Genetic and monoclonal antibody blockade of GDF8 enhances musculoskeletal recovery and mitigates posttraumatic osteoarthritis following ligament injury [cartilage]
Background: Musculoskeletal disorders contribute to a substantial proportion of disability among people worldwide. Anterior cruciate ligament (ACL) tears are among the most frequent knee injuries, and a majority of patients will go on to develop knee osteoarthritis within 10 years. Traditional rehabilitation following injury has limited success restoring muscle strength and mitigating the onset of posttraumatic knee osteoarthritis. Growth differentiation factor 8 (GDF8), or myostatin, is a myokine that has been implicated in the pathogenesis of musculoskeletal degeneration following ACL injury. This study investigated GDF8 levels in injured human skeletal muscle and serum and compared the efficacy of a humanized monoclonal GDF8 antibody against a placebo in a mouse model of injury-induced osteoarthritis (surgically induced ACL tear). Muscle GDF8 peaks rapidly following ACL injury, and early induction of GDF8 in skeletal muscle was predictive of atrophy, weakness and periarticular bone loss in patients six months following surgical ACL reconstruction. GDF8 antibody administration at the time of injury substantially reduced muscle atrophy, weakness and fibrosis in the mouse ACL injury model. GDF8 antibody treatment rescued the skeletal muscle and articular cartilage transcriptomic response to ACL injury and attenuated the severity of injury-induced knee osteoarthritis. Subcutaneous treatment with GDF8 antibody also diminished loss of periarticular bone microarchitecture. Genetic deletion of GDF8 neutralized musculoskeletal deficits in response to ACL injury. Our findings support an opportunity for rapid targeting of GDF8 to enhance functional musculoskeletal injury recovery and mitigate the development posttraumatic knee osteoarthritis, which could substantially reduce the disability burden associated with this injury. Overall design: Comparative gene expression was assessed in mouse cartilage tissue in non-ACL injured (control) limbs and ACL-transected (injured) limbs at 7-days post-injury in both placebo-treated and anti-GDF8 antibody-treated mice (pooled cartilage samples from 4 mice per treatment)