Abstract
The effects of growth and differentiation factorβ5 (GDFβ5) on ligament healing were studied using a gap injury model of the medial collateral ligament in rat knee joints. The administration of GDFβ5 once at the time of surgery significantly improved the mechanical properties of the femurβligamentβtibia complex. At 3 weeks after surgery, 30 Β΅g of GDFβ5 improved the ultimate tensile strength of the complex by 41%, and the stiffness by 60%, compared with the vehicle control (pβ<β0.05 for both; Fisher's PLSD test). The observation with a transmission electron microscopy revealed that GDFβ5 increased the diameter of collagen fibrils in the repair tissue, which was considered to be a possible mechanism for the positive result in the biomechanical testing. Quantitative PCR and in situ hybridization revealed enhanced type I procollagen expression by GDFβ5, and the PCR analysis also revealed that the GDFβ5 treatment reduced the expression of type III procollagen relative to type I procollagen. The PCR analysis further showed that the expression of decorin and fibromodulin was relatively reduced against type I procollagen by the growth factor, which was considered to be responsible for the increase of collagen fibril diameter in the repair tissue. No adverse effects were observed, and the use of GDFβ5 was considered a promising approach to facilitate ligament healing. Β© 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res