Nerve outgrowth and neuropeptide expression during the remodeling of human burn wound scars: A 7-month follow-up study of 22 patients

Increasing data suggest that the skin nerve system is involved in wound healing. The objective of this study was to investigate the outgrowth of nerve fibers during the burn wound remodeling process and to analyze possible differences between normotrophic and hypertrophic burn wounds. In a prospective study, biopsies were taken from 22 patients with spontaneously healed partial-thickness burns at 1, 4 and 7-month post-burn. Nerve outgrowth and the expression of the neuropeptides substance P, neurokinin A, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y was monitored using immunohistochemistry. Our results showed that the number of nerve fibers gradually increased in both the dermis and the epidermis, but that they did not reach the levels of expression present in matched unburned skin of the same patient. A significantly higher number of nerve fibers were observed in normotrophic scars compared with hypertrophic scars. The number of neuropeptides-containing nerves in normotrophic and hypertrophic scars were similar. In conclusion: 7 months after wound closure, burn wound scars contain less nerve fibers than unburned skin. The significantly higher number of nerve fibers in normotrophic, compared with hypertrophic scars suggests a regulatory role for the skin nerve system in the outcome of burn wound healing.