The extracellular matrix influences the miRNA landscape of human mesenchymal stromal/stem cells

Mesenchymal stromal/stem cells (MSCs) are promising therapeutic tools secreting a broad repertoire of pleiotropic molecules that promote tissue repair and regeneration. Recent advances in cell sheet technique demonstrate powerful improvement of MSCs regenerative capacity within the sheet retaining appropriate microenvironmental cues and suggest the instructing role of extracellular matrix (ECM). We found previously that the secretome of MSCs cultured on decellularized MSCs-derived ECM (dECM) is significantly enriched with dozen of cytokines, chemokines and growth factors in comparison to the secretome of MSCs cultured on routine plastic dishes. Enriched secretome was shown to have improved chemotactic and angiogenic properties, to stimulate C2C12 myoblast proliferation and promote skeletal muscle regeneration in murine in vivo model (Ushakov et al., 2024; Ushakov, Burova, 2024). Here we report novel findings about dECM-induced changes in miRNAs profile, another regulatory component of MSCs secretome. We performed miRNA-seq and found 17 differentially expressed miRNAs in endometrial MSCs (MESCs) with miR-146a-5p most upregulated. We also checked it's expression in MSCs of various origin exposed to dECM and found miR-146a-5p upregulation to be correlated with general dECM-induced paracrine response. Besides, we found that miR-146a-5p mimic transfected to C2C12 myoblasts promote their proliferation suggesting miR-146a-5p contribution to myotropic effects of enriched secretome. These results provide new insights into how ECM as the component of MSCs niche influences secretory phenotype and modulate MSCs therapeutic properties. Overall design: miRNA-seq profiling of mesenchymal stromal/stem cells derived from desquamated endometrium of menstrual blood of three healthy donors cultured for 72 hours on control plastic (polystyrene) dishes and cell-derived decellularized extracellular matrix (dECM)-coated dishes.