Lef1 expression in fibroblasts maintains developmental potential in adult skin to regenerate wounds

Abstract

Scars are a serious health concern for burn victims and individuals with skin conditions associated with wound healing. Here, we identify regenerative factors in neonatal murine skin that transforms adult skin to regenerate instead of only repairing wounds with a scar, without perturbing development and homeostasis. Using scRNA-seq to probe unsorted cells from regenerating, scarring, homeostatic, and developing skin, we identified neonatal papillary fibroblasts that form a transient regenerative cell type that promotes healthy skin regeneration in young skin. These fibroblasts are defined by the expression of a canonical Wnt transcription factor Lef1 and using gain- and loss of function genetic mouse models, we demonstrate that Lef1 expression in fibroblasts primes the adult skin macroenvironment to enhance skin repair, including regeneration of hair follicles with arrector pili muscles in healed wounds. Finally, we share our genomic data in an interactive, searchable companion website (https://skinregeneration.org/). Together, these data and resources provide a platform to leverage the regenerative abilities of neonatal skin to develop clinically tractable solutions that promote the regeneration of adult tissue.

More than just bricks and mortar: Fibroblasts and ECM in skin health and disease

“…This regenerative phenomenon, also known as wound‐induced hair follicle neogenesis (WIHN) 29,30 is highly desirable, yet normally not achievable clinically and variable across species, being prominent in spiny mice 31,32 and deficient in rats 33 and pigs 34 . Cellular heterogeneity in the WIHN model has been recently studied using scRNA‐seq 35–39 . The major focus on these studies has been to better understand the lineage origin and the transcriptomic states of regeneration‐competent wound fibroblasts, that can become new dermal papilla cells of neogenic hair follicles.…”

“…The major focus on these studies has been to better understand the lineage origin and the transcriptomic states of regeneration‐competent wound fibroblasts, that can become new dermal papilla cells of neogenic hair follicles. Phan et al compared the transcriptional features of fibroblasts from three recently published scRNA‐seq datasets on hair‐forming and hairless wounds 35,38,39 . Compared to hairless wounds, fibroblast populations in hair‐forming wounds are enriched for retinoic acid binding protein Crabp1 , a marker of upper wound cells 33 .…”

Single‐cell transcriptomic analysis of small and large wounds reveals the distinct spatial organization of regenerative fibroblasts

“…To investigate differences between scarring and regenerative wound repair, we performed a scRNA‐seq analysis from fibroblasts of two scarring wounds and two types of wounds that regenerate hair follicles (Figure 1). We utilized previously published data from Abbasi et al, 2020 and Phan et al, 2020 15,16 . scRNA‐seq experiments performed in Phan et al sequenced all of the cells from single‐cell suspensions of scarring and regenerating wounds.…”

“…These comparisons of regenerating and scarring wounds using scRNA‐seq have mapped diverse populations of fibroblast within the wound beds but have not fully understood how they can differentiate into dermal papilla to support hair follicle reformation. However, two recent publications investigating the differences between scarring and regenerating wounds by scRNA‐seq now provide a foundational data set to investigate the ability to regenerate 15,16 …”

Mapping the molecular and structural specialization of the skin basement membrane for inter-tissue interactions

“…Abnormal early anagen and catagen entry phenotype is also observed upon DP-specific β-catenin gene deletion 40 . Thus, we investigated the change in DP cell identity by examining the expression of LEF1, a key DP marker mediating canonical Wnt signalling 41 and HF development and regeneration 42,43 . Nuclear LEF1 was detected in DP cells in the telogen HFs of control mice (P84), but not in those of Lama5 cKO mice (Fig.…”