Chondroprotective Effects of a Single PRP Injection in a Spontaneous Osteoarthritis Model of Dunkin Hartley Guinea Pig: An Immunohistochemical Analysis.

PURPOSE OF THE STUDY: The evaluation of anti-apoptotic and chondroprotective properties of a single injection of PRP using immunohistochemistry (IHC). METHODS: This was a placebo-controlled blinded experimental study. Ten healthy Dunkin Hartley guinea pigs were selected. One knee of each animal was injected with a single injection of PRP (Group A); the contralateral knee acted as a control and was injected with a single injection of normal saline (Group B). These groups were further divided into A3 and B3 based on the timeline of animal sacrifice (3 months) and A6 and B6 (6 months). The formalin-preserved articular cartilage blocks were subjected to IHC to stain Aggrecan, Caspase-3, and Collagen-2. RESULTS: The mean IHC score was significantly low for Caspase-3 (p-0.029) in intervention group (A3) in comparison to placebo control group (B3) pointing towards decreased apoptosis. The mean IHC values were significantly higher for Collagen II (p-0.011) for intervention group (A6) in contrast to control group (B6); values were also significantly low for Caspase-3 (p-0.029) in A6 as compared to B6. The mean Caspase-3 values were significantly higher in A6 as compared to A3 (p-0.029). CONCLUSION: The impact of a solitary injection of PRP on upregulation of anabolic pathways inside cartilage is relatively slower as compared to its effect on downregulation of apoptotic pathways. Even a single PRP injection holds the potential to change cartilage microenvironment, but the effects are not long lasting.