ObjectiveTo study the immunogenicity of human bone marrow mesenchymal stem cells (BMSCs) and the suppression ability to the proliferation of peripheral blood mononuclear cell (PBMC) during osteogenic, chondrogenic, and adipogenic differentiations. MethodsBMSCs were isolated from bone marrow of healthy donors and were induced to osteogenic, chondrogenic, and adipogenic differentiations for 7, 14, and 21 days. The expressions of human leukocyte antigen (HLA) class I and class II were detected by flow cytometry. PBMC were isolated from peripheral blood of healthy donors and were co-cultured with BMSCs at a ratio of 10∶1 for 5 days. The suppression ability of undifferentiated and differentiated BMSCs to proliferation of PBMC were detected by flow cytometry. ResultsThe HLA class I expression was observed but almost no expression of HLA class II was seen in undifferentiated BMSCs. There was no obviously change of the HLA class I and class II expressions during osteogenic and chondrogenic differentiations (P>0.05), and a low expression of HLA class II was kept. The HLA class I expression gradually increased at 14 and 21 days after adipogenic differentiation, showing significant differences when compared with the value at 0 and 7 days (P<0.05);the HLA class II expression also gradually increased at 7, 14, and 21 days after adipogenic differentiation, showing significant differences when compared with the value at 0 day (P<0.05). There was no proliferation of PBMC without the stimulation of CD3 and CD28 microspheres and significant proliferation was observed when CD3 and CD28 microspheres were added, and undifferentiated BMSCs could significantly inhibit the proliferation of PBMC. There was no obvious change of the ability of BMSCs to inhibit the proliferation of PBMC during osteogenic and chondrogenic differentiations (P>0.05);and the ability of BMSCs to inhibit the proliferation of PBMC was gradually weakened at 7, 14, and 21 days after adipogenic differentiation, showing significant differences among different time points (P<0.05). ConclusionBMSCs maintain low immunogenicity and strong immune suppression ability during osteogenic and chondrogenic differentiations, which are suitable for allogenic tissue engineering repair and cell transplantation. However, increased immunogenicity and decreased immune suppression ability after adipogenic differentiation may not be suitable for allogenic tissue engineering repair and cell transplantation.
ObjectiveTo investigate the anti-apoptotic ability of synovium-derived mesenchymal stem cells (SMSCs) by comparing the apoptosis induced by tumor necrosis factor α (TNF-α) between SMSCs and bone marrow mesenchymal stem cells (BMSCs). MethodSMSCs and BMSCs were isolated with tissue adhering and density gradient centrifugation respectively, and cells at passages 3-5 were used in further experiments. After immunophenotype identification and differentiation induction, cells were divided into 4 groups. In the experimental groups, apoptosis of SMSCs and BMSCs were induced by 20 ng/mL TNF-α and 10 μg/mL cycloheximide, and cells were cultured in normal culture medium in the control groups. Cellular morphology were observed by inverted phase contrast microscope. After apoptosis induction for 24 hours, cell viability was determined by cell counting kit 8 assay and apoptotic index was detected by flow cytometer. Moreover, the level of Cleaved Caspase-8, 3 were determined by Western blot. ResultsBoth SMSCs and BMSCs accorded with the definition criteria of MSCs according to results of immunophenotype identification and differentiation induction. After apoptosis induction, cells became shrinking and partially floated and cellular morphologies became worse than those in the control groups. After apoptosis induction for 24 hours, cell viabilities of SMSCs and BMSCs in the control groups were both 100%, and no apoptotic cells were observed. However, cell viabilities of SMSCs and BMSCs in the experimental groups were 60.13%±8.63% and 46.55%±10.54% respectively, which were both significantly lower than those in the control groups (P<0.05) , and cell viability in the SMSCs experimental group was significantly higher than that in the BMSCs experimental group (t=3.152, P=0.006) . The apoptotic index was 36.54%±8.63% in the SMSCs experimental group and was 53.77%±11.52% in the BMSCs experimental group, both were significantly higher than the control groups (1.12%±0.24% and 1.35%±0.31%) (P<0.05) . What's more, it was significantly lower in SMSCs experimental group than that in BMSCs experimental group (t=3.785, P=0.001) . Moreover, no expression of Cleaved Caspase-8, 3 was detected in the control groups. But the levels of Cleaved Caspase-8, 3 were significantly enhanced in the experimental groups and they were lower in SMSCs than in BMSCs (t=13.870, P=0.000; t=7.309, P=0.000) . ConclusionsTNF-α induced apoptosis is lower in SMSCs than in BMSCs, which means that SMSCs may have stronger anti-apoptosis ability than BMSCs.