Endothelial tip cell-mediated angiogenesis and repair after neonatal stroke

项目摘要/摘要 新生儿中风是导致死亡和残疾的重要原因，诊断往往被延误。的确有 对局灶性缺血再灌注损伤的修复机制认识不足 这是导致早期中风的最常见原因。血管生成、纤维化和血管周围细胞再生 在很近的地方，旁分泌信号支持内皮细胞的相互作用，这对修复至关重要。 调节这一神经血管生态位可能是改善脑缺血损伤后预后的潜在靶点 发育中的大脑。促红细胞生成素和基于细胞的疗法已经成为有希望的延迟治疗方法 治疗中风的策略，尽管它们的受益机制仍不完全清楚。它很可能是动态的 促血管生成生长因子的释放和促红细胞生成素下游信号通路的激活 受体在不同脑区和不同时间对内皮细胞亚型的影响不同 受伤后得分。此外，局部纤维化在早期损伤进展和修复中的明确作用 局灶性脑损伤尚不清楚。有效地诱导长期的、功能性的血管生成需要了解 以及模仿发育中的大脑的机制。我们的目标是了解当地 局灶性脑缺血再灌注后缺血区和梗死区的血管生成与纤维化 在发育中的脑损伤，并确定再生和修复的机制 通过关注血管反应来延迟促红细胞生成素。在目标1中，我们将检验假设 血管前端的内皮尖端细胞对新生儿卒中后的血管生成至关重要 延迟促红细胞生成素将促进血管生成并改变内皮细胞亚型基因表达谱 促进TIP细胞计划。在目标2中，我们将对缺血核心和血管周围的成纤维细胞和血管周围细胞进行量化。 卒中后急性期、亚急性期和慢性期梗塞周围半暗带的变化及测定促红细胞生成素 信号影响局部纤维化和修复。最后，在目标3中，我们将确定和修改特定的信令 检验促红细胞生成素调节的动态内皮细胞信号是关键假说的途径 用于促进局灶性脑损伤后的局部血管生成。这将确定关键的、可修改的路径 对新生儿中风后的损伤进展和修复很重要。我们的主要假设是 促红细胞生成素治疗将促进血管生长和重塑，减少亚急性纤维化和 星形胶质细胞在缺血中心的增殖，并增强血管周围信号转导改善 新生儿卒中后的组织学和功能结局。这三个目标将共同探索 特定细胞亚型和途径在局灶性脑损伤后恢复中的作用，更广泛的目标是 优化治疗策略以改善全脑损伤常见原因后的长期结果 目前还没有治疗方法。

PROJECT SUMMARY/ABSTRACT Neonatal stroke is an important cause of death and disability, and diagnosis is often delayed. There is insufficient knowledge regarding repair mechanisms that occur in response to focal ischemia-reperfusion injury that is the most common cause of early stroke. Angiogenesis, fibrosis, and perivascular cell repopulation occur in close proximity, with paracrine signaling supporting endothelial cell interactions that are vital for repair. Modulating this neurovascular niche may be a potential target for enhancing outcomes after ischemic injury in the developing brain. Erythropoietin and cell-based therapies have emerged as promising delayed treatment strategies for stroke, although the mechanism of their benefit is still not entirely clear. It is likely that dynamic release of pro-angiogenic growth factors and activation of signaling pathways downstream of erythropoietin receptor have differential effects on endothelial cell subtypes in distinct brain regions and at different time points after injury. In addition, the defined role of local fibrosis in injury progression and repair following early focal brain injury is unknown. Effectively inducing long-term, functional angiogenesis requires understanding and mimicking mechanisms that occur in the developing brain. Our objectives are to understand local angiogenesis and fibrosis in ischemic and peri-infarct regions following focal ischemia-reperfusion injury in the developing brain, and to determine the mechanisms of regeneration and repair with delayed erythropoietin by focusing on the vascular response. In Aim 1, we will test the hypothesis that endothelial tip cells at the vascular front are critical for angiogenesis following neonatal stroke, and that delayed erythropoietin will enhance angiogenesis and alter endothelial cell-subtype gene expression profiles to promote tip cell programs. In Aim 2, we will quantify fibroblasts and perivascular cells in the ischemic core and peri-infarct penumbra in the acute, subacute, and chronic stages after stroke and determine how erythropoietin signaling impacts local fibrosis and repair. Finally, in Aim 3, we will determine and modify specific signaling pathways to test the hypothesis that dynamic endothelial cell signaling modulated by erythropoietin is crucial for promoting local angiogenesis following focal brain injury. This will determine critical, modifiable pathways important for injury progression and repair following neonatal stroke. Our primary hypothesis is that delayed erythropoietin treatment will promote vascular growth and remodeling, reduce subacute fibrosis and astrocytic proliferation in the ischemic core, and enhance perivascular signaling to improve histological and functional outcomes after neonatal stroke. Together, these three aims will explore the roles of specific cellular subtypes and pathways in recovery after focal brain injury, with the broader goal of optimizing therapeutic strategies to improve long-term outcomes after a common cause of full-term brain injury that currently has no therapy.