Role of TRPM4 channel inhibitor 9-phenanthrenol in osteoarthritis chondrocytes

Abstract

Objective To investigate whether TRPM4 channel inhibitor 9-phenanthrol can attenuate human osteoarthritis (OA) chondrocytes hypertrophy and cartilage explant matrix degeneration and to study the effect of 9-phenanthrol on apoptosis of OA chondrocytes to provide an experimental basis for the treatment of OA. Methods Human OA chondrocytes and cartilage explants, obtained from subjects with OA undergoing total knee arthroplasty, were cultured in the absence (blank group) or presence of different concentrations of 9-phenanthrol. Runx-2, MMP-13, COL II, and aggrecan mRNA expression was determined by real-time quantitative PCR (RT-qPCR) after 24 h of incubation. The effect of 9-phenanthrol on the apoptosis of OA chondrocytes was detected by TUNEL staining with fluorescence microscopy and flow cytometry with Annexin V and 7-AAD double staining after 1 day of incubation with 9-phenanthrol. Results According to RT-qPCR results, it was unable to judge the effect of 9-phenanthrol on hypertrophic differentiation and cell metabolism in OA chondrocytes, and the mRNA expression levels of chondrocyte hypertrophy indexes Runx-2 and MMP13 increased compared with the control group, suggesting that 9-phenanthrol may promote chondrocyte hypertrophy at the mRNA level. TUNEL staining with fluorescence microscopy showed that compared with the control group, the apoptosis rate of cells treated with 2×10-5 mol/L 9-phenanthrol was significantly decreased (P < 0.05), while no significant difference was observed in other concentration groups, although there was a decreasing trend compared with the control group. Flow cytometry with Annexin V and 7-AAD double staining showed that compared with the control group, the rate of apoptotic cartilage cells in the l×10-5 mol/L, 2×10-5 mol/L, and 4×10-5 mol/L 9-phenanthrol groups significantly decreased (P < 0.05), while no significant difference was observed in other two concentration groups, although there was a decreasing trend compared with the control group. Conclusion 9-phenanthrenol promotes the proliferation and differentiation of OA chondrocytes at the cellular level and may promote the development of OA. However, 9-phenanthrenol can also reduce the apoptosis of OA chondrocytes and thus has positive significance in the treatment of OA. Key words: Osteoarthritis; Transient receptor potential M4; 9-phenanthrol; Chondrocyte hypertrophy; Apoptosis