Therapeutic Role of Platelet Rich Plasma in Formaldehyde-Induced Arthritis in Adult Male Albino Rats

Introduction Osteoarthritis (OA) is a common health problem. Platelet-rich plasma (PRP) has been recognized to enhance articular cartilage metabolism. Aim of the work the study was designed to investigate the influence of PRP on cartilage healing after induction of arthritis. Material and methods Forty two adult male albino rats were used in this study. The rats were randomly divided into three groups: Group I (n = 18): the control group (Ia, Ib & Ic) Ib & Ic were injected intra-articularly with saline and left for 3 and 6 weeks. Group II (n = 12): arthritic group, in which osteoarthritis was induced by injection of 0.02ml 5% formaldehyde once in the right knee joints, left without treatment, and were sacrificed after three weeks (IIa) or after six weeks (IIb). Group III(n = 12): arthritis was induced as group II, one week later, the rats were intra-articularly injected with single dose of 0.3ml PRP in the same joint then were sacrificed three weeks (IIIa) or six weeks (IIIb) after formaldehyde injection. At the end of the study the right knee joints were taken, decalcified then processed for paraffin sections to be examined by light microscope using H&E, toluidine blue and Masson’s trichrome (MTC) stains. Immunohistochemistry for caspase-3 enzyme was done to demonstrate apoptotic chondrocytes. Morphometric study was conducted to measure the thickness of the non-calcified cartilage, count the chondrocytes and synovial membrane inflammatory cells and Mankin's score. Then statistical analysis was done. Results The arthritic groups revealed irregular surface of the articular cartilage, loss of the articular matrix and bone eburnation. Moreover, there was apparent hypocellularity and disorganization of the chondrocytes. Osteoclasts and osteoblasts were seen invading the osteochondral junction. MTC stained sections of the synovial membrane showed deposition of thick collagen bundles with heavy inflammatory cell infiltrate and numerous blood vessels. The affinity of the articular cartilage to toluidine blue stain was apparently decreased while caspase-3 immunoreactivity was apparent in many chondrocytes .Group IIIa demonstrated almost similar histological findings as the control group; regular articular cartilage surface with regularly arranged chondrocytes in the different cartilage zones. Synovial membrane illustrated minimal inflammatory cell infiltrate with thin collagen bundles and small blood vessels in MTC stained sections. There was high affinity of the articular cartilage to the toluidine blue stain and few chondrocytes showed positive caspase-3 immunoreactivity. Group IIIb revealed continuous surface of the articular cartilage, yet with minimal fibrillation in some areas. Osteoblasts and osteoclasts were seen invading the calcified cartilage. Synovial membrane showed deposition of dense collagen bundles with some inflammatory cell infiltrate. Toluidine blue sections revealed decreased articular cartilage affinity to the stain while caspase-3 immunoreactivity was evident in many chondrocytes. The morphometric results and statistical analysis confirmed the histological findings. Conclusion Intra-articular injection of PRP demonstrated advantageous role on articular cartilage healing, however, these effects appeared to be transient. So the need of multiple injections of PRP has to be considered in cases of OA.