Comparisons of wound healing among excisional, laser-created, and standard thermal burns in porcine wounds of equal depth.

The present study was designed to characterize similarities and differences among three wounding modalities in partial-thickness porcine wounds. We hypothesized that inherent differences, such as endogenous cytokine delivery into excisional wounds or ablation of eschar during laser vaporization, should accelerate the magnitude and sequence of reparative events above the delayed repair that is frequently observed in patients with burns. A constant mid-dermal depth of injury was created by a Padgett dermatome, a computer-controlled pulsed CO(2) laser, or a temperature-controlled metal template. Wounds were harvested after 5, 10, or 15 days. After 5 days, significant resurfacing differences were apparent with values of 54% in excisions, 29% in lasers, and 12% in standard thermal burns. Sequences of fibroblastic proliferation were measurably different among the three wound modalities. At day 5 the bromodeoxyuridine labeling index for fibroblasts showed laser wound levels greater than excision wound levels, which were greater than burn wound levels; but by day 10, the proliferative profiles indicated that burn wound levels were greater than excision wound levels, which were greater than laser wound levels. Capillary areas (an assessment of angiogenesis) differed among the three wound types throughout the study. Peak values were observed at day 5 in both excisional and laser injuries; however, standard thermal burns did not peak until day 10. Both the magnitude and sequence of expression of three matrix metalloproteinases (-1, -2, and -9) differed among the three types of injuries. Laser wounds showed the earliest peak in matrix metalloproteinase-1 expression, whereas burns showed the least expression at day 5. In conclusion, although the three types of wounds undergo similar reparative processes such as reepithelialization, fibroblastic proliferation, angiogenesis, and expression of matrix metalloproteinases, the magnitude and temporal sequences are measurably altered among the three wound modalities. A greater understanding of specific differences within wound environments may lead to more insightful design of interventional wound therapies.