The aims of this study were to (1) determine whether platelet-rich plasma (PRP) could be prepared as a bioactive scaffold capable of endogenous growth factor release for cartilage repair; (2) compare the chondrogenic differentiation ability of mesenchymal stem cells (MSCs) from bone marrow (BMSC) and from adipose (ADSC) seeded within the PRP scaffold; and (3) test the efficacy of ADSC-PRP construct in cartilage regeneration in vivo. In vitro evaluation showed that a 3-dimensional scaffold with a mesh-like microstructure was formed from PRP, with the capability of endogenous growth factor release and ready cell incorporation. Upon seeding in the PRP scaffold, BMSC showed higher proliferation rate, and higher expression of cartilage-specific genes and proteins than ADSC. In an osteochondral defect model in rabbits, implanted BMSC seeded within PRP scaffold also exhibited better gross appearance and histological and immunohistochemical characteristics, higher cartilage-specific gene and protein expression as well as subchondral bone regeneration. ADSC seeded constructs developed into functional chondrocytes secreting cartilaginous matrix in rabbits at 9 weeks post-implantation. Our findings suggest that PRP is a candidate bioactive scaffold capable of releasing endogenous growth factors and that BMSC and ADSC seeded within the PRP scaffold differentiate into chondrocytes and may be suitable for cell-based cartilage repair.
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