BACKGROUND: Previous studies have demonstrated that normal rat liver homogenate supernatant can induce human umbilical cord mesenchymal stem cells to differentiate into hepatocyte-like cells with partial hepatocyte
functions. However, whether fibrotic liver homogenate supernatant can work or how the inducing effect is remains unclear.
OBJECTIVE: To investigate the differentiation potential of human umbilical cord mesenchymal stem cells into hepatocytes under the normal liver and fibrotic liver microenvironment in vitro.
METHODS: Liver fibrosis was induced in the SD rats by repeated intraperitoneal injections of 3% thioacetamide at a dose of 200 mg/kg body mass, twice a week for 4 weeks, and then fibrotic liver tissues and normal liver tissues were used to prepare liver homogenate supernatants. Passage 3 human umbilical cord mesenchymal stem cells were used and divided into standard control group (cells were cultured in DMEM/F12 with 10% fetal bovine serum), fibrotic liver homogenate supernatants group (cells were cultured in DMEM/F12 with 10% fetal bovine serum and 50 g/L fibrotic liver homogenate supernatants), normal liver homogenate supernatants group (cells were cultured in DMEM/F12 with 10% fetal bovine serum and 100 g/L normal liver homogenate supernatants). The morphological changes of the cells in each group were recorded under inverted microscope; the protein levels of CK18, AFP, CYP3A4, CYP2E1, CYP2D6 and TPH2 were evaluated using western blot assay. Furthermore, the concentration of albumin in the cells was measured.
RESULTS AND CONCLUSION: After a 7-day inducement, the stem cells in liver homogenate supernatants groups lost their fusiform shape and changed into hepatocyte-like cells with the morphous of round shape. Compared with the standard control group, the hepatocyte-like cells in the two liver homogenate supernatants groups exhibited human hepatocyte biomarkers, CK18 and AFP. The standard control group cells could express a little amount of CYP2E1, while cells in the two liver homogenate supernatants groups could express CYP3A4, CYP2E1, CYP2D6, TPH2. Compared with the standard control group, the expression level of CYP2E1 in the two liver homogenate supernatants groups increased significantly (P < 0.01), and however, the relative levels of CYP3A4, CYP2E1, CYP2D6, TPH2 in the two liver homogenate supernatants groups showed no statistical significance (P > 0.05). At the same time, compared with the standard control group, the concentration of albumin in the two liver homogenate supernatants groups markedly increased (P < 0.01), but there was no difference between the two liver homogenate supernatants groups (P > 0.05). Experimental findings demonstrated that both of normal liver tissue and fibrotic liver tissue microenvironments could induce human umbilical cord mesenchymal stem cells to differentiate into hepatocyte-like cells. To achieve the same effect, compared with normal liver tissue, fibrotic liver tissue required lower concentrations, suggesting that fibrotic liver tissue microenvironment may be more conducive to differentiation of umbilical cord mesenchymal stem cells into hepatocytes.