Abstract:Objective: This study aimed to investigate the promotion effect of low molecular weight hyaluronic acid (LMW-HA) on phenotypic transformation of mice cardiac fibroblasts and the role of CD44 and S100A4 in this process. Methods: Cardiac fibroblasts (CFs) were isolated and cultured from neonatal ICR mice and then stimulated by LMW-HA. The proliferation of CFs was measured by CCK-8 and EdU, and we used Western Blotting, quantitative RT-PCR and Immunofluorescence to determine myocardial fibrosis. We extracted nuclear and cytoplasmic protein of CD44 and S100A4 to specified the nuclear translocation by WB and Immunofluorescence. To measure aforesaid indicators once again after treatment of the CD44 inhibitor BRIC-235. Results: CCK-8 and EdU determined that the optimal concentration of LMW-HA stimulation was 0.8mg/ml. WB, qRT-PCR and IF showed that LMW-HA stimulation significantly increased the level of myocardial fibrosis markers (α-SMA and Collagen 3), but CD44 remained unchanged, and S100A4 gradually increased over time. The protein of CD44 and S100A4 were transferred into the nucleus at the same time. BRIC-235 can inhibit these changes. Conclusions: LMW-HA can promote the differentiation of mice cardiac fibroblasts, which is regulated by the nuclear translocation of CD44 and S100A4 and the activation of downstream signaling pathway. This may be a new therapeutic target of myocardial fibrosis in the future.