The Evaluation of Platelet Lysate Incorporation into the Microfracture Clot in a Pig Model

Abstract

Cartilage injuries present a significant clinical burden due to the tissue's limited regenerative capacity. Microfracture (Mfx) remains the gold standard of cartilage repair but often results in inadequate defect fill and inferior tissue formation. Point-of-care augmentations to the Mfx environment represent implementable and cost-effective methods to enhance outcomes. The objective of this study was to evaluate platelet lysate (PL) as an adjuvant to microfracture-based cartilage repair, with the goal of maintaining tissue volume and promoting functional repair. We first evaluated the impact of PL on the activity of marrow-derived cells (MDCs) in monolayer culture, demonstrating an increase in cellular area and proliferation. Next, we incorporated PL into fibrin gels (to mimic fibrin-rich Mfx), and MDCs encapsulated within PL-containing fibrin gels exhibited increased proliferation, increased cellular area, and reduced fibrosis markers. We observed that PL incorporation into fibrin gels led to clear changes to initial nanostructure and an increase in initial mechanical properties, and this led to less MDC-mediated contraction during culture. These findings suggested that time-zero augmentation of Mfx with PL may alter both cellular signaling and Mfx clot structure/remodeling. Finally, we evaluated PL-augmented Mfx in a porcine trochlear osteochondral defect model (t=5 weeks). While PL-treated defects exhibited reduced contraction and improved macroscopic appearance over Mfx alone, micro-CT and mechanical testing revealed no significant differences in subchondral bone remodeling or repair tissue stiffness. Histological analysis and grading showed no significant improvements in cartilage repair quality across treatment groups, suggesting that while PL may influence early clot stability, its effects on long-term tissue maturation remain uncertain. Future studies are needed to determine whether PL-based Mfx augmentation consistently provides sustained functional benefits.