Deciphering molecular determinants of vascular heterogeneity for organ repair

描述（由申请人提供）：器官再生承诺无限接近替代组织。目前的器官再生模式依赖于成体组织限制性干细胞和祖细胞的移植来修复受损的器官。然而，愈合受损的器官往往导致纤维化，几乎没有功能恢复。该提案挑战了流行的观点，并测试了另一种补充方法，即再生也可以由组织特异性血管内皮细胞（EC）指导，作为一个指导性的小生境，以促进器官再生和修复，而不会引起适应不良的纤维化。这一概念是基于我们的发现，即血管不仅仅是输送氧气和营养物质的被动管道，而是器官功能的积极参与者。事实上，我们的小组已经开创了组织特异性EC产生一组定义的非纤维化旁分泌介质（称为“血管分泌因子”）的变革性概念，以直接诱导器官再生而无纤维化。然而，再生功能和内皮细胞所产生的血管分泌因子依赖于它们起源的器官。事实上，血管分泌异质性的分子决定因素是未知的。因此，我们假设，通用的，未指定的，EC获得组织特异性功能的过程中的“体内教育”，其中血管外的线索触发转录程序。指定的EC被认证为部署组织特异性血管分泌生长因子，其驱动器官修复而没有异常的促纤维化重塑。我们的目标是确定调节EC血管分泌功能的组织特异性的转录因子（TF），以便可以对通用EC进行编程，以靶向特定的血管床，以促进再生。为了验证这一变革性假设并将这些概念转化为临床应用，我们将解决以下目标：目的1）确定血管异质性和器官型再生功能的分子决定因素;目的2）确定并验证组织特异性EC所产生的分子信号和血管分泌因子，这些分子信号和血管分泌因子促进器官修复而不会引起纤维化。我们已经开发了技术来繁殖来自小鼠和人类多能干细胞的通用EC和那些从羊膜细胞转录重编程的EC。这项工作有望通过揭示内皮细胞在器官修复中的动态、组织特异性作用，推翻单功能、惰性微血管系统的科学概念。成功完成拟议的研究将使“受过教育的”，组织特异性EC的治疗使用，家庭对他们的天然受损器官和供应组织特异性血管分泌信号，以协调器官再生。或者，一旦已知血管分泌因子，可以直接递送。这种变革性的方法开辟了新的治疗研究途径，以刺激器官修复而不留下疤痕。

DESCRIPTION (provided by applicant): Organ regeneration promises unlimited access to replacement tissues. The current paradigm of organ regeneration is dependent on transplantation of adult tissue-restricted stem and progenitor cells to repair the damaged organ. However, healing injured organs often leads to fibrosis with little recovery of function. This proposal challenges the prevailing viewpoint and tests an alternative complimentary approach that regeneration could also be directed by tissue-specific vascular endothelial cells (ECs) functioning as an instructive niche to promote organ regeneration and repair without provoking maladaptive fibrosis. This notion is based on our finding that blood vessels are not just the passive plumbing for delivery of oxygen and nutrients, but are active participants in organ function. Indeed, our group has pioneered the transformative concept that tissue-specific ECs produce a defined set of non- fibrotic paracrine mediators, called "Angiocrine Factors" to directly induce organ regeneration without fibrosis. Yet, regenerative function and the repertoire of angiocrine factors elaborated by ECs depend upon the organ from which they originate. Indeed, the molecular determinants of angiocrine heterogeneity are unknown. Thus, we hypothesize that generic, unspecified, ECs acquire tissue specific function by a process of "in vivo education" wherein extra-vascular cues trigger transcriptional programs. Specified ECs are credentialed to deploy tissue-specific angiocrine growth factors that drive organ repair without aberrant pro-fibrotic remodeling. Our objective here is to identify transcription factors (TFs) regulating tissue-specification of EC angiocrine function so that generic ECs can be programmed to target particular vascular beds to promote regeneration. To test this transformative hypothesis and translate these concepts for clinical use we will address the following objectives: Aim 1) Identify molecular determinants of vascular heterogeneity and organotypic regenerative function; Aim 2) Determine and validate the molecular signals and angiocrine factors elaborated by tissue-specific ECs that promote organ repair without provoking fibrosis. We have developed technologies to propagate generic ECs derived from mouse and human pluripotent stem cells and those ECs transcriptionally reprogrammed from amniotic cells. The proposed work is expected to overturn the scientific conceptualization of a monofunctional, inert, microvasculature by revealing a dynamic, tissue-specified role for ECs in organ repair. Successful completion of the proposed studies will enable therapeutic use of "educated", tissue-specified ECs that home to their native injured organs and supply tissue-specific angiocrine signals to orchestrate organ regeneration. Alternatively, once known the angiocrine factors could be delivered directly. This transformative approach opens new therapeutic avenues of research to stimulate organ repair without scarring.