Kinetics of blood flow during healing of excisional full-thickness skin wounds in pigs as monitored by laser speckle perfusion imaging.

BACKGROUND/PURPOSE: The laser speckle perfusion imaging (LSPI) system is a new, non-invasive technique for rapidly and reproducibly measuring tissue perfusion. The high resolution and frame rate of the LSPI overcome many of the limitations of traditional laser Doppler imaging techniques. Therefore, LSPI is a useful means for evaluating blood flow in a variety of situations. The present study investigates the ability of the LSPI system to detect temporal changes in blood flow during the healing of cutaneous wounds in a well-characterized animal model. METHODS: Full-thickness excisional skin wounds (2 x 2 cm) were created on the backs of juvenile female red Duroc pigs. Every week post-injury, the wounds were measured and photographed, and normalized blood flow values were determined using the LSPI system. RESULTS: Tissue perfusion values were available after complete re-epithelialization and removal of the eschar, at day 21. At this point, wound blood flow was significantly elevated as compared with the surrounding, uninvolved skin. Wound blood flow declined steadily during healing, and approached normal values by day 35 post-injury. CONCLUSION: The kinetics of blood flow during excisional wound healing in the red Duroc model are comparable with that previously observed in laser Doppler imaging of healing human skin wounds and hypertrophic scars. These results therefore confirm that the red Duroc is a good model of human wound healing, and further indicates that the LSPI is an excellent technique for evaluating angiogenesis and neovascularization during healing in this and other models.

Skin wound healing in the first generation (F1) offspring of Yorkshire and red Duroc pigs: evidence for genetic inheritance of wound phenotype.

Fibroproliferative scars in humans often demonstrate familial inheritance patterns, and genetics may contribute to healing and scarring. Genetic factors may also influence the scarring phenotype in a porcine model. Healing of full thickness excisional skin wounds in Yorkshire pigs closely resembles normal healing in humans, while identical wounds in red Duroc pigs form hypercontracted, hyperpigmented scars. The present study has evaluated the healing process in the first generation cross (F1) of red Duroc and Yorkshire pigs. Gross and histologic analysis revealed that the F1 animals exhibit an intermediate healing phenotype, with some features of each parent breed. F1 full thickness wounds were significantly hypercontracted and fibrotic, but apigmented. Analysis of mRNA expression patterns for a panel of relevant molecules (N=32) in the F1 animals revealed some similarities to each parent breed, as well as unique patterns for other molecules. Furthermore, a depth dependency to the healing response was observed at the gross, histologic, and molecular levels, with deep dermal wounds healing similar to Yorkshire wounds. These findings suggest that the genetic contribution to scar phenotype in this animal model is complex. However, the results indicate that further understanding in this model may provide insights into risk factors for hypertrophic scarring in human burn patients.