Angiogenic hydrogel composites for microvascular integration of organoid grafts

项目摘要/摘要 微血管的移植物整合是I型细胞替代策略的关键下一步 糖尿病患者。宿主连接的微血管的结合对于植入后移植物的存活至关重要。 长期影响葡萄糖反应和全身性胰岛素释放的动力学。导演 含有胰岛的合成水凝胶中的血管生成将确保宿主连接的微血管形成 移植，但对血管生成的控制仍然有限。我们的长期目标是理解生理信号是如何从 细胞微环境影响血管生成的关键步骤，并设计工程方法来 将这些线索结合到可翻译的生物材料中。血管生成涉及一系列时空上的 受控的细胞程序包括内皮尖细胞的激活和定向侵袭，集体迁移 顶端细胞和随之而来的茎细胞，以及多细胞链的增殖和管腔。我们的前辈 研究表明，在聚集过程中，尖端细胞迁移和茎细胞增殖之间存在关键平衡 形成功能性微血管所需的迁移，以及水凝胶的降解性调节集体 血管内皮细胞的迁移。此外，我们还率先开发了包含物理线索的水凝胶复合材料 一种合成纤维，可促进内皮细胞向间充质细胞的转变并导致静止的内皮细胞 细胞采取侵袭性行为，提示TIP细胞导致血管生成芽。总而言之，这些观察结果 支持我们的中心假设：水凝胶结构的模块化控制可以驱动血管生成 支持hPSC来源的胰岛类器官功能的微血管系统。使用新型复合材料 水凝胶，器官组织模型，以及体内血管和胰岛功能的评估，我们的目标是 了解血管生成过程中内皮细胞决策的微环境调节。在AIM 1，我们将利用含有细胞黏附引导纤维的水凝胶复合材料来进行表型转化 静止的内皮细胞转化为侵袭性的TIP细胞。在目标2中，我们将设计水凝胶交联和微尺度 多孔性驱动内皮柄细胞增殖并建立集合体之间的数量关系 柄细胞迁移、增殖事件和微血管内化。在目标3中，我们将在体外和体内使用 体内模型检测材料引导的血管生成和由此产生的微血管生成对血管生成的影响 含hPSC来源胰岛的水凝胶移植物的功能。拟议的研究将1)揭示 血管生成过程中表型转变的微环境调节和2)确定生物材料设计 支持功能性血管生成的参数。我们预计制定的战略将提供 对工程化胰岛移植物的微血管支持将与含有其他 需要新陈代谢的实质组织。

PROJECT SUMMARY/ABSTRACT Graft integration of microvasculature is a critical next step for cell replacement strategies for type I diabetics. The incorporation of host-connected microvasculature is essential for post-implantation graft survival and over the longer-term impacts the kinetics of glucose response and systemic insulin delivery. Directing angiogenesis into islet-containing synthetic hydrogels would guarantee host-connected microvasculature in the graft, but control over angiogenesis remains limited. Our long-term goal is to understand how physical cues from the cellular microenvironment impinge upon critical steps of angiogenesis and devise engineering methods to incorporate these cues into translatable biomaterials. Angiogenesis involves a series of spatiotemporally controlled cellular programs including endothelial tip cell activation and directed invasion, collective migration of leading tip cells and ensuing stalk cells, and proliferation and lumenization of the multicellular strand. Our prior work demonstrates a critical balance between tip cell migration and stalk cell proliferation during collective migration required for forming functional microvessels, and that hydrogel degradability modulates the collectivity of endothelial cell migration. Further, we have pioneered hydrogel composites containing physical cues in the form of synthetic fibers that promote endothelial-to-mesenchymal transition and cause quiescent endothelial cells to adopt invasive behavior suggestive of tip cells that lead angiogenic sprouts. Together, these observations motivate our central hypothesis: modular control of hydrogel structure can drive the angiogenic formation of microvasculature that supports the function of hPSC-derived pancreatic islet organoids. Using novel composite hydrogels, organotypic tissue models, and assessments of vascular and islet function in vivo, we aim to understand the microenvironmental regulation of endothelial cell decision-making during angiogenesis. In Aim 1, we will utilize hydrogel composites containing cell-adhesive guidance fibers to phenotypically transition quiescent endothelial cells into invasive tip cells. In Aim 2, we will engineer hydrogel crosslinking and microscale porosity to drive endothelial stalk cells proliferation and establish quantitative relationships between collective migration of stalk cells, proliferative events, and microvessel lumenization. In Aim 3, we will use in vitro and in vivo models to examine the impact of material-guided angiogenesis and resulting microvasculature on the function of hydrogel grafts containing hPSC-derived islets. The proposed studies will 1) shed light on the microenvironmental regulation of phenotypic transitions during angiogenesis and 2) identify biomaterial design parameters that support functional angiogenesis. We anticipate the developed strategies to provide microvascular support to engineered pancreatic islet grafts will have bearing on grafts containing other metabolically demanding parenchymal tissues.