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，例如严重肢体缺血。为了解决组织血管化这一具有挑战性的问题，人们已经探索了多种策略，包括一种或多种促血管生成因子的递送、细胞疗法的使用以及血管化前组织的移植。通过将这三种主要策略的一些有吸引力的元素与模块化组织工程的最新进展相结合，这个多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运重建。内皮细胞（EC）和间充质干细胞（MSC）将被封装在基于生物材料的模块中，随着培养时间的推移，可以在这些微组织中形成稳定的、周细胞投资的血管单位。将评估邻近微组织中血管的融合，并测试邻近芽形成吻合的候选机制。这一机制的基础假设是，融合部分取决于邻近维管芽之间细胞产生的和基质繁殖的牵引力。我们的总体策略是在体外进行血管化模块，这些模块可以快速相互结合并与宿主血管结合，从而在体内递送后恢复缺血组织的血液灌注。这一战略将通过完成三个具体目标来评估。在Aim 1中，我们将描述和量化封装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。目的2将侧重于这些预血管化模块的相互作用，评估它们在体外模型组织中的融合能力，并将测试一种解释新生毛细血管如何相互连接的候选机制。在Aim 3中，我们将在已建立的后肢缺血模型中比较我们的方法与其他两种基于细胞的策略的治疗效果。这三个目标的成功完成可能会导致一种新的强大的技术，可以快速恢复几乎任何缺血组织中的血管床，从而提供了潜力

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.