Generation of an osteogenic graft from human placenta and placenta-derived mesenchymal stem cells

Retention of Key Characteristics of Unprocessed Chorion Tissue Resulting in a Robust Scaffold to Support Wound Healing

Placental membranes have been widely studied and used clinically for wound care applications, but there is limited published information on the benefits of using the chorion membrane. The chorion membrane represents a promising source of placental-derived tissue to support wound healing, with its native composition of extracellular matrix (ECM) proteins and key regulatory proteins. This study examined the impact of hypothermic storage on the structure of chorion membrane, ECM content, and response to degradation in vitro. Hypothermically stored chorion membrane (HSCM) was further characterized for its proteomic content, and for its functionality as a scaffold for cell attachment and proliferation in vitro. HSCM retained the native ECM structure, composition, and integrity of native unprocessed chorion membrane and showed no differences in response to degradation in an in vitro wound model. HSCM retained key regulatory proteins previously shown to be present in placental membranes and promoted the attachment and proliferation of fibroblasts in vitro. These data support the fact that hypothermic storage does not significantly impact the structure and characteristics of the chorion membrane compared to unprocessed tissue or its functionality as a scaffold to support tissue growth.

Cell Sheet Technology as an Engineering-Based Approach to Bone Regeneration

Bone defects that are congenital or the result of infection, malignancy, or trauma represent a challenge to the global healthcare system. To address this issue, multiple research groups have been developing novel cell sheet technology (CST)-based approaches to promote bone regeneration. These methods hold promise for use in regenerative medicine because they preserve cell-cell contacts, cell-extracellular matrix interactions, and the protein makeup of cell membranes. This review introduces the concept and preparation system of the cell sheet (CS), explores the application of CST in bone regeneration, highlights the current states of the bone regeneration via CST, and offers perspectives on the challenges and future research direction of translating current knowledge from the lab to the clinic.

Allogenic Use of Human Placenta-Derived Stromal Cells as a Highly Active Subtype of Mesenchymal Stromal Cells for Cell-Based Therapies

The application of mesenchymal stromal cells (MSCs) from different sources, including bone marrow (BM, bmMSCs), adipose tissue (atMSCs), and human term placenta (hPSCs) has been proposed for various clinical purposes. Accumulated evidence suggests that the activity of the different MSCs is indirect and associated with paracrine release of pro-regenerative and anti-inflammatory factors. A major limitation of bmMSCs-based treatment for autologous application is the limited yield of cells harvested from BM and the invasiveness of the procedure. Similar effects of autologous and allogeneic MSCs isolated from various other tissues were reported. The easily available fresh human placenta seems to represent a preferred source for harvesting abundant numbers of human hPSCs for allogenic use. Cells derived from the neonate tissues of the placenta (f-hPSC) can undergo extended expansion with a low risk of senescence. The low expression of HLA class I and II on f-hPSCs reduces the risk of rejection in allogeneic or xenogeneic applications in normal immunocompetent hosts. The main advantage of hPSCs-based therapies seems to lie in the secretion of a wide range of pro-regenerative and anti-inflammatory factors. This renders hPSCs as a very competent cell for therapy in humans or animal models. This review summarizes the therapeutic potential of allogeneic applications of f-hPSCs, with reference to their indirect pro-regenerative and anti-inflammatory effects and discusses clinical feasibility studies.

Decellularized Human Chorion Membrane as a Novel Biomaterial for Tissue Regeneration

Although some placenta-derived products are already used for tissue regeneration, the human chorion membrane (HCM) alone has been poorly explored. In fact, just one study uses decellularized HCM (dHCM) with native tissue architecture (i.e., without extracellular matrix (ECM) suspension creation) as a substrate for cell differentiation. The aim of this work is to fully characterize the dHCM for the presence and distribution of cell nuclei, DNA and ECM components. Moreover, mechanical properties, in vitro biological performance and in vivo biocompatibility were also studied. Our results demonstrated that the HCM was successfully decellularized and the main ECM proteins were preserved. The dHCM has two different surfaces, the reticular layer side and the trophoblast side; and is biocompatible both in vitro and in vivo. Importantly, the in vivo experiments demonstrated that on day 28 the dHCM starts to be integrated by the host tissue. Altogether, these results support the hypothesis that dHCM may be used as a biomaterial for different tissue regeneration strategies, particularly when a membrane is needed to separate tissues, organs or other biologic compartments.

Effects of human placenta-derived mesenchymal stem cells with NK4 gene expression on glioblastoma multiforme cell lines

Poor prognosis and low survival are commonly seen in patients with glioblastoma multiforme (GBM). Due to the specific nature of solid tumors such as GBM, delivery of therapeutic agents to the tumor sites is difficult. So, one of the major challenges in the treatment of these tumors is a selection of appropriate method for drug delivery. Mesenchymal stem cells (MSCs) have a unique characteristic in migration toward the tumor tissue. In this regard, the present study examined the antitumor effects of manipulating human placenta-derived mesenchymal stem cells (PDMSCs) with NK4 expression (PDMSC-NK4) on GBM cells. After separation and characterization of PDMSCs, these cells were transduced with NK4 which was known as the antagonist of hepatocyte growth factor (HGF). The results indicated that engineered PDMSCs preferably migrate into GBM cells by transwell coculture system. In addition, the proliferation of the GBM cells significantly reduced after coculture with these cells. In fact, manipulated PDMSCs inhibited growth of tumor cells by induction of apoptosis. Our findings suggested that besides having antitumor effects, PDMSCs can also be applied as an ideal cellular vehicle to target the glioblastoma multiforme.

In vitro osteodifferentiation of intact human amniotic membrane is not beneficial in the context of bone repair

The human amniotic membrane (hAM) is an attractive biomaterial for regenerative medicine, as it contains amniotic mesenchymal stromal cells (hAMSC), epithelial cells (hAEC) and growth factors. We examined the potential use of hAM in orthopaedic and maxillofacial bone surgery, integrating the requirements of current regulations regarding advanced therapy medicinal products (ATMP) in the European Union. Previous studies have described the potential osteodifferentiation of intact hAM during whole-tissue culture in osteogenic conditions. The present study aims to determine whether in vitro osteodifferentiation of hAM is needed in the context bone repair, and the influence of this process on tissue structure, cell phenotype and cell function. Different conditions (fresh or cultured hAM; intact or hAM-derived cells) were tested. Phenotypic and functional analyses were performed with standard approaches (cell culture and staining, histological and immunolabelling) as well as original approaches (tissue staining, energy dispersive X-ray and X-ray diffraction). In our study, non-osteodifferentiated hAM (i.e., fresh or native hAM) exhibited innate pre-osteoblastic potential. Osteodifferentiation of fresh hAM induced a change in tissue structure, cell phenotype and function. Therefore, we hypothesize that pre-osteodifferentiation may not be necessary, especially if it induces unwanted changes. To our surprise, in these osteogenic conditions, hAEC had a mesenchymal phenotype with osteocyte function, and even native synthesis of hydroxyapatite, focusing osteogenic potential mainly in this epithelial layer. In conclusion, in vitro osteodifferentiation by tissue culture does not appear to be necessary for hAM to be used as an innovative ATMP for bone repair.

Improved bone regeneration through amniotic membrane loaded with buccal fat pad-derived MSCs as an adjuvant in maxillomandibular reconstruction

BACKGROUND

Human amniotic membranes (HAMs), as a biological membrane with healing, osteogenic, and cell therapy potential, has been in the spotlight to enhance the outcomes of treating bone defects. Present study aims to clinically assess the potential of HAM loaded with buccal fat pad-derived stem cells (BFSCs) as an osteogenic coverage for onlay bone grafts to maxillomandibular bone defects.

MATERIALS AND METHODS

Nine patients with jaw bone defects were enrolled in the present study. The patients were allocated to two study groups: Iliac crest bone graft with HAM coverage (n = 5), and Iliac bone grafts covered with HAM loaded with BFSCs (n = 4). Five months following the grafting and prior to implant placement, cone beam computed tomography was performed for radiomorphometric analysis.

RESULTS

The mean increase in bone width was found to be significantly greater in the HAM + BFSCs group (4.42 ± 1.03 mm versus 3.07 ± 0.73 mm, p < 0.05). Further, the changes in vertical dimension were greater in the HAM + BFSCs group (4.66 ± 1.06 mm versus 4.14 ± 1.03 mm, p > 0.05).

CONCLUSION

Combined use of HAM with mesenchymal stem cells may enhance bone regeneration specifically in the horizontal dimension. Moreover, this methodology reduces the amount of harvested autogenous bone and diminish secondary bone resorption.

Similarities between induced membrane and amniotic membrane: Novelty for bone repair

Previous clinical studies have shown the efficacy of a two-stage surgical procedure - the induced membrane (IM) technique - for reconstruction of large bone defects or bone non-union. The first stage involves radical debridement and insertion of a cement spacer into the bone defect. The second stage, performed weeks to months later, consists of removing the spacer while leaving the foreign body membrane induced by the cement in place, and then filling the cavity with bone autograft. The IM has been shown to (1) act as a protective physical barrier by preventing bone autograft resorption and (2) act as a bioreactor by promoting healing through revascularisation and growth factor secretion, and by concentrating mesenchymal stem cells (MSC) with osteogenic properties. New solutions to reduce this surgical procedure to a single step are being explored, for example by using an IM-like bioactive and protective barrier inserted into the bone defect at the same time as bone graft.

Fresh and in vitro osteodifferentiated human amniotic membrane, alone or associated with an additional scaffold, does not induce ectopic bone formation in Balb/c mice

The human amniotic membrane (hAM) has been successfully used as a natural carrier containing amniotic mesenchymal stromal cells, epithelial cells and growth factors. It has a little or no immunogenicity, and possesses useful anti-microbial, anti-inflammatory, anti-fibrotic and analgesic properties. It has been used for many years in several indications for soft tissue repair. We previously reported that hAM represents a natural and preformed sheet containing highly potent stem cells, and could thus be used for bone repair. Indeed, native hAM possesses pre-osteoblastic potential that can easily be stimulated, even as far as mineralization, by means of in vitro osteogenic culture. However, cell culture induces damage to the tissue, as well as to cell phenotype and function. The aim of this study was to evaluate new bone formation by fresh and in vitro osteodifferentiated hAM, alone or associated with an additional scaffold presenting osteoinductive properties. Moreover, we also aimed to determine the effect of in vitro hAM pre-osteodifferentiation on its in vivo biocompatibility/tissue degradation. Results showed that neither fresh nor osteodifferentiated hAM induced ectopic bone formation, whether or not it was associated with the osteoinductive scaffold. Secondly, fresh and osteodifferentiated hAM presented similar in vivo tissue degradation, suggesting that in vitro hAM pre-osteodifferentiation did not influence its in vivo biocompatibility.

Current View on Osteogenic Differentiation Potential of Mesenchymal Stromal Cells Derived from Placental Tissues

Mesenchymal stromal cells (MSC) isolated from human term placental tissues possess unique characteristics, including their peculiar immunomodulatory properties and their multilineage differentiation potential. The osteogenic differentiation capacity of placental MSC has been widely disputed, and continues to be an issue of debate. This review will briefly discuss the different MSC populations which can be obtained from different regions of human term placenta, along with their unique properties, focusing specifically on their osteogenic differentiation potential. We will present the strategies used to enhance osteogenic differentiation potential in vitro, such as through the selection of subpopulations more prone to differentiate, the modification of the components of osteo-inductive medium, and even mechanical stimulation. Accordingly, the applications of three-dimensional environments in vitro and in vivo, such as non-synthetic, polymer-based, and ceramic scaffolds, will also be discussed, along with results obtained from pre-clinical studies of placental MSC for the regeneration of bone defects and treatment of bone-related diseases.

Placental-derived stem cells: Culture, differentiation and challenges

Stem cell therapy is a promising approach to clinical healing in several diseases. A great variety of tissues (bone marrow, adipose tissue, and placenta) are potentially sources of stem cells. Placenta-derived stem cells (p-SCs) are in between embryonic and mesenchymal stem cells, sharing characteristics with both, such as non-carcinogenic status and property to differentiate in all embryonic germ layers. Moreover, their use is not ethically restricted as fetal membranes are considered medical waste after birth. In this context, the present review will be focused on the biological properties, culture and potential cell therapy uses of placental-derived stem cells. Immunophenotype characterization, mainly for surface marker expression, and basic principles of p-SC isolation and culture (mechanical separation or enzymatic digestion of the tissues, the most used culture media, cell plating conditions) will be presented. In addition, some preclinical studies that were performed in different medical areas will be cited, focusing on neurological, liver, pancreatic, heart, muscle, pulmonary, and bone diseases and also in tissue engineering field. Finally, some challenges for stem cell therapy applications will be highlighted. The understanding of the mechanisms involved in the p-SCs differentiation and the achievement of pure cell populations (after differentiation) are key points that must be clarified before bringing the preclinical studies, performed at the bench, to the medical practice.

Early gestation chorionic villi-derived stromal cells for fetal tissue engineering

AIM: To investigate the potential for early gestation placenta-derived mesenchymal stromal cells (PMSCs) for fetal tissue engineering.

METHODS: PMSCs were isolated from early gestation chorionic villus tissue by explant culture. Chorionic villus sampling (CVS)-size tissue samples (mean = 35.93 mg) were used to test the feasibility of obtaining large cell numbers from CVS within a clinically relevant timeframe. We characterized PMSCs isolated from 6 donor placentas by flow cytometry immunophenotyping, multipotency assays, and through immunofluorescent staining. Protein secretion from PMSCs was examined using two cytokine array assays capable of probing for over 70 factors in total. Delivery vehicle compatibility of PMSCs was determined using three common scaffold systems: fibrin glue, collagen hydrogel, and biodegradable nanofibrous scaffolds made from a combination of polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA). Viral transduction of PMSCs was performed using a Luciferase-GFP-containing lentiviral vector and efficiency of transduction was tested by fluorescent microscopy and flow cytometry analysis.

RESULTS: We determined that an average of 2.09 × 10⁶ (SD ± 8.59 × 10⁵) PMSCs could be obtained from CVS-size tissue samples within 30 d (mean = 27 d, SD ± 2.28), indicating that therapeutic numbers of cells can be rapidly expanded from very limited masses of tissue. Immunophenotyping by flow cytometry demonstrated that PMSCs were positive for MSC markers CD105, CD90, CD73, CD44, and CD29, and were negative for hematopoietic and endothelial markers CD45, CD34, and CD31. PMSCs displayed trilineage differentiation capability, and were found to express developmental transcription factors Sox10 and Sox17 as well as neural-related structural proteins NFM, Nestin, and S100β. Cytokine arrays revealed a robust and extensive profile of PMSC-secreted cytokines and growth factors, and detected 34 factors with spot density values exceeding 10³. Detected factors had widely diverse functions that include modulation of angiogenesis and immune response, cell chemotaxis, cell proliferation, blood vessel maturation and homeostasis, modulation of insulin-like growth factor activity, neuroprotection, extracellular matrix degradation and even blood coagulation. Importantly, PMSCs were also determined to be compatible with both biological and synthetic material-based delivery vehicles such as collagen and fibrin hydrogels, and biodegradable nanofiber scaffolds made from a combination of PLA and PLGA. Finally, we demonstrated that PMSCs can be efficiently transduced (> 95%) with a Luciferase-GFP-containing lentiviral vector for future in vivo cell tracking after transplantation.

CONCLUSION: Our findings indicate that PMSCs represent a unique source of cells that can be effectively utilized for in utero cell therapy and tissue engineering.

Cat amniotic membrane multipotent cells are nontumorigenic and are safe for use in cell transplantation

Amnion-derived mesenchymal stem cells (AMSCs) are multipotent cells with an enhanced ability to differentiate into multiple lineages. AMSCs can be acquired through noninvasive methods, and therefore are exempt from the typical ethical issues surrounding stem cell use. The objective of this study was to isolate and characterize AMSCs from a cat amniotic membrane for future application in regenerative medicine. The cat AMSCs were harvested after mechanical and enzymatic digestion of amnion. In culture medium, the cat AMSCs adhered to a plastic culture dish and displayed a fibroblast-like morphology. Immunophenotyping assays were positive for the mesenchymal stem cell-specific markers CD73 and CD90 but not the hematopoietic markers CD34, CD45, and CD79. Under appropriate conditions, the cat AMSCs differentiated into osteogenic, chondrogenic, and adipogenic cell lineages. One advantage of cat AMSCs was nonteratogenicity, assessed 4 weeks post injection of undifferentiated AMSCs into immunodeficient mice. These findings suggest that cat amniotic membranes may be an important and useful source of mesenchymal stem cells for clinical applications, especially for cell or tissue replacement in chronic and degenerative diseases.

Placental mesenchymal stem cells: a unique source for cellular cardiomyoplasty

In coronary heart disease, the use of stem cells for regeneration purposes has been broadly studied. Whereas bone marrow mesenchymal stem cells remain the most extensively investigated, other cell sources have been reported. Here we discuss and compare the characteristics of placenta-derived mesenchymal stem cells as a novel alternative cell source for cellular cardiomyoplasty. These cells are isolated from the human term placenta, which is normally discarded post partum. With their lack of ethical conflicts and young age, the readily available placenta-derived mesenchymal stem cells could be more suitable for myocardial regenerative therapy.

"Trophoblast islands of the chorionic connective tissue" (TICCT): a novel placental histologic feature

INTRODUCTION

We found isolated or clustered trophoblasts in the chorionic connective tissue of the extraplacental membranes, and defined this novel histologic feature as the "trophoblast islands of the chorionic connective tissue" (TICCT). This study was conducted to determine the clinical significance of TICCT.

METHODS

Immunohistochemistry for cytokeratin-7 was performed on the chorioamniotic membranes (N = 2155) obtained from singleton pregnancies of 1199 uncomplicated term and 956 preterm deliveries. The study groups comprised 1236 African-American and 919 Hispanic women. Gestational age ranged from 24(+0) weeks to 41(+6) weeks. Multiple logistic regression analysis was performed to investigate the magnitude of association between patient characteristics and the presence of TICCT.

RESULTS

The likelihood of TICCT was significantly associated with advancing gestational age both in term (OR: 1.29, 95% CI: 1.16-1.45, p < 0.001) and preterm deliveries (OR: 1.19, 95% CI: 1.07-1.32, p = 0.001) . Hispanic women were less likely than African-American women to have TICCT across gestation in term (OR: 0.23, 95% CI: 0.18-0.31, p < 0.001) and preterm pregnancies (OR: 0.41, 95% CI: 0.29-0.58, p < 0.001). Women with a female fetus were significantly more likely to have TICCT than women with a male fetus, in both term (OR: 1.64, 95% CI: 1.28-2.11, p < 0.001) and preterm gestations (OR: 2.04, 95% CI: 1.46-2.85, p < 0.001). TICCT was 40% less frequent in the presence of chronic placental inflammation [term (OR: 0.60, 95% CI: 0.45-0.81, p = 0.001) and preterm gestations (OR: 0.58, 95% CI: 0.40-0.84, p = 0.003)] and in parous women at term (OR: 0.60, 95% CI: 0.44-0.81, p = 0.001).

CONCLUSIONS

Our findings suggest that the duration of pregnancy, fetal sex, and parity may influence the behavior of extravillous trophoblast and placental mesenchymal cells.

Reproductive stem cell differentiation: extracellular matrix, tissue microenvironment, and growth factors direct the mesenchymal stem cell lineage commitment

The mesenchymal stem cells (MSCs) have awakened interest in regenerative medicine due to its high capability to proliferate and differentiate in multiple specialized lineages under defined conditions. The reproductive system is considered a valuable source of MSCs, which needs further investigations. Many factors have been reported as critical for these cell lineage specification and determination. In this review, we discuss the main effects of extracellular matrix or tissue environment and growth factors in the cell lineage commitment, including the reproductive stem cells. The MSCs responses to culture medium stimuli or to soluble factors probably occur through several intracellular activation pathways. However, the molecular mechanisms in which the cells respond to these mechanical or chemical perturbations remain elusive. Recent findings suggest a synergic effect of microenvironment and soluble cell culture factors affecting cell differentiation. For future applications in cell therapy, protocols of reproductive MSCs differentiation must be established.

In vitro differentiation of osteocytes and adipocytes from human placenta-derived cells

OBJECTIVE

To investigate the capability of human placenta-derived adherent cells to differentiate into osteocytes and adipocytes.

METHODS

Placenta-derived adherent cells were isolated by type IV collagenase digestion of a single freshly obtained human placenta and cultured under standard conditions. Cell surface markers of adherent cells from passages 3 - 9 were analysed by flow cytometry. Osteocytic differentiation was induced with β-glycerol phosphate, vitamin C and dexamethasone and confirmed by Alizarin red staining. Adipocytic differentiation was induced with dexamethasone and insulin and confirmed by oil red O staining.

RESULTS

Placenta-derived adherent cells were positive for high levels of CD44 and CD105 and very low levels of CD29 but were negative for CD34, CD45 and CD19. This pattern of cell surface markers is identical to human mesenchymal stem cells. Alizarin red-positive cells were detected 10 days after the induction of osteocyte differentiation. Oil red O-positive cells were detected 7 days after the induction of adipocyte differentiation.

CONCLUSIONS

Placenta-derived adherent cells can differentiate into either osteocytes or adipocytes in vitro. The human placenta may provide an alternative source of mesenchymal stem cells for basic research and clinical use.

Ontological differences in first compared to third trimester human fetal placental chorionic stem cells

Human mesenchymal stromal/stem cells (MSC) isolated from fetal tissues hold promise for use in tissue engineering applications and cell-based therapies, but their collection is restricted ethically and technically. In contrast, the placenta is a potential source of readily-obtainable stem cells throughout pregnancy. In fetal tissues, early gestational stem cells are known to have advantageous characteristics over neonatal and adult stem cells. Accordingly, we investigated whether early fetal placental chorionic stem cells (e-CSC) were physiologically superior to their late gestation fetal chorionic counterparts (l-CSC). We showed that e-CSC shared a common phenotype with l-CSC, differentiating down the osteogenic, adipogenic and neurogenic pathways, and containing a subset of cells endogenously expressing NANOG, SOX2, c-MYC, and KLF4, as well as an array of genes expressed in pluripotent stem cells and primordial germ cells, including CD24, NANOG, SSEA4, SSEA3, TRA-1-60, TRA-1-81, STELLA, FRAGILIS, NANOS3, DAZL and SSEA1. However, we showed that e-CSC have characteristics of an earlier state of stemness compared to l-CSC, such as smaller size, faster kinetics, uniquely expressing OCT4A variant 1 and showing higher levels of expression of NANOG, SOX2, c-MYC and KLF4 than l-CSC. Furthermore e-CSC, but not l-CSC, formed embryoid bodies containing cells from the three germ layer lineages. Finally, we showed that e-CSC demonstrate higher tissue repair in vivo; when transplanted in the osteogenesis imperfecta mice, e-CSC, but not l-CSC increased bone quality and plasticity; and when applied to a skin wound, e-CSC, but not l-CSC, accelerated healing compared to controls. Our results provide insight into the ontogeny of the stemness phenotype during fetal development and suggest that the more primitive characteristics of early compared to late gestation fetal chorionic stem cells may be translationally advantageous.

Characterization of placenta-derived mesenchymal stem cells cultured in autologous human cord blood serum

Human placenta-derived mesenchymal stem cells (P-MSCs) have drawn increasing attention in the field of stem cell research due to their potential in clinical applications as well as their rich and easy to procure cell source. While studies demonstrating the potential of P-MSCs for therapeutic transplantations have been documented, a clinically compliant procedure for P-MSC expansion in vitro has yet to be established. To this end, previous studies have demonstrated that MSCs of bone marrow and cord blood origins cultured in human cord blood serum (hCBS) are comparable to those cultured in fetal bovine serum (FBS), indicating that hCBS may be an alternative to FBS for the development of in vitro cell expansion procedures free of animal components. However, stem cells from origins other than bone marrow or cord blood, particularly from human placental tissues, which have demonstrated a good potential for clinical applications, have not been characterized under similar conditions. In this study, in an attempt to define a clinically compliant protocol for P-MSC expansion in vitro, we examined the effects of human hCBS as a replacement for FBS on cell proliferation capacity, differentiation potential, MSC-specific phenotypic expression and the genetic stability of P-MSCs in cultures. P-MSCs expanded in vitro in autologous hCBS maintained the capacity of self‑renewal and expressed surface antigens characteristic of bone marrow-derived mesenchymal stem cells. Under differentiation conditions, the P-MSCs expanded in hCBS developed into adipogenic, osteogenic and neurogenic cell phenotypes. Chromosomal karyotyping and single cell gel electrophoresis analysis demonstrated that P-MSCs cultured in autologous hCBS were genetically stable. These results suggest that autologous hCBS may be used as an alternative to FBS for the in vitro expansion of P-MSCs for clinical applications.