Establishing a xenograft model with CD-1 nude mice to study human skin wound repair

Abstract

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, the authors 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 1.2-cm-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 postoperative day 14. Hematoxylin and eosin and Masson trichome staining confirmed scar formation in the wounded human skin. Using a novel artificial intelligence algorithm using picrosirius red staining, scar formation was confirmed in human wounded skin compared with the unwounded skin. Histologically, CD31+ immunostaining confirmed vascularization of the xenograft. The xenograft exclusively showed human collagen type 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. Clinical Relevance Statement: Radiation-induced fibrosis is a widely prevalent clinical phenomenon without a well-defined treatment at this time. This study will help establish a small-animal model to better understand and develop novel therapeutics to treat irradiated human skin.

A tension offloading patch mitigates dermal fibrosis induced by pro-fibrotic skin injections

“…(14,32) This tool allows for unbiased, quantitative assessment of the complex architecture of fibrotic tissue, and allows for specimens to be objectively compared on the basis of their ECM ultrastructure. We have previously validated this image analysis pipeline in multiple fibrotic conditions across species (including mouse, pig, and human) (14,(32)(33)(34)(35)(36) and have shown that the fibrotic ECM features measured by our algorithm are clinically relevant (strongly predictive of highly clinically significant differences in patient survival in pancreatic cancer (32)).…”

“…To address this question, we employed a human foreskin xenograft model, which we have previously validated and used to study the effects of potential anti-fibrotic interventions. (36,40) We engrafted human foreskin samples onto the dorsum of immune-deficient mice (CD-1 nude -to prevent graft rejection), as previously reported, (36) then subjected xenografts to repeated injections of bleomycin with or without adjunct injections of recombinant IL4 protein; other grafts were made and not injected with bleomycin, as an UW/non-fibrotic control (Fig. 4A-B).…”