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The effect of insulinlike growth factor I on wound healing variables and macrophages in rats
R V Mueller1, T K Hunt, A Tokunaga
1Department of Surgery, University of California-San Francisco.
Objective:
To assess the effect of insulinlike growth factor I (IGF-I) depletion and restoration on the number of wound macrophages and wound healing variables.
Design:
Fourteen-day, placebo-controlled trial.
Setting:
Animal research laboratory.
Study Participants:
Sham-operated and hypophysectomized healthy male rats weighing 300 g.
Intervention:
Random assignment to a 14-day IGF-I (10 micrograms per wound per day) or placebo infusion directly into standardized Hunt-Schilling dorsal wound chambers.
Main Outcome Measures:
Wound healing variables (dry tissue weight, total protein, DNA, and hydroxyproline content), and number and concentration of wound macrophages.
Results:
The IGF-I depletion in hypophysectomized rats decreased wound protein, DNA, and hydroxyproline content of wounds by 50%, and IGF-I infusion returned these variables to near that of sham-operated rats. Wound macrophage concentrations decreased by 50% from control in the IGF-I depleted rats and increased to 75% of control with IGF-I infusion.
Conclusion:
Insulinlike growth factor I may have a fundamental role in wound healing and may exert part of its stimulatory effect through macrophages. Although an independent effect of hypophysectomy on macrophages and collagen deposition is not excluded, we believe it is unlikely given the return to normal values with IGF-I infusion.