Abstract: Abstract: Objective　To study the effect of total saponins of pueraria lobata (TSPL) on the differentiation of rat bone marrow mesenchymal stem cells (BMSCs) into nucleus pulposus-like cells and its mechanism. Methods　An animal model of lumbar intervertebral disc degeneration in rats was established in vitro. The rats were divided into sham group, model group, 30 mg/kg TSPL treatment group and 50 mg/kg TSPL treatment group. The primary cultured rat BMSCs were divided into four groups: BMSCs group, BMSCs-TSPL (10, 20, 30, 40, 50 μmol/L) group, BMSCs-TSPL (30 μmol/L) -FK866 ［a specific inhibitor of nicotinamide phosphoribosyltransferase (NAMPT), 2.5 μmol/L］ group and BMSCs -TSPL (30 μmol/L) -SRT2104 (a Sirt1 activator, 10 μmol/L) group. The contents of glycosaminoglycan in cells and tissues were detected by dimethylmethylene blue method, and the mRNA and protein expression levels of nucleus pulposus-like cells related genes COL2A1, Aggrecan, Sox9, Tie2 and Sirt1 were measured with RT-qPCR and Western blot assay. WST-8 method was used to detect the level of nicotinamide adenine dinucleotide (NAD +) in cells. Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of adenosine triphosphate (ATP) and NAMPT, respectively. Results　Compared with the sham operation group, the content of glycosaminoglycan in the intervertebral disc L5-S1 tissue was decreased in the model group (P＜0.05). Compared with the model group the content of glycosaminoglycan increased in TSPL treatment group, and the effect of 50 mg/kg TSPL treatment was better than that of 30 mg/kg treatment (P＜0.05). Compared with BMSCs group, the mRNA and protein expression levels of glycosaminoglycan, COL2A1, Aggrecan, Sox9 and Sirt1 and the contents of NAD+, ATP and NAMPT increased in TSPL group and TSPL+SRT2104 group, but the expression level of Tie2 decreased (P＜0.05). Compared with BMSCs-TSPL group, the mRNA and protein levels of COL2A1, aggrecan, Sox9 and Sirt1 and the contents of glycosaminoglycan, NAD+, ATP and NAMPT decreased after treatment with FK866, while the above indexes increased after  treatment with SRT2104 (P＜0.05). Conclusion　TSPL could induce BMSCs to differentiate into nucleus pulposus-like cells through the NAMPT/Sirt1 axis.

Key words: intervertebral disc degeneration, PUERARIA LOBATA, mesenchymal stromal cells, nicotinamide phosphoribosyltransferase, total saponins of pueraria lobata, bone marrow mesenchymal stem cells, nucleus pulposus like cells, the NAMPT-Sirt1 axis