Clearance of p21-highly-expressing senescent cells accelerates cutaneous wound healing

Targeting senescent cells for therapeutic purposes is gaining momentum across various organ systems. However, concerns about potential off-target effects have been raised. Previous studies have shown that removing senescent cells expressing high levels of p16 (p16high) can hinder processes like wound healing. Here, we identify a distinct senescent cell population during dermal wound healing characterized by high expression level of p21 (p21high) using the p21-Cre mouse model. Using a standard cutaneous injury model, we find that eliminating p21high cells can expedite wound closure, in contrast to the effects of removing p16high cells. Through Xenium, a single cell spatial imaging platform, we show that p21high cells are distinct from p16high cells, with p21high cells mainly comprising fibroblasts, immune cells, keratinocytes, and endothelial cells with a pro-inflammatory profile. Moreover, inhibition of NF-kB signaling specifically from p21high cells partially contributes to the accelerated wound healing rates. These findings highlight the heterogeneity of senescent cells during wound healing responses within the skin and likely in other conditions. Wound tissue samples were harvested from mice at day 2, 4, and 12 post-injury, as well as from unwounded controls. Total RNA was extracted using TRIzol, purified with chloroform, isopropanol, and ethanol, and dissolved in RNase-free water. 500 ng RNA per sample was prepared for sequencing using the TruSeq Stranded mRNA kit and Illumina NovaSeq 6000. Reads were trimmed with Trimmomatic, mapped to GRCm39 using HISAT2, and gene expression was quantified with htseq-count.