Abstract

In this work, a nucleoside inhibitor of DNA methyltransferases, zebularine, was investigated as a wound healing and regeneration promoting agent. It was found that a high dose of intraperitoneally delivered zebularine improved punch wound closure in the ear pinna in mice. Both cytidine, a zebularine analogue, and uridine, a zebularine metabolite, did not promote ear pinna hole closure. The effect of zebularine on ear pinna healing was dose-dependent. Further experiments showed that zebularine administration should be carried out shortly after the injury as several-day delays resulted in decreased effectiveness. Transcriptional activity of genes related to stem cell development and maintenance and cell cycle progression regulation was evaluated in the ear pinna tissues regenerating in response to zebularine treatment. Two of the crucial cell pluripotency genes, Nanog and Sox2, were remarkably induced in zebularine-treated ear pinnae on day 7 after injury. Also, the Cdkn2a gene encoding an inhibitor of a cell cycle progression was significantly upregulated in zebularine-treated pinnae. These findings suggest that zebularine enhances wound repair by activating genes that are silenced in adult tissues in normal conditions. Preliminary trials to translate the zebularine regenerative therapy to other injury models were performed. Topically delivered zebularine moderately accelerated dorsal skin wound healing in mice and positively affected the tissue architecture in the restored skin. This observation suggests that zebularine might drive skin repair into a regenerative response. Besides, a pilot experiment was carried out to evaluate the zebularine treatment effect on sciatic nerve healing following a crush-injury. To my knowledge, the zebularine-induced ear pinna regeneration is the first example of regenerating a complex tissue by use of an epigenetic inhibitor in vivo. These findings indicate that epigenetic modulation might become an essential step in regenerative therapies.

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