeneic and xenogeneic placenta-derived cells reduces bleomycin-induced lung fibrosis. Cell Transplant 2009;18:405–22. 106 Kranz A, Wagner D-C, Kamprad M et al. Transplantation of placenta-derived mesenchymal stromal cells upon experimental stroke in rats. Brain Res 2010;1315:128–36. 107 Yarygin KN, Kholodenko IV, Konieva AA et al. Mechanisms of positive effects of transplantation of human placental mesenchymal stem cells on recovery of rats after experimental ischemic stroke. Bull Exp Biol Med 2009;148:862– 8. 108 Yu LC, Wall DA, Sandler E et al. Unrelated cord blood transplant experience by the pediatric blood and marrow transplant consortium. Pediatr Hematol Oncol 2001; 18:235–45. 109 Schoeberlein A, Mueller M, Reinhart U et al. Homing of placenta-derived mesenchymal stem cells after perinatal intracerebral transplantation in a rat model. Am J Obstet Gynecol 2011;205:277.e1–6. 110 Kadam S, Muthyala S, Nair P et al. Human placenta-derived mesenchymal stem cells and islet-like cell clusters generated from these cells as a novel source for stem cell therapy in diabetes. RDS 2010;7:168– 82. 111 Soon-Shiong P, Feldman E, Nelson R et al. Long-term reversal of diabetes by the injection of immunoprotected islets. Proc Natl Acad Sci USA 1993;90:5843– 7. 112 Lanzoni G, Alviano F, Marchionni C et al. Isolation of stem cell populations with trophic and immunoregulatory functions from human intestinal tissues: potential for cell therapy in inflammatory bowel disease. Cytotherapy 2009;11:1020– 31. 113 Ishikane S, Ohnishi S, Yamahara K et al. Allogeneic injection of fetal membrane-derived mesenchymal stem cells induces therapeutic angiogenesis in a rat model of hind limb ischemia. Stem Cells 2008;26:2625–33. 114 Hwang JH, Shim SS, Seok OS et al. Comparison of cytokine expression in mesenchymal stem cells from human placenta, cord blood, and bone marrow. J Korean Med Sci 2009;24:547. 115 Prather WR, Toren A, Meiron M et al. The role of placental-derived adherent stromal cell (PLX-PAD) in the treatment of critical limb ischemia. Cytotherapy 2009;11:427– 34. 116 Parolini O, Caruso M. Review: preclinical studies on placenta-derived cells and amniotic membrane: an update. Placenta 2011;32(Suppl 2):S186– 95. 117 Sant’Anna LB, Cargnoni A, Ressel L et al. Amniotic membrane application reduces liver fibrosis in a bile duct ligation rat model. Cell Transplant 2011;20:441–53. 118 Ismail A, Ramsis R, Sherif A et al. Use of human amniotic stem cells for common bile duct reconstruction: vascularized support of a free amnion graft. Med Sci Monit 2009;15:BR243– 7. 119 Ueno H, Weissman IL. The origin and fate of yolk sac hematopoiesis: application of chimera analyses to developmental studies. Int J Dev Biol 2010;54:1019– 31. 120 Gekas C, Rhodes KE, Van Handel B et al. Hematopoietic stem cell development in the placenta. Int J Dev Biol 2010;54:1089–98. 121 Weissman IL. Stem cells: units of development, units of regeneration, and units in evolution. Evolution 2000;100:157–68. 122 Weissman IL, Shizuru JA. The origins of the identification and isolation of hematopoietic stem cells, and their capability to induce donor-specific transplantation tolerance and treat autoimmune diseases. Blood 2008;112:3543–53. 123 McGrath KE, Palis J. Hematopoiesis in the yolk sac: more than meets the eye. Exp Hematol 2005;33:1021– 8. 124 Ottersbach K, Dzierzak E. The placenta as a haematopoietic organ. Int J Dev Biol 2010;54:1099– 106. 125 Broxmeyer HE, Douglas GW, Hangoc G et al. Human umbilical cord blood as a potential source of transplantable hematopoietic stem/progenitor cells. Proc Natl Acad Sci USA 1989;86:3828– 32. 126 Ditadi A, de Coppi P, Picone O et al. Human and murine amniotic fluid c-KitþLin-cells display hematopoietic activity. Blood 2009;113:3953–60. 127 Gekas C, Dieterlen-Lie`vre F, Orkin SH et al. Hematopoietic stem cells. Dev Cell 2005;8: 365–75.
Placenta as a reservoir of stem cells
British Medical Bulletin 2012
Page 25 of 25
Downloaded from http://bmb.oxfordjournals.org/ by guest on November 26, 2012
128 Alvarez-Silva M, Belo-Diabangouaya P, Salau¨n J et al. Mouse placenta is a major hematopoietic organ. Development 2003;130:5437– 44. 129 Ottersbach K, Dzierzak E. The murine placenta contains hematopoietic stem cells within the vascular labyrinth region. Developmental Cell 2005;8:377–87. 130 Caprioli A, Jaffredo T, Gautier R et al. Blood-borne seeding by hematopoietic and endothelial precursors from the allantois. Proc Natl Acad Sci USA 1998;95:1641–6. 131 Tavian M, Robin C, Coulombel L et al. The human embryo, but not its yolk sac, generates lympho-myeloid stem cells: mapping multipotent hematopoietic cell fate in intraembryonic mesoderm. Immunity 2001;15:487–95. 132 Robin C, Bollerot K, Mendes S et al. Human placenta is a potent hematopoietic niche containing hematopoietic stem and progenitor cells throughout development. Stem Cell 2009;5:385– 95. 133 Coulombel L. Identification of hematopoietic stem/progenitor cells: strength and drawbacks of functional assays. Oncogene 2004;23:7210– 22. 134 De Coppi P, Bartsch G, Siddiqui MM et al. Isolation of amniotic stem cell lines with potential for therapy. Nat Biotechnol 2007;25:100– 6. 135 Barlow S, Brooke G, Chatterjee K. Comparison of human placenta-and bone marrowderived multipotent mesenchymal stem cells. Stem Cell 2008;1108:1095– 108. 136 Mihu CM, Mihu D, Costin N et al. Isolation and characterization of stem cells from the placenta and the umbilical cord. Rom J Morphol Embryol 2008;49:441–6. 137 Rao MS, Mattson MP. Stem cells and aging: expanding the possibilities. Mech Ageing Dev 2001;122:713– 34. 138 Hass R, Kasper C, Bo¨hm S et al. Different populations and sources of human mesenchymal stem cells (MSC): a comparison of adult and neonatal tissue-derived MSC. Cell Commun Signal 2011;9:12. 139 Brooke G, Tong H, Levesque J-P et al. Molecular trafficking mechanisms of multipotent mesenchymal stem cells derived from human bone marrow and placenta. Stem Cells Dev 2008;17:929–40. 140 Strakova Z, Livak M, Krezalek M et al. Multipotent properties of myofibroblast cells derived from human placenta. Cell Tissue Res 2008;332:479–88. 141 Cavallo C, Cuomo C, Fantini S et al. Comparison of alternative mesenchymal stem cell sources for cell banking and musculoskeletal advanced therapies. J Cell Biochem 2011;112:1418– 30.
