| Bone marrow (BM) and umbilical cord (UC) are the major sources of cell-based therapeutics. Mesenchymal stem cells (MSC) from BM and UC were isolated to compare their biological characteristics and immunosuppression ability for clinical choice. Then we investigate the changes of genes in human UC-MSCs therapy for hepatic cirrhosis in rat model. At last we evaluate the impact of MSCs against hepatic injury and explore the role of N-acetyltransferase 8 (NAT8) in this process.UC-MSC and BM-MSC were cultured under the same condition. The phenotypic characteristics and immunosuppressive effects of UC-MSC were compared with those of BM-MSC. Gene chip was used to compare the genes differentially expressed between UC-MSC and BM-MSC. Hepatic cirrhosis in SD rats was induced with carbon tetrachloride subcutaneous injection and alcohol orally. UC-MSCs or PBS were transplanted by intravenous injection. Histopathological staining and serological testing were used to compare the morphology and liver function among different groups. The gene expression alterations were calculated between PBS group and UC-MSC group by gene microarray analysis. We injected MSCs systemically via the tail vein in the SD rat model of 70% hepatic injury and measured the biochemical and pathologic alterations to assess the therapeutic effect of MSC transplantation. Subsequently, we evaluated the expression levels of NAT8 by western blotting in vivo. Concurrently, hydrogen peroxide (H2O2) was used in vitro to mimic oxidative injury and to induce apoptosis in the human normal liver cell line L02 to evaluate the protective effects of MSC conditioned medium (MSC-CM) on L02 cells. In addition, we downregulated or upregulated NAT8 expression in L02 cells and induced apoptosis by using H2O2 to study the protective role of NAT8.Flow cytometry (FCM) and differentiation results affirmed that our cells contained MSC. Results indicated that UC-MSC shared most of the characteristics of BM-MSC, including morphology and immunophenotype. Compared with UC-MSC, BM-MSC expressed more genes associated with immune response. Meanwhile, the categories of up-regulated genes in UC-MSC were concentrated in organ development and growth. The results of serological assay and histopathology confirmed the animal model of hepatic cirrhosis and transplantation of MSC could improve the liver function. Gene microarray analysis showed that compared with the control group, UC-MSC up-regulated complement coagulation related genes, down-regulated genes related to cell proliferation, cell cycle and collagen synthesis. In vitro assays, MSC-CM had a direct inhibitory effect on hepatocyte apoptosis induced by H2O2. Moreover, overexpression or downregulation of NAT8 prevented or aggravated hepatocyte apoptosis induced by H2O2, respectively.It is concluded that the higher proliferation capacity, low human leukocyte antigen-ABC expression, and immunosuppression make UC-MSC an excellent alternative to BM-MSC for cell therapies. The differences between BM-MSC and UC-MSC gene expression could be explained by their ontogeny and different microenvironment in origin tissue. These differences could affect their efficacy in different therapeutic applications. The results suggested UC-MSC might improve the liver function through increased the expression of complement coagulation related genes, and inhibit cell proliferation and collagen deposition. MSC transplantation provides support to the injured liver by inhibiting hepatocellular apoptosis and stimulating NAT8 regeneration. |
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