Low-intensity treadmill exercise promotes rat dorsal wound healing

In order to investigate the promoting effect of low-intensity treadmill exercise on rat dorsal wound healing and the mechanism, 20 Sprague-Dawley rats were randomly divided into two groups: exercise group (Ex) and non-exercise group (non-ex). The rats in Ex group were given treadmill exercise for one month, and those in non-ex group raised on the same conditions without treadmill exercise. Both groups received dorsal wound operation with free access to food and water. By two-week continuous observation and recording of the wound area, the healing rate was analyzed. The blood sample was collected at day 14 post-operation via cardiac puncture for determination of the number of endothelial progenitor cells (EPCs) by flow cytometry, and the concentrations of relevant cytokines such as basic fibroblast growth factor (bFGF), endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) were measured by ELISA. The skin tissue around the wound was dissected to observe the vascular density under the microscope after HE staining, to detect the mRNA level of VEGFR2 and angiopoietin-1 (Ang-1) receptor using RT-qPCR, and protein expression of a-smooth muscle actin (αSMA) and type III collagen (ColIII) using Western blotting. It was found that the wound area in Ex group was smaller at the same time point than in non-ex group. The number of circulating EPCs was greater and the concentrations of vasoactive factors such as VEGF, eNOS and bFGF were higher in Ex group than in non-ex group. HE staining displayed a higher vessel density in Ex group than in non-ex group. Moreover, the mRNA expression of VEGFR2 and Ang-1 detected in the wound tissue in Ex group was higher than in non-ex group. Meanwhile, the protein expression of αSMA and ColIII was more abundant in Ex group than in non-ex group. Conclusively, the above results demonstrate Ex rats had a higher wound healing rate, suggesting low-intensity treadmill exercise accelerates wound healing. The present work may provide some hint for future study of treating refractory wound.