Molecular, histologic, and gross phenotype of skin wound healing in red Duroc pigs reveals an abnormal healing phenotype of hypercontracted, hyperpigmented scarring.

This study examined dermal wound healing in juvenile red Duroc pigs and determined that these animals exhibit a unique healing phenotype at multiple levels. Gross and histologic analysis revealed that full-thickness and deep dermal (1.8 mm deep) wounds both heal via formation of hypercontracted, hyperpigmented scars. Molecular analysis using reverse-transcriptase polymerase chain reaction and porcine-specific primer sets revealed that types I and III collagen, heat shock protein 47, bone morphogenetic protein-1, several proteoglycans, and tissue inhibitor of metalloproteinases 1-3 all showed a unique biphasic pattern of mRNA expression compared to previous results with Yorkshire pigs. This pattern was characterized by an initial peak of expression early after wounding, followed by a return to near-normal levels by days 28-42, and then a second increase in mRNA levels at days 56-70. The second phase of increased gene expression correlated with an increased collagen deposition as observed by picrosirius red staining and polarizing light microscopy. Reverse-transcriptase polymerase chain reaction analysis also revealed a prolonged expression of matrix metalloproteinase-2 compared to previous findings in the Yorkshire strain. Further characterization of the genetics and molecular biology associated with the red Duroc phenotype may provide insight into aberrant human wound healing.