Angiogenic hydrogel composites for microvascular integration of organoid grafts

项目总结/摘要 微血管的移植物整合是I型糖尿病细胞替代策略的关键下一步 糖尿病人宿主连接的微血管系统的整合对于植入后移植物的存活至关重要 并且长期影响葡萄糖反应和全身胰岛素输送的动力学。引导 血管生成进入含胰岛的合成水凝胶将保证宿主连接的微血管系统， 移植，但对血管生成的控制仍然有限。我们的长期目标是了解身体暗示是如何从 细胞微环境影响血管生成的关键步骤， 将这些线索整合到可翻译的生物材料中。血管生成涉及一系列时空过程 控制细胞程序，包括内皮尖端细胞活化和定向侵袭， 引导尖端细胞和随后的柄细胞，以及多细胞链的增殖和管腔化。我们事先 这项工作表明，在集体迁移过程中，尖端细胞迁移和柄细胞增殖之间存在关键的平衡。 形成功能性微血管所需的迁移，并且水凝胶可降解性调节聚集性 内皮细胞的迁移。此外，我们已经开创了含有物理线索的水凝胶复合材料， 一种合成纤维，促进内皮细胞向间充质细胞转化，并导致静止的内皮细胞 细胞采取侵入行为，提示尖端细胞导致血管生成芽。总之，这些观察 激发我们的中心假设：水凝胶结构的模块化控制可以驱动血管生成形成， 微血管系统支持hPSC衍生的胰岛类器官的功能。使用新型复合材料 水凝胶，器官型组织模型，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中 1，我们将利用含有细胞粘附导向纤维的水凝胶复合材料， 静止的内皮细胞转化为侵袭性的尖端细胞。在目标2中，我们将设计水凝胶交联和微尺度 多孔性，以驱动内皮柄细胞增殖，并建立集体之间的定量关系 柄细胞迁移、增殖事件和微血管腔化。在目标3中，我们将使用体外和体内 体内模型，以检查材料引导的血管生成和所产生的微血管对血管生成的影响。 含有hPSC衍生的胰岛的水凝胶移植物的功能。拟议的研究将1）阐明 血管生成过程中表型转变的微环境调节和2）鉴定生物材料设计 支持功能性血管生成的参数。我们预计制定的战略将提供 对工程胰岛移植物的微血管支持将对含有其他血管的移植物产生影响。 需要代谢的实质组织。

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.