LAUSR

BACKGROUND A significant gap exists in the translatability of small animal models to human subjects. One important factor is poor laboratory models involving human tissue. Thus, we have created a viable postnatal human skin xenograft model using athymic mice. METHODS Discarded human foreskins were collected following circumcision. All subcutaneous tissue was removed from these samples sterilely. Host CD-1 nude mice were then anesthetized, and dorsal skin was sterilized. A 1.2cm diameter, full-thickness section of dorsal skin was excised. The foreskin sample was then placed into the full-thickness defect in the host mice and sutured into place. Xenografts underwent dermal wounding using a 4 mm punch biopsy after engraftment. Xenografts were monitored for 14 days after wounding and then harvested. RESULTS At 14 days postoperatively, all mice survived the procedure. Grossly, the xenograft wounds showed formation of a human scar at POD-14. H&E and Masson Trichome staining confirmed scar formation in the wounded human skin. Using a novel Artificial Intelligence (AI) algorithm using Picrosirius-Red staining, scar formation was confirmed in human wounded skin compared to the unwounded skin. Histologically, CD31 + immunostaining confirmed vascularization of the xenograft. The xenograft exclusively showed human collagen I, CD26 +, and human nuclear antigen in the human scar without any staining of these human markers in the murine skin. CONCLUSION The proposed model demonstrates wound healing to be a local response from tissue resident human fibroblasts and allows for reproducible evaluation of human skin wound repair in a preclinical model.