Deciphering molecular determinants of vascular heterogeneity for organ repair

描述(由申请者提供)：器官再生承诺无限制地获得替代组织。目前的器官再生模式依赖于移植成人组织受限的干细胞和祖细胞来修复受损的器官。然而，修复受损的器官往往会导致纤维化，功能恢复很少。这一建议挑战了流行的观点，并测试了另一种互补的方法，即再生也可以由组织特异性血管内皮细胞(ECs)引导，作为一个有指导意义的利基，在不引发适应不良纤维化的情况下促进器官再生和修复。这一概念是基于我们的发现，即血管不仅是输送氧气和营养的被动管道，而且是器官功能的积极参与者。事实上，我们的团队率先提出了一种变革性的概念，即组织特异性内皮细胞产生一组明确的非纤维化旁分泌介质，称为“血管分泌因子”，直接诱导器官再生，而不是纤维化。然而，血管内皮细胞所阐述的再生功能和血管分泌因子的库取决于它们起源的器官。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，普通的、未指定的内皮细胞通过“体内教育”过程获得组织特异性功能，在这种过程中，血管外线索触发转录程序。特定的内皮细胞被授权部署组织特异性血管分泌生长因子，这些因子可以推动器官修复，而不会出现异常的促纤维化重塑。我们的目标是识别调节EC血管分泌功能的转录因子(TF)，以便通用ECs可以被编程为靶向特定的血管床以促进再生。为了验证这一变革性假说并将这些概念转化为临床应用，我们将致力于以下目标：目的1)确定血管异质性和器官再生功能的分子决定因素；目的2)确定和验证组织特异性内皮细胞所阐述的促进器官修复而不引发纤维化的分子信号和血管分泌因子。我们已经开发出技术来繁殖来自小鼠和人类多能干细胞的通用内皮细胞，以及那些从羊膜细胞转录重新编程的内皮细胞。这项拟议的工作有望通过揭示内皮细胞在器官修复中动态的、特定于组织的作用，颠覆对单功能、惰性微血管系统的科学概念化。拟议研究的成功完成将使“受过教育的”、特定于组织的内皮细胞在治疗上得到应用，这些内皮细胞是天然受损器官的家园，并提供组织特有的血管分泌信号来协调器官再生。或者，一旦知道血管分泌因子，就可以直接给药。这种变革性的方法为刺激器官修复而不留下疤痕的研究开辟了新的治疗途径。

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.