Aberrant expression and significance of OCT-4A transcription factor in leukemia cells.

OBJECTIVE: To determine the contribution of the OCT-4 to the pathogenesis of leukemia. METHODS: Bone marrow (BM) samples obtained from 72 patients with leukemia, and 18 normal healthy subjects were assayed for their OCT-4 expression using both flow cytometry and RT-PCR. RESULTS: OCT-4 expression in BM nucleated cells of acute leukemia patients (n=33) was significantly higher than that of complete remission and chronic phase leukemia patients (n=39, p<0.001) and healthy donors (n=18, p<0.001). OCT-4 expression had a significant positive relation with CD34 expression (n=43, r=0.721, p<0.001) and the proportion of naive cells (n=60, r=0.687, p<0.001). In addition, the results of QRT-PCR detection showed that the OCT-4A had increased expression in BM nucleated cells in the patients with acute leukemia (n=33, median 16.585, range 0.38-169.62) compared to that in leukemia patients with chronic phase and in complete remission (n=39, median 3.34, range 0.04-44.49, p<0.001) and that of normal controls (n=18, median 2.89, range 0.18-16.23, p<0.001). CONCLUSION: OCT-4A expression was significantly increased in the BM nucleated cells of patients with acute leukemia, indicating that OCT-4A may play an important role in the pathogenesis of leukemia and may serve as a molecular target for the development of novel diagnostic and treatment strategies in leukemia.

Expression and role of Toll-like receptors on human umbilical cord mesenchymal stromal cells.

BACKGROUND AIMS: Toll-like receptors (TLRs) play an important role in innate and adaptive immunity by recognizing pathogen-associated molecular patterns (PAMPs). METHODS: In the present study, we investigated the expression and role of TLRs on human umbilical cord mesenchymal stromal cells (UC-MSCs). The proliferation, differentiation and immunoregulatory activity of UC-MSCs primed with or without TLR ligands were determined. RESULTS: At the RNA level, the expression of TLR2, 4, 6 and 9 was relatively higher than that of other TLRs. However, TLR3 and TLR4 expression were relatively higher at the protein level. UC-MSCs expressed functional TLRs by nuclear factor-κB activation and cytokine expression assay. Poly-inosinic acid:cytidylic acid [Poly(I:C)] stimulation inhibited the proliferation of UC-MSCs, but the ligand of other TLRs had no significant effect. Poly(I:C) stimulation enhanced the adipogenic differentiation capability of UC-MSCs, but lipopolysaccharide inhibited the adipogenic differentiation. Poly(I:C) and CpG-oligonucleotide promoted the immunosuppressive potentiality of UC-MSCs, accompanied with the phosphorylation of interferon regulatory factor 3 (IRF3) and increased expression of indoleamine 2,3-dioxygenase and interferon ß, whereas activation of other TLR ligands (synthetic analog fibroblast-stimulating lipopeptide-1 and lipopolysaccharide) failed to affect the immunoregulatory activity of UC-MSCs. CONCLUSIONS: Taken together, our data demonstrated that TLR activation influenced the function of UC-MSCs, which might have important implications in future efforts to explore the clinical potentials of UC-MSCs.

CD72 gene expression in immune thrombocytopenia.

To explore the role of CD72 in the pathogenesis of immune thrombocytopenia (ITP), we detected CD72, Sema4D, IL-2, IL-4, and IFN-γ mRNA expressions and the levels of plasma Sema4D, IL-2, IL-4, IL-6, and IFN-γ in ITP patients (n = 39) and controls (n = 23). The levels of plasma IL-2, IL-4, and IL-6 were assayed by radioimmunoassay, and the levels of plasma IFN-γ and Sema4D were analyzed by enzyme-linked immunosorbent assay. Sema4D, CD72, IL-2, IFN-γ, and IL-4mRNA expressions were analyzed by real-time quantitative reverse-transcription polymerase chain reaction. The expression of CD72 mRNA in ITP patients (n = 23) with active disease was significantly lower than that in patients in remission (p = 0.029) (n = 16) and controls (p = 0.0296) (n = 23). The IFN-γ/IL-4 mRNA (Th1/Th2) expression in ITP patients with active disease and in remission was significantly higher than that in controls (p = 0.0023, p = 0.0125, respectively). The expression of IL-2 mRNA in ITP patients with active disease was significantly lower than that in patients in remission (p = 0.0418) and controls (p = 0.004). The level of plasma IL-2 in ITP patients with active disease was significantly lower than that in patients in remission (p = 0.0029) and controls (p = 0.0101). The levels of plasma IL-4 in ITP patients with active disease and in remission were significantly higher than that of controls (p = 0.0093, p = 0.0053, respectively). CD72 mRNA expression level might correlate with Sema4D mRNA expression in peripheral blood mononuclear cells and level of plasma IL-2 in active ITP patients (p = 0.024 and p = 0.036). Our findings suggest that CD72 might be involved in the pathophysiological process of the ITP disease by increasing B-cell receptor signals.

Bone marrow-derived cells can acquire renal stem cells properties and ameliorate ischemia-reperfusion induced acute renal injury.

BACKGROUND: Bone marrow (BM) stem cells have been reported to contribute to tissue repair after kidney injury model. However, there is no direct evidence so far that BM cells can trans-differentiate into renal stem cells. METHODS: To investigate whether BM stem cells contribute to repopulate the renal stem cell pool, we transplanted BM cells from transgenic mice, expressing enhanced green fluorescent protein (EGFP) into wild-type irradiated recipients. Following hematological reconstitution and ischemia-reperfusion (I/R), Sca-1 and c-Kit positive renal stem cells in kidney were evaluated by immunostaining and flow cytometry analysis. Moreover, granulocyte colony stimulating factor (G-CSF) was administrated to further explore if G-CSF can mobilize BM cells and enhance trans-differentiation efficiency of BM cells into renal stem cells. RESULTS: BM-derived cells can contribute to the Sca-1(+) or c-Kit(+) renal progenitor cells population, although most renal stem cells came from indigenous cells. Furthermore, G-CSF administration nearly doubled the frequency of Sca-1+ BM-derived renal stem cells and increased capillary density of I/R injured kidneys. CONCLUSIONS: These findings indicate that BM derived stem cells can give rise to cells that share properties of renal resident stem cell. Moreover, G-CSF mobilization can enhance this effect.

Establishment of a new method to induce the differentiation of embryonic pancreatic cells into mature endocrine cells.

OBJECTIVE: To establish a new culture method to induce the differentiation of embryonic pancreatic cells into mature endocrine cells. METHODS: Mouse embryos at day 12.5 were used and embryonic pancreata were isolated. The isolated embryonic pancreata were cultured on the filter for 7 days, which floated in the dish containing medium. During culture, the expression of pancreas duodenum homeobox-1 (PDX-1), a pancreatic stem cell marker, was examined at day 1. The expression of neurogenin 3 (Ngn3), a pancreatic progenitor cell marker, was examined at day 3. The expressions of endocrine and exocrine markers, insulin, glucagon, and carboxypeptidase (CPA) were examined at day 7 by immunohistochemistry. The kinetics of pancreatic marker expression during culture was assayed by real-time PCR. RESULTS: Many pancreatic stem cells still existed in embryonic pancreata cultured for 1 day; meanwhile, these pancreatic stem cells proliferated in high rate. A large amount of pancreatic progenitor cells were found in embryonic pancreata cultured for 3 days.Pancreatic stem/progenitor cells differentiated into mature endocrine and exocrine cells in embryonic pancreata after having been cultured for 7 days. Furthermore, the expression pattern of pancreatic marker is consistent with that in vivo. CONCLUSION: We successfully established a new culture method, with which embryonic pancreatic cells can efficiently differentiate into mature endocrine cell.

Interleukin-27 enhances the production of tumour necrosis factor-α and interferon-γ by bone marrow T lymphocytes in aplastic anaemia.

Aplastic anaemia (AA) is considered as an immune-mediated bone marrow failure syndrome. The mechanism is involved with a variety of immune molecules including interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α) and interleukins (ILs). IL-27 is a novel member of the IL-12 family, which mediates T cell response and enhances the production of IFN-γ. However, little is known about the role of IL-27 in the development of AA. This study investigated the role of IL-27 and its receptor IL-27R in the pathogenesis of AA. Both the mRNA expression of IL-27/IL-27R subunits in the bone marrow mononuclear cells (BMMNCs) and the levels of IL-27 in the marrow plasma in AA were found to be higher than in controls. Increased IL-27 correlated with the disease severity of AA. Subsequently, we stimulated marrow T lymphocytes with recombinant human (rh)IL-27 and found that rhIL-27 enhanced the production of TNF-α and IFN-γ in both CD4(+) and CD8(+) T lymphocytes from AA patients. We also detected increased TNF-α and IFN-γ in the supernatants of BMMNCs from AA patients after IL-27 stimulation. In conclusion, our data suggest that elevated IL-27 and IL-27-induced TNF-α and IFN-γ overproduction might be involved in the pathogenesis of AA.

Development and investigational new drug application of mesenchymal stem/stromal cells products in China.

Mesenchymal stem/stromal cells (MSCs) have broad application prospects for regenerative medicine due to their self-renewal, high plasticity, ability for differentiation, and immune response and modulation. Interest in turning MSCs into clinical applications has never been higher than at present. Many biotech companies have invested great effort from development of clinical grade MSC product to investigational new drug (IND) enabling studies. Therefore, the growing demand for publication of MSC regulation in China necessitates various discussions in accessible professional journals. The National Medical Products Administration has implemented regulations on the clinical application of MSCs therapy. The regulations for MSCs products as drug have been updated in recent years in China. This review will look over the whole procedure in allogeneic MSC development, including regulations, guidance, processes, quality management, pre-IND meeting, and IND application for obtaining an approval to start clinical trials in China. The review focused on process and regulatory challenges in the development of MSCs products, with the goal of providing strategies to meet regulatory demands. This article describes a path for scientists, biotech companies, and clinical trial investigators toward the successful development of MSC-based therapeutic product.

The Promise of Mesenchymal Stem Cells Therapy for Acute Respiratory Distress Syndrome Caused by COVID-19.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) since Dec 2019, known as COVID-19 or 19-nCoV, has led to a major concern of the potential for not only an epidemic but a pandemic in China and now it seems to be a public health problem all over the world. The general mortality rate of the COVID-19 was about 3%. However, the mortality risk seems to be a significant increase in elderly and cases with chronic disease, who are more likely to develop into acute respiratory distress syndrome (ARDS). There still lacks effective methods for ARDS of COVID-19 patients and the prognosis was poor. Mesenchymal Stem Cells (MSCs) based treatment has the advantage of targeting numerous pathophysiological components of ARDS by secreting a series of cell factors, exerting anti-inflammatory, antioxidative, immunomodulatory, antiapoptotic, and proangiogenic effects, resulting in significant structural and functional recovery following ARDS in various preclinical models. Recently, pilot clinical studies indicated MSCs based therapy was promise in treatment of ARDS caused by SARS-CoV-2. However, little is known about MSCs therapy for ARDS caused by COVID-19.

Suppression of ABCG2 inhibits cancer cell proliferation.

The ATP-binding cassette efflux transporter, ABCG2, is widely expressed in a variety of normal tissues, stem cells, as well as cancer cells. Existing data suggest that ABCG2 plays an important role in the maintenance of the stem cell phenotype and multidrug resistance of cancer cells. However, the potential role of ABCG2 in other cellular processes remains speculative and poorly understood. Here, we demonstrated that ABCG2 is involved in the proliferation of cancer cells. We used RNA interference approach to efficiently and specifically down-regulate ABCG2 protein levels in MCF-7/MX and A549 cells. We showed that knockdown of ABCG2 significantly inhibited the proliferation of these cells. Suppression of ABCG2 reduced the percentage of cells in the S phase of the cell cycle and enhanced G0/G1 accumulation. The G0/G1 growth arrest was associated with down-regulation of cyclin D3 and up-regulation of p21. Furthermore, blocking of ABCG2 function by chemical inhibitor fumitremorgin C also inhibited cell proliferation via the prolonged G0/G1 interval. Taken together, these findings suggest that ABCG2 correlates with cell cycle progression, highlighting a novel function of ABCG2 in cancer cell proliferation.

No contribution of umbilical cord mesenchymal stromal cells to capillarization and venularization of hepatic sinusoids accompanied by hepatic differentiation in carbon tetrachloride-induced mouse liver fibrosis.

BACKGROUND AIMS: The acceleration of capillarization and venularization of hepatic sinusoids after cell therapy would not be beneficial to restoration after liver disease. The goal was to observe the effects of umbilical cord (UC)-derived mesenchymal stromal cells (MSC) on liver microcirculation and their therapeutic potential in liver fibrosis. METHODS: Human UC MSC labeled with or without CM-DIL were transplanted into NOD/SCID mice with carbon tetrachloride (CCl4)-induced chronic liver fibrosis models. Because of the high autofluorescence on the injured liver sections, we used immunohistochemistry, Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR), but not immunofluorescence, in order to avoid false images under a confocal fluorescence microscope. RESULTS: Human-specific alpha-fetoprotein and albumin mRNA and proteins were detected in CCl4-treated mouse livers receiving human UC MSC transplants. We only observed the gene expression of human-specific endothelial-like cells markers CD31 and KDR by RT-PCR, but not protein expression by immunohistochemistry, in UC MSC-transplanted mouse livers. Vascular endothelial growth factor (VEGF) expression in injured livers 4 weeks after UC MSC transplantation was higher than in normal livers. However, UC MSC injection did not increase significantly the vascular density labeled by CD31 and (vWF) in the injured livers of UC MSC-transplanted mice compared with non-transplanted mice after CCl4 treatment. In addition, liver function was partly improved after UC MSC transplantation. CONCLUSIONS: Human UC MSC can differentiate into hepatocyte-like cells but do not accelerate the capillarization and venularization of hepatic sinusoids, finally leading to the partial improvement of liver function in mice with CCl4-mediated chronic liver fibrosis.

Stem/progenitor cells in liver injury repair and regeneration.

Morbidity and mortality from cirrhosis is increasing rapidly in the world. Currently, orthotopic liver transplantation is the only definitive therapeutic option. However, its clinical use is limited, because of poor long-term graft survival, donor organ shortage and high costs associated with the procedure. Stem cell replacement strategies are therefore being investigated as an attractive alternative approach to liver repair and regeneration. In this review we discuss recent preclinical and clinical investigations that explore the therapeutic potential of stem cells in repair of liver injuries. Several types of stem cells. including embryonic stem cells, haematopoietic stem cells and mesenchymal stem cells, can be induced to differentiate into hepatocyte-like cells by defined culture conditions in vitro. Stem cell transplantation has been shown to significantly improve liver function and increase animal survival in experimentally-induced liver-injury models. Moreover, several pilot clinical studies have reported encouraging therapeutic effects in patients treated with stem cells. Although there remain many unresolved issues, the available data support the notion that stem cell technology may lead to the development of effective clinical modalities for human liver diseases.

[Differentiation of human umbilical cord derived mesenchymal stem cells into low immunogenic and functional hepatocyte-like cells in vitro].

OBJECTIVE: To investigate the biological function of hepatocyte-like cells derived from mesenchymal stem cells that isolated from human umbilical cord UC-MSCs in vitro, and to detect the changes in the immunogenicity of the differentiated hepatocyte-like cells (DHC). METHODS: Transdifferentiation of UC-MSCs into hepatic lineage in vitro was induced in modified two-step induction medium. The expressions of hepatic specific markers were detected by RT-PCR analysis and immunofluorescence staining at different time points after induction. The levels of albumin and urea in the supernatants of cultures were measured by enzyme-linked immunosorbent assay. Furthermore, the immunosuppressive property of DHC was detected by one-way mixed lymphocyte culture. RESULTS: The mRNA and proteins of alpha fetoprotein (AFP), albumin (ALB),and cytokeratin-19 (CK-19) were expressed in naive UC-MSCs at low levels. DHC highly expressed hepatic markers AFP, ALB, CK-19, and tryptophan 2, 3-dioxygenase 14 and 28 days after hepatic differentiation and were accompanied by an increased production of ALB and urea in supernatant in a time-dependent manner. DHC did not express human leukocyte antigen DR antigen and significantly decreased the lymphocyte proliferation. CONCLUSION: UC-MSCs are able to differentiate into functional hepatocyte-like cells in vitro, while the immunogenicity of DHC remains low.

Differentiation of human umbilical cord mesenchymal stromal cells into low immunogenic hepatocyte-like cells.

BACKGROUND AIMS: Mesenchymal stromal cells (MSC) isolated from several human tissues have been known to differentiate into the hepatic lineage in vitro, but the immunogenicity of the differentiated hepatocyte-like cells (DHC) has not been reported. Umbilical cord (UC) MSC are thought to be an attractive cell source for cell therapy because of their young age and low infection rate compared with adult tissue MSC. METHODS: Hepatic differentiation of UC-MSC was induced with a 2-step protocol. The expressions of hepatic markers were detected by RT-PCR and immunofluorescence staining. Albumin production and urea secretion were measured by ELISA and colorimetric assay respectively. The immunosuppressive properties of DHC was detected by mixed lymphocyte culture. RESULTS: After incubation with specific growth factors, including hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF), UC MSC exhibited a high hepatic differentiation ability in an adherent culture condition. The differentiated UC MSC showed hepatocyte-like morphology and expressed several liver-specific markers at gene and protein levels. Furthermore, the DHC exhibited hepatocyte-specific functions, including albumin secretion, low-density lipoprotein uptake and urea production. More importantly, DHC did not express major histocompatibility complex (MHC) II antigen and were not able to induce lymphocyte proliferation in mixed lymphocyte culture, as undifferentiated UC MSC did. CONCLUSIONS: Our results indicate that UC MSC are able to differentiate into functional hepatocyte-like cells that still retain their low immunogenicity in vitro. More importantly, DHC incorporated into the parenchyma of liver when transplanted into mice with CCl(4)-induced liver injury. Therefore, DHC may be an ideal source for cell therapy of liver diseases.

Systematic comparison of hUC-MSCs at various passages reveals the variations of signatures and therapeutic effect on acute graft-versus-host disease.

BACKGROUND: Mesenchymal stem cells are heterogenous populations with hematopoietic supporting and immunomodulating capacities. Enormous studies have focused on their preclinical or clinical therapeutic effects, yet the systematic study of continuous in vitro passages on signatures and functions of UC-MSCs at both the cellular and molecular levels is still lacking. METHODS: In this study, to systematically evaluate the biological properties of MSCs at various passages, we analyzed biomarker expression, cell proliferation and apoptosis, chromosome karyotype, and tri-lineage differentiation potential. Subsequently, we took advantage of whole-exome sequencing to compare the somatic hypermutation of hUC-MSCs at P3, P6, and P15 including SNV and INDEL mutations. In addition, to explore the safety of the abovementioned hUC-MSCs, we performed metabolic pathway enrichment analysis and in vivo transplantation analysis. Furthermore, we cocultured the abovementioned hUC-MSCs with UCB-CD34+ HSCs to evaluate their hematopoietic supporting capacity in vitro. Finally, we transplanted the cells into acute graft-versus-host disease (aGVHD) mice to further evaluate their therapeutic effect in vivo. RESULTS: The hUC-MSCs at P3, P6, and P15 showed similar morphology, biomarker expression, and cytokine secretion. hUC-MSCs at P15 had advantages on adipogenic differentiation and some cytokine secretion such as IL-6 and VEGF, with disadvantages on cell proliferation, apoptosis, and osteogenic and chondrogenic differentiation potential. Based on the SNP data of 334,378 exons and bioinformatic analyses, we found the somatic point mutations could be divided into 96 subsets and formed 30 kinds of signatures but did not show correlation with risk of tumorigenesis, which was confirmed by the in vivo transplantation experiments. However, hUC-MSCs at P15 showed impaired hematologic supporting effect in vitro and declined therapeutic effect on aGVHD in vivo. CONCLUSIONS: In this study, we systematically evaluated the biological and genetic properties of hUC-MSCs at various passages. Our findings have provided new references for safety and effectiveness assessments, which will provide overwhelming evidence for the safety of hUC-MSCs after continuous in vitro passages both at the cellular and molecular levels for the first time. Taken together, our studies could help understand the controversial effects of disease treatment and benefit the clinical research of UC-MSCs.

Hemangiopoietin promotes endothelial cell proliferation through PI-3K/Akt pathway.

Hemangiopoietin (HAPO) is a novel human growth factor acting on the primitive cells of both hematopoietic and endothelial cell lineages. Our previous study has shown that HAPO exerts a proliferative effect on endothelial cells. However, the mechanism of this action remains unclear. Thus, we studied the signal transduction pathway whereby HAPO promotes cell proliferation in human umbilical vein endothelial cells (HUVECs). In this study, recombinant human HAPO (rhHAPO) stimulated the proliferation of HUVECs in a dose-dependent manner. The transient phosphorylation of Akt occurred after addition of rhHAPO to HUVECs. LY294002, a specific inhibitor of PI-3K, significantly inhibited Akt phosphorylation and completely abrogated HAPO-stimulated proliferation of HUVECs. rhHAPO enhanced the expression of cyclin D1, where as LY294002 inhibited the up-regulation of cyclin D1. Moreover, rhHAPO is able to selectively enhance the mitogenic activity of VEGF for vascular endothelial cells. Overall, these findings demonstrate that HAPO induces endothelial cell proliferation through the PI-3K/Akt pathway.

Comparison of Teratoma Formation between Embryonic Stem Cells and Parthenogenetic Embryonic Stem Cells by Molecular Imaging.

With their properties of self-renewal and differentiation, embryonic stem (ES) cells hold great promises for regenerative therapy. However, teratoma formation and ethical concerns of ES cells may restrict their potential clinical applications. Currently, parthenogenetic embryonic stem (pES) cells have attracted the interest of researchers for its self-renewing and pluripotent differentiation while eliciting less ethic concerns. In this study, we established a model with ES and pES cells both stably transfected with a double-fusion reporter gene containing renilla luciferase (Rluc) and red fluorescent protein (RFP) to analyze the mechanisms of teratoma formation. Transgenic Vegfr2-luc mouse, which expresses firefly luciferase (Fluc) under the promoter of vascular endothelial growth factor receptor 2 (Vegfr2-luc), was used to trace the growth of new blood vessel recruited by transplanted cells. Bioluminescence imaging (BLI) of Rluc/Fluc provides an effective tool in estimating the growth and angiogenesis of teratoma in vivo. We found that the tumorigenesis and angiogenesis capacity of ES cells were higher than those of pES cells, in which VEGF/VEGFR2 signal pathway plays an important role. In conclusion, pES cells have the decreased potential of teratoma formation but meanwhile have similar differentiating capacity compared with ES cells. These data demonstrate that pES cells provide an alternative source for ES cells with the risk reduction of teratoma formation and without ethical controversy.

VE-Cadherin regulates the self-renewal of mouse embryonic stem cells via LIF/Stat3 signaling pathway.

With the abilities of self-renewal and differentiation, embryonic stem (ES) cells provide an unlimited source for stem cell-based therapeutics. However, the maintenance of ES cells with mouse embryonic fibroblasts (MEFs) can limit the clinical translation of ES cells. In the present study, we synthesized a fusion protein of the immunoglobulin G (IgG) fragment crystallizable region and vascular endothelial cadherin (VE-cadherin) extracellular domain (VE-cad-Fc) as a substrate for mouse ES cell culture, and we hypothesized that VE-cadherin could enhance the pluripotency and self-renewal of ES cells. Furthermore, we introduced a Stat3 reporter imaging system into ES cells and investigated the mechanism of the pluripotency enhancement mediated by VE-cadherin through cultured ES cells on VE-cad-Fc-coated plates using molecular imaging techniques. The resulting data revealed that VE-cad-Fc could activate the Stat3 signaling pathway, leading to the upregulation of stemness-related markers SSEA-1 and alkaline phosphatase (ALP). Moreover, VE-cad-Fc recovered the expression of Oct4, c-Myc, Nanog, Sox2, Tbx3 and Klf4 in differentiated ES cells, as well as enhanced the pluripotency of ES cells. In conclusion, VE-cadherin fusion protein coating methods provide an alternative towards feeder free culture of ES cells, and the strategy developed in the present study may benefit the clinical translation of ES cell-based therapeutics.

Isolation and characterization of human umbilical cord mesenchymal stem cells with hematopoiesis-supportive function and other potentials.

BACKGROUND AND OBJECTIVES: Adult bone marrow (BM) is the major source of mesenchymal stem cells (MSC) for cell therapy. However, aspiration of BM involves invasive procedures. We isolated MSC from human full term umbilical cord tissues (UC). The biological characteristics of MSC derived from UC (UC-MSC) were further determined and compared with normal adult bone marrow-derived MSC (BM-MSC). DESIGN AND METHODS: MSC were isolated from UC by enzyme digestion and cultured in appropriate growth medium. The isolation efficiency, cell yield, colony-forming unit-fibroblast (CFU-F) frequency, growth kinetics, phenotypic characteristics, multi-lineage differentiation capacity, cytokine spectrum as well as hematopoiesis-supportive function of UC-MSC were determined and compared with those of BM-MSC. RESULTS: MSC were successfully isolated from all 36 UC and six BM samples we collected for this study. The mean number of nucleated cells isolated from UC was 1yen106/cm and the yield of adherent cells was 8.6yen105/cm. UC-MSC shared most of the characteristic of BM-MSC, including fibroblastic-like morphology, immunophenotype, cell cycle status, adipogenic and osteogenic differentiation potentials, and hematopoiesis-supportive function. The CFU-F frequency was higher in UC nucleated cells (1:1609 +/- 0.18) than in BM nucleated cells (1:35700 +/- 0.01) (p < 0.05). Furthermore, in comparison with BM-MSC, the UC-MSC had a higher proliferation capacity and lower levels of expression of CD106 and HLA-ABC (p < 0.05). Immunofluoresent and western blot assays revealed that UC-MSC had a higher percentage of neuron specific enolase-positive cells than had BM-MSC after neuronal induction. Finally, reverse transcriptase polymerase chain reaction analysis showed that UC-MSC had a cytokine spectrum very similar to that of BM-MSC, including expression of the mRNA of stem cell factor, leukemia inhibitor factor, macrophage-colony stimulating factor, Flt3-ligand, interleukin-6, vascular endothelial growth factor and stromal-derived factor-1, but UC-MCS additionally expressed mRNA of granulocyte macrophage and granulocyte colony-stimulating factors. After co-culture with CD34+ cord blood cells for 5 weeks, no significant difference in colony-forming cells was observed between the CD34+ cells/UC-MSC and CD34+ cells/BM-MSC co-cultures (p > 0.05). INTERPRETATION AND CONCLUSIONS: We have established a protocol to isolate abundant MSC from human umbilical cords with a 100% success rate. The comparative study indicates that UC is an excellent alternative to BM as a source of MSC for cell therapies.

[In vitro vasculogenesis and angiogenesis of mouse embryonic stem cells].

OBJECTIVE: To explore an optional condition to induce mouse embryonic stem (ES) cells to differentiate into endothelial cells and to establish in vitro models of vasculogenesis and angiogenesis. METHODS: Mouse ES cells were cultured in differentiation medium containing a cocktail of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), interleukin-6 (IL-6) and erythropoietin (EPO) in 1% methylcellulose to induce formation of embryoid bodies (EBs). At day 11, EBs were harvested and suspended in rat-tail collagen type I with the same cocktail of cytokines cultured for three additional days. The differentiation of ES cells into endothelial cells, processes of vasculogenesis and angiogenesis were examined using immunostaining of EBs slices and whole-mount immunocytochemistry of EBs with monoclonal antibodies (mAbs) against platelet endothelial cell adhesion molecule-1 (PECAM-1) and alpha-smooth muscle actin (SMA). RESULTS: Under appropriate culture conditions; ES cells spontaneously differentiated and formed EBs containing vascular structures and tubular channels, which were positive for PECAM-1 co-differentiated with smooth muscle. When not treated with angiogenic growth factors, PECAM-1-positive cells could not organize into vascular structures of 11-day-old EBs. In the presence of angiogenic factors 11-day old EBs embedded into type I collagen, and rapidly developed an endothelial networks. Whole-mount immunocytochemistry of collagen gel with anti-PECAM-1 antibody showed the formation of primary vascular structures sprouting from EBs. Quantitative analysis revealed that 100 microg/ml thalidomide significantly reduced the number and length of EBs endothelial sprouting. CONCLUSIONS: Mouse ES cells can differentiate into endothelial cells combined with smooth muscle differentiation during EBs formation and further develop endothelial outgrowths after EBs embedded into collagen, which respectively recapitulate vasculogenesis, angiogenesis, and arteriogenesis processes in vivo. The models provide a useful tool to investigate vasculogenesis, angiogenesis, and arteriogenesis mechanisms and evaluate the effects of angiogenic and angiostatic agents.

Impaired immunomodulatory ability of bone marrow mesenchymal stem cells on CD4(+) T cells in aplastic anemia.

Aplastic anemia (AA) is a marrow failure syndrome mediated by aberrant T-cell subsets. Mesenchymal stem cells (MSCs) play an important role in maintaining immune homeostasis through modulating a variety of immune cells. However, little is known about the immunomodulation potential of bone marrow MSCs (BM-MSCs) in AA. Here, we reported that BM-MSCs from AA patients were reduced in suppressing the proliferation and clonogenic potential of CD4(+) T cells and the production of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), which was associated with decreased prostaglandin E2 (PGE2). Meanwhile, BM-MSCs from AA patients were defective to promote CD4(+)CD25(+)FOXP3(+) regulatory T cells expansion through reduced transforming growth factor-ß (TGF-ß). No significant difference between AA and normal BM-MSCs was observed in affecting the production of interleukins (IL)-4, IL-10 and IL-17. Our data indicate that BM-MSCs were impaired in maintaining the immune homeostasis associated with CD4(+) T cells, which might aggravate the marrow failure in AA.