Efeito do plasma rico em plaquetas no reparo do tendão de aquiles em ratos

Abstract

The increasing incidence of tendon injuries is a constant challenge in orthopaedic medicine. The use of platelet-rich plasma (PRP) is a strategy widely explored in the clinic because it is believed to accelerate the tendon repair process. However, the PRP clinical efficacy is uncertain, and more studies that aim to a better understanding of this treatment are needed. The aim of this research was to evaluate the PRP effect on the Achilles tendon (AT) repair of rats. A total of 242 rats were used, where 181 animals were randomly distributed in 6 different experiments. The remaining animals were used as blood donors (n=49) and for flow cytometry (n=12). The lesion was performed by transection of the right AT. The repair evaluation occurred after 11 and 14 postoperative days, with a mechanical testing machine. Peak force was considered the primary variable. Variations in the PRP production protocols, leukocyte concentration and physical activity of the rats were tested. ELISA test was performed to quantify platelet-derived growth factor (PDGF-AB) present in PRP. Pathogenfree animals and animals contaminated with Staphylococcus aureus (S. aureus) were used. Standard PRP platelet concentration was at least 5 times higher than that of the peripheral blood, and it was possible to have either a high or a low leukocyte concentration in the preparation. PDGF-AB levels in inactivated PRP were 7.3 μg/mL (SD 6.0; n=4) and in plasma were below the detection levels (0.03 ng/mL). In the experiments performed with pathogen-free rats, no significant effect of PRP could be observed on tendon repair. In the same way, no significant difference could be found in the rats treated with PRP with higher or lower leukocyte concentration. In contrast, rats contaminated with S. aureus showed increased tendon force after PRP treatment. Significant interaction between bacteriological status and PRP treatment was verified (p=0.003). It was further observed that healthy rats had higher levels of cytotoxic T cells in their spleens. The difference in response to treatment in contaminated rats suggests that the PRP effect is dependent on the immune status of the animals. This is the first study that suggests the possibility of interaction between microbiota and tendon repair. Extrapolation of this treatment to the clinic remains dubious.