Heat shock‐pretreated bone marrow mesenchymal stem cells accelerate wound healing in a diabetic foot ulcer rat model

Diabetic foot ulcers (DFUs) are the severe chronic complications of diabetes, amputation is required when ulcers cause severe loss of tissue or evoke a life-threatening infection. Mesenchymal stem cells (MSCs) have shown a good effect in helping DFU healing, though the efficiency needs to be improved. This study aimed to investigate the effects of heat shock pretreatment on the improvement of the therapeutic effects of MSCs. Primary rat bone marrow MSCs (BMSCs) were isolated and stimulated with heat shock pretreatment and then tested on a DFU rat model. Alkaline phosphatase, Alizarin Red S, and Oil Red O were stained to check the osteogenic differentiation ability of heat shock-pretreated BMSCs. The effect of heat shock pretreatment on the inflammatory response of macrophages was studied with the lipopolysaccharides stimulation model on a mouse macrophage cell line RAW264.7. The impact of heat shock-pretreated BMSCs on dermal fibroblasts was also checked. Last, heat shock-pretreated BMSCs were tested on a DFU rat model. Heat shock-pretreated BMSCs were characterized by the expression of CD105 and CD44. Heat shock pre-stimulation did not affect cell viability when cultured up to 96 h. Heat shock pre-stimulated BMSCs inhibited the inflammatory response by reducing the pro-inflammatory cytokine production (IL-1β, IL-6, and TNF-α) and enhancing the anti-inflammatory cytokine production (IL-10) (at least all p < 0.01), as well as increasing the ratio of M2 polarization macrophages to M1 polarization in vitro (p < 0.001). Heat shock pre-stimulated BMSCs enhanced the growth and migration of dermal fibroblasts in vitro (p < 0.001). Heat shock-BMSCs promoted the M2 polarization level of macrophages in wound tissues in a DFU rat model. Heat shock pretreatment could enhance the therapeutic effect of BMSCs on wound healing in a DFU rat model.