Medical News Today delivers the latest on understanding and enhancing muscle regeneration: Plasminogen activator inhibitor-1 (PAI-1) "levels appear to increase with aging, and may explain, in part, the loss of repair capacity as we age. [Scientists] plans to see whether manipulating PAI-1 levels can restore muscle repair in old muscles. ... PAI-1 levels also appear to be higher in muscle diseases [in which] muscle repair processes can't keep up with the degeneration caused by the disease. ... The plasminogen system likely has multiple roles in muscle repair. Understanding how the plasminogen system works in skeletal muscle may give some clues to improving repair of different tissues, especially heart, which is similar in many ways to skeletal muscle."