Background and objectives: Galectin-3 promotes fibroblast-to-myofibroblast differentiation and facilitates injury repair. Previous studies have shown that exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-ex) promote the differentiation of myocardial fibroblasts into myofibroblasts under inflammatory environment. Whether hucMSC-ex derived Galectin-3 (hucMSC-ex-Galectin-3) plays an important role in fibroblast-to-myofibroblast differentiation is the focus of this study.
Methods and results: Galectin-3 was knocked-down by siRNA in hucMSCs, and then exosomes were extracted. Fibroblasts were treated with LPS, LPS＋hucMSC-ex, LPS＋negative control-siRNA-ex (NC-ex), or LPS＋ Galectin-3-siRNA-ex (si-ex) in vitro. The coronary artery of the left anterior descending (LAD) branch was permanently ligated, followed by intramyocardial injection with phosphate buffered saline(PBS), hucMSC-ex, hucMSC-NC-ex, or hucMSC-si-ex in vivo. Western blot, RT-PCR, and immunohistochemistry were used to detect the expression of markers related to fibroblast-to-myofibroblast differentiation and inflammatory factors. Migration and contraction functions of fibroblasts were evaluated using Transwell migration and collagen contraction assays, respectively. β-catenin expression was detected by western blot and immunofluorescence. The results showed that hucMSC-ex increased the protein expression of myofibroblast markers, anti-inflammatory factors, and β-catenin. HucMSC-ex also reduced the migration and promoted the contractility of fibroblasts. However, hucMSC-si-ex did not show these activities.
Conclusions: HucMSC-ex-Galectin-3 promoted the differentiation of cardiac fibroblasts into myofibroblasts in an inflammatory environment, which was associated with increased β-catenin levels.
Keywords: Cardiac fibroblasts; Galectin-3; Mesenchymal stem cell; Myofibroblasts.