The Wharton's jelly of the umbilical cord contains mucoid connective tissue and fibroblast-like cells. Using flow cytometric analysis, we found that mesenchymal cells isolated from the umbilical cord express matrix receptors (CD44, CD105) and integrin markers (CD29, CD51) but not hematopoietic lineage markers (CD34, CD45). Interestingly, these cells also express significant amounts of mesenchymal stem cell markers (SH2, SH3). We therefore investigated the potential of these cells to differentiate into cardiomyocytes by treating them with 5-azacytidine or by culturing them in cardiomyocyteconditioned medium and found that both sets of conditions resulted in the expression of cardiomyocyte markers, namely N-cadherin and cardiac troponin I. We also showed that these cells have multilineage potential and that, under suitable culture conditions, are able to differentiate into cells of the adipogenic and osteogenic lineages. These findings may have a significant impact on studies of early human cardiac differentiation, functional genomics, pharmacological testing, cell therapy, and tissue engineering by helping to eliminate worrying ethical and technical issues.

Human mesenchymal stem cells isolated from Wharton's jelly of the umbilical cord were induced to transform into dopaminergic neurons in vitro through stepwise culturing in neuron-conditioned medium, sonic hedgehog, and FGF8. The success rate was 12.7%, as characterized by positive staining for tyrosine hydroxylase (TH), the rate-limiting catecholaminergic synthesizing enzyme, and dopamine being released into the culture medium. Transplantation of such cells into the striatum of rats previously made Parkinsonian by unilateral striatal lesioning with the dopaminergic neurotoxin 6-hydroxydopamine partially corrected the lesion-induced amphetamine-evoked rotation. Viability of the transplanted cells at least 4 months after transplantation was identified by positive TH staining and migration of 1.4 mm both rostrally and caudally. These results suggest that human umbilical mesenchymal stem cells have the potential for treatment of Parkinson's disease. STEM CELLS 2006; 24:115-124

BackgroundThere is a widespread interest in developing renewable sources of islet-replacement tissue for type I diabetes mellitus. Human mesenchymal cells isolated from the Wharton's jelly of the umbilical cord (HUMSCs), which can be easily obtained and processed compared with embryonic and bone marrow stem cells, possess stem cell properties. HUMSCs may be a valuable source for the generation of islets.Methodology and Principal FindingsHUMSCs were induced to transform into islet-like cell clusters in vitro through stepwise culturing in neuron-conditioned medium. To assess the functional stability of the islet-like cell clusters in vivo, these cell clusters were transplanted into the liver of streptozotocin-induced diabetic rats via laparotomy. Glucose tolerance was measured on week 12 after transplantation accompanied with immunohistochemistry and electron microscopy analysis. These islet-like cell clusters were shown to contain human C-peptide and release human insulin in response to physiological glucose levels. Real-time RT-PCR detected the expressions of insulin and other pancreatic β-cell-related genes (Pdx1, Hlxb9, Nkx2.2, Nkx6.1, and Glut-2) in these islet-like cell clusters. The hyperglycemia and glucose intolerance in streptozotocin-induced diabetic rats was significantly alleviated after xenotransplantation of islet-like cell clusters, without the use of immunosuppressants. In addition to the existence of islet-like cell clusters in the liver, some special fused liver cells were also found, which characterized by human insulin and nuclei-positive staining and possessing secretory granules.Conclusions and SignificanceIn this study, we successfully differentiate HUMSCs into mature islet-like cell clusters, and these islet-like cell clusters possess insulin-producing ability in vitro and in vivo. HUMSCs in Wharton's Jelly of the umbilical cord seem to be the preferential source of stem cells to convert into insulin-producing cells, because of the large potential donor pool, its rapid availability, no risk of discomfort for the donor, and low risk of rejection.

BackgroundHuman umbilical mesenchymal stem cells (HUMSCs) isolated from Wharton's jelly of the umbilical cord can be easily obtained and processed compared with embryonic or bone marrow stem cells. These cells may be a valuable source in the repair of spinal cord injury.Methodology/Principal FindingsWe examine the effects of HUMSC transplantation after complete spinal cord transection in rats. Approximately 5×105 HUMSCs were transplanted into the lesion site. Three groups of rats were implanted with either untreated HUMSCs (referred to as the stem cell group), or HUMSCs treated with neuronal conditioned medium (NCM) for either three days or six days (referred to as NCM-3 and NCM-6 days, respectively). The control group received no HUMSCs in the transected spinal cord. Three weeks after transplantation, significant improvements in locomotion were observed in all the three groups receiving HUMSCs (stem cell, NCM-3 and NCM-6 days groups). This recovery was accompanied by increased numbers of regenerated axons in the corticospinal tract and neurofilament-positive fibers around the lesion site. There were fewer microglia and reactive astrocytes in both the rostral and caudal stumps of the spinal cord in the stem cell group than in the control group. Transplanted HUMSCs survived for 16 weeks and produced large amounts of human neutrophil-activating protein-2, neurotrophin-3, basic fibroblast growth factor, glucocorticoid induced tumor necrosis factor receptor, and vascular endothelial growth factor receptor 3 in the host spinal cord, which may help spinal cord repair.Conclusions/SignificanceTransplantation of HUMSCs is beneficial to wound healing after spinal cord injury in rats.

We investigated the effect of human umbilical mesenchymal stem cells (HUMSCs) from Wharton's jelly on carbon tetrachloride (CCl 4 )-induced liver fibrosis in rats. Rats were treated with CCl 4 for 4 weeks, and this was followed by a direct injection of HUMSCs into their livers. After 4 more weeks of CCl 4 treatment (8 weeks in all), rats with HUMSC transplants [CCl 4 (8W)ϩHUMSC liver] exhibited a significant reduction in liver fibrosis, as evidenced by Sirius red staining and a collagen content assay, in comparison with rats treated with CCl 4 for 8 weeks without HUMSC transplants [CCl 4 (8W)]. Moreover, rats in the CCl 4 (8W)ϩHUMSC (liver) group had significantly lower levels of serum glutamic oxaloacetic transaminase, glutamic pyruvate transaminase, ␣-smooth muscle actin, and transforming growth factor-␤1 in the liver, whereas the expression of hepatic mesenchymal epithelial transition factor-phosphorylated type (Met-P) and hepatocyte growth factor was up-regulated, in comparison with the CCl 4 (8W) group. Notably, engrafted HUMSCs scattered mostly in the hepatic connective tissue but did not differentiate into hepatocytes expressing human albumin or ␣-fetoprotein. Instead, these engrafted, undifferentiated HUMSCs secreted a variety of bioactive cytokines that may restore liver function and promote regeneration. Human cytokine assay revealed that the amounts of human cutaneous T cell-attracting chemokine, leukemia inhibitory factor, and prolactin were substantially greater in the livers of the CCl 4 (8W)ϩHUMSC (liver) group, with considerably reduced hepatic inflammation manifested by a micro positron emission tomography scan. Our findings suggest that xenogeneic transplantation of HUMSCs is a novel approach for treating liver fibrosis and may be a promising therapeutic intervention in the future. Liver Transpl 15: 484-495, 2009.

Mesenchymal stem cells (MSCs) found in bone marrow (BM)-MSCs are an attractive source for the regeneration of damaged tissues. Alternative postnatal, perinatal, and fetal sources of MSCs are also under intensive investigation. MSCs from the Wharton's jelly matrix of umbilical cord (WJ)-MSCs have higher pancreatic and endothelial differentiation potentials than BM-MSCs, but the underlying mechanisms are poorly understood. We compared the gene expression profiles, enriched canonical pathways, and genetic networks of BM-MSCs and WJ-MSCs. WJ-MSCs express more angiogenesis- and growth-related genes including epidermal growth factor and FLT1, whereas BM-MSCs express more osteogenic genes such as RUNX2, DLX5, and NPR3. The gene expression pattern of BM-MSCs is more similar to osteoblasts than WJ-MSCs, suggesting a better osteogenic potential. In contrast, WJ-MSCs are more primitive because they share more common genes with embryonic stem cells. BM-MSCs are more sensitive to environmental stimulations because their molecular signatures altered more significantly in different culture conditions. WJ-MSCs express genes enriched in vascular endothelial growth factor and PI3K-NFκB canonical pathways, whereas BM-MSCs express genes involved in antigen presentation and chemokine/cytokine pathways. Drylab results could be verified by wetlab experiments, in which BM-MSCs were more efficient in osteogenic and adipogenic differentiation, whereas WJ-MSCs proliferated better. WJ-MSCs thus constitute a promising option for angiogenesis, whereas BM-MSCs in bone remodeling. Our results reveal systematically the underlying genes and regulatory networks of 2 MSCs from unique ontological and anatomical origins, as well as the resulted phenotypes, thereby providing a better basis for cell-based therapy and the following mechanistic studies on MSC biology.

Background and Purpose-Stroke is a cerebrovascular defect that leads to many adverse neurological complications.Current pharmacological treatments for stroke remain unclear in their effectiveness, whereas stem cell transplantation shows considerable promise. Previously, we have shown that human umbilical mesenchymal stem cells (HUMSCs) can differentiate into neurons in neuronal-conditioned medium. Here we evaluate the therapeutic potential of HUMSC transplantation for ischemic stroke in rats. Methods-Focal cerebral ischemia was produced by middle cerebral artery occlusion and reperfusion. The HUMSCs treated with neuronal-conditioned medium or not treated were transplanted into the ischemic cortex 24 hours after surgery. Results-Histology and MRI revealed that rats implanted with HUMSCs treated with neuronal-conditioned medium or not treated exhibited a trend toward less infarct volume and significantly less atrophy compared with the control group, which received no HUMSCs. Moreover, rats receiving HUMSCs showed significant improvements in motor function, greater metabolic activity of cortical neurons, and better revascularization in the infarct cortex. Implanted HUMSCs, treated or not treated, survived in the infarct cortex for at least 36 days and released neuroprotective and growth-associated cytokines, including brain-derived neurotrophic factor, platelet-derived growth factor-AA, basic fibroblast growth factor, angiopoietin-2, CXCL-16, neutrophil-activating protein-2, and vascular endothelial growth factor receptor-3. Conclusions-Our results demonstrate the therapeutic benefits of HUMSC transplantation for ischemic stroke, likely due to the ability of the cells to produce growth-promoting factors. Thus, HUMSC transplantation may be an effective therapy in the future.

Neuronal transplantation has provided a promising approach for treating neurodegenerative diseases. Recently, efforts have been directed at in vitro induction of various stem cells to transform into neurons. We report the first successful quantities in an in vitro attempt at directing the transformation into neurons of human umbilical mesenchymal cells, which are capable of rapid proliferation in vitro and are easily available. When cultured in neuronal conditioned medium, human umbilical mesenchymal cells started to express neuron-specific proteins such as NeuN and neurofilament (NF) on the 3rd day and exhibited retraction of the cell body, elaboration of processes, clustering of cells and expression of functional mRNA responsible for the synthesis of subunits of the kainate receptor and glutamate decarboxylase on the 6th day. Between the 9th and 12th days, the percentage of human umbilical mesenchymal cells expressing NF was as high as 87%, while functionality was demonstrated by glutamate invoking an inward current. At this stage, cells were differentiated into mature neurons in the post mitosis phase.