The effect of platelet-rich plasma on the repair of muscle injuries in rats☆

OBJECTIVE The need for therapeutic options for muscle injuries, which are increasingly frequent among sports practitioners, was the motivation for this experimental study, which had the aim of evaluating the histological effects of platelet-rich plasma (PRP) on repairs to muscle tissues of rats. METHODS PRP was obtained by means of double centrifugation of blood from five animals. In 30 rats, an injury was produced in the middle third of the belly of the gastrocnemius muscle of each hind limb. These injuries did not receive any treatment in six rats (12 legs). In 24 rats, 0.9% physiological serum was injected into the injury in the left leg and PRP into the injury in the right leg. Samples from the treated and untreated tissue were evaluated histologically 7 and 21 days after the procedures. RESULTS The quantity of collagen in the injuries treated with PRP was significantly lower than that in the other injuries, in the evaluation made 7 days after the procedure, but it became equal to the other groups in the evaluation done on the 21st day. There was a significant increase (p < 0.001) in the quantity of collagen from the 7th to the 21st day in the injuries treated with PRP, but this was not seen in the injuries treated using other methods. The inflammatory process was shown to be more intense in the injuries treated with PRP than in the injuries of the other treatment groups, in the evaluation done 7 days after the procedure. However, the morphological aspects of these injuries were seen to be similar to those of the untreated injuries, 21 days after the procedure. CONCLUSION PRP promoted complete tissue restitution between the 7th and 21st days in experimental muscle injuries.