Engineering Capillary Networks

描述（由申请人提供）：缺血性疾病仍然是美国和世界范围内发病率和死亡率的主要原因，在糖尿病患者中尤其成问题。细胞疗法已被证明可以在各种模型中增强局部血管化和灌注，但迄今为止，临床试验中患者的改善程度并不高。这可能与成功植入并参与重建血管系统的移植细胞的百分比很小以及目前对细胞发挥其作用的机制的了解有限有关。在这个项目中要解决的具体假设是，移植的内皮祖细胞建立血管网络和缓解组织缺血的能力，可以显着提高通过提供适当的启动细胞从生物材料载体到缺氧组织的持续释放。将按照以下目标对该假设进行评价：（1）确定载体微环境的适当设计是否可以调节内皮祖细胞基因表达、通过材料的迁移和向周围组织中的分散，（2）定量内皮祖细胞的持续递送和组织再增殖以缓解SCID小鼠中的急性和慢性外周缺血的能力，并确定该作用的机制，和（3）使用STZ诱导的小鼠和四氧嘧啶诱导的兔糖尿病模型，检查材料介导的内皮祖细胞递送增强糖尿病背景下外周缺血恢复的能力。从这些研究中产生的数据和系统可能会影响生物学和工程研究的几个领域，并导致缺血组织再血管化的临床策略。也许最重要的是，在这个项目中将开发一种新的方法，旨在有效地用能够协调新血管形成的细胞重新填充缺血组织。这种方法将在外周缺血的情况下进行研究，但这种方法也可以用于治疗冠状动脉疾病和其他涉及组织缺血的情况。我们预计，自体细胞最初将用于这些应用中，并且迄今为止在内皮祖细胞分离和扩增方面开发的临床经验将直接应用于这种方法的细胞来源方面。这些研究还将提高目前对两种细胞群体- EPCs和OECs在血管形成中的作用的理解，这可能会导致未来新血管形成的全新策略。 公共卫生相关性：严重的肢体缺血每年影响大量的美国人，并且是肢体截肢的主要原因。这些研究的目标是创造一种新的细胞移植方法，这种方法可以逆转患肢的血流损失。该项目开发的材料可能提供一种更实用和有效的方法，使用干细胞群来治愈这些患者。

DESCRIPTION (provided by applicant): Ischemic disease remains a major cause of morbidity and mortality in the USA and worldwide, and is particularly problematic in diabetics. Cell therapies have been demonstrated to enhance local vascularization and perfusion in a variety of models, but patient improvement in the clinical trials to date has been modest. This likely relates to the small percentage of transplanted cells that engraft successfully and participate in rebuilding the vasculature, and the current limited knowledge of the mechanism(s) by which the cells exert their effects. The specific hypothesis to be addressed in this project is that the ability of transplanted endothelial progenitor cells to build a vascular network and relieve tissue ischemia can be dramatically enhanced by providing a sustained release of appropriately primed cells into the hypoxic tissue from a biomaterial vehicle. This hypothesis will be evaluated with the following set of aims: (1) Determine if appropriate design of a vehicle microenvironment can regulate endothelial progenitor cell gene expression, migration through the material and dispersion into the surrounding tissue, (2) Quantify the ability of a sustained delivery and tissue repopulation by endothelial progenitor cells to relieve acute and chronic peripheral ischemia in SCID mice, and determine the mechanism(s) of this effect, and (3) Examine the ability of material-mediated endothelial progenitor cell delivery to enhance recovery from peripheral ischemia in the context of diabetes, using a STZ induced mouse and an alloxan-induced rabbit model of diabetes. The data and systems arising from these studies may impact several areas of biology and engineering research, and lead to clinical strategies to revascularize ischemic tissue. Perhaps most importantly, a new approach will be developed in this project that aims to effectively repopulate ischemic tissues with cells competent to orchestrate neovascularization. This approach will be investigated in the context of the peripheral ischemia, but this approach would also find utility in the treatment of coronary artery disease and other situations involving tissue ischemia. We anticipate that autologous cells would initially be used in these applications, and the clinical experience developed to date in endothelial progenitor isolation and expansion will directly apply to the cell source aspects of this approach. These studies will also improve the current understanding of the role of the two cell populations - EPCs and OECs in vascularization, and this may lead to completely new strategies of neovascularization in the future. PUBLIC HEALTH RELEVANCE: Critical limb ischemia affects large number of Americans each year, and is a leading cause of limb amputation. The goal of these studies is to create a new approach to transplant cells that can potentially reverse the loss of blood flow to afflicted limbs. The materials developed in this project may provide a more practical and effective means of using stem cell populations to cure these patients.