Effect of macrophage stimulation on collagen biosynthesis in the healing wound

Abstract

Immunomodulators that enhance macrophage function have been shown to be beneficial in a number of wound-healing models in humans and in experimental animals. The exact mechanism of this improved healing is unclear. To assess the role of collagen biosynthesis, the immunomodulator glucan phosphate was utilized in two murine models of wound healing, i.e., colon anastomosis and full-thickness skin incision. Tensile strength was evaluated using computer-assisted constant velocity tensiometry. Collagen biosynthesis was determined by assaying hydroxyproline content of wound hydrolysates by N-(9-fluorenyl)methoxycarbonyl/o-phthalaldehyde high-performance liquid chromatography. Experimental animals were treated with (1-3)-beta-D-glucan phosphate (250 mg/kg) intravenously 24 hours prior to colon anastomosis or skin incision. A second dose of glucan phosphate was given immediately postoperatively. Control animals received dextrose and water (5% w/v) intravenously. Tensile strength and hydroxyproline content were measured on postoperative Day 3. In the skin wound model, glucan phosphate treatment increased (P < 0.05) tensile strength by 42 per cent (342.5 +/- 12.2 vs 241.8 +/- 4.8 g), and hydroxyproline content was increased by 23.5 per cent (242.0 +/- 14.4 vs 196.8 +/- 10.5 pmol/microg; P < 0.05). In the glucan phosphate group, colon tensile strength was significantly (P < 0.05) increased by 34 per cent (34.2 +/- 2.3 g vs 45.8 +/- 2.1 g), and hydroxyproline content was increased by 7 per cent (47.45 +/- 3.31 vs 44.34 +/- 3.74 pmol/microg). These data indicate that macrophage modulation with glucan phosphate will increase tensile strength in experimental colon and skin wounds. In addition, we observed a positive correlation between glucan phosphate treatment, wound tensile strength, and collagen biosynthesis.