| Description |
- Background and Hypothesis
Cutaneous wound healing is a complex process that is typically characterized by significant inflammation and fibrosis, culminating in the formation of a scar. Improper wound healing can lead to complications, including functionally limiting and disfiguring scars, with lasting consequences. Notably, in contrast to adult skin, fetal skin can regenerate with minimal scarring prior to late gestation. However, the mechanisms governing skin regeneration and scarless healing are not fully understood. This study aims to identify the critical components of scarless healing by profiling the fetal transition from scarless to scarring healing. We investigated whether there are pro-regenerative genes that play essential roles in orchestrating this transition and whether these factors could be harnessed to improve healing and fibrosis in adult skin.
Methods and Results
Pregnant rats of gestational age E16.5 (scarless) and E18.5 (scarring) were used. The rats were anesthetized with isoflurane and a midline laparotomy was performed to expose the uterus. The uterus overlying individual fetuses was carefully incised to expose the fetal dorsal thorax. A 1 mm2 section of integument was excised. Saline was instilled into the uterus and the abdomen was closed with suture. Rats were sacrificed at 1 and 3 days post-injury, and fetal tissue was collected. Analysis of scarless versus scarring fetal skin was performed using immunohistochemistry and immunofluorescence. Single-nuclei RNA sequencing (snRNA-seq) was performed on sorted nuclei obtained from both uninjured and injured fetal skin to profile gene expression changes in the transition from scarless versus scarring healing. To assess whether the pro-regenerative genes identified through the snRNA-seq results could be delivered to injured skin, a recombinant adeno-associated virus (rAAV) vector carrying a green fluorescent protein (GFP) gene was introduced via local subcutaneous injection at the time of fetal skin injury. Immunofluorescent analysis of the fetal skin showed successful transduction of GFP.
Conclusions
Fetal skin exhibits the ability to regenerate normal tissue architecture and function after cutaneous injury. An exploration into the fetal transition from scarless to scarring healing has the potential for improving wound healing in humans. Work is underway to identify injury-responsive gene regulatory elements during the scarless to scarring transition using ATAC-seq. Our ongoing studies include viral manipulation to harness gene regulatory elements and pro-regenerative genes to target gene expression to injury sites and improve wound healing and fibrosis. With a greater understanding of fetal scarless wound healing, future work may lead to novel therapies for people who suffer from significant scarring or chronic non-healing wounds.
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