TY - JOUR T1 - Evidence based journal watch JF - British Journal of Sports Medicine JO - Br J Sports Med SP - 953 LP - 954 VL - 40 IS - 11 A2 - , Y1 - 2006/11/01 UR - http://bjsm.bmj.com/content/40/11/953.abstract N2 - Negishi S, Li Y, Usas A.Am J Sports Med 2005;33:1816–24OpenUrlAbstract/FREE Full Text Professor Martin P Schwellnus, University of Cape Town, South Africa Background: In the repair of injured skeletal muscle neutralisation of the effect of transforming growth factor-b1 (a key fibrotic cytokine) by the hormone relaxin may prevent fibrosis, increase muscle regeneration, and thereby improve the recovery following muscle injury. Research question/s: Does the administration of relaxin, a member of the family of insulin-like growth factors, reduce fibrosis and improve the healing of injured muscle? Methodology:Materials:Two studies: study 1 (in vitro), myoblasts (C2C12 cells) and myofibroblasts (transforming growth factor-β1-transfected myoblasts); study 2 (in vivo), 24 female mice. Experimental procedure: In vitro study: myoblasts and myofibroblasts were incubated with relaxin and cell growth and differentiation were determined (myogenic and fibrotic protein expression). In vivo study: relaxin was injected intramuscularly at different time points (none = control, days 3, 7 and 14) after the induction of a laceration injury in the skeletal muscle of the mice. Measures of outcome: Skeletal muscle healing (histological, immunohistochemical, and physiologic parameters). Main finding/s:: In vivo study: relaxin administrtion decreased myofibroblast proliferation, down-regulated expression of the fibrotic protein α-smooth muscle actin in a dose-dependent manner. In vitro study: relaxin administration enhanced muscle regeneration, reduced fibrosis, and improved injured muscle strength. Conclusion/s: In an … ER -