Biomechanics of single chondrocytes and osteoarthritis

Osteoarthritis is a significant, debilitating disease that afflicts millions of Americans, yet its etiology is poorly understood. However, there is substantial evidence that biomechanical factors play a role in the development and progression of osteoarthritis. Previous work has demonstrated that biomechanical factors such as an acute insult or the cumulative effects of repetitive loads can induce degenerative changes in joints, cartilage explants, and isolated chondrocytes. Nevertheless, all of these studies suffer from the limitation that the precise nature of the mechanical loads experienced by individual cells is not well defined. Implementation of a single-cell approach, employing existing cell mechanics methodologies and molecular techniques such as single-cell reverse transcriptase-polymerase chain reaction (RT-PCR), offers an exciting new means to identify which biomechanical factors precipitate pathological changes in chondrocytes indicative of osteoarthritis. This article reviews the particular methods used in mechanical studies of single cells with emphasis on techniques that have been used to investigate chondrocytes and similar anchorage-dependent cell types.The fundamentals of RT-PCR and its application at the single-cell level are also discussed.