Effects of Recombinant Adeno-Associated Virus-Mediated Overexpression of <i>Bone Morphogenetic Protein 3</i> on the Chondrogenic Fate of Human Bone Marrow-Derived Mesenchymal Stromal Cells.

Implantation of genetically modified chondrogenically competent human bone marrow-derived mesenchymal stromal cells (hMSCs) is an attractive strategy to improve cartilage repair. The goal of this study was to examine the potential benefits of transferring a sequence coding for the <i>bone morphogenetic protein 3</i> (<i>BMP-3</i>) that modulates bone and cartilage formation, using recombinant adeno-associated virus (rAAV) vectors on the chondroreparative activities of hMSCs. Undifferentiated and chondrogenically induced primary human MSCs were treated with an rAAV-h<i>BMP-3</i> construct to evaluate its effects on the proliferative, metabolic, and chondrogenic activities of the cells compared with control (reporter rAAV-<i>lacZ</i> vector) condition. Effective <i>BMP-3</i> expression was noted both in undifferentiated and chondrogenically differentiated cells in the presence of rAAV-h<i>BMP-3</i> relative to rAAV-<i>lacZ</i>, stimulating cell proliferation and extracellular matrix (proteoglycans, type-II collagen) deposition together with higher levels of chondrogenic <i>sex-determining region Y-type high-mobility group box 9</i> (<i>SOX9</i>) expression. rAAV-h<i>BMP-3</i> also advantageously decreased terminal differentiation, hypertrophy, and osteogenesis (type-I/-X collagen and alkaline phosphatase expression), with reduced levels of osteoblast-related <i>runt-related transcription factor 2</i> (<i>RUNX-2</i>) transcription factor and <i>β-catenin</i> (osteodifferentiation mediator) and <i>enhanced parathyroid hormone-related protein</i> expression (inhibitor of hypertrophic maturation, calcification, and bone formation). This study shows the advantage of modifying hMSCs with rAAV-h<i>BMP-3</i> to trigger adapted chondroreparative activities as a source of improved cells for transplantation protocols in cartilage defects.