Mechanical stretching enhances the cellular and paracrine effects of bone marrow mesenchymal stem cells on diabetic wound healing.

BACKGROUND: Diabetic wounds present persistent clinical challenges characterized by disrupted extracellular matrix (ECM) homeostasis, which critically impedes tissue regeneration. While bone marrow-derived mesenchymal stem cells (BMSCs) exhibit therapeutic potential through ECM remodeling, conventional transplantation strategies are limited by suboptimal cell retention and transient therapeutic effects. METHODS: BMSCs cultured on Flexcell plates were subjected to programmable mechanical stretching using a custom-built spherical cell-stretching system. Strain rate- and duration-dependent effects on paracrine signaling and ECM secretion were longitudinally assessed through western blot ting and ELISA. The optimized mechanical parameters (15% deformation, 1440 cycles, 5-s vertex residence time) were subsequently applied to generate BMSC sheets. Comparative analyses of biological activity and mechanical properties were performed between non-stretched controls and mechanically optimized groups. In vivo therapeutic efficacy was evaluated in diabetic rat models through wound closure kinetics, Masson's trichrome staining, and immunofluorescence detection of neovascularization markers. Mechanistic insights were obtained via transcriptomic profiling of stretch-activated signaling pathways. RESULTS: Mechanical stretching significantly upregulated type I collagen, type III collagen, vascular endothelial growth factor, and transforming growth factor-beta (TGF-β) secretion in BMSCs. The optimized stretching parameters (15% deformation, 1440 cycles, and 5-s vertex residence time) promoted BMSC proliferation while reducing apoptosis without compromising stemness. Mechanical stretching facilitated the formation of layered cell sheets with more organized collagen deposition and higher mechanical strength, expediting wound healing in diabetic rats through enhanced re-epithelialization and neovascularization. RNA sequencing analysis revealed that mechanical stretching significantly upregulated mechanosensitive molecules, mechanical stimulation signaling pathways, and cellular behavior regulatory pathways, particularly those associated with mechanical stimuli response, integrin binding, ECM secretion, and intercellular adhesion. CONCLUSIONS: Mechanically stretched BMSC cell sheets can promote diabetic wound healing by enhancing cellular activity, paracrine of growth factors, and ECM components.