Platelet rich plasma enhances the immunohistochemical expression of platelet derived growth factor and vascular endothelial growth factor in the synovium of the meniscectomized rat models of osteoarthritis

This study was carried out on a rat model of surgically-induced osteoarthritis (OA) to assess the histological and immunohistochemical changes in the synovial membrane and to evaluate the effects of intra-articular injection of platelet rich plasma (PRP) in such cases. Forty five male albino rats were divided into 3 equal groups; control, surgically-induced OA and surgically-induced OA followed by intra-articular injection of PRP. Knee joints were processed for histological and immunohistochemical staining with anti-platelet derived growth factor (PDGF-A) and anti-vascular endothelial growth factor (VEGF) and the area percentages of immunostaining were measured by digital image analysis. Serum levels of PDGF-A and VEGF were analyzed by ELISA. The osteoarthritis research society international (OARSI) score was significantly higher in OA (2433.8 ± 254) than in control (230.4 ± 37.8; p < 0.001) and in PRP-treated tissues (759.7 ± 45.8; p < 0.001). The immunostained area percentages for PDGF-A was significantly higher in PRP-treated tissues (20.6 ± 2.4) than in OA (11.06 ± 1.3; p = 0.007) and in control tissues (4.1 ± 0.78; p < 0.001). Likewise, the immunostained area percentage for VEGF was significantly higher in PRP-treated tissues (22.5 ± 1.6) than in OA (14.9 ± 1; p = 0. 002) and in control tissues (6.5 ± 0.7; p < 0.001). ELISA analysis revealed a significant increase in serum levels of the PDGF-A and VEGF after intraarticular PRP injection when compared to the other groups (p < 0.000). The present study concluded that intra-articular injection of PRP could produce optimizing effects in surgically induced OA in the form of; decreasing the OARSI score, improving the inflammatory events in synovium and modulating the PDGF-A and VEGF serum levels and synovial tissue immunoexpression. These effects could be reflected positively on the associated chondral defect.