Lanolin and epidermal growth factor in healing of partial-thickness pig wounds

A total of 80 partial-thickness wounds (4.4 cm2 size, 400 micron deep) was inflicted by electrokeratome in the dermal skin layer of four piglets, 15 kg body weight. The wounds were treated with gauze (control), lanolin cream (Lanolor or Lanolin with emulsifiers, Squibb) or with human epidermal growth factor (EGF) delivered in lanolin cream (10 micrograms EGF/mL cream). The treatment was applied every 12 hours for 12 to 120 hours after wounding. The reepithelization rate of the wound was determined by standardized morphometric method. In addition, we measured the thickness of the dermis and cell counts in the dermis. We found that most of the statistically significant enhancement of the epithelization rate, thickness of the dermis, and higher cell count in the dermis were attributed to the effect of lanolin cream alone. The additional significant enhancement of healing by EGF over that of lanolin alone was documented in one of our experiments, but was only marginal. In another experiment using another commercial formulation of lanolin, we found no difference between the effect of EGF and lanolin. Several hypotheses were suggested to explain the effect of the two tested lanolin cream formulations, which induced strong inflammatory reaction in the wound.