The addition of collagen scaffolds to human cell therapy to modify skin identity

Summary: Abstract Body: Skin identity is controlled by a combination of intrinsic features of the epidermis and dermis as well as crosstalk between the two compartments. The modification of skin identity has clinical potential, such as the conversion of residual limb/stump (Non-volar) skin of an amputee to pressure-responsive palmoplantar (Volar) skin in an effort to enhance prosthesis use and minimize skin breakdown. Features of volar skin, including greater epidermal thickness and dermal papillary elastin expression, likely contribute to its resilience. In our past human clinical trial we demonstrated the efficacy of ectopic volar fibroblasts to partially enhance non-volar epidermis and dermis with volar features. While our past human trial only included cells, we sought to test if the inclusion of extracellular matrix might enhance outcomes. In particular, we hypothesized that collagen, as the principal component of the fibroblast niche, might support ectopic fibroblast engraftment and function. We therefore tested the effects of ectopic volar fibroblasts a unique collagen scaffold on non-volar skin of human volunteers. We observed an increase in volar characteristics in non-volar skin 5 months post-injection, including increased epidermal thickness, skin firmness, and dermal papillary elastin expression. Supporting reprogrammed epithelial-mesenchymal crosstalk, total/single-cell RNA sequencing and Xenium in situ analysis revealed that ectopic volar fibroblasts with collagen had the strongest impact on gene ontology categories related to cornification, limb development, and skin morphogenesis. However, the addition of the collagen scaffold to ectopic fibroblasts also had unexpected effects on human skin, broadly increasing cell density of pan-fibroblasts and immune cells, and modifying keratinocyte differentiation for example through increases in IVL gene expression. This approach highlights the unique effects of extracellular matrix on human skin function and suggests new approaches to regenerative medicine. Sam S. Lee¹, Yingchao Xue¹, Ang Li¹, Elizabeth Winnicki¹, Nina Rossa Haddad¹, Arieana Johnson¹, Leigh Curvin-Aquilla¹, Minji Park¹, Joshua Kim¹, Jeremy C. Lee¹, Sewon Kang¹, Luis A. Garza¹ 1. Dermatogy, Johns Hopkins Medicine, Baltimore, MD, United States. Stem Cell Biology, Tissue Regeneration and Wound Healing