# Mechanoresponsive Engrailed-1-negative fibroblasts activate Engrailed-1 to promote fibrosis in wound healing

> **NIH NIH R01** · STANFORD UNIVERSITY · 2021 · $317,427

## Abstract

7. Project Summary/Abstract
Adult human skin heals by developing fibrotic scar tissue, which can result in devastating disfigurement, growth
restriction, and permanent functional loss. Despite a plethora of clinical options, no current treatment strategies
successfully prevent or reverse this fibrotic process, and scars and their sequelae cost the United States over
$20 billion every year. Progress towards the development of new therapies has been significantly hindered by a
lack of understanding of the specific cell populations responsible for scarring. In 2015, our group reported that
Engrailed-1 (En-1) lineage-positive fibroblasts (EPFs) are responsible for the vast majority of dorsal scar
production in postnatal mice. In early fetal gestation, mice heal scarlessly via skin regeneration, an ideal outcome
mediated by En-1 lineage-negative fibroblasts (ENFs; the predominant fetal fibroblast). However, it has not been
established if ENFs contribute to postnatal wound healing. In this proposal, we explore for the first time the
postnatal conversion of ENFs to pro-fibrotic EPFs (postnatally-derived EPFs; pEPFs) within the wound
environment. First, histology, immunohistochemistry, and wounding in a novel transgenic mouse model will be
used to study the conversion of ENFs to pEPFs during wound healing. By examining the behavior of ENF
subpopulations (derived from papillary dermis, reticular dermis, and hypodermis) in the wound environment and
confirming our findings in a tamoxifen-inducible mouse model of En-1 activation, we will precisely define the ENF
population that gives rise to pro-fibrotic pEPFs. Second, we will establish the specific wound environment cues
that drive ENF-to-EPF transition. Given that mechanical forces are known to modulate both scar burden and
fibroblast activity, we will use in vitro and in vivo models to examine the effects of mechanical environment on
En-1 activation. We will further use transcriptomic and epigenomic profiling to explore the role of
mechanotransduction signaling in ENF-to-EPF transition and pEPF function. Third, having established a
mechanotransduction mechanism underlying En-1 activation in wound ENFs, we will inhibit
mechanotransduction signaling with the goal of blocking ENF-to-EPF transition. Specifically, we will assess
whether blocking mechanotransduction results in ENF-mediated wound healing with reduced fibrosis. Our
ultimate translational goal is to develop therapeutics that target fibrogenic fibroblasts to promote regenerative
healing. Collectively, the proposed work will significantly enhance our understanding of the key molecular and
cellular determinants of cutaneous scarring, inform the development of novel anti-scarring therapies, and shed
light on the cellular origin of dermal scarring fibroblasts.

## Key facts

- **NIH application ID:** 10130573
- **Project number:** 5R01GM136659-02
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** MICHAEL T LONGAKER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $317,427
- **Award type:** 5
- **Project period:** 2020-04-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10130573

## Citation

> US National Institutes of Health, RePORTER application 10130573, Mechanoresponsive Engrailed-1-negative fibroblasts activate Engrailed-1 to promote fibrosis in wound healing (5R01GM136659-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10130573. Licensed CC0.

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