With the capacities of multiple differentiation, immunoregulatory activities and easy handling for isolation and culture expansion, human bone marrow mesenchymal stem cells (MSCs) have been utilized in clinical trials for the prevention and treatment of graft-versus-host disease in allogeneic bone marrow transplantation, repair of bone and cartilage defects and treatment of cardiac infarction and liver injury. However, increasingly experimental data indicate that a great deal of issues, such as intra-neutralization of calf serum proteins into cultured MSCs, survival of engrafted cells and subsequent cell differentiation tendency, should be in stringent consideration before clinical trials are designed. In this paper, these issues that should be raised and solved in clinical trials with MSCs were reviewed.
Bone Marrow Transplantation ; adverse effects ; Clinical Trials as Topic ; Graft vs Host Disease ; prevention & control ; Humans ; Mesenchymal Stem Cell Transplantation ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Research Design

Objective: To investigate the role of human umbilical vein endothelial cells (HUVEC) in supporting hematopoiesis and the expansion of hematopoietic stem/progenitor cells in vitro. Methods: According to the fact that HUVEC supernatant has colony stimulating activity shown by methylcellulose colony-forming assay and HUVEC can maintain the survival of mononuclear cells for at least four weeks in vitro, CD34+ cells from umbilical cord blood were seeded with (HUVEC group) or without (control group) HUVEC monolayer. Every week cells were collected and counted, the frequency of CFU-GM was measured by using methylcellulose colony-forming assay, and the percentage of CD34+ and CD41a+ cells was measured by flow cytometry. Results: In control group，all the CD34+ cells died in two weeks. However, in HUVEC group,most nucleated cells and CD34+ cells were expanded by 68.1±14.8 fold and 6.6±1.4 fold，respectively at the third week while CFU-GM expansion reached its peak (5.7±2.1 fold) at the week 2. Moreover, the percentage of CD41a+ cells was enhanced significantly, reaching a maximum (15.6%) at the week 3. Conclusions:HUVEC can support hematopoiesis in vitro and expand the hematopoietic progenitor cells and CD41a+ cells in direct contact coculture.

This study was purposed to investigate the angiogenesis-promoting activities of human mesenchymal stem cells (hMSCs) modified by hepatocyte growth factor (HGF) and the underlying mechanisms. The hMSCs were transfected by recombinant adenoviral vector carrying human HGF gene and seeded onto the chicken chorioallantoic membrane. Three days later, the number of blood vessels was counted and their angiogenic response was compared with those of hMSCs of same generation, recombinant basic fibroblast growth factor (bFGF) and alpha-MEM as control. The expression levels of bFGF, VEGF, angiopoietin-1 and angiopoietin-2 were evaluated by RT-PCR assay. The results showed that gene-modified hMSCs exhibited greatest activity to promote angiogenesis while the angiogenic response was nearly same between groups treated by hMSCs and bFGF, all of which were significantly higher than that observed in control (p < 0.01). RT-PCR analysis revealed that hMSCs constitutively expressed multiple angiogenesis-associated growth factors and their levels seemed up-regulated by HGF gene transfer. It is concluded that HGF gene-modified hMSCs show a potent angiogenesis-promoting function and may be useful in the treatment of ischemic disorders.
Animals ; Cells, Cultured ; Chick Embryo ; Chickens ; Hepatocyte Growth Factor ; genetics ; Humans ; Mesenchymal Stromal Cells ; Neovascularization, Physiologic ; genetics ; Transfection

Hepatocyte growth factor (HGF) is a pleiotropic cytokine, its roles in the physiology and pathology of immune system, have been investigated thoroughly, great deal of data have been documented on its immunoregulatory activity. In this review, according to advance of study on HGF in recent years, the role of HGF in the immune regulation, such as immunoregulatory effects of HGF on T lymphocytes, B lymphocytes and dendritic cell, modulation of HGF on specific humoral and cellular immune response, control of acute GVHD and acceleration of myeloid and immunologic reconstitution in allogenetic bone marrow transplantation models, promotion of tissue repair and regeneration, and alleviation of immune rejection in allogeneic organ transplantation including the heart, liver and kidney transplantation, prevention of grafts from injury as well as applicably useful of HGF in the therapy of autoimmune disorders were summarized.
Animals ; Graft Rejection ; immunology ; prevention & control ; Graft vs Host Disease ; immunology ; prevention & control ; Graft vs Leukemia Effect ; immunology ; Hepatocyte Growth Factor ; physiology ; Humans ; Immunity, Cellular ; immunology

The aim of this study was to investigate if transfusion of mesenchymal stem cells (MSC) could exhibit beneficial effects on rheumatoid arthritis. Human bone marrow MSC were intraperitoneally injected into Wistar rats with collagen-induced arthritis at a dose of 10(7) on the next day (preventive group) or 2 weeks (treatment group) after collagen II induction, once a week for 2 weeks (preventive group) or 4 weeks (treatment group). The control group was given normal saline (NS) at corresponding time. The symptom scorings were documented weekly from the second week of the induction. On week 6, the hind joints of the rats were pathologically examined and the activation status of splenocytes was analyzed by flow cytometry. The results showed that all the rats developed arthritis and subsequent joint abnormality. On the sixth week, symptom scores of the rats that received MSC preventive (9.5 ± 0.5) or therapeutic (9.4 ± 0.6) infusions had no significant difference between each other, but were significantly greater than those of the NS controls (7.6 ± 0.6, P < 0.05). Consistently, pathological examination on the involved knees showed that the synovitis and arthritis scorings of MSC treated rats were greatly elevated compared with NS controls. Furthermore, the ratios of CD86(+) cells in the spleens of MSC prevention, MSC treatment and NS control groups were (4.16 ± 1.48), (4.06 ± 1.97) and (4.15 ± 2.04) respectively, while those of CD11b/c(+)CD86(+) cells were (1.04 ± 0.68), (0.95 ± 0.56) and (0.98 ± 0.44), all of which were significantly higher than those of healthy controls [(0.97 ± 0.18) and (0.30 ± 0.17), P < 0.05 for both parameters]. It is concluded that MSC infusion has little beneficial effects on collagen-induced arthritis in rats, conversely, MSC therapy aggravated the damage of the involved joints, its underlying mechanisms need to be further investigated.
Animals ; Arthritis, Experimental ; pathology ; prevention & control ; therapy ; Bone Marrow Cells ; Cells, Cultured ; Humans ; Male ; Mesenchymal Stem Cell Transplantation ; Mesenchymal Stromal Cells ; cytology ; Rats ; Rats, Wistar ; Transplantation, Heterologous ; Treatment Outcome

In the present study, an attempt was made to prove the question whether endothelial cell precursors exist in blood circulation during postnatal period. CD34(+) cells were harvested from G-CSF mobilized adult blood and umbilical cord blood and incubated onto fibronectin/gelatin-coated Petric dishes in the presence of recombinant human vascular endothelial cell growth factor(rhVEGF) and basic fibroblast growth factor(rhbFGF). Endothelial cell lineage was identified by von Willebrand factor(vWF) expression and Ulex europous agglutinin I(UEA-I) binding capacity. The results showed that a firmly adherent cell monolayer formed when CD34(+) cells, but not CD34(-) cells, were cultured for 5 - 6 weeks as described before. Immunocytochemistry and flow cytometry analysis showed that almost all of the adherent cells were vWF-positive and around 90% were able to bind UEA-I specifically. These findings demonstrate that angioblasts exist in the circulation during postnatal life and therefore, vasculogenesis might occur in adults.

This study was undertaken to investigate the antitumor activity of rhG-CSF mobilized blood mononuclear cells (G-PBMC) from normal donor activated by rhIL-2 alone or in combination with rhIL-12 in vitro. LDH release assay was used to determine the cytotoxicity activity of G-PBMC against K562 (NK-sensitive) and Raji cells (NK-resistant). The phenotype of the activated G-PBMC was assayed by flow cytometry. Results suggested that the cytotoxicity of the fresh G-PBMC was low before IL-2/IL-12 stimulation. G-PBMC developed marked cytotoxicity after 24 hours of IL-2 activation, with more significant increase for further 48 hours induction. When G-PBMCs were exposed to combination of IL-2 and IL-12, the cytotoxicity was significantly enhanced. The proportions of CD3(+) T cells and CD8(+) T cells were increased when G-PBMC incubated with IL-2 for 72 hours. However, CD56(+) cells were significantly elevated when G-PBMC exposed to IL-2 and IL-12 for 7 days. It is concluded that G-PBMC activated by IL-2 had evident antitumor activity, which was further increased when IL-2 in combination with IL-12. These results demonstrate that IL-2 and IL-12 treatment in vitro might promote the graft-versus-leukemia (GVL) response of G-PBMC.

Recent reports have clearly demonstrated that bone marrow cells can be differentiated into neurons, suggesting the existence of cells with the differentiation capacity in the bone marrow cell population. It is well known that hematopoietic stem cells as well as mesenchymal stem cells (MSCs) can be transplanted and therefore, alternative of them might contribute to the process. In the present study it was addressed whether marrow MSCs could be coaxed into neuron-specific antigen bearing cells and if so, whether the differentiated cells possess the cytochemical features seen in neurons. The report here showed that high concentration of 2-mercaptoethanol (2-ME) could induce some of the MSCs into neuron-like cells expressing neurofilament (NF) and neuron specific enolase (NSE). The neuron-like cells were alkaline phosphotase positive while the others MSCs were kept negative. Cells treated with 2-ME were positive for alpha-naphthylacetate esterase and glycogen and negative for acetylchonlinesterase, which were similar with the results seen in untreated cells. Furthermore, Nissel body was not observed in treated cells shown by toluidine blue staining. Therefore, it is likely that the cells described here seem not belong to the neuronal lineage. These findings, however, reveal that human MSCs could alter their committed fates under some circumstances.

Endothelial cells are the critical cell component of hematopoietic microenvironment. For the purpose of facilitating the study on modulating effect of endothelial cells in hematopoiesis, a human umbilical vein cell line, IEC, was established. Primary human umbilical vein endothelial cells were transfected with the plasmid pSV(3neo) carried SV40 large T antigen by lipofection. The IEC cells expressed factor VIII and the UEA I-binding ratio was about 97%. The chromosome variation was existed in the cell line, with the karyotype 45, XX, -18, 18q(+). The cell line retained the proliferative capacity at least 25 passages. IEC cells stimulated the growth of granulocyte-macrophage progenitor cells in coculture of cord blood CD34(+) cells with IEC cells. It is concluded that IEC cell line possessed the biological features of endothelial cell and supported hematopoiesis in vitro.

Mesenchymal stem cells (MSC) are the ideal adult stem cells in cell/gene therapy and tissue engineering for their features of easily-handling, highly proliferative capacity in vitro, low immunogenicity and immunomodulatory ability. MSC, as a kind of cellular drug, have been utilized in a phase III clinical trial to treat refractory graft-versus-host disease (GVHD). However, the essences of MSC in culture remain elusive so far. Whether the cells expanded in vitro are stem cells per se, and if not, why expanded MSC maintain their multiple differentiation ability? And are the MSC cultivated in vitro homogeneous and if not, what the heterogeneity stands for? Focusing on the heterogeneity of MSC in culture in vitro, the above questions are briefly discussed in this review.
Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Humans ; Mesenchymal Stromal Cells ; cytology