The effect of combinations of growth factors on ligament healing.

Platelet-derived growth factor, basic fibroblast growth factor, and insulin-like growth factor Type 1 have demonstrated chemotactic and mitogenic properties in vitro that could benefit healing ligaments. These growth factors also have demonstrated in vivo effects when used in skin wound-healing models. In a previous study, bFGF and IGF-1, used alone, failed to improve healing. The authors wished to test the hypothesis that platelet-derived growth factor alone or combinations of platelet-derived growth factor plus insulin-like growth factor Type 1, platelet-derived growth factor plus basic fibroblast growth factor, or basic fibroblast growth factor plus insulin-like growth factor Type 1 would increase the healing efficiency of ligaments because of their effects on different parts of the cell replication cycle and their abilities to induce chemotaxis. Ligaments receiving platelet-derived growth factor alone were 73% +/- 55% stronger than their contralateral internal controls (p < 0.0025). Stiffness increased 94% +/- 63% over controls (p < 0.0025), and breaking energy was 101% +/- 104% > controls (p < 0.1). Ligaments treated with a combination of platelet-derived growth factor plus insulin-like growth factor Type 1 and platelet-derived growth factor plus basic fibroblast growth factor also had increases in rupture force, stiffness, and breaking energy over internal controls. Ligaments treated with a combination of basic fibroblast growth factor plus insulin-like growth factor Type 1 also appeared to have some improved healing; the results, however, did not prove to be statistically significant. Synergistic effects of growth factor combinations were not evident.