Introduction and objectivesThe development of cardiac fibrosis (CF) and hypertrophy (CH) can lead to heart failure. Mesenchymal stem cells (MSCs) have shown promise in treating cardiac diseases. However, the relationship between MSCs and splicing factor arginine/serine rich-3 (SFRS3) remains unclear. In this study, our objectives are to investigate the effect of MSCs on SFRS3 expression, and their impact on CF and CH. Additionally, we aim to explore the function of the overexpression of SFRS3 in angiotensin II (Ang II)-treated cardiac fibroblasts (CFBs) and cardiac myocytes (CMCs). MethodsRat cardiac fibroblasts (rCFBs) or rat cardiac myocytes (rCMCs) were co-cultured with rat MSCs (rMSCs). The function of SFRS3 in Ang II-induced rCFBs and rCMCs was studied by overexpressing SFRS3 in these cells, both with and without the presence of rMSCs. We assessed the expression of SFRS3 and evaluated the cell cycle, proliferation and apoptosis of rCFBs and rCMCs. We also measured the levels of interleukin (IL)-β, IL-6 and tumor necrosis factor (TNF)-α and assessed the degree of fibrosis in rCFBs and hypertrophy in rCMCs. ResultsrMSCs induced SFRS3 expression and promoted cell cycle, proliferation, while reducing apoptosis of Ang II-treated rCFBs and rCMCs. Co-culture of rMSCs with these cells also repressed cytokine production and mitigated the fibrosis of rCFBs, as well as hypertrophy of rCMCs triggered by Ang II. Overexpression of SFRS3 in the rCFBs and rCMCs yielded identical effects to rMSC co-culture. ConclusionMSCs may alleviate Ang II-induced cardiac fibrosis and cardiomyocyte hypertrophy by increasing SFRS3 expression in vitro.