Preformed vascular modules designed for inosculation with host tissue

描述(由申请人提供)：在许多缺血情况下，快速恢复血流对于恢复组织功能至关重要，例如严重的肢体缺血。人们探索了多种策略来解决组织血管化这一具有挑战性的问题，包括输送一种或多种促血管生成因子，使用基于细胞的治疗方法，以及移植血管前组织。通过将所有这三种主要策略的一些吸引人的元素与模块化组织工程的最新进展相结合，这一多PI项目将创造一种创新的、微创的方法来刺激体内缺血组织的血管重建。内皮细胞(EC)和间充质干细胞(MSC)将被包裹在基于生物材料的模块中，以允许随着培养时间的推移在这些微组织中形成稳定的周细胞投资的血管单位。将评估相邻微组织中的血管融合，并测试相邻芽形成吻合的候选机制。这种机制背后的假设是，融合部分依赖于细胞产生的和基质传播的相邻维管束之间的牵引力。我们的总体策略是在体外进行血管化的模块，这些模块彼此之间以及与宿主血管快速融合，从而在体内交付后恢复对缺血组织的血液灌流。这一战略将通过完成三个具体目标进行评估。在目标1中，我们将表征和量化包裹在模块化生物材料中的EC和MSC发展成原始血管样网络的能力。目标2将专注于这些预血管模块的相互作用，评估它们在体外与模型组织融合的能力，并将测试解释新生毛细血管如何相互连接的候选机制。在目标3中，我们将在已建立的后肢缺血模型中，将我们的方法与其他两种基于细胞的策略的治疗效果进行比较。这三个目标的成功实现可能会导致一种新的、强大的技术，在几乎任何缺血组织中快速恢复血管床，从而提供 广泛影响目前治疗外周动脉疾病、冠状动脉疾病和糖尿病并发症的临床方法。这些研究还将提高目前对EC、MSC及其微环境在毛细血管形态发生中的协同作用的理解，这反过来可能导致重要的新发现，可以加强组织血管形成的策略。

DESCRIPTION (provided by applicant): Rapid restoration of blood flow is vital to restoring tissue function in many ischemic conditions, such as critical limb ischemia. A variety of strategies have been explored to solve the challenging problem of tissue vascularization, including delivery of one or more pro-angiogenic factors, the use of cell-based therapies, and the transplantation of pre-vascularized tissues. By combining some of the attractive elements of all three of these major strategies with recent advances in modular tissue engineering, this multi-PI project will create an innovative, minimally invasive approach to stimulate revascularization of ischemic tissue in vivo. Endothelial cells (EC) and mesechymal stem cells (MSC) will be encapsulated in biomaterial-based modules to allow formation of stable, pericyte-invested vascular units within these microtissues over time in culture. Inosculation of vessels in adjacent microtissues will be assessed and a candidate mechanism by which neighboring sprouts form anastomoses will be tested. Underlying this mechanism is the hypothesis that inosculation depends in part on cell-generated and matrix- propagated tractional forces between neighboring vascular sprouts. Our overall strategy is to perform vascularized modules in vitro that rapidly inosculate with each other and with host vessels, and thereby restore blood perfusion to an ischemic tissue following delivery in vivo. This strategy will be evaluated by completing three Specific Aims. In Aim 1, we will characterize and quantify the ability of EC and MSC encapsulated within modular biomaterials to develop into primitive vessel-like networks. Aim 2 will focus on the interactions of these prevascularized modules, assessing their ability to inosculate in a model tissue in vitro, and will test a candidate mechanism explaining how nascent capillaries interconnect. In Aim 3, we will compare the therapeutic efficacy of our approach head-to-head with two other cell-based strategies in an established model of hind limb ischemia. Successful completion of these three aims may lead to a new and powerful technique to rapidly restore vascular beds in virtually any ischemic tissue, and thereby offers the potential to broadly impact current clinical approaches to treating peripheral arterial disease, coronary artery disease, and complications due to diabetes. These studies will also improve current understanding of the synergistic roles of EC, MSC, and their microenvironment on capillary morphogenesis, which in turn may lead to important new discoveries that can enhance tissue vascularization strategies.