1352 Ectopic fibroblasts to modify skin identity

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. Greater KRT9 expression, higher epidermal thickness, larger keratinocyte cytoplasmic size, and longer collagen length are markers of volar skin and likely contribute to volar skin resiliency. Given the capacity of fibroblasts to modify keratinocyte differentiation, we hypothesized that volar fibroblasts might partially influence the above features. First, we demonstrated unique gene expression changes to external pressure forces on volar fibroblasts in vitro. We then confirmed the capacity of volar fibroblasts to induce volar keratinocyte features in bioprinted skin constructs. We subsequently tested the effects of mismatched (i.e. ectopic) volar fibroblasts in non-volar skin in a clinical trial of healthy volunteers. We find increased volar measures in non-volar skin after volar fibroblast injection maintained even after 5 months. Total and single cell RNA seq demonstrates that ectopic volar fibroblasts have the greatest effect on ontology categories of cornified envelope, keratinization, morphogenesis of epithelium, and keratinocyte cell differentiation, with confirmed immuno-histologic changes in pEGFR and Notch pathway (RBPJ). This approach suggests a novel therapeutic angle for any site-specific skin diseases.