In vitro effects of bone marrow mesenchymal stem cells on HBV replication with the participation of lymphocytes

Abstract

Objective To investigate the in vitro effects of bone marrow mesenchymal stem cells (BM MSCs) on the replication of HBV with the participation of lymphocytes and to analyze the possible mechanism. Methods The HBV genomic DNA transfected HepG2.2.15 cell line was used to evaluate the HBV replication. Bone marrow and spleen samples were collected from BN rats for the isolation of BM MSCs and T lymphocyte cells, respectively. Five groups of co-culturing with different cells were designed in this study. The cellular activities of lymphocytes and HepG2.2.15 cells were detected at the time of 24 h, 48 h and 72 h after co-culturing by using MTT method. The levels of HBV DNA and HBV cccDNA were detected by real-time polymerase chain reaction (PCR). T cell subsets in co-culture were measured by using fluorescence labeled antibodies and flow cytometry analysis. ELISA was used to detect the levels of cytokines in the supernatant of cultured cells. Results Compared with HepG2.2.15 cells group, BM MSCs+ HepG2.2.15 cells and splenic lymphocytes+ HepG2.2.15 cells co-culture groups, the levels of HBV DNA and HBV cccDNA were significantly decreased in splenic lymphocytes+ BM MSCs+ HepG2.2.15 cells co-culture group after 48 h of culture [HBV DNA: (181.000±14.731) IU/ml vs (6270.000±300.450) IU/ml, (2564.000±231.058) IU/ml, (2433.300±302.379) IU/ml; HBV cccDNA: (4.330×105±0.464×105) IU/ml vs (11.100×105±0.375×105) IU/ml, (8.930×105±0.778×105) IU/ml, (9.850×105±0.810×105) IU/ml; P<0.01]. The secretion of IFN-γ in the supernatant of co-cultured cells was negatively correlated with HBV DNA level, but the levels of IL-10 and IL-22 were positively correlated with HBV DNA. The ratio of CD4+ /CD8+ cells was increased in splenic lymphocytes+ BM MSCs+ HepG2.2.15 cells co-culture group. The percentage of CD8+ cells showed a positive correlation with HBV DNA. Conclusion BM MSCs could inhibit the expression of HBV DNA to enhance the clearance of HBV strains. It might be possibly due to rebalancing of Tc1/Tc2 cells and regulating the expression of autocrine agents and cytokines. Key words: Hepatitis B virus; Bone marrow mesenchymal stem cells; Lymphocyte cells; Cytokine