Muscle injuries and repair: current trends in research.

After injury, muscle healing occurs through different phases, including (1) degeneration and inflammation, (2) muscle regeneration, and (3) development of fibrosis. The severity and type of muscle injury influence the healing process. Enhancement of muscle regeneration and prevention of muscle fibrosis can improve muscle healing. Growth factors, including basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1), and nerve growth factor (NGF), can improve muscle regeneration, but the post-injury healing process remains incomplete. The use of anti-fibrosis agents that antagonize the effect of transforming growth factor-β1 (TGF-β1) can prevent fibrosis and improve muscle healing, resulting in nearly complete recovery. Optimal muscle recovery may require the use of novel technologies, such as gene therapy and tissue engineering, to achieve both high levels and long-term persistence of these growth factors and cytokines within the injured muscle. Muscle injury presents a challenging problem in traumatology, as injured muscles heal very slowly and often with incomplete functional recovery. It has been observed that injured muscles can initiate regeneration promptly, but the healing process is often inefficient and hindered by the formation of scar tissue, which may contribute to the tendency for muscle injury to recur. The enhancement of muscle regeneration and the prevention of muscle fibrosis through the use of biological approaches are being investigated in an effort to improve muscle healing after injury. In this Current Concepts Review, we will outline the structure and histological organization of skeletal muscle and describe the basic physiology of skeletal muscle contraction. We will subsequently summarize the biological and pathological processes that occur in skeletal muscle after injury (i.e., degeneration, inflammation, regeneration, and fibrosis) and present the clinical treatments currently available for injured skeletal muscle. Finally, we will discuss current trends in research, which include the improvement of regeneration and the inhibition of fibrosis in injured skeletal …