In vitro differentiation of human cord blood-derived unrestricted somatic stem cells towards an endodermal pathway

BACKGROUND: Pluripotent unrestricted somatic stem cells (USSC) from UC blood can differentiate into hepatic cells in the in utero sheep model, resulting in 20% human albumin-producing parenchymal hepatic cells without cell fusion or tumor-formation events. Additionally, we have shown in vitro differentiation of USSC by hepatocyte growth factor and oncostatin M induction, causing changes in the gene expression towards the endodermal lineage. Positive glycogen synthase expression and a positive periodic acid-schiff reaction demonstrated a functional production of polysaccharides in the cells. METHODS: We describe the in vitro differentiation of USSC towards an endodermal pathway using different matrices, growth factors and organic substances. Also, co-cultures of USSC with primary cells of endodermal tissue were prepared to mimic the biologic niche. We investigated the effect of direct co-culture of USSC with primary rat hepatocytes or with sheep tissue of endodermal origin. Direct co-cultures were set up to ensure cell-cell contacts. For co-cultures without cell-cell contacts, transwell inlays with 1-microm membranes were used to separate the cells. Furthermore, the effect of endodermally conditioned medium was investigated. Changes in the gene expression patterns were analyzed by RT-PCR. RESULTS: We have shown that USSC can differentiate in vitro into an endodermal-like cell with a phenotype similar to hepatic cells. Differentiation of USSC with growth factors, retinoic acid, matrigel matrix and different co-cultures led to an increased expression of albumin and also to the detection of GSC, SOX 17, Cyp2B6, Cyp3A4, Gys2, HNF4a, ISL-1 and Nkx6.1. In addition, functional albumin secretion was observed. DISCUSSION: Although the differentiation assays demonstrated here produce only an immature hepatocyte-like cell, endodermaly differentiated USSC might be a useful alternative for cell replacement in the future.     

Hepatocyte growth factor/c-MET axis-mediated tropism of cord blood-derived unrestricted somatic stem cells for neuronal injury

An under-agarose chemotaxis assay was used to investigate whether unrestricted somatic stem cells (USSC) that were recently characterized in human cord blood are attracted by neuronal injury in vitro. USSC migrated toward extracts of post-ischemic brain tissue of mice in which stroke had been induced. Moreover, apoptotic neurons secrete factors that strongly attracted USSC, whereas necrotic and healthy neurons did not. Investigating the expression of growth factors and chemokines in lesioned brain tissue and neurons and of their respective receptors in USSC revealed expression of hepatocyte growth factor (HGF) in post-ischemic brain and in apoptotic but not in necrotic neurons and of the HGF receptor c-MET in USSC. Neuronal lesion-triggered migration was observed in vitro and in vivo only when c-MET was expressed at a high level in USSC. Neutralization of the bioactivity of HGF with an antibody inhibited migration of USSC toward neuronal injury. This, together with the finding that human recombinant HGF attracts USSC, document that HGF signaling is necessary for the tropism of USSC for neuronal injury. Our data demonstrate that USSC have the capacity to migrate toward apoptotic neurons and injured brain. Together with their neural differentiation potential, this suggests a neuroregenerative potential of USSC. Moreover, we provide evidence for a hitherto unrecognized pivotal role of the HGF/c-MET axis in guiding stem cells toward brain injury, which may partly account for the capability of HGF to improve function in the diseased central nervous system.     

Transplanted human cord blood-derived unrestricted somatic stem cells preserve high-energy reserves at the site of acute myocardial infarction

Background aimsIt has been demonstrated that transplantation of human cord blood-derived unrestricted somatic stem cells (USSC) in a porcine model of acute myocardial infarction (MI) significantly improved left ventricular (LV) function and prevented scar formation as well as LV dilation. Differentiation, apoptosis and macrophage mobilization at the infarct site could be excluded as the underlying mechanisms. The paracrine effect of the cells is most likely to be observed as the cause for the USSC treatment. The aim of our study was to examine the cardiomyocyte metabolism and the role of high-energy phosphates at the marginal infarct.MethodsUSSC were transplanted into the myocardium of the LV, which was supplied by a ligated circumflex artery. Forty-eight hours later, the hearts were harvested and biopsies were performed from the marginal infarct zone surrounding the site of the cell injection. The concentrations of creatinine phosphate (CP), adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) were determined by chromatography.ResultsThe concentration of ADP, ATP and CP in the marginal zone of the infarction was significantly higher in the USSC group. The mean global left ventricular ejection fraction (LVEF) (SD) was 64% (8%) before MI; post-MI, LVEF decreased to 35% (9%).ConclusionsPreservation of high-energy phosphates in the marginal infarct zone suggests that the preservation of energy reserves of surviving cardiomyocytes is a possible mechanism of action of transplanted stem cells in acutely ischemic myocardium.     

Umbilical cord blood-derived cells for tissue repair

Hematopoietic tissue-derived cells, including stem cells, have been shown to generate solid organ tissue-specific cells. Besides bone marrow and peripheral blood, umbilical cord blood (UCB) has the advantage of being an easily accessible stem cell source provided as a banked cell product. Using the xenogeneic human into NOD/SCID mouse stem cell transplant model preliminary data suggest UCB-derived tissue-specific cells generated in liver, pancreas, CNS and endothelium. In a clinical sex-mismatched UCB transplant setting Y-positive, UCB-derived gastrointestinal epithelial cells and CNS-specific cells have been identified in female patients. The potential therapeutic use of UCB cells for tissue repair is, however, limited by a low total stem cell number available and by HLA-disparity.     

Good manufacturing practice-grade production of unrestricted somatic stem cell from fresh cord blood

Background aimsThe discovery of unrestricted somatic stem cells (USSC), a non-hematopoietic stem cell population, brought cord blood (CB) to the attention of regenerative medicine for defining more protocols for non-hematopoietic indications. We demonstrate that a reliable and reproducible method for good manufacturing practice (GMP)-conforming generation of USSC is possible that fulfils safety requirements as well as criteria for clinical applications, such as adherence of strict regulations on cell isolation and expansion.MethodsIn order to maintain GMP conformity, the automated cell processing system Sepax (Biosafe) was implemented for mononucleated cell (MNC) separation from fresh CB. After USSC generation, clinical-scale expansion was achieved by multi-layered CellSTACKs (Costar/Corning). Infectious disease markers, pyrogen and endotoxin levels, immunophenotype, potency, genetic stability and sterility of the cell product were evaluated.ResultsThe MNC isolation and cell cultivation methods used led to safe and reproducible GMP-conforming USSC production while maintaining somatic stem cell character.ConclusionsTogether with implemented in-process controls guaranteeing contamination-free products with adult stem cell character, USSC produced as suggested here may serve as a universal allogeneic stem cell source for future cell treatment and clinical settings.     

A comparison between osteogenic differentiation of human unrestricted somatic stem cells and mesenchymal stem cells from bone marrow and adipose tissue

To evaluate the potential of three stem cells for cell therapy and tissue engineering applications, the biological behavior and osteogenic capacity of the newly introduced cord-blood-derived, unrestricted somatic stem cells (USSC) were compared with those of mesenchymal stem cells isolated from bone marrow (BM-MSC) and adipose tissue (AT-MSC). There was no significant difference between the rates of proliferation of the three stem cells. During osteogenic differentiation, alkaline phosphatase (ALP) activity peaked on day 7 in USSC compared to BM-MSC which showed the maximum value of ALP activity on day 14. However, BM-MSC had the highest ALP activity and mineralization during osteogenic induction. In addition, AT-MSC showed the lowest capacity for mineralization during differentiation and had the lowest ALP activity on days 7 and 14. Although AT-MSC expressed higher levels of collagen type I, osteonectin and BMP-2 in undifferentiated state, but these genes were expressed higher in BM-MSC during differentiation. BM-MSC also expressed higher levels of ALP, osteocalcin and Runx2 during induction. Taking together, BM-MSC showed the highest capacity for osteogenic differentiation and hold promising potential for bone tissue engineering and cell therapy applications.     

Evaluation of unrestricted somatic stem cells as a feeder layer to support undifferentiated embryonic stem cells

The use of unrestricted somatic stem cells (USSCs) holds great promise for future clinical applications. Conventionally, mouse embryonic fibroblasts (MEFs) or other animal‐based feeder layers are used to support embryonic stem cell (ESC) growth; the use of such feeder cells increases the risk of retroviral and other pathogenic infection in clinical trials. Implementation of a human‐based feeder layer, such as hUSSCs that are isolated from human sources, lowers such risks. Isolated cord blood USSCs derived from various donors were used as a novel, supportive feeder layer for growth of C4mES cells (Royan C4 ESCs). Complete cellular characterization using immunocytochemical and flow cytometric methods were performed on murine ESCs (mESCs) and hUSSCs. mESCs cultured on hUSSCs showed similar cellular morphology and presented the same cell markers of undifferentiated mESC as would have been observed in mESCs grown on MEFs. Our data revealed these cells had negative expression of Stat3, Sox2, and Fgf4 genes while showing positive expression for Pou5f1, Nanog, Rex1, Brachyury, Lif, Lifr, Tert, B2m, and Bmp4 genes. Moreover, mESCs cultured on hUSSCs exhibited proven differentiation potential to germ cell layers showing normal karyotype. The major advantage of hUSSCs is their ability to be continuously cultured for at least 50 passages. We have also found that hUSSCs have the potential to provide ESC support from the early moments of isolation. Further study of hUSSC as a novel human feeder layer may lead to their incorporation into clinical methods, making them a vital part of the application of human ESCs in clinical cell therapy. Mol. Reprod. Dev. 79: 709–718, 2012. © 2012 Wiley Periodicals, Inc.     

Optimization of immunomagnetic separation for cord blood-derived hematopoietic stem cells

Background  

There is a growing interest in cord blood as a source of primitive stem cells with the capacity for multilineage differentiation. Pure cell fractions are needed for the characterization and in vitro expansion of stem cells as well as for their use in preclinical research. However, enrichment of stem cells is challenging due to the lack of stem cell-specific markers and gentle protocols for the isolation of highly pure stem cell fractions. Protocols developed for the enrichment of peripheral blood-derived stem cells have been found to be suboptimal for cord blood.     

人脐带间充质干细胞在组织工程中的研究进展

人脐带间充质干细胞是一类具有自我更新、增殖和多向分化潜能的干细胞,具有来源广泛、易于采集、保存和运输、无异体排斥、避免伦理争议等诸多优点.流式细胞仪分析发现人脐带间充质干细胞高表达间质细胞标志(CD44、CD105)、整合素受体(CD29、CD49b、CD49c、CD51),不表达造血系标志(CD34、CD45)人白细胞抗原HLA-DR和内皮细胞标志CD31.人脐带间充质干细胞在体内外可以分化为骨细胞、软骨细胞、肝细胞、心肌细胞、骨骼肌细胞以及神经元细胞等.目前人脐带间充质干细胞在组织工程骨、人工血管以及基因治疗等临床应用研究中已逐渐深入,并已显示出广阔的应用前景.本文就人脐带间充质干细胞的生物学特性及其在组织工程中的研究作一综述.     

Differentiating characterization of human umbilical cord blood-derived mesenchymal stem cells in vitro

It has been demonstrated that the number and differentiating potential of bone marrow mesenchymal stem cells (MSCs) decrease with age. Therefore, the search for alternative sources of MSCs is of significant value. In the present study, MSCs were isolated from umbilical cord blood (UCB) by combining gradient density centrifugation with plastic adherence. Cultured cells were treated with ascorbate acid-2-phosphate, dexamethasone, beta-glycerophosphate dexamethasone, insulin, 1-methyl-3-isobutylxamthine, indomethacin, beta-mercaptoethanol, butylated hydroxyanisole, FGF-4 and HGF. Differentiating characterization of UCB-derived MSCs were detected by cytochemistry, immunocytochemistry, radioimmunoassay, RT-PCR and urea assay. The results showed UCB-derived MSCs could differentiate into osteoblasts, adipocytes and neuron-like cells. When MSCs were cultured with FGF-4 and HGF, approximately 63.6% of cells became small, round and epithelioid on day 28 by morphology. Compared with the control, levels of AFP in the supernatant liquid increased significantly from day 12 and were higher on day 28 (P<0.01). Albumin increased significantly from day 16 (P<0.01). Urea was first detected on day 20 (P<0.01), and continued to increase on day 28 (P<0.01). Cells first expressed CK-18 on day 16 through immunocytochemistry analysis. RT-PCR analysis showed that differentiated cells could express a number of hepatocyte-specific genes in a time-dependent manner. Glycogen storage was first seen on day 24. Our results suggest that UCB-derived MSCs can differentiate not only into osteoblasts, adipocytes and neuron-like cells, but also into hepatocytes. Human UCB-derived MSCs are a new source of cell types for cell transplantation and therapy.     

Application of human umbilical cord blood-derived mesenchymal stem cells in disease models

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are regarded as an alternative source of bone marrow-derived mesenchymal stem cells because collection of cord blood is less invasive than that of bone marrow. hUCB-MSCs have recently been studied for evaluation of their potential as a source of cell therapy. In this review, the general characteristics of hUCB-MSCs and their therapeutic effects on various diseases in vitro and in vivo will be discussed.     

Prospects for the therapeutic development of umbilical cord blood-derived mesenchymal stem cells

Umbilical cord blood (UCB) is a primitive and abundant source of mesenchymal stem cells (MSCs). UCB-derived MSCs have a broad and efficient therapeutic capacity to treat various diseases and disorders. Despite the high latent self-renewal and differentiation capacity of these cells, the safety, efficacy, and yield of MSCs expanded for ex vivo clinical applications remains a concern. However, immunomodulatory effects have emerged in various disease models, exhibiting specific mechanisms of action, such as cell migration and homing, angiogenesis, anti-apoptosis, proliferation, anti-cancer, anti-fibrosis, anti-inflammation and tissue regeneration. Herein, we review the current literature pertaining to the UCB-derived MSC application as potential treatment strategies, and discuss the concerns regarding the safety and mass production issues in future applications.     

Effects of hypoxia on proliferation of human cord blood-derived mesenchymal stem cells

The purpose of our study was to examine the influence of hypoxia on proliferation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs). The mononuclear cells were separated by density gradient centrifugation from human umbilical cord blood and then, respectively, cultured under hypoxia (5 % O₂) or normoxia (20 % O₂). Their cell morphology, cell surface markers, β-galactosidase staining, cell growth curve, DNA cycle, and the expression of hypoxia-inducible factor-1α (HIF-1α) were evaluated. We found that hypoxia, in part via HIF-1α, improved the proliferation efficiency, and prevented senescence of hUCB-MSCs without altering their morphology and surface markers. These results demonstrated that hypoxia provides a favorable culture condition to promote hUCB-MSCs proliferation in vitro, which is a better way to obtain sufficient numbers of hUCB-MSCs for research and certainly clinical application.     

In vitro mesengenic potential of human umbilical cord blood-derived mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) have been paid a great deal of attention because of their unprecedented therapeutic merits endowed by powerful ex vivo expansion and multilineage differentiation potential. Umbilical cord blood (UCB) is a convenient but not fully proven source for hMSCs, and hence, greater experience is required to establish UCB as a reliable source of hMSCs. To this end, we attempted to isolate hMSC-like adherent cells from human UCB. The isolated cells were highly proliferative and exhibited an immunophenotype of CD13+ CD14- CD29+ CD31- CD34- CD44+ CD45- CD49e+ CD54+ CD90+ CD106- ASMA+ SH2+ SH3+ HLA-ABC+ HLA-DR-. More importantly, these cells, under appropriate conditions, could differentiate into a variety of mesenchymal lineage cells such as osteoblasts, chondrocytes, adipocytes, and skeletal myoblasts. This mesengenic potential assures that the UCB-derived cells are multipotent hMSCs and further implicates that UCB can be a legitimate source of hMSCs.