How exercise protects joints in aging-related osteoarthritis
Osteoarthritis is one of the leading causes of pain, disability and loss of mobility among older adults worldwide. While regular exercise is strongly recommended for people with osteoarthritis and is known to protect joint tissue, we still do not fully understand the biological mechanisms by which this protection occurs. Gaining a better understanding of how exercise elicits this benefit will help us develop new interventions and therapies that reproduce its effects, especially for patients who face barriers to participating in regular exercise.
The authors wanted to understand whether circulating extracellular vesicles (EVs)—nanoparticles released by cells into the bloodstream—play a role in mediating the protective effects of exercise on joint health. Specifically, they investigated whether exercise alters the molecular cargo carried by EVs and whether these changes can directly improve cartilage health in aging and osteoarthritic joints.
The approach spanned EV analyses, cell culture experiments, mouse studies of aging-associated osteoarthritis and human exercise interventions.
In the human portion of the study, older adults participated in a structured aerobic exercise program, and the authors collected blood samples before and after three months of training. Using these blood samples, they analyzed how aerobic exercise altered the molecular contents of circulating EVs and evaluated the biological effects of these exercise-derived EVs on cartilage cells and joint tissues. They also identified and tested specific molecules that were enriched in EVs after training.
The researchers found that moderate-intensity exercise significantly changed the molecular cargo of circulating EVs in ways that promoted cartilage health and tissue resilience. Specifically, EVs collected after exercise improved cellular and cartilage tissue health in the knee joint.
Among the molecular signals enriched after exercise, the authors identified microRNA-29 as a key mediator of the beneficial effects. Delivery of microRNA-29 to aged osteoarthritic joints restored more youthful characteristics in cartilage cells and reduced features associated with joint degeneration.
The findings provide new insight into how exercise promotes joint health and help explain why physical activity is beneficial for people with osteoarthritis. By identifying specific biological signals that are altered by exercise, this work brings us closer to understanding the molecular pathways underlying rehabilitation interventions.
Looking forward, these discoveries may inform the development of new treatment approaches for osteoarthritis, including therapies that utilize EVs or their molecular cargo. These strategies would be especially impactful for people who are unable to engage in sufficient physical activity because of pain, disability or other health limitations, and show how regenerative medicine can be paired with traditional rehabilitation principles and approaches.
The researchers anticipate that this work will help guide the design of clinical programs that are focused on maximizing the biological responses associated with joint protection and tissue health.
