Exploring vascular-mesenchymal interactions in the stem cell niche

项目摘要/摘要 血管在与细胞分化、组织分化有关的器官发生中起着关键的发育作用 除了向发育中的组织输送氧气和代谢物外，还包括形态发生和干细胞利基。 血管发育失调与许多出生缺陷有关，并与 肿瘤的进展和转移。尽管对人类健康有这些广泛的影响，但 潜在的血管系统在基本生物过程中的指导作用知之甚少，代表着一种 该领域的主要知识缺口。我们最近在小鼠身上的研究表明，血管-间充质串扰 是胎儿睾丸器官发生的重要过程。当男性性别决定通路在 假定是睾丸，内皮细胞迁移到睾丸形成新的血管网络。有趣的是，血管 卵巢不会在同一发育阶段发生重塑。有人提出，支持细胞， 睾丸的支持细胞是睾丸器官发生的主要驱动力，但我们最近的工作表明 血管-间充质相互作用是睾丸形成过程中的一种重要的形态发生力量。是否具有启发性 血管系统在胎儿睾丸中的其他环境中的作用尚不清楚。我们的初步数据揭示了一个新的角色 睾丸血管维持睾丸间质细胞(LCS)的祖细胞，LCS是睾丸中的类固醇生成细胞 睾丸间质间隔是产生睾酮所必需的，睾酮是性激素的关键激素 分化和成虫生育能力。当我们阻断早期胎儿睾丸的血管发育时， LC分化，祖细胞数量减少，强烈提示血管是一种 LC利基市场的关键组成部分。然而，血管系统的分子和细胞基础 教育能力是未知的。我们的长期目标是了解哪些类型的细胞对 维持LC生态位，并发现调节LC分化的分子信号。我们将测试我们的 中心假设血管-间充质串扰是建立和维持血管-间充质串扰所必需的。 LC生态位通过两个特定的目标：1)描述组成以下所需的血管生态位的细胞类型 建立和维持LC前体细胞；以及2)阐明潜在的分子机制 LC生态位内的内皮-祖细胞相互作用，关注内皮细胞之间的Notch信号 和间质间充质。为了实现这些目标，我们将采用：体内遗传小鼠模型；体外 整个器官培养系统；体外原代细胞共培养技术；以及整个器官延时活体成像。 这些方法将使我们能够发现血管系统背后的关键分子信号和细胞玩家 在组织干细胞生态位中的重要发育作用，我们预计这将与研究直接相关 性发育障碍(DSD)和其他生殖系统出生缺陷，与激素相关 男性不育症与器官发生和肿瘤发生中的血管形成相关事件。

Project Summary/Abstract Blood vessels play critical developmental roles in organogenesis related to cellular differentiation, tissue morphogenesis, and stem cell niches, in addition to delivering oxygen and metabolites to developing tissues. Dysregulation of vascular development is associated with a number of birth defects and is intimately linked to tumor progression and metastasis. In spite of these broad human health implications, the mechanisms that underlie vasculature’s instructive roles in essential biological processes are poorly understood and represent a major knowledge gap in the field. Our recent work in mice demonstrated that vascular-mesenchymal crosstalk is a vital process during fetal testis organogenesis. When the male sex determination pathway is triggered in the presumptive testis, endothelial cells migrate into the testis to form new vascular networks. Interestingly, vascular remodeling does not occur in the ovary at the same developmental stage. It has been proposed that Sertoli cells, the supporting cells of the testis, are the main drivers of testis organogenesis, but our recent work showed that vascular-mesenchymal interactions are a critical morphogenetic force in testis formation. Whether instructive roles for vasculature exist in other contexts in the fetal testis is unclear. Our preliminary data reveal a novel role for testicular vasculature in maintaining progenitors for Leydig cells (LCs), which are steroidogenic cells in the testis interstitial compartment required for the production of testosterone, a critical hormone for sexual differentiation and adult fertility. When we blocked vascular development of the early fetal testis, supernumerary LCs differentiated and fewer progenitor cells were maintained, strongly suggesting that blood vessels are a critical component of the LC niche. However, the molecular and cellular underpinnings of vasculature’s instructive capacity are unknown. Our long-term goals are to understand which cell types are essential for maintaining the LC niche and to uncover the molecular signals that regulate LC differentiation. We will test our central hypothesis that vascular-mesenchymal crosstalk is required for the establishment and maintenance of the LC niche through 2 specific aims: 1) to delineate the cell types that comprise the vascular niche required for the establishment and maintenance of LC progenitors; and 2) to elucidate the molecular mechanisms underlying endothelial-progenitor interactions within the LC niche, focusing on Notch signaling between endothelial cells and interstitial mesenchyme. To accomplish these aims, we will employ: in vivo genetic mouse models; ex vivo whole organ culture systems; in vitro primary cell co-culture techniques; and whole organ time-lapse live imaging. These approaches will allow us to uncover key molecular signals and cellular players that underlie vasculature’s vital developmental role in a tissue stem cell niche, which we anticipate will have direct relevance for the study of disorders of sexual development (DSDs) and other birth defects of the reproductive system, hormone-related male infertility, and vascularization-associated events in organogenesis and tumorigenesis.