Growth hormone increases the biomechanical strength and collagen deposition rate during the early phase of skin wound healing

Abstract

The effects of biosynthetic human growth hormone on the biomechanical properties and collagen deposition rate of wound healing were investigated in rat skin incisional wounds after 4 days of healing. Biosynthetic human growth hormone induced a pronounced, < or =94%, and dose-dependent increase in the mechanical strength of wounds in the dose range of 0.125 to 2 mg/kg/day. A new method for in vivo studies of the collagen deposition rate in granulation tissue of the wound cleft was applied. The production of (3)H-hydroxy-l-proline was measured by injecting (3)H-proline intravenously into the rats with a large flooding dose of unlabeled proline which reduces reutilization of (3)H-proline and reduces the influence of de novo synthesis of proline. Extractable collagens, which are not bound in the wound tissue and therefore do not contribute mechanical strength to it, were removed from the samples. Labeled and unlabeled proline were determined simultaneously by reverse-phase high-performance liquid chromatography with ultraviolet detection and flow scintillation counting of these amino acids. At day 4 the collagen deposition rate in the incisional wound zone, 0.4 mm wide containing the wound cleft, was 1.8% per hour of the collagen present in the wound zone. The collagen deposition rate was increased by 149% by biosynthetic human growth hormone 2 mg/kg/day compared with the control group. This result indicates that the increased biomechanical strength of the skin incisional wounds of the groups treated with biosynthetic human growth hormone was produced by an increased deposition of collagen in the wound cleft.