人皮肤成纤维细胞直接重编程为表皮干细胞及表皮干细胞命运决定的表观遗传机制研究

获取足够数量表皮干细胞是解决皮肤创面修复的重要手段。成熟细胞失去原型态获得新的细胞表型，称为细胞重编程。我们利用转录因子和适宜微环境成功建立了成纤维细胞向表皮干细胞重编程的诱导模型。目前，如何提高重编程效率并增加诱导性表皮干细胞的稳定性和均一性是亟待解决的关键问题。我们认为对重编程机制的认识是解决这些问题的切入点。最新研究显示细胞发生重编程是表观遗传信息改变导致基因表达变化的结果。因此，本项目拟从转录因子和微环境、表观遗传修饰调控（DNA甲基化、组蛋白修饰、染色质重塑和染色质可及性）及基因表达三维角度分析成纤维细胞向表皮干细胞重编程的机制，建立以表观遗传修饰为中心的分子调控网路，破译细胞命运转归的要素用以优化现有模型，为建立高效、安全的定向分化手段提供线索和平台。由此建立的分子机制研究方案和相关技术手段将为今后细胞重编程研究提供可靠的模式和参考，也为表皮干细胞治疗的临床实现奠定夯实的基础。

Generation of enough epidermal stem cells is critical for the repair and regeneration of the injured skin for patients with extensive full-thickness burns or traumas. The process that a fully differentiated cell loses its own phenotype and gains a new one is called somatic cell reprogramming. We successfully developed a reprogramming model to generate epidermal stem cell-like cells from human fibroblasts by using specific transcription factors and providing permissive mciroenvironment. However, how to increase the reprogramming efficiency and promote the stability and homogeneity of induced epidermal stem cell-like cells are the key issues to be solved. A deeper understanding of the mechanisms underlying reprogramming will allow us to coax cells into a desired fate, and thereby decrease heterogeneity of induced cells. Most recent studies suggest that somatic cell reprogramming is the result of gene expression alterations induced by epigenetic changes. Accordingly, we attempt to study the in-depth mechanism of this reprogramming model from three dimensional views which include transcription factors and microenvironment, epigenetic modification and gene expression. The research on epigenetic pathways will consist of DNA methylation, histone modification, chromatin remodeling and chromatin accessibillity. By doing this, we aim to map the epigenetic modification-centered molecular regulating network, based on which the initial events controlling cell fate conversion are to be uncovered and appropriate interventions adopted to optimize our established reprogramming model. Gaining insight into how target molecules interact with each other as well as their interaction with the cellular environment will allow for more efficient and stable reprogramming and eventually small molecule-based control of cell states. Any progress being made in the proposed study would benefit the development of replacement stragies using induced epidermal stem cells for clinical appliacation in the near future.