Abstract
BACKGROUND: In volumetric muscle loss (VML) injuries, spontaneous muscle regeneration capacity is limited. The implantation of autologous adipose tissue in the affected area is an option to treat these lesions; however, the effectiveness of this therapy alone is insufficient for a complete recovery of the damaged muscle. This study examined the influence of treadmill exercise on the rehabilitation of VML injuries reconstructed with autologous adipose tissue, as a strategy to counteract the limitations of spontaneous regeneration observed in these injuries. METHODS: Forty adult male Wistar rats were divided into eight groups of five individuals each: normal control (NC), regenerative control (RC), VML control (VML), VML injury reconstructed with fresh autologous adipose tissue (FAT), exercise-rehabilitated control (RNC), exercise-rehabilitated regenerative control (RRC), exercise-rehabilitated VML injury (RVML), and exercise-rehabilitated VML injury reconstructed with fresh autologous adipose tissue (RFAT). Histological and histochemical staining techniques were used for the analysis of structural features and histomorphometric parameters of the tibialis anterior muscle. Grip strength tests were conducted to assess muscle force. RESULTS: Exercise rehabilitation decreased the proportion of disoriented fibers in RFAT vs. FAT group. The percentage of fibrosis was significantly higher in FAT and RFAT groups versus NC and RNC groups but did not vary significantly between FAT and RFAT groups. Overall, muscle grip strength and fiber size increased significantly in the exercise-rehabilitated groups compared to control groups. CONCLUSIONS: To conclude, rehabilitation with physical exercise tended to normalize the process of muscle repair in a model of VML injury reconstructed with fresh autologous adipose tissue, but it did not reduce the intense fibrosis associated with these injuries.