Effects of rAAV-Mediated Overexpression of sox9 and TGF-beta via Alginate Hydrogel-Guided Vector Delivery on the Chondroreparative Activities of Human Bone Marrow-Derived Mesenchymal Stromal Cells

Recombinant adeno-associated virus (rAAV) vectors have a strong potential to promote the healing of traumatic cartilage defects and osteoarthritic lesions upon delivery and overexpression of therapeutic genes from suitable biomaterials that support a controlled release of the candidate constructs. The goal of the present work is to examine whether the administration of chondrogenic rAAV sox9 and rAAV TGF-beta gene vehicles via alginate hydrogel-guided vector delivery stimulates the biological and chondroreparative activities of human bone marrow-derived mesenchymal stromal cells (hMSCs) as a source of improved reparative cells for future implantation in sites of cartilage damage. The delivery of rAAV using an alginate (AlgPH155) hydrogel system is successfully achieved in hMSCs over time (21 days), leading to the effective overexpression of sox9 and TGF-beta that significantly increases the proliferation and chondrogenic differentiation activities of the cells relative to control (marker lacZ) gene transfer while advantageously preventing premature hypertrophy, osteogenesis, and mineralization. This study reveals the potential of alginate hydrogel-based systems to control the delivery of rAAV (sox9 and TGF-beta) gene vectors to adeptly trigger the chondroreparative activities of hMSCs for future applications that aim at improving cartilage repair.