Implantation of rAAV5-IGF-I Transduced Autologous Chondrocytes Improves Cartilage Repair in Full-thickness Defects in the Equine Model
Authors: Kyla F Ortved, Laila Begum, Hussni O Mohammed, Alan J Nixon
Journal: Molecular Therapy (2014)

Cartilage injury often precipitates osteoarthritis which has driven research to bolster repair in cartilage impact damage. Autologous chondrocytes transduced with rAAV5-IGF-I were evaluated in chondral defects in a well-established large animal model. Cartilage was harvested from the talus of 24 horses; chondrocytes were isolated and stored frozen. Twenty million cells were cultured and transduced with 105 AAV vg/cell prior to implantation. Chondrocytes from eight horses were transduced with rAAV5-IGF-I, chondrocytes from eight horses with rAAV5-GFP, and chondrocytes from eight horses were not transduced. A 15 mm full-thickness chondral defect was created arthroscopically in the lateral trochlear ridge of the femur in both femoropatellar joints. Treated defects were filled with naive or gene-enhanced chondrocytes, in fibrin vehicle. Control defects in the opposite limb received fibrin alone. rAAV5-IGF-I transduced chondrocytes resulted in significantly better healing at 8 week arthroscopy and 8 month necropsy examination when compared to controls. At 8 months, defects implanted with cells expressing IGF-I had better histological scores compared to control defects and defects repaired with naive chondrocytes. This included increased chondrocyte predominance and collagen type II, both features of hyaline-like repair tissue. The equine model closely approximates human cartilage healing, indicating AAV-mediated genetic modification of chondrocytes may be clinically beneficial to humans. Cartilage injury often precipitates osteoarthritis which has driven research to bolster repair in cartilage impact damage. Autologous chondrocytes transduced with rAAV5-IGF-I were evaluated in chondral defects in a well-established large animal model. Cartilage was harvested from the talus of 24 horses; chondrocytes were isolated and stored frozen. Twenty million cells were cultured and transduced with 105 AAV vg/cell prior to implantation. Chondrocytes from eight horses were transduced with rAAV5-IGF-I, chondrocytes from eight horses with rAAV5-GFP, and chondrocytes from eight horses were not transduced. A 15 mm full-thickness chondral defect was created arthroscopically in the lateral trochlear ridge of the femur in both femoropatellar joints. Treated defects were filled with naive or gene-enhanced chondrocytes, in fibrin vehicle. Control defects in the opposite limb received fibrin alone. rAAV5-IGF-I transduced chondrocytes resulted in significantly better healing at 8 week arthroscopy and 8 month necropsy examination when compared to controls. At 8 months, defects implanted with cells expressing IGF-I had better histological scores compared to control defects and defects repaired with naive chondrocytes. This included increased chondrocyte predominance and collagen type II, both features of hyaline-like repair tissue. The equine model closely approximates human cartilage healing, indicating AAV-mediated genetic modification of chondrocytes may be clinically beneficial to humans.