Targeted silencing of Engrailed-1 reprograms profibrotic fibroblast lineage for scarless wound healing.

Skin wounds typically heal with dysfunctional scarring, a fibrotic process largely driven by Engrailed-1 (En1) lineage-positive fibroblasts (EPFs). However, the potential reversibility of EPFs' profibrotic effects and corresponding therapeutic strategies remain elusive. Here, we develop a nanoscale fibroblast-mimic carrier (FibroMC) for targeted delivery of En1-specific small interfering RNA (siEn1) to fibroblasts, aiming to inhibit En1 expression and reverse their profibrotic effects. FibroMC was constructed by functionalizing Food and Drug Administration-approved ionizable lipid nanoparticles with fibroblast cell membrane. With incorporated cell membrane proteins (e.g., Integrin β1 and N-cadherin), FibroMC was preferentially taken up by fibroblasts, leading to potent silencing of En1 in all EPF populations both in vitro and in vivo. Consequently, FibroMC treatment significantly inhibited collagen I expression and myofibroblast differentiation. A single dose of topical application of FibroMC to the wound effectively restored collagen architecture, regenerated skin appendages, recovered skin mechanical property, and ultimately prevented scar formation. Our findings demonstrate that FibroMC-mediated En1 silencing can reverse the profibrotic effect of EPFs, offering a promising therapeutic strategy for scarless wound healing.