Induction of umbilical cord blood mesenchymal stem cells into neuron-like cells in vitro

Regulation of mesenchymal stem cell differentiation by autophagy

Autophagy, a process that isolates intracellular components and fuses them with lysosomes for degradation, plays an important cytoprotective role by eliminating harmful intracellular substances and maintaining cellular homeostasis. Mesenchymal stem cells (MSCs) are multipotent progenitor cells with the capacity for self-renewal that can give rise to a subset of tissues and therefore have potential in regenerative medicine. However, a variety of variables influence the biological activity of MSCs following their proliferation and transplantation in vitro. The regulation of autophagy in MSCs represents a possible mechanism that influences MSC differentiation properties under the right microenvironment, affecting their regenerative and therapeutic potential. However, a deeper understanding of exactly how autophagy is mobilized to function as well as clarifying the mechanisms by which autophagy promotes MSCs differentiation is still needed. Here, we review the current literature on the complex link between MSCs differentiation and autophagy induced by various extracellular or intracellular stimuli and the molecular targets that influence MSCs lineage determination, which may highlight the potential regulation of autophagy on MSCs' therapeutic capacity, and provide a broader perspective on the clinical application of MSCs in the treatment of a wide range of diseases.

Mesenchymal Stem Cell Transplantation: Neuroprotection and Nerve Regeneration After Spinal Cord Injury

Spinal Cord Injury (SCI), with its morbidity characteristics of high disability rate and high mortality rate, is a disease that is highly destructive to both the physiology and psychology of the patient, and for which there is still a lack of effective treatment. Following spinal cord injury, a cascade of secondary injury reactions known as ischemia, peripheral inflammatory cell infiltration, oxidative stress, etc. create a microenvironment that is unfavorable to neural recovery and ultimately results in apoptosis and necrosis of neurons and glial cells. Mesenchymal stem cell (MSC) transplantation has emerged as a more promising therapeutic options in recent years. MSC can promote spinal cord injury repair through a variety of mechanisms, including immunomodulation, neuroprotection, and nerve regeneration, giving patients with spinal cord injury hope. In this paper, it is discussed the neuroprotection and nerve regeneration components of MSCs' therapeutic method for treating spinal cord injuries.

Integrin α5β1 Mediated Cellular Reorganization in Human Mesenchymal Stem Cells During Neuronal Differentiation

BACKGROUND/AIM

Mesenchymal stem cells (MSCs) have been widely used for yielding neurons in culture to study nervous system pathologies and develop regenerative approaches. In this study, cellular rearrangements of human MSCs related to the expression of the fibronectin common receptor integrin α5β1 and its cell surface localization during neuronal differentiation, were examined.

MATERIALS AND METHODS

Proliferation kinetics of neuronal induced hMSCs (hMd-Neurons) were quantified by BrdU assay, and hMd-Neurons were immunostained for neuronal marker expression. Additionally, cDNA and protein samples were collected at different time points for integrin α5β1 expression analysis.

RESULTS

Endogenous integrin α5β1 expression was significantly upregulated by day 6 and maintained until day 12. Cell surface localization of α5β1 integrin was increased by day 6; the integrin was internalized into the cytosol by day 12.

CONCLUSION

Integrin dynamics around day 6 of differentiation might be involved in neuronal differentiation and maturation or specification of hMd-Neurons.

Adipose-Derived Mesenchymal Stromal Cells in Regenerative Medicine: State of Play, Current Clinical Trials, and Future Prospects

Significance: Wound healing is a complex process involving pain and inflammation, where innervation plays a central role. Managing wound healing and pain remains an important issue, especially in pathologies such as excessive scarring (often leading to fibrosis) or deficient healing, leading to chronic wounds. Recent Advances: Advances in therapies using mesenchymal stromal cells offer new insights for treating indications that previously lacked options. Adipose-derived mesenchymal stromal cells (AD-MSCs) are now being used to a much greater extent in clinical trials for regenerative medicine. However, to be really valid, these randomized trials must imperatively follow strict guidelines such as consolidated standards of reporting trials (CONSORT) statement. Indeed, AD-MSCs, because of their paracrine activities and multipotency, have potential to cure degenerative and/or inflammatory diseases. Combined with their relatively easy access (from adipose tissue) and proliferation capacity, AD-MSCs represent an excellent candidate for allogeneic treatments. Critical Issues: The success of AD-MSC therapy may depend on the robustness of the biological functions of AD-MSCs, which requires controlling source heterogeneity and production processes, and development of biomarkers that predict desired responses. Several studies have investigated the effect of AD-MSCs on innervation, wound repair, or pain management separately, but systematic evaluation of how those effects could be combined is lacking. Future Directions: Future studies that explore how AD-MSC therapy can be used to treat difficult-to-heal wounds, underlining the need to thoroughly characterize the cells used, and standardization of preparation processes are needed. Finally, how this a priori easy-to-use cell therapy treatment fits into clinical management of pain, improvement of tissue healing, and patient quality of life, all need to be explored.

Comparative separation methods and biological characteristics of human placental and umbilical cord mesenchymal stem cells in serum-free culture conditions

Background

Mesenchymal stem cells (MSCs) are considered to be an effective tool for regenerative medicine with promising applications for clinical therapy. However, incongruent data has been reported partially owing to their functional heterogeneity. To provide sufficient and suitable clinical seed cells derived from the placenta for MSC therapy, we compared the various current isolation methods, as well as the biological characteristics, of different human placenta mesenchymal stem cells (hPMSCs).

Methods

We selected placentas from 35 informed donors and exploited three commonly used methods. MSCs were isolated from different parts of placental tissue including umbilical cord (UC), amniotic membrane (AM), chorionic membrane (CM), chorionic villi (CV), and deciduae (DC). The appropriate isolation methods for each type of hPMSCs were first assessed. The resulting five MSC types from the same individuals were identified based on their surface marker expression, proliferation capacity, transcriptome, differentiation, multipotency and karyotype.

Results

All three methods successfully isolated the five hPMSC types from placental tissues. However, the UC-MSCs were most effectively separated via the tissue explant method, while the enzymatic digestion method was found to be more suitable for separating CV-MSCs, owing to its higher output efficiency compared to the other methods. Alternatively, the perfusion method was complicated and exhibited the lowest efficiency for cell isolation and uniformity. Furthermore, we determined that UC-MSCs and CV-MSCs express a higher level of paracrine cytokines and display much stronger proliferative capacity as well as superior extraction efficiency. Finally, karyotype analysis revealed that DC-MSCs are derived from the mother, while the other cell types are derived from the fetus. Moreover, the different hPMSCs exhibited unique gene expression profiles, which may prove advantageous in treatment of a broad range of diseases.

Conclusions

hPMSCs from different sources are similar yet also unique. Our results describe the biological characteristics of five hPMSCs and provide insights to aide in the selection process of candidates for MSCs treatment. Overall, UC- and CV-MSCs appear to be ideal sources of primary MSCs for clinical treatment and future research.

Mesenchymal Stem Cells for Regenerative Medicine

In recent decades, the biomedical applications of mesenchymal stem cells (MSCs) have attracted increasing attention. MSCs are easily extracted from the bone marrow, fat, and synovium, and differentiate into various cell lineages according to the requirements of specific biomedical applications. As MSCs do not express significant histocompatibility complexes and immune stimulating molecules, they are not detected by immune surveillance and do not lead to graft rejection after transplantation. These properties make them competent biomedical candidates, especially in tissue engineering. We present a brief overview of MSC extraction methods and subsequent potential for differentiation, and a comprehensive overview of their preclinical and clinical applications in regenerative medicine, and discuss future challenges.

MSCs ameliorates DPN induced cellular pathology via [Ca2+ ]i homeostasis and scavenging the pro-inflammatory cytokines

The MSCs of various origins are known to ameliorate or modulate cell survival strategies. We investigated, whether UCB MSCs could improve the survival of the human neuronal cells and/or fibroblast assaulted with DPN sera. The results showed, the co-culture of UCB MSCs with human neuronal cells and/or fibroblasts could effectively scavenge the pro-inflammatory cytokines TNF-α, IL-1β, IFN-ɤ and IL - 12 and control the pro-apoptotic expression of p53/Bax. Further co-culture of UCB MSCs have shown to induce anti-inflammatory cytokines like IL-4, IL-10 and TGF-β and anti-apoptotic Bclxl/Bcl2 expression in the DPN sera stressed cells. Amelioration of elevated [Ca²⁺ ]_i and cROS, the portent behind the NFκB/Caspase-3 mediated inflammation in DPN rescued the cells from apoptosis. The results of systemic administration of BM MSCs improved DPN pathology in rat as extrapolated from human cell model. The BM MSCs ameliorated prolonged distal motor latency (control: 0.70 ± 0.06, DPN: 1.29 ± 0.13 m/s DPN + BM MSCs: 0.89 ± 0.02 m/s, p < 0.05) and lowered high amplitude of compound muscle action potentials (CMAPs) (control: 12.36 ± 0.41, DPN: 7.52 ± 0.61 mV, DPN + MSCs: 8.79 ± 0.53 mV, p < 0.05), while slowly restoring the plasma glucose levels. Together, all these results showed that administration of BM or UCB MSCs improved the DPN via ameliorating pro-inflammatory cytokine signaling and [Ca²⁺ ]_i homeostasis.

Evaluation of motor neuron differentiation potential of human umbilical cord blood- derived mesenchymal stem cells, in vitro

Many people suffer from spinal cord injuries annually. These deficits usually threaten the quality of life of patients. As a postpartum medically waste product, human Umbilical Cord Blood (UCB) is a rich source of stem cells with self- renewal properties and neural differentiation capacity which made it useful in regenerative medicine. Since there is no report on potential of human umbilical cord blood-derived mesenchymal stem cells into motor neurons, we set out to evaluate the differentiation properties of these cells into motor neuron-like cells through administration of Retinoic Acid(RA), Sonic Hedgehog(Shh) and BDNF using a three- step in vitro procedure. The results were evaluated using Real-time PCR, Flowcytometry and Immunocytochemistry for two weeks. Our data showed that the cells changed into bipolar morphology and could express markers related to motor neuron; including Hb-9, Pax-6, Islet-1, NF-H, ChAT at the level of mRNA and protein. We could also quantitatively evaluate the expression of Islet-1, ChAT and NF-H at 7 and 14days post- induction using flowcytometry. It is concluded that human UCB-MSCs is potent to express motor neuron- related markers in the presence of RA, Shh and BDNF through a three- step protocol; thus it could be a suitable cell candidate for regeneration of motor neurons in spinal cord injuries.

Effect of Extremely Low Frequency Electromagnetic Field on MAP2 and Nestin Gene Expression of Hair Follicle Dermal Papilla Cells

Introduction

In recent years, the extremely low frequency electromagnetic field (ELF-EMF) has attracted a great deal of scientific interest. The ELF-EMF signal is able to control ion transport across ion channels and therefore induce cell differentiation.

Aim

The purpose of this study was to investigate the effect of ELF-EMF (50 Hz, 1 mT) on MAP2 and Nestin gene expression of dermal papilla mesenchymal cells (DPCs).

Methods

In order to examine the effect of chemical and electromagnetic factors on gene expression, 4 experimental groups, namely chemical (cell exposure to chemical signals), EMF (exposing cells to ELF-EMF), chemical-EMF (subjecting cells to chemical signals and ELF-EMF) and control (with no treatment) groups, were prepared, treated for 5 days, and studied. To assess the effect of extended test time on the expression of neural differentiation markers (Nestin and MAP2), an EMF group was prepared and treated for a period of 14 consecutive days. The beneficial role of EMF in inducing neural differentiation was shown by real-time PCR analysis.

Results

The higher expression of MAP2 after 14 days compared to that after 5 days and decrease of cell proliferation on days 5 to 20 were indicative of the positive effect of extending treatment time on neural differentiation by evaluation of gene expression in EMF group.

Characterization and Expression of Senescence Marker in Prolonged Passages of Rat Bone Marrow-Derived Mesenchymal Stem Cells

The present study is aimed at optimizing the in vitro culture protocol for generation of rat bone marrow- (BM-) derived mesenchymal stem cells (MSCs) and characterizing the culture-mediated cellular senescence. The initial phase of generation and characterization was conducted using the adherent cells from Sprague Dawley (SD) rat's BM via morphological analysis, growth kinetics, colony forming unit capacity, immunophenotyping, and mesodermal lineage differentiation. Mesenchymal stem cells were successfully generated and characterized as delineated by the expressions of CD90.1, CD44H, CD29, and CD71 and lack of CD11b/c and CD45 markers. Upon induction, rBM-MSCs differentiated into osteocytes and adipocytes and expressed osteocytes and adipocytes genes. However, a decline in cell growth was observed at passage 4 onwards and it was further deciphered through apoptosis, cell cycle, and senescence assays. Despite the enhanced cell viability at later passages (P4-5), the expression of senescence marker, β-galactosidase, was significantly increased at passage 5. Furthermore, the cell cycle analysis has confirmed the in vitro culture-mediated cellular senescence where cells were arrested at the G0/G1 phase of cell cycle. Although the currently optimized protocols had successfully yielded rBM-MSCs, the culture-mediated cellular senescence limits the growth of rBM-MSCs and its potential use in rat-based MSC research.

Massive Clonal Selection and Transiently Contributing Clones During Expansion of Mesenchymal Stem Cell Cultures Revealed by Lentiviral RGB-Barcode Technology

Mesenchymal stem (or stromal) cells (MSCs) have been used in more than 400 clinical trials for the treatment of various diseases. The clinical benefit and reproducibility of results, however, remain extremely variable. During the in vitro expansion phase, which is necessary to achieve clinically relevant cell numbers, MSCs show signs of aging accompanied by different contributions of single clones to the mass culture. Here we used multicolor lentiviral barcode labeling to follow the clonal dynamics during in vitro MSC expansion from whole umbilical cord pieces (UCPs). The clonal composition was analyzed by a combination of flow cytometry, fluorescence microscopy, and deep sequencing. Starting with highly complex cell populations, we observed a massive reduction in diversity, transiently dominating populations, and a selection of single clones over time. Importantly, the first wave of clonal constriction already occurred in the early passages during MSC expansion. Consecutive MSC cultures from the same UCP implied the existence of more primitive, MSC culture-initiating cells. Our results show that microscopically homogenous MSC mass cultures consist of many subpopulations, which undergo clonal selection and have different capabilities. Among other factors, the clonal composition of the graft might have an impact on the functional properties of MSCs in experimental and clinical settings.

SIGNIFICANCE

Mesenchymal stem cells (MSCs) can easily be obtained from various adult or embryonal tissues and are frequently used in clinical trials. For their clinical application, MSCs have to be expanded in vitro. This unavoidable step influences the features of MSCs, so that clinical benefit and experimental results are often highly variable. Despite a homogenous appearance under the microscope, MSC cultures undergo massive clonal selection over time. Multicolor fluorescence labeling and deep sequencing were used to demonstrate the dynamic clonal composition of MSC cultures, which might ultimately explain the variable clinical performance of the cells.

Transplantation of mesenchymal stem cells in a laryngeal carcinoma patient with radiation myelitis

Radiation myelitis is a rather rare but devastating complication following therapeutic irradiation to neoplasms when the spinal cord is included within the radiation field. Symptoms of radiation myelitis with the therapeutic doses of radiation commonly employed are usually delayed and most often appear about 6 to 24 months following irradiation. So far, no treatment has proved satisfactory.

Transplantation of allogeneic mesenchymal stem cells has been a promising therapy strategy for many disorders in the central nervous system, such as multiple sclerosis, neuromyelitis optica, and autoimmune encephalomyelitis. The cell-base therapy has shown to act to limit inflammation of central nervous system, stimulate neurogenesis, protect axons and promote remyelination. But it has not been established as a therapeutic option for radiation myelitis.

In this report, we describe the outcome of allogeneic umbilical cord-derived mesenchymal stem cell transplantation in a patient with laryngeal carcinoma who developed radiation-induced myelitis of his spinal cord with characteristic magnetic resonance imaging changes.

Regenerative Therapy and Immune Modulation Using Umbilical Cord Blood-Derived Cells

Since the first cord blood transplantation in 1988, umbilical cord blood has become an important option as a source of cells for hematopoietic transplantation. Beyond its role in regenerating the blood and immune systems to treat blood diseases and inherited metabolic disorders, the role of nonhematopoietic progenitor cells in cord blood has led to new and emerging uses of umbilical cord blood in regenerative therapy and immune modulation. In this review, we provide an update on the clinical and preclinical studies using cord blood-derived cells such as mesenchymal stromal cells, endothelial-like progenitor cells, and others. We also provide insight on the use of cord blood cells as vehicles for the delivery of therapeutic agents through gene therapy and microvesicle-associated strategies. Moreover, cord blood can provide essential reagents for regenerative applications. Clinical activity using cord blood cells is increasing rapidly and this review aims to provide an important update on the tremendous potential within this fast-moving field.

Mesenchymal stromal cells derived from human umbilical cord tissues: primitive cells with potential for clinical and tissue engineering applications

Mesenchymal stem or stromal cells (MSCs) have a high potential for cell-based therapies as well as for tissue engineering applications. Since Friedenstein first isolated stem or precursor cells from the human bone marrow (BM) stroma that were capable of osteogenesis, BM is currently the most common source for MSCs. However, BM presents several disadvantages, namely low frequency of MSCs, high donor-dependent variations in quality, and painful invasive intervention. Thus, tremendous research efforts have been observed during recent years to find alternative sources for MSCs.In this context, the human umbilical cord (UC) has gained more and more attention. Since the UC is discarded after birth, the cells are easily accessible without ethical concerns. This postnatal organ was found to be rich in primitive stromal cells showing typical characteristics of bone-marrow MSCs (BMSCs), e.g., they grow as plastic-adherent cells with a fibroblastic morphology, express a set of typical surface markers, and can be directly differentiated at least along mesodermal lineages. Compared to BM, the UC tissue bears a higher frequency of stromal cells with a higher in vitro expansion potential. Furthermore, immune-privileged and immune-modulatory properties are reported for UC-derived cells, which open highly interesting perspectives for clinical applications.

Prospective isolation and characterization of human bone marrow-derived MSCs

There is an increasing interest in adult stem cells, especially mesenchymal stem/stromal cells (MSCs), in hematology and regenerative medicine because of the simplicity of isolation and ex vivo expansion of these cells. Conventionally, MSCs are functionally isolated from tissue based on their capacity to adhere to the surface of culture flasks. This isolation procedure is hampered by the unpredictable influence of secreted molecules and interactions with co-cultured hematopoietic and other unrelated cells, as well as by the arbitrarily selected removal time of non-adherent cells prior to the expansion of MSCs. Finally, functionally isolated cells do not provide biological information about the starting population. To circumvent these limitations, several strategies have been developed to facilitate the prospective isolation of MSCs based on the selective expression or absence of surface markers. The isolation and ex vivo expansion of these cells require an adequate quality control of the source and product. Here we summarize the most frequently used markers and introduce new targets for antibody-based isolation and characterization of bone marrow-derived MSCs.

Characterization and in vitro differentiation potency of early-passage canine amnion- and umbilical cord-derived mesenchymal stem cells as related to gestational age

Fetal adnexa are a non-controversial source of mesenchymal stem cells (MSCs) that have high plasticity, a high proliferation rate, and the ability to differentiate towards multiple lineages. MSC populations have been characterized for their stemness and differentiation capabilities; more recent work has focused on MSC selection and on establishing predictable elements to discriminate the cells with the most potential for regenerative medicine. In this study, we cytogenetically and molecularly characterized and followed the in vitro proliferation and differentiation potential of early-passage canine amniotic membrane MSCs (AM-MSCs) and umbilical cord matrix MSCs (UCM-MSCs) isolated from fetuses at early (35-40 days) and late (45-55 days) gestational ages. We found that cells from both fetal gestational ages showed similar features. In all examined cell lines, the morphology of proliferating cells typically appeared fibroblast-like. Population doublings, passaged up to 10 times, increased significantly with passage number. In both cell types, cell viability and chromosomal number and structure were not affected by gestational age at early passages. Passage-3 AM- and UCM-MSCs from both gestational phases also expressed embryonic (POU5F1) and mesenchymal (CD29, CD44) stemness markers, whereas hematopoietic and histocompatibility markers were never found in any sample. Passage-3 cell populations of each cell type were also multipotential as they could differentiate into neurocytes and osteocytes, based on cell morphology, specific stains, and molecular analysis. These results indicated that MSCs retrieved from the UCM and AM in the early and late fetal phases of gestation could be used for canine regenerative medicine.

Stem cell-based therapy for neonatal lung disease: it is in the juice

Bronchopulmonary dysplasia, the chronic lung disease of prematurity, is the most common complication in extremely premature infants (born before 28 wk gestation). Despite advances in perinatal care, modern clinical management remains devoid of therapies specifically promoting lung repair and lung growth. Recent progress in stem cell biology has uncovered the promise of stem/progenitor cells to repair damaged organs. Contrary to the original theory that stem cells engraft and repopulate the damaged organ, evidence suggests that stem cells act via a paracrine mechanism. This review highlights the preclinical evidence for the therapeutic potential of cell-based therapies in animal models of neonatal chronic lung injury and the multiple therapeutic avenues offered by soluble stem cell-derived factors.

Adipose stem cells as alternatives for bone marrow mesenchymal stem cells in oral ulcer healing

BACKGROUND AND OBJECTIVES

Adipose tissue is now recognized as an accessible, abundant, and reliable site for the isolation of adult stem cells suitable for tissue engineering and regenerative medicine applications.

METHODS AND RESULTS

Oral ulcers were induced by topical application of formocresol in the oral cavity of dogs. Transplantation of undifferentiated GFP-labeled Autologous Bone Marrow Stem Cell (BMSCs), Adipose Derived Stem Cell (ADSCs) or vehicle (saline) was injected around the ulcer in each group. The healing process of the ulcer was monitored clinically and histopathologically. Gene expression of vascular endothelial growth factor (VEGF) was detected in MSCs by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Expression of VEGF and collagen genes was detected in biopsies from all ulcers.

RESULTS

MSCs expressed mRNA for VEGF MSCs transplantation significantly accelerated oral ulcer healing compared with controls. There was increased expression of both collagen and VEGF genes in MSCs-treated ulcers compared to controls.

CONCLUSIONS

MSCs transplantation may help to accelerate oral ulcer healing, possibly through the induction of angiogenesis by VEGF together with increased intracellular matrix formation as detected by increased collagen gene expression. This body of work has provided evidence supporting clinical applications of adipose-derived cells in safety and efficacy trials as an alternative for bone marrow mesenchymal stem cells in oral ulcer healing.

Effect of mesenchymal stem cells and a novel curcumin derivative on Notch1 signaling in hepatoma cell line

This study was conducted to evaluate the effect of mesenchymal stem cells (MSCs) and a novel curcumin derivative (NCD) on HepG2 cells (hepatoma cell line) and to investigate their effect on Notch1 signaling pathway target genes. HepG2 cells were divided into HepG2 control group, HepG2 cells treated with MSC conditioned medium (MSCs CM), HepG2 cells treated with a NCD, HepG2 cells treated with MSCs CM and NCD, and HepG2 cells treated with MSCs CM (CM of MSCs pretreated with a NCD). Expression of Notch1, Hes1, VEGF, and cyclin D1 was assessed by real-time, reverse transcription-polymerase chain reaction (RT-PCR) in HepG2 cells. In addition, HepG2 proliferation assay was performed in all groups. Notch1 and its target genes (Hes1 and cyclin D1) were downregulated in all treated groups with more suppressive effect in the groups treated with both MSCs and NCD. Also, treated HepG2 cells showed significant decrease in cell proliferation rate. These data suggest that modulation of Notch1 signaling pathway by MSCs and/or NCD can be considered as a therapeutic target in HCC.

Reviewing and updating the major molecular markers for stem cells

Stem cells (SC) are able to self-renew and to differentiate into many types of committed cells, making SCs interesting for cellular therapy. However, the pool of SCs in vivo and in vitro consists of a mix of cells at several stages of differentiation, making it difficult to obtain a homogeneous population of SCs for research. Therefore, it is important to isolate and characterize unambiguous molecular markers that can be applied to SCs. Here, we review classical and new candidate molecular markers that have been established to show a molecular profile for human embryonic stem cells (hESCs), mesenchymal stem cells (MSCs), and hematopoietic stem cells (HSCs). The commonly cited markers for embryonic ESCs are Nanog, Oct-4, Sox-2, Rex-1, Dnmt3b, Lin-28, Tdgf1, FoxD3, Tert, Utf-1, Gal, Cx43, Gdf3, Gtcm1, Terf1, Terf2, Lefty A, and Lefty B. MSCs are primarily identified by the expression of CD13, CD29, CD44, CD49e, CD54, CD71, CD73, CD90, CD105, CD106, CD166, and HLA-ABC and lack CD14, CD31, CD34, CD45, CD62E, CD62L, CD62P, and HLA-DR expression. HSCs are mainly isolated based on the expression of CD34, but the combination of this marker with CD133 and CD90, together with a lack of CD38 and other lineage markers, provides the most homogeneous pool of SCs. Here, we present new and alternative markers for SCs, along with microRNA profiles, for these cells.

Advances in cell lineage reprogramming

As a milestone breakthrough of stem cell and regenerative medicine in recent years, somatic cell reprogramming has opened up new applications of regenerative medicine by breaking through the ethical shackles of embryonic stem cells. However, induced pluripotent stem (iPS) cells are prepared with a complicated protocol that results in a low reprogramming rate. To obtain differentiated target cells, iPS cells and embryonic stem cells still need to be induced using step-by-step procedures. The safety of induced target cells from iPS cells is currently a further concerning matter. More broadly conceived is lineage reprogramming that has been investigated since 1987. Adult stem cell plasticity, which triggered interest in stem cell research at the end of the last century, can also be included in the scope of lineage reprogramming. With the promotion of iPS cell research, lineage reprogramming is now considered as one of the most promising fields in regenerative medicine, will hopefully lead to customized, personalized therapeutic options for patients in the future.

Mesenchymal stem or stromal cells from amnion and umbilical cord tissue and their potential for clinical applications

Mesenchymal stem or stromal cells (MSC) have proven to offer great promise for cell-based therapies and tissue engineering applications, as these cells are capable of extensive self-renewal and display a multilineage differentiation potential. Furthermore, MSC were shown to exhibit immunomodulatory properties and display supportive functions through parakrine effects. Besides bone marrow (BM), still today the most common source of MSC, these cells were found to be present in a variety of postnatal and extraembryonic tissues and organs as well as in a large variety of fetal tissues. Over the last decade, the human umbilical cord and human amnion have been found to be a rich and valuable source of MSC that is bio-equivalent to BM-MSC. Since these tissues are discarded after birth, the cells are easily accessible without ethical concerns.

H3K9me-enhanced DNA hypermethylation of the p16INK4a gene: an epigenetic signature for spontaneous transformation of rat mesenchymal stem cells

To explore the mechanisms underlying spontaneous transformation of mesenchymal stem cells (MSCs), changes in senescence-associated molecules, particularly the epigenetic modification of the p16(INK4a) gene, including histone H3 lysine 27/9 methylation (H3K27/9me) and DNA methylation, were investigated in cultured adult rat bone marrow MSCs at different stages during the transformation process. It was shown that the MSCs underwent replicative senescence after 24 to 25 population doublings, characterized by positive staining for senescence-associated β-galactosidase, increased expression of p16(INK4a) and p21, and downregulated phosphorylation of Rb. The upregulation of p16(INK4a) was associated with decreased expression of enhancer of the zeste homolog 2 (Ezh2), and reduced levels of H3K27me and DNA methylation in the p16(INK4a) gene. At week 4 of senescence, reproliferating cells emerged among the senescent MSCs. These senescence-escaped MSCs lost their senescence-related markers (including p16(INK4a)) and became highly proliferative. In addition to H3K27me, another H3 modification pattern, H3K9me, appeared in the p16(INK4a) gene, accompanied by an enhanced DNA methylation. With continued culture, the senescence-escaped MSCs did not show any sign of growth arrest and gained the capacity for anchorage-independent growth. These immortalized (transformed) MSCs showed further enhanced DNA methylation of the p16(INK4a) gene by increased H3K9me. Ezh2 knockdown with shRNA eliminated H3K27me-mediated DNA methylation of the p16(INK4a) gene in presenescent MSCs, but had no effect on H3K9me-enhanced DNA hypermethylation in the cells after senescence escape. These findings identify an Ezh2- and H3K27me-independent, but H3K9me-enhanced, DNA hypermethylation of the p16(INK4a) gene, which might be an epigenetic signature for MSC spontaneous transformation.

Development and evaluation of a trehalose-contained solution formula to preserve hUC-MSCs at 4°C

Human mesenchymal stem cells (hMSCs) hold great promise in cell therapy and regenerative medicine. Various preclinical and clinical trials have been carried out to illustrate the therapeutic potential of these cells. However, one major challenge for manufacturing clinical grade hMSCs is the requisition of current good manufacturing practice (cGMP) grade practices in cell isolation, processing, storage, and distribution. Development of non-toxic and animal serum-free preservation medium is critical for storage and distribution of mesenchymal stem cells (MSCs). In this study, we developed a solution formula that could preserve MSCs at 4°C for up to 3 weeks. In the solution, trehalose is a key ingredient for maintaining survival of MSCs. Among the concentrations investigated, 40 mM trehalose showed the best outcome with the viability maintained more than 92.7 ± 1.5% for 7 days. Cells preserved in the solution formula for 3 weeks still remained about 70% viability, and produced results similar to those of freshly harvested hMSCs in terms of growth kinetics, expression profile of cell surface antigens, and differentiation potential. In summary, storage of MSCs in the medium makes it far easier for transporting the cells from processing units to clinical sites.

Transplantation of umbilical cord-derived mesenchymal stem cells as a novel strategy to protect the central nervous system: technical aspects, preclinical studies, and clinical perspectives

The prevention of perinatal neurological disabilities remains a major challenge for public health, and no neuroprotective treatment to date has proven clinically useful in reducing the lesions leading to these disabilities. Efforts are, therefore, urgently needed to test other neuroprotective strategies including cell therapies. Although stem cells have raised great hopes as an inexhaustible source of therapeutic products that could be used for neuroprotection and neuroregeneration in disorders affecting the brain and spinal cord, certain sources of stem cells are associated with potential ethical issues. The human umbilical cord (hUC) is a rich source of stem and progenitor cells including mesenchymal stem cells (MSCs) derived either from the cord or from cord blood. hUC MSCs (hUC-MSCs) have several advantages as compared to other types and sources of stem cells. In this review, we will summarize the most recent findings regarding the technical aspects and the preclinical investigation of these promising cells in neuroprotection and neuroregeneration, and their potential use in the developing human brain. However, extensive studies are needed to optimize the administration protocol, safety parameters, and potential preinjection cell manipulations before designing a controlled trial in human neonates.

Isolation, proliferation, cytogenetic, and molecular characterization and in vitro differentiation potency of canine stem cells from foetal adnexa: a comparative study of amniotic fluid, amnion, and umbilical cord matrix

The possibility to isolate canine mesenchymal stem cells (MSCs) from foetal adnexa is interesting since several canine genetic disorders are reported to resemble similar dysfunctions in humans. In this study, we successfully isolated, cytogenetically and molecularly characterized, and followed the differentiation potency of canine MSCs from foetal adnexa, such as amniotic fluid (AF), amniotic membrane (AM), and umbilical cord matrix (UCM). In the three types of cell lines, the morphology of proliferating cells typically appeared fibroblast-like, and the population doubling time (DT) significantly increased with passage number. For AF- and AM-MSCs, cell viability did not change with passages. In UCM-MSCs, cell viability remained at approximately constant levels up to P6 and significantly decreased from P7 (P < 0.05). Amnion and UCM-MSCs expressed embryonic and MSC markers, such as Oct-4 CD44, CD184, and CD29, whereas AF-MSCs expressed Oct-4, CD44. Expression of the hematopoietic markers CD34 and CD45 was not found. Dog leucocyte antigens (DLA-DRA1 and DLA-79) were expressed only in AF-MSCs at P1. Isolated cells of the three cell lines at P3 showed multipotent capacity, and differentiated in vitro into neurocyte, adipocyte, osteocyte, and chondrocyte, as demonstrated by specific stains and expression of molecular markers. Cells at P4 showed normal chromosomal number, structure, and telomerase activity. These results demonstrate that, in dog, MSCs can be successfully isolated from foetal adnexa and grown in vitro. Their proven stemness and chromosomal stability indicated that MSCs could be used as a model to study stem cell biology and have an application in therapeutic programs.

Analysis of cell characterization using cell surface markers in the dermis

BACKGROUND

In recent years, it has been reported that stem cells exist in the mesenchymal tissues of the bone marrow and adipose. These stem cells are thought to express specific cell surface markers such as CD44, CD54, CD105, CD90, and CD271 and have been confirmed to be pluripotent. Furthermore, although it has been reported that stem cells are also present in the dermis, their cell surface markers and characteristics are not fully understood.

OBJECTIVE

To confirm the presence of stem cells in the dermis and their ability, employing the mesenchymal stem cell markers which have previously been reported as an indication.

METHODS

We analyzed the percentages of CD44 (+), CD54 (+), CD90 (+), CD105 (+), and CD271 (+) cells in the dermis of neonatal mice (HR-1 mouse) by performing immunostaining and FACS. Secondly, we isolated each type of marker-positive and -negative cells from dermal tissues and evaluated their proliferation potential and their ability to differentiate into adipocytes, osteoblasts, and chondrocytes.

RESULTS

According to the immunostaining and FACS results, we confirmed that stem cells that express CD44, CD54, CD90, CD105, and CD271 are present in the dermal tissues of neonatal mice. In addition, when we measured the proliferation and differentiation potentials of each type of marker-positive cells, it was revealed that cells expressing CD54 or CD271 have a high proliferation potential and are able to differentiate into adipocytes, osteoblasts, and chondrocytes.

CONCLUSIONS

These results indicated that dermal tissues contain stem cells that express CD44, CD54, CD90, CD105, and CD271 which are stem cell markers. More precisely, it was suggested that both CD54 (+) and CD271 (+) stem cells have high proliferation and differentiation potentials.

Systematic chromosomal aberrations found in murine bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are studied as a cellular source for the treatment of various diseases. In this work, we isolated and cultivated murine bone marrow-derived MSCs. After a first observation of a solid tumor in a mouse injected with these cells, we systematically explored their chromosomal stability. We observed in all the cytogenetically analyzed cases gross chromosomal alterations every time the MSCs went through the senescence crisis while the lymphocytes from the same animals showed a normal chromosome count. This observation was confirmed in different mouse strains, with different culture protocols, and even in short-term cultures after a hematopoietic cell negative immunodepletion performed in order to accelerate the isolation procedure. Therefore, we conclude that murine MSCs display high chromosomal instability and can generate tumors, and that care must be taken before using them for the evaluation of MSC therapeutic potential.

Derivation efficiency, cell proliferation, freeze-thaw survival, stem-cell properties and differentiation of human Wharton's jelly stem cells

Human mesenchymal stem cells (MSC) are non-controversial multipotent stem cells. Their presence in umbilical cord blood (UCB) has been debated in some studies and others report low counts per cord blood unit and poor proliferation rates. On the other hand, Wharton's jelly of human umbilical cords appears to be a rich source of human MSC. This study derived 13 human Wharton's jelly stem cell (WJSC) lines from 13 human umbilical cords (100%) and recovered 4.7 +/- 0.2 x 10(6) live WJSC/cm of cord before culture. Complex culture medium produced greater proliferation rates of the WJSC in culture compared with simple medium. The mean population doubling times were 24.47 +/- 0.33 to 26.25 +/- 0.50 h in complex medium. The stem-cell markers of the WJSC were retained for at least 10 passages in both media. After programmed machine freezing, the thaw-survival rates of WJSC were 85-90% and they could be differentiated into neurons. Given the high derivation efficiency, availability of large numbers of fresh live cells, high expansion capabilities, prolonged maintenance of stem-cell properties and differentiation potential, it is proposed that human WJSC may be frozen at the same time as UCB in cord blood banks for regenerative medicine purposes.

The role of bone marrow-derived mesenchymal stem cells in treating formocresol induced oral ulcers in dogs

BACKGROUND

Mesenchymal stem cells (MSCs), a subpopulation of adult somatic stem cells, are an attractive stem cell source in regenerative medicine because of their multipotentiality. In this study, the effects of MSCs transplantation on oral ulcer healing were examined.

METHODS

Mesenchymal stem cells were isolated from bone marrow aspirates of dogs by dish adherence and expanded in culture. Oral ulcers were induced by topical application of formocresol in the oral cavity of dogs. Either autologous MSCs or vehicle (saline) was injected around the ulcer. The healing process of the ulcer was monitored clinically and histopathologically. Gene expression of vascular endothelial growth factor (VEGF) was detected in MSCs by reverse transcription-polymerase chain reaction. Expression of VEGF and collagen genes was detected in biopsies from all ulcers.

RESULTS

Mesenchymal stem cells expressed mRNA for VEGF MSCs transplantation significantly accelerated oral ulcer healing compared with controls. There was increased expression of both collagen and VEGF genes in MSCs-treated ulcers compared with controls.

CONCLUSION

Mesenchymal stem cells transplantation may help accelerate oral ulcer healing, possibly through the induction of angiogenesis by VEGF together with increased intracellular matrix formation as detected by increased collagen gene expression.

Effect of freshly isolated autologous tissue resident stromal cells on cardiac function and perfusion following acute myocardial infarction

BACKGROUND

The aim of this study was to investigate the effect of intracoronary administration of freshly isolated, uncultured autologous tissue-derived stromal cells on cardiac function and perfusion after acute infarction in pigs.

METHODS

A transmural myocardial infarction in a porcine model was induced by occlusion of the mid LAD with an angioplasty balloon for 3 h. Upon reperfusion, freshly isolated, uncultured autologous stromal cells (1.5×10⁶ cells/kg) or control solution was injected into the infarct artery. Cardiac function and area at risk were determined by (99m)Tc-SPECT.

RESULTS

Eight weeks after infarction, cell treated pigs showed a 20% smaller myocardial perfusion defect compared to control animals (35±9% vs. 44±5% of LV, treated vs. control, respectively, p<0.05). The reduction of the perfusion defect was associated with a significantly higher myocardial salvage index in the cell group as well as a significant increase in ejection fraction compared to control (EF at 8 weeks 43±7% vs. 35±3%, treated vs. control, respectively, p<0.05). This functional improvement was reflected by an increased wall thickness of the infarct and border zone in the treated group (11.2±2.2 mm) compared to control (8.6±1.6 mm, p<0.05) as well as an increased capillary density in the border zone (treated vs. control; 41.6±17.9 vs. 32.9±12.6 capillaries per 0.1 mm², p<0.05).

CONCLUSIONS

This study demonstrates for the first time that recovery and intracoronary delivery of uncultured autologous tissue derived stromal cells at time of vessel reperfusion is feasible and improves ventricular function.

Human umbilical cord blood-derived mesenchymal stem cells attenuate hyperoxia-induced lung injury in neonatal rats

Recent evidence suggests mesenchymal stem cells (MSCs) can downmodulate bleomycin-induced lung injury, and umbilical cord blood (UCB) is a promising source for human MSCs. This study examined whether intratracheal or intraperitoneal transplantation of human UCB-derived MSCs can attenuate hyperoxia-induced lung injury in immunocompetent newborn rats. Wild-type Sprague-Dawley rats were randomly exposed to 95% oxygen or air from birth. In the transplantation groups, a single dose of PKH26-labeled human UCB-derived MSCs was administered either intratracheally (2 x 10(6) cells) or intraperitoneally (5 x 10(5) cells) at postnatal day (P) 5. At P14, the harvested lungs were examined for morphometric analyses of alveolarization and TUNEL staining, as well as the myeoloperoxidase activity, the level of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and transforming growth factor (TGF)-beta mRNA, alpha-smooth muscle actin (SMA) protein, and collagen levels. Differentiation of MSCs to the respiratory epithelium was also evaluated both in vitro before transplantation and in vivo after transplantation. Despite one fourth dosage of MSCs, significantly more PKH26-labeled donor cells were recovered with intratracheal administration than with intraperitoneal administration both during normoxia and hyperoxia. The hyperoxia-induced increase in the number of TUNEL-positive cells, myeloperoixdase activity, and the level of IL-6 mRNA were significantly attenuated with both intratracheal and intraperitoneal MSCs transplantation. However, the hyperoxia-induced impaired alveolarization and increased the level of TNF-alpha and TGF-beta mRNA, alpha-SMA protein, and collagen were significantly attenuated only with intratracheal MSCs transplantation. MSCs differentiated into respiratory epithelium in vitro and a few PKH26-positive donor cells were colocalized with pro surfactant protein C in the damaged lungs. In conclusion, intratracheal transplantation of human UCB-derived MSCs is more effective than intraperitoneal transplantation in attenuating the hyperoxia-induced lung injury in neonatal rats.

Morpho-functional characterization of human mesenchymal stem cells from umbilical cord blood for potential uses in regenerative medicine

Mesenchymal stem cells (MSCs) represent a promising source of progenitor cells having the potential to repair and to regenerate diseased or damaged skeletal tissues. Bone marrow (BM) has been the first source reported to contain MSCs. However, BM-derived cells are not always acceptable, due to the highly invasive drawing and the decline in MSC number and differentiative capability with increasing age. Human umbilical cord blood (UCB), obtainable by donation with a noninvasive method, has been introduced as an alternative source of MSCs. Here human UCB-derived MSCs isolation and morpho-functional characterization are reported. Human UCB-derived mononuclear cells, obtained by negative immunoselection, exhibited either an osteoclast-like or a mesenchymal-like phenotype. However, we were able to obtain homogeneous populations of MSCs that displayed a fibroblast-like morphology, expressed mesenchym-related antigens and showed differentiative capacities along osteoblastic and early chondroblastic lineages. Furthermore, this study is one among a few papers investigating human UCB-derived MSC growth and differentiation on three-dimensional scaffolds focusing on their potential applications in regenerative medicine and tissue engineering. UCB-derived MSCs were proved to grow on biodegradable microfiber meshes; additionally, they were able to differentiate toward mature osteoblasts when cultured inside human plasma clots, suggesting their potential application in orthopedic surgery.

Squalene selectively protects mouse bone marrow progenitors against cisplatin and carboplatin-induced cytotoxicity in vivo without protecting tumor growth

Squalene, an isoprenoid antioxidant is a potential cytoprotective agent against chemotherapy-induced toxicity. We have previously published that squalene protects light-density bone marrow cells against cis-diamminedichloroplatinum( II) (cisplatin)-induced toxicity without protecting tumor cells in vitro. Here, we developed an in vivo mouse model of cisplatin and cis-diammine (cyclobutane-1,1-dicarboxylato) platinum(II) (carboplatin)-induced toxicity to further investigate squalene-mediated LD-BM cytoprotection including the molecular mechanism behind selective cytoprotection. We found that squalene significantly reduced the body weight loss of cisplatin and carboplatin-treated mice. Light-density bone marrow cells from squalene-treated mice exhibited improved formation of hematopoietic colonies (colony-forming unit-granulocyte macrophage). Furthermore, squalene also protected mesenchymal stem cell colonies (colony-forming unit-fibroblast) from cisplatin and carboplatin-induced toxicity. Squalene-induced protection was associated with decreased reactive oxygen species and increased levels of glutathione and glutathione peroxidase/glutathione-S-transferase. Importantly, squalene did not protect neuroblastoma, small cell carcinoma, or medulloblastoma xenografts against cisplatin-induced toxicity. These results suggest that squalene is a potential candidate for future development as a cytoprotective agent against chemotherapeutic toxicity.

Mesodermal fate decisions of a stem cell: the Wnt switch

Stem cells are a powerful resource for cell-based transplantation therapies in osteodegenerative disorders, but before some kinds of stem cells can be applied clinically, several aspects of their expansion and differentiation need to be better controlled. Wnt molecules and members of the Wnt signaling cascade have been ascribed a role in both these processes in vitro as well as normal development in vivo. However some results are controversial. In this review we will present the hypothesis that both canonical and non-canonical signaling are involved in mesenchymal cell fate regulation, such as adipogenesis, chondrogenesis and osteogenesis, and that in vitro it is a timely switch between the two that specifies the identity of the differentiating cell. We will specifically focus on the in vitro differentiation of adipocytes, chondrocytes and osteoblasts contrasting embryonic and mesenchymal stem cells as well as the role of Wnts in mesenchymal fate specification during embryogenesis.

Tissue engineering: strategies, stem cells and scaffolds

Tissue engineering scaffolds are designed to influence the physical, chemical and biological environment surrounding a cell population. In this review we focus on our own work and introduce a range of strategies and materials used for tissue engineering, including the sources of cells suitable for tissue engineering: embryonic stem cells, bone marrow-derived mesenchymal stem cells and cord-derived mesenchymal stem cells. Furthermore, we emphasize the developments in custom scaffold design and manufacture, highlighting laser sintering, supercritical carbon dioxide processing, growth factor incorporation and zoning, plasma modification of scaffold surfaces, and novel multi-use temperature-sensitive injectable materials.

Evaluation of neural plasticity in adult stem cells

The role of stem cells has long been known in reproductive organs and various tissues including the haematopoietic system and skin. During the last decade, stem cells have also been identified in other organs, including the nervous system, both during development and in post-natal life. More recently, evidence has been presented that stem cells thought to be responsible for the generation of mature differentiated cells of one organ, such as haematopoietic stem cells, may have the ability to also differentiate across lineages and contribute to tissues other than haematopoietic cells, including neuronal tissue, suggesting that easily accessible stem cells sources may one day be useful in the therapy of ischaemic (stroke) and also degenerative diseases of the nervous system. Here, we will evaluate the validity of such claims based on a number of criteria we believe need to be fulfilled to definitively conclude that certain stem cells can give rise to functional neural cells that might be suitable for therapy of neural disorders.

Blood into beta-cells: can adult stem cells be used as a therapy for Type 1 diabetes?

In the past 10 years there have been substantial developments in adult stem cell research, and the transplantation of these cells now holds great promise for regenerative medicine, such as in the treatment of Type 1 diabetes. A large proportion of studies have focused on stem cells sourced from hematopoietic tissues: bone marrow, umbilical cord blood and peripheral blood. Attempts to transdifferentiate these cells into insulin-producing cells, both in vivo and in vitro, have produced conflicting results. Although insulin production and normalization of blood glucose levels have been described in some studies, the true mechanism of stem cell plasticity remains in question - are the functional changes seen due to true transdifferentiation or do they result from cell fusion or other factors? There is evidence that stem cell plasticity is a true phenomenon, but whether it will ever be of therapeutic benefit for Type 1 diabetes remains uncertain.

Proliferation, differentiation, and cytokine secretion of human umbilical cord blood-derived mononuclear cells in vitro

OBJECTIVE

Human umbilical cord blood (hUCB)-derived mononuclear cells were previously shown to exert therapeutic effects in a number of animal models of nervous system impairment. However, the mechanisms underlying the structural and functional improvements are still unclear. As cell replacement seems to be a rare or absent event in vivo, we suggest secondary mechanisms, by which the therapeutic effect of transplanted mononuclear cells might be mediated. We investigated the potential of hUCB-derived mononuclear cells in vitro to proliferate, differentiate, and to secrete factors possibly beneficial for the host brain tissue in vivo.

METHODS

Using a succession of distinct culture media, mononuclear cells were stimulated by growth factor combinations, e.g., epidermal growth factor (EGF)/fibroblast growth factor-2 (FGF-2) or nerve growth factor (NGF)/retinoic acid (RA). Expression of hematological and neural marker proteins was investigated by immunoblotting, immunocytochemistry, and fluorescence-activated cell analysis. Secretion of proteins was assayed using a human cytokine antibody array, and quantified via enzyme-linked immunosorbent assay.

RESULTS

Mononuclear cells were shown to undergo proliferation in the presence of EGF/FGF-2. When cells were cultured in NGF/RA-containing medium, neuronal and glial marker proteins were expressed, indicating differentiation. In the presence of either growth factor combination, cells in vitro secrete interleukins, growth factors, and chemotactic proteins.

CONCLUSION

Although capable of incipient differentiation, cytokine secretion of hUCB-derived mononuclear cells envisages the potential of an indirect effect in vivo. Most factors detected in conditioned medium are renowned for their anti-inflammatory, neuroprotective, angiogenic, or chemotactic actions, thus, providing the means for a therapeutic outcome mediated by secondary effects.

Molecular and secretory profiles of human mesenchymal stromal cells and their abilities to maintain primitive hematopoietic progenitors

Mesenchymal stromal cells (MSC) provide a supportive cellular microenvironment and are able to maintain the self-renewal capacity of hematopoietic progenitor cells (HPC). Isolation procedures for MSC vary extensively, and this may influence their biologic properties. In this study, we have compared human MSC isolated from bone marrow (BM) using two culture conditions, from cord blood (CB), and from adipose tissue (AT). The ability to maintain long-term culture-initiating cell frequency and a primitive CD34(+)CD38(-) immunophenotype was significantly higher for MSC derived from BM and CB compared with those from AT. These results were in line with a significantly higher adhesion of HPC to MSC from BM and CB versus MSC from AT. We have compared the cytokine production of MSC by cytokine antibody arrays, enzyme-linked immunosorbent assay, and a cytometric bead array. There were reproducible differences in the chemokine secretion profiles of various MSC preparations, but there was no clear concordance with differences in their potential to maintain primitive function of HPC. Global gene expression profiles of MSC preparations were analyzed and showed that adhesion proteins including cadherin-11, N-cadherin, vascular cell adhesion molecule 1, neural cell adhesion molecule 1, and integrins were highly expressed in MSC preparations derived from BM and CB. Thus, MSC from BM and CB are superior to MSC from AT for maintenance of primitive HPC. The latter property is associated with specific molecular profiles indicating the significance of cell-cell junctions but not with secretory profiles. Disclosure of potential conflicts of interest is found at the end of this article.

Mesenchymal progenitors able to differentiate into osteogenic, chondrogenic, and/or adipogenic cells in vitro are present in most primary fibroblast-like cell populations

MSCs and mesenchymal progenitor cells (MPCs) are studied for their potential in regenerative medicine. MSCs in particular have great potential, because various reports have shown that they can differentiate into many different cell types. However, the difference between mesenchymal stem/progenitor cells and so-called fibroblasts is unclear. In this study, we found that most of the distinct populations of primary fibroblast-like cells derived from various human tissues, including lung, skin, umbilical cord, and amniotic membrane, contained cells that were able to differentiate into at least one mesenchymal lineage, including osteoblasts, chondrocytes, and adipocytes. We therefore propose that primary fibroblast-like cell populations obtained from various human tissues do not comprise solely fibroblasts, but rather that they also include at least MPCs and possibly MSCs, to some extent. Disclosure of potential conflicts of interest is found at the end of this article.

The role of mesenchymal stem cells in maintenance and repair of bone

The maintenance of stable bone mass during adult life, following rapid skeletal growth during childhood, is the result of a carefully controlled balance between the activities of bone forming (osteoblast) and bone resorbing (osteoclast) cells. Although skeletal turnover continues throughout adult life, the net effect of formation and resorption on bone mass is zero in healthy individuals. Later in life, bone mass begins to fall as resorption outpaces formation, particularly in post-menopausal women, which leads to increased fracture risk. The opposing actions of these two cell types are coupled by molecular interactions between them that are thought to be influenced by the actions of the precursor cells of the osteoblast lineage, mesenchymal stem cells (MSCs). In addition to regulating normal skeletal homeostasis, MSCs also play an important role in fracture repair. Bone fracture or injury initiates a series of cellular and molecular pathways that commence with hematoma formation and an inflammatory cascade that regulates MSCs activity leading to fracture healing and the reestablishment of skeletal integrity. Although tremendous strides have been made in increasing our understanding of bone biology, there is surprisingly little data about the role of MSCs in vivo in the maintenance of skeletal integrity or fracture repair. In recent years, the pivotal importance of anabolic therapies in the setting of osteoporosis in which bone mass is substantially increased above and beyond what is attainable with the bisphosphonate class of drugs has put MSC biology firmly on the scientific agenda. Although the biology of cultured MSCs is reasonably well understood, the biology of MSCs in vivo in both bone turnover and fracture repair remains poorly understood. The recent phenotypic characterization of in vivo MSCs and the ability to prospectively purify such cells will open up new avenues of research into a better understanding of the role of MSCs in bone turnover. The purpose of this article is to review bone and fracture biology from the perspective of recent advances in our understanding of MSCs and to highlight the major deficiencies in our current knowledge.

Fibroblast growth factor-4 and hepatocyte growth factor induce differentiation of human umbilical cord blood-derived mesenchymal stem cells into hepatocytes

AIM

To investigate the differentiation of human umbilical cord blood (HUCB)-derived mesenchymal stem cells (MSCs) into hepatocytes by induction of fibroblast growth factor-4 (FGF-4) and hepatocyte growth factor (HGF), and to find a new source of cell types for therapies of hepatic diseases.

METHODS

MSCs were isolated by combining gradient density centrifugation with plastic adherence. When HUCB-derived MSCs reached 70% confluence, they were cultured in Iscove modified Dulbecco medium (IMDM) supplemented with 10 mL/L FBS, 20 ng/mL HGF and 10 ng/mL FGF-4. The medium was changed every 4 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Expression of CK-18 was detected by immunocytochemistry. Glycogen storage in hepatocytes was determined by PAS staining.

RESULTS

By combining gradient density centrifugation with plastic adherence, we could isolate MSCs from 25.6% of human umbilical cord blood. When MSCs were cultured with FGF-4 and HGF, approximately 63.6% of cells became small, round and epithelioid on d 28 by morphology. Compared with the control, the level of AFP increased significantly from d 12 to 18.20+/-1.16 microg/L (t = 2.884, P<0.05) in MSCs cultured with FGF-4 and HGF, and was higher (54.28+/-3.11 microg/L) on d 28 (t = 13.493, P<0.01). Albumin increased significantly on d 16 (t = 6.68, P<0.01) to 1.02+/-0.15 microg/mL, and to 3.63+/-0.30 microg/mL on d 28 (t = 11.748, P<0.01). Urea (4.72+/-1.03 micromol/L) was detected on d 20 (t = 4.272, P<0.01), and continued to increase to 10.28+/-1.06 micromol/L on d 28 (t = 9.276, P<0.01). Cells expressed CK-18 on d 16. Glycogen storage was observed on d 24.

CONCLUSION

HUCB-derived MSCs can differentiate into hepatocytes by induction of FGF-4 and HGF. HUCB-derived MSCs are a new source of cell types for cell transplantation therapy of hepatic diseases.

Comparative characteristics of mesenchymal stem cells from human bone marrow, adipose tissue, and umbilical cord blood

OBJECTIVE

Various preparative protocols have been proposed for the acquisition and cultivation of mesenchymal stem cells (MSC). Whereas surface antigen markers have failed to precisely define this population, microarray analysis might provide a better tool for characterization of MSC.

METHODS

In this study, we have analyzed global gene expression profiles of human MSC isolated from adipose tissue (AT), from umbilical cord blood (CB), and from bone marrow (BM) under two growth conditions and have compared them to terminally differentiated human fibroblasts (HS68). Profiles were compared using our Human Genome Microarray representing 51.144 different cDNA clones.

RESULTS

Cultured with the appropriate conditions, osteogenic and adipogenic differentiation could be confirmed in all MSC preparations but not in fibroblasts. No phenotypic differences were observed by flow cytometry using a panel of 22 surface antigen markers. Whereas MSC derived from different donors using the same culture procedure yielded a consistent and reproducible gene expression profile, many genes were differentially expressed in MSC from different ontogenetic sources or from different culture conditions. Twenty-five genes were overlapping and upregulated in all MSC preparations from AT, CB, and BM as compared to HS68 fibroblasts. These genes included fibronectin, ECM2, glypican-4, ID1, NF1B, HOXA5, and HOXB6. Many genes upregulated in MSC are involved in extracellular matrix, morphogenesis, and development, whereas several inhibitors of the Wnt pathway (DKK1, DKK3, SFRP1) were highly expressed in fibroblasts.

CONCLUSION

Our results have provided a foundation for a more reproducible and reliable quality control using genotypic analysis for defining MSC.

Mesenchymal stem cells feeder layer from human umbilical cord blood for ex vivo expanded growth and proliferation of hematopoietic progenitor cells

Ex vivo expansion of hematopoietic stem cells was suggested as the best way of overcoming problems caused by limited hematopoietic cell number for cord blood transplantation. In this study, we quantified and characterized an ex vivo expansion capacity of umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) as a cell feeder layer for support of UCB-derived committed hematopoietic progenitor cells (HPCs) in the absence or presence of recombinant cytokines. The UCB-derived MSCs used in the study differentiated into osteoblast, chondrocytes, and adipocytes under proper conditions. Frequencies in colony forming unit-granulocyte, macrophage, colony forming unit-granulocyte, erythrocyte, macrophage, megakaryocyte, burst forming unit-erythrocyte, and colony forming unit-erythrocyte increased to 3.46-, 9.85-, 3.64-, and 2.03-folds, respectively, only in culture supplemented by UCB-derived MSCs as a cell feeder layer without recombinant cytokines (culture condition C). Identified expansion kinetics in all kinds of committed HPCs showed plateaus at 7 culture days, suggesting some consumable components were required for the expansion. Physiological importance and different roles for different committed HPCs of UCB-derived MSCs as a cell feeder layer were revealed by a distinguished expansion capacity for colony forming unit-megakaryocyte. The preferred maintenance of CD33(-)CD34(+) in culture condition C was also identified. The presence of cobblestone-like areas as hematopoietic microenvironment and various cell feeder layer-originated hematopoietic cytokines including interleukin-1beta and granulocyte, macrophage-colony stimulating factor were suggested as underlying mechanisms for the identified expansion capacity. The present numeric and biological information about intrinsic expansion capacity for UCB-derived committed HPCs will increase further biological and clinical applications of UCB-derived MSCs.

Mesenchymal stem/progenitor cells developed in cultures from UC blood

Background Whether umbilical cord blood (UCB) serves as a source of mesenchymal stem/progenitor cells (MSPC) is controversial. MSPC are the best candidates for cellular therapy of orthopedic skeletal tissues. In order to explore the possibility of UCB as a useful source of MSPC, we identified, expanded in culture, and characterized MSPC from UCB harvests on a large scale. Methods Mononuclear cells isolated from UCB harvests (n=411) were cultured in media supplemented with 10% FBS. MSPC-like cells cultured from each UCB harvest were expanded ex vivo by successive subcultivation. UCB harvests with a more than 1000-fold expanding capacity (n=9) were examined for surface Ag phenotypes and in vitro differentiation potentials into osteogenic, chondrogenic and adipogenic lineages. Results Ninety-five out of a total of 411 UCB units (23.1%) generated MSPC-like cells during cultivation. Nine UCB units (2.2%) yielded MSPC with more than 1000-fold expansion capacity. These cells positively expressed MSPC-related Ag, but did not express myeloid, histocompatibility or endothelial Ag. These cells also possessed multiple capacities for osteogenic, chondrogenic and adipogenic differentiation. Discussion Although the incidence of UCB harvests producing MSPC in culture was low, some of them showed a more than 1000-fold expanding capacity, which is enough in cell numbers to be an allogeneic source for cellular therapy. Our results may encourage the use of UCB as an attractive target for allogeneic cellular therapeutic options in tissue engineering.