Abstract: BACKGROUND: How to improve the expansion of cells, reduce cell loss, increase homing rate and reduce apoptosis is the main problem in the preclinical research of human umbilical cord mesenchymal stem cells. Ginsenoside Rg1 can promote the proliferation and differentiation of mesenchymal stem cells in different microenvironments in vitro or in vivo, which may be a candidate drug to improve the efficiency of human umbilical cord mesenchymal stem cell transplantation. 
OBJECTIVE: To investigate the effect of human umbilical cord mesenchymal stem cells co-culture combined with ginsenoside Rg1 on pentobarbital sodium induced heart failure cell model. 
METHODS: H9C2 cells were divided into five groups: Control group, pentobarbital sodium group, human umbilical cord mesenchymal stem cell group, ginsenoside Rg1 group, and human umbilical cord mesenchymal stem cell + ginsenoside Rg1 group. H9C2 cells in the control group were cultured in normal DMEM for 24 hours. H9C2 cells in the other groups were cultured in DMEM containing 0.8% pentobarbital sodium for 7 minutes to establish a heart failure cell model. After modeling, above models were treated with human umbilical cord mesenchymal stem cells, ginsenoside Rg1, or their combination. CCK-8 assay and EdU staining were used to detect cell proliferation. TUNEL assay was used to detect cell apoptosis. Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities were detected according to kit instructions. The mRNA levels of tumor necrosis factor α, interleukin 1β, and interleukin 6 in the supernatant were determined by ELISA. The mRNA levels of tumor necrosis factor α, interleukin 1β, interleukin 6, Bax, and Bcl2 in the cells were determined by RT-qPCR. The protein levels of Bax, Bcl2, Toll-like receptor 4, p65, and p-p65 were determined by western blot assay.  
RESULTS AND CONCLUSION: (1) Compared with the pentobarbital sodium group, H9C2 cell viability and EdU positive rate were increased; TUNEL positive rate and Bax mRNA and protein expression were decreased, and Bcl-2 mRNA and protein expression were increased; Na+-K+ -ATPase activity decreased; Ca2+-Mg2+-ATPase activity increased; tumor necrosis factor α, interleukin-1β, and interleukin-6 levels decreased in H9C2 cell supernatant, and tumor necrosis factor α, interleukin-1β, and interleukin-6 mRNA expression decreased in H9C2 cells; the expression of toll-like receptor 4 and P-P65 protein decreased with significant difference in human umbilical cord mesenchymal stem cell group, ginsenoside Rg1 group and human umbilical cord mesenchymal stem cell + ginsenoside Rg1 group (P < 0.05). (2) Compared with human umbilical cord mesenchymal stem cell group and ginsenoside Rg1 group, the above indexes in human umbilical cord mesenchymal stem cells + ginsenoside Rg1 group were further improved (P < 0.05). The results showed that human umbilical cord mesenchymal stem cells combined with ginsenoside Rg1 promoted the viability of heart failure cells induced by pentobarbital sodium and inhibited inflammation mediated by the Toll-like receptor 4/nuclear factor κB pathway.

Key words: human umbilical cord mesenchymal stem cell, H9C2 cell, heart failure, ginsenoside Rg1, pentobarbital sodium, Toll-like receptor 4, nuclear factor κB