Evaluation of Growth factor Enhanced Matrix rhPDGF-BB in Combination with a Biphasic Collagen Implant for Osteochondral Defect Repair in a Caprine Model

Introduction: We hypothesize that combining rhPDGF-BB with a collagen matrix in an acute caprine osteochondral defect, rhPDGF-BB will: Increase the quantity of bone in the subchondral region over matrix alone; and improve the quality of the repair for the overlying tissue.

Materials and Methods: Osteochondral defects were surgically created in the medial femoral condyles of 32 Boer Cross Goats. Animals were randomized to receive no treatment (empty), implant alone, or implant plus three doses of rhPDGF-BB. Outcome measures of gross morphology scores, micro CT, and histopathology were assessed at 12 weeks.

Results: rhPDGF-BB significantly improved gross articular cartilage repair score; improved tissue integration, thickness, surface regularity and decreased cyst formation, significantly improving total cartilage repair score. rhPDGF-BB treated defects demonstrated increased subchondral bone and the presence of osseous bridging spanning the defect space in the HIGH dose rhPDGF-BB group.

Discussion/Conclusion: Throughout the study, no safety issues were observed. Enhanced bony bridging was apparent in the high-dose rhPDGF-BB group. Accordingly, the addition of rhPDGF-BB significantly decreased the incidence of subchondral cyst formation. rhPDGF-BB increased the quantity and integration of the repair tissue. A longer time point is needed to evaluate hyaline cartilage repair. Enhancement of the subchondral bone and surface repair suggest that rhPDGF-BB may have promise as a therapeutic treatment for osteochondral defect repair.

Acknowledgment: Funding was provided by Lynch Biologics/BioMimetic Therapeutics. Lynch Biologics would like to thank Applied Biological Concepts, LLC for the surgical care of the animals in this study.