Spatial, molecular and functional characterization of organ-specific lymphatic endothelial progenitor cells

淋巴管系统控制体液平衡、脂质、抗原和免疫细胞的运输。因此，淋巴系统在脂质代谢、肿瘤转移和免疫中起着核心作用，因此它与肥胖、自身免疫、动脉粥样硬化和癌症等常见疾病的发病机制有关。最近，新的、非静脉来源的淋巴内皮祖细胞（LEPCs）有助于器官特异性淋巴血管的形成，例如在肠系膜中，已经被发现。我假设胚胎起源定义了分子和功能上不同的LEPC群体，其中一个LEPC群体的缺陷可能解释了原发性淋巴水肿中淋巴功能障碍的器官特异性表现。在该计划中，利用新的报告菌株进行遗传谱系追踪，将应用最先进的成像技术、荧光激活细胞分选和单细胞测序来解析肠系膜lepc的精确空间起源、功能和分子身份。非静脉源性lepc和静脉源性lepc的基因表达谱比较可能揭示lepc特异性基因，这些基因可能决定肠系膜淋巴血管系统的不同功能。一个或两个体外验证的特征基因在肠系膜淋巴血管形成和功能中的作用将在体内使用转基因小鼠模型进行研究。这项工作将确定器官特异性lepc的确切起源、易位机制以及分子和功能差异。总之，这些结果可能揭示调节和决定器官特异性淋巴管发育和功能的分子和细胞机制，可以作为开发治疗与淋巴功能障碍相关疾病的新治疗策略的基础。

The lymphatic vasculature controls fluid homeostasis, transport of lipids, antigens, and immune cells. Hence it plays central roles in lipid metabolism, tumor metastasis and immunity and consequently the lymphatic system is implicated in the pathogenesis of common diseases such as obesity, autoimmunity, atherosclerosis and cancer. Recently, novel, non-venous-derived lymphatic endothelial progenitor cells (LEPCs) that contribute to the formation of organ-specific lymphatic vasculatures, e.g. in the mesentery, have been identified. I hypothesize that the embryonic origin defines molecularly and functionally distinct LEC populations, and that defects in one of the LEPC populations may account for the organ-specific manifestation of lymphatic dysfunction in primary lymphedema.In the proposed project genetic lineage tracing using novel reporter strains, state of the art imaging, fluorescence-activated cell sorting and single cell sequencing will be applied to decipher the precise spatial origin, function as well as the molecular identity of mesenteric LEPCs. Comparison of the gene expression profiles of non-venous and venous-derived LEPCs and LECs may reveal LEPC-specific genes that potentially determine the distinct functions of the mesenteric lymphatic vasculature. The role of one or two in vitro validated signature genes in the formation and function of the mesenteric lymphatic vasculature will be investigated in vivo using transgenic mouse models. This work will identify the precise origin(s), translocation mechanisms as well as molecular and functional differences between organ-specific LEPCs. Together these results may uncover molecular and cellular mechanisms regulating and determining organ-specific lymphatic vessel development as well as function that could serve as basis for the development of novel therapeutic strategies for the treatment of diseases associated with lymphatic dysfunction.