Abstract: Isolation and Characterization of a Fibroblast Sub-Population Responsible for Cutaneous Scarring in the Ventral Dermis

Abstract

PURPOSE: Recent studies have demonstrated the functional heterogeneity of fibroblasts, particularly in terms of their activities during wound healing. Both location within the dermis and embryonic lineages1 provide a means by which we may now identify the sub-populations of fibroblasts chiefly responsible for connective tissue deposition during scar formation in the dorsal dermis.1,2 However, whether these findings translate to the ventral dermis have yet to be elucidated. METHODS:Prrx1Cre/Rosa26mTmG mice, were used to trace two fibroblast lineages restricted to the ventral dermis. Fibroblasts of different embryonic lineages—based on Prrx1 expression—were isolated from ventral fetal and adult dermis at a series of time points, including the late-gestational transition from scarless to scar-forming wound healing. ATAC-seq (Assay for Transposase-Accessible Chromatin with high throughput sequencing) was also performed in isolated pre- and post-gestational fibroblasts. RESULTS: Histological analysis revealed that the Prrx1-positive lineage contributed to the majority of connective tissue during scar formation. Flow cytometry demonstrated a shift in fibroblast sub-populations over the course of gestation. Differential patterns of chromatin accessibility shown by ATAC-seq further demonstrated the heterogeneic nature of fibroblasts within the ventral dermis at an epigenetic level. CONCLUSIONS: As in the dorsal dermis, fibroblasts of the ventral dermis demonstrate functional heterogeneity. Further studies may allow targeting of specific sub-populations to improve wound healing. 1. Rinkevich Y, Walmsley GG, Hu MS, et al. Skin fibrosis. Identification and isolation of a dermal lineage with intrinsic fibrogenic potential. Science. 2015;348(6232):aaa2151. 2. Lichtenberger BM, Mastrogiannaki M, Watt FM. Epidermal [beta]-catenin activation remodels the dermis via paracrine signalling to distinct fibroblast lineages. Nat Commun. 2016;7. DISCLOSURE/FINANCIAL SUPPORT:This work was supported in part by the California Institute for Regenerative Medicine (CIRM) Clinical Fellow training grant TG2-01159 (to M.S.H.), the Transplant and Tissue Engineering Fellowship Award (to M.S.H. and E.R.Z.), Center for Personal Dynamic Regulates (to H.Y.C.), NIH grant P50 HG007735 (to H.Y.C), NIH grant R01 GM087609 (to H.P.L.), the Hagey Laboratory for Pediatric Regenerative Medicine and The Oak Foundation (to H.P.L. and M.T.L.), NIH grant U01 HL099776 (to M.T.L.), and the Gunn/Olivier fund (to M.T.L.).