Comparison of Human, Porcine & Rodent Wound Healing with New Miniature Swine Study Data
Liu, J., Kim, D., Brown, L., Madsen, T., Bouchard, G.F
Accidental wounds are one of the most common reasons for human visits to hospital emergency services. Healthy individuals normally heal accidental skin wounds in a rapid period if complications, such as infections, can be avoided. Aged individuals or diabetics frequently suffer delayed wound healing. Wound researchers require efficient animal models which are predictive of human responses. Pig skin is anatomically, physiologically, biochemically and immunologically similar to human skin, and the skin is ‘fixed skin’ like humans and unlike rodents or rabbits. Loose skin allows accelerated closure of surgically induced rodent wounds by primary contraction unlike the normal primary response of re-epithelialization in swine and humans. Pig skin mirrors human skin in having a sparse haircoat, a relatively thick epidermis, similar epidermal turnover kinetics, lipid composition and carbohydrate biochemistry, lipid biophysical properties, and a similar arrangement of dermal collagen and elastic fibers. In our studies, healthy juvenile miniature swine wound re-epithelialization progressed relatively quickly (average 0.109 mm/hr at d19) while geriatrics progressed more slowly (average 0.048 mm/hr at d32). Untreated adult diabetic Yucatan miniature swine wound re-epithelialization rates were 88% of conventional non-diabetic (control) Yucatan models at d29 post wounding. Postulations for this minor difference will be offered. Control juvenile or young adult Sinclair or Yucatan miniature swine dermal wounds heal at faster rates (re-epithelialization rate) than those of geriatric or diabetic animals. The healing rate differential can be as high as 2:1 for juveniles over geriatrics. Porcine or miniature swine models offer significant advantages and have a record of predicting treatment modalities in human over models with loose skin. Miniature swine models can provide useful efficacy data for novel cutaneous therapy products.