Cellular plasticity and lineage in mammalian digit tip regeneration

项目摘要 老鼠、猴子和人类在截肢后可以再生指尖。这种与生俱来的合成形式 组织再生是一个高度协调的过程，涉及多种组织类型相互作用， 替换的手指尖与正确的组成和模式。定义手指尖的独特之处， 分子信号或细胞类型，以及它与再生的关系，可以为更广泛的再生工作提供信息， 非再生组织这一过程的一个立足点是最近对小鼠细胞的表征 指端芽基，截肢后形成的祖细胞的集合，这是产生 到再生组织。我们的单细胞RNA测序为基础的分析的芽鉴定13 分子上不同的成纤维细胞群。有了这个，我们现在有了特定的细胞群， 评估其在指端再生中的功能。我们认为，成纤维细胞的亚群在 再生小鼠趾尖包括可分离的作用，包括祖细胞，结构和生态位因子， 产生细胞，其中一个亚群可以促进复合组织再生。在本提案中，我们重点关注 指尖成纤维细胞的异质性，旨在确定每一个的起源，功能和再生潜力， 这些人口。我们将分析小鼠成纤维细胞亚群的空间组织， 并确定那些由祖细胞组成。使用单细胞RNA测序 谱系追踪，我们将确定何时建立成人手指的指尖异质性，并定义 成纤维细胞群体对再生组织的细胞可塑性和再生贡献。 最后，我们将研究手指尖成纤维细胞亚群与成纤维细胞在身份和功能上的关系 非再生性近端截肢总的来说，本项目产生的数据将提供一个 全面了解指端成纤维细胞的异质性群体， 再生，这将为更广泛的复合组织再生奠定基础。

PROJECT SUMMARY Mice, monkeys, and humans can regenerate their digit tips following amputation. This innate form of composite tissue regeneration is a highly coordinated process involving multiple tissue types interacting to form a replacement digit tip with the proper composition and pattern. Defining what is unique to the digit tip in terms of molecular signals or cell types, and how it relates to regeneration, can inform broader regeneration efforts of non-regenerative tissues. One foothold into this process is the recent cellular characterization of the mouse digit tip blastema, the collection of progenitor cells that forms following amputation that is necessary to give rise to the regenerating tissue. Our single cell RNA sequencing-based analysis of the blastema identified 13 molecularly distinct fibroblast populations. With this, we now have specific cellular populations to individually assess for their function(s) in digit tip regeneration. We propose that the subpopulations of fibroblasts in the regenerating mouse digit tip encompass separable roles including progenitors, structural, and niche-factor- producing cells, of which a subset may promote composite tissue regeneration. In this proposal, we focus on digit tip fibroblast heterogeneity and aim to determine the origin, function, and regenerative potential of each of these populations. We will analyze the spatial organization of the fibroblast subpopulations in mouse and human digit tips and determine those comprised of progenitor cells. Using single cell RNA sequencing with lineage tracing, we will determine when the digit tip heterogeneity of the adult digit is established, and define the cellular plasticity and regenerative contribution of the fibroblast populations to the regenerated tissue. Finally, we will investigate how the digit tip fibroblast subpopulations relate in identity and function to fibroblasts from non-regenerative proximal amputations. Collectively, the data generated in this project will provide a comprehensive understanding of the heterogeneous population of digit tip fibroblasts in the context of regeneration, which will lay the foundation for composite tissue regeneration on a broader scale.