Background: Delayed-healing traumatic, surgical, and chronic wounds can be detrimental to patients and the health care system. The authors set out to investigate the effects of complement C5, a naturally occurring chemotactic cytokine, on wounds.
Methods: The authors examined the effects of complement C5 on the rat paired skin incision model. Each rat served as its own control where topical collagen was applied to one incision and 100 nM of C5 in collagen vehicle was applied to the other incision. Rats were killed on days 3 (n = 6), 7 (n = 6), and 28 (n = 5) after wounding.
Results: There was a statistically significant, 65 percent increase in maximum wound breaking strength with the topical application of C5 at day 3 (p < 0.01). The increase persisted to 14 percent at 7 days after wounding (p < 0.05). When compared with the sham group, the C5-treated wound strength increased by 83 percent at day 3 and 64 percent at day 7. There was no change in breaking strength at 28 days. Western blot analysis demonstrated a significant increase in collagen and fibronectin content in the C5-treated wounds.
Conclusions: Topical application of C5 to skin wounds significantly increases wound healing maximum breaking strength as early as 3 days and up to 7 days after wounding. C5 accelerated wound healing by at least 4 days in the first week of wounding. This was correlated with an increase in vascular permeability, increased inflammatory cell recruitment, subsequent fibroblast migration, and increased collagen deposition.