ABSTRACT
Objective To investigate the role of human umbilical cord mesenchymal stem cell-derived extracellular vesicle (hUC-MSC-EV) in the regeneration of fibrotic liver. Methods C57BL/6 mice were randomly divided into the 70% normal liver resection group (Oil+PHx group), 70% liver fibrosis resection group (CCl4+PHx group) and 70% liver fibrosis resection+mesenchymal stem cell-derived extracellular vesicle (MSC-EV) treatment group (CCl4+PHx+MSC-EV group), with 8 mice in each group. LX-2 cell lines were assigned into the phosphate buffer solution (PBS) group, transforming growth factor (TGF)-β group and TGF-β+MSC-EV group. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) in mice after partial liver resection were detected in each group. The expression levels of liver fibrosis and proliferation-related parameters were analyzed in each group. The messenger RNA (mRNA) expression levels of epidermal growth factor (EGF), fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) in LX-2 cells were detected in each group, and their effects on HGF expression in mouse liver were observed. Results Compared with the Oil+PHx group, the serum levels of AST, ALT and LDH were up-regulated, and the degree of fibrosis was more severe, the positive area of Sirius red and α-smooth muscle actin (α-SMA) staining was larger, and the expression level of α-SMA protein was up-regulated in the CCl4+PHx group. Compared with the CCl4+PHx group, the serum levels of AST, ALT and LDH were decreased, the degree of fibrosis was slighter, the positive area of Sirius red and α-SMA staining was decreased, and the expression level of α-SMA protein was down-regulated in the CCl4+PHx+MSC-EV group, and the differences were statistically significant (all P < 0.05). Compared with the Oil+PHx group, the protein expression levels of Ki67 and proliferating cell nuclear antigen (PCNA) were lower in the CCl4+PHx group. Compared with the CCl4+PHx group, the protein expression levels of Ki67 and PCNA were increased in the CCl4+PHx+MSC-EV group, and the differences were statistically significant (all P < 0.05). Compared with the PBS group, the expression level of CollagenⅠ mRNA in LX-2 cells was increased, the expression level of α-SMA protein was up-regulated and the expression level of HGF protein was decreased in the TGF-β group. Compared with the TGF-β group, the expression level of CollagenⅠ mRNA in LX-2 cells was decreased, the expression levels of HGF mRNA and protein were increased, and the expression level of α-SMA protein was decreased in the TGF-β+MSC-EV group, the differences were statistically significant (all P < 0.05). The expression level of HGF protein in the CCl4+PHx group was lower than that in the Oil+PHx group, whereas the difference was not statistically significant (P > 0.05). The expression level of HGF protein in the CCl4+PHx+MSC-EV group was higher than that in the CCl4+PHx group, and the difference was statistically significant (P < 0.05). Conclusions The regenerative capacity of fibrotic liver is weaker than that of normal liver. hUC-MSC-EV may alleviate liver fibrosis and improve liver regeneration by promoting HGF secretion from actived hepatic stellate cells and effectively enhancing the regenerative capacity of fibrotic liver.
ABSTRACT
Objective To explore the mechanism of human umbilical cord mesenchymal stem cell (HUC-MSC) alleviating ischemia-reperfusion injury (IRI) of liver cells through mitochondrial transfer. Methods Normal human liver cell line L02 was divided into the blank control group, oxygen-glucose deprivation (OGD) group, experimental control group, and L02 and HUC-MSC co-culture group (L02+HUC-MSC group). L02+HUC-MSC group was further divided into 10:1 co-culture subgroup (group A), 4:1 co-culture subgroup (group B), 2:1 co-culture subgroup (group C), 1:1co-culture subgroup (group D) and 1:2 co-culture subgroup (group E) according to different co-culture ratio of L02 and HUC-MSC. The apoptosis rate and relative reactive oxygen species (ROS) level of L02 cells were detected by flow cytometry. The MitoTracker positive rate of L02 cells was detected by flow cytometry. The mitochondrial transfer from HUC-MSC to L02 cells was observed by laser confocal microscope. Results The apoptosis rate and relative ROS level of L02 cells in the OGD group were significantly higher than those in the blank control group (both P < 0.05). Compared with the OGD group, the apoptosis rates of L02 cells in group B, C, D and E were significantly decreased (all P < 0.05), and the relative ROS level of L02 cells in group E was significantly declined (P < 0.05). The MitoTracker positive rate of L02 cells did not significantly differ between group A and experimental control group (P>0.05), whereas the MitoTracker positive rates of L02 cells in group B, C, D and E were significantly higher than that in the experimental control group in a concentration-dependent manner (all P < 0.05). Under the laser confocal microscope, mitochondrial transfer fromHUC-MSC to L02 cells could be observed through tunneling nanotube (TNT). Conclusions HUC-MSC may alleviate cell apoptosis and reduce ROS level of liver cells after IRI via direct mitochondrial transfer between cells.
ABSTRACT
At present, surgical and endoscopic interventions are mainly employed to treat ischemic-type biliary lesion (ITBL). Due to the disadvantages of single therapeutic strategy, high difficulty and expensive medical cost, it is urgent to identify a novel treatment option. Mesenchymal stem cell (MSC) has become potential seed cell for tissue and organ repair in regenerative medicine due to its high self-renewal capability, multi-directional differentiation potential, low immunogenicity and immunoregulatory effects, etc. Recent studies have demonstrated that MSC transplantation into ITBL animal models may not only home to the injured area, but also promote the repair of injured biliary tract tissues through anti-apoptotic and pro-angiogenic effect, which indicates that MSC transplantation is expected to become a new strategy for the treatment of ITBL. In this article, the biological characteristics of MSC, the mechanism and clinical application of MSC transplantation for ITBL were reviewed.