Extracellular matrix hydrogels for treating ischemia

描述（由申请人提供）：尽管组织工程学最近取得了进展，但仅在美国，与心血管疾病相关的缺血导致每年约500，000例心肌梗死（MI）患者死亡，每年超过100，000例外周动脉疾病（PAD）患者截肢。因此，我们的长期目标是开发新的微创组织工程疗法来治疗心肌和严重肢体缺血。对于MI，已将材料与细胞一起注射以增加细胞保留和存活，或单独注射以增加内源性细胞迁移到梗死区域，包括新血管形成，以覆盖和支持左心室（LV）壁，或两者兼而有之。在PAD和严重肢体缺血的情况下，很少有生物材料被检查，迄今为止，它们仅被研究用于改善生长因子和细胞递送。目前没有材料满足任一应用的理想支架的所有要求，即促进新血管形成以减少缺血环境，促进内源性或外源性添加的细胞的细胞粘附、存活和成熟，以及可注射的能力。此外，没有一种能够充分模拟生物化学信号，而生物化学信号是它们旨在替代的天然细胞外基质（ECM）所固有的。我们的实验室已经产生了可注射的，组织特异性ECM水凝胶，我们表明它有潜力满足理想支架的所有要求。这些可注射材料类似于体内心肌和骨骼肌细胞外环境，因为它们分别含有在心肌或骨骼肌ECM中发现的天然生物化学线索的复杂分类。我们已经证明，这两种材料都有潜力招募内源性细胞，以促进血管形成。此外，在MI模型中注射心肌基质保留了心脏功能和LV几何形状，而注射骨骼肌基质增强了后肢缺血模型中肌肉祖细胞的募集和增殖。此外，我们在体外研究表明，这些材料促进肌肉祖细胞成熟。我们假设基于ECM的水凝胶，其来源于天然肌肉ECM并含有复杂的组织特异性生化信号，可以单独递送以增加内源性细胞募集或与外源性细胞一起递送以改善细胞存活和成熟，从而为MI和严重PAD提供有效的治疗。这项申请将针对以下具体目标：1）确定单独的可注射脱细胞心肌基质氢对心肌梗死后负性左心室重构、内源性心肌细胞存活、细胞浸润和心脏功能的影响，2）确定单独的可注射脱细胞骨骼肌基质水凝胶对细胞凋亡和浸润、新血管形成、和灌注，和3）确定外源性肌肉祖细胞在可注射的肌肉ECM衍生的水凝胶的环境中对新血管形成和细胞移植保留、存活和成熟的影响。

DESCRIPTION (provided by applicant): Despite recent advances in tissue engineering, ischemia related to cardiovascular disease results in the death of approximately 500,000 patients per year in the case of myocardial infarction (MI) and greater than 100,000 amputations per year in the case of peripheral artery disease (PAD) in the US alone. Therefore, our long-term goal is the development of new, minimally invasive tissue-engineered therapies for the treatment of myocardial and critical limb ischemia. For MI, materials have been injected with cells in order to increase cell retention and survival, or alone to increase endogenous cell migration into the infarct area, including neovascularization, to thicken and support the left ventricular (LV) wall, or both. In the case of PAD and critical limb ischemia, very few biomaterials have been examined, and to date, they have only been studied for improving growth factor and cell delivery. No current materials meet all of the requirements of an ideal scaffold for either application, namely the ability to promote neovascularization to reduce the ischemic environment, to promote cell adhesion, survival, and maturation of endogenous or exogenously added cells, and to be injectable. Moreover, none adequately mimic the biochemical cues, which are inherent to the native extracellular matrix (ECM) that they are intended to replace. Our lab has generated injectable, tissue specific ECM hydrogels, which we show have the potential to meet all of the requirements of an ideal scaffold. These injectable materials resemble the in vivo cardiac and skeletal muscle extracellular milieu in that they contain a complex assortment of the native biochemical cues found in cardiac or skeletal muscle ECM, respectively. We have shown that both materials have the potential to recruit endogenous cells to promote vascularization. Furthermore, injection of the myocardial matrix in a MI model preserves cardiac function and LV geometry, while injection of the skeletal muscle matrix enhances the recruitment and proliferation of muscle progenitors in a hindlimb ischemia model. In addition, we show in vitro studies that these materials promote muscle progenitor maturation. We hypothesize that ECM based hydrogels, which are derived from native muscle ECM and contain complex, tissue specific biochemical cues, can be delivered alone to increase endogenous cell recruitment or with exogenous cells to improve cell survival and maturation, thereby providing effective therapies for MI and severe PAD. This application will address the following specific aims: 1) To determine the influence of an injectable acellular myocardial matrix hydrogen alone on post-myocardial infarction negative left ventricular remodeling, endogenous cardiomyocyte survival, cell infiltration, and cardiac function, 2) To determine the influence of an injectable acellular skeletal muscle matrix hydrogel alone on cell apoptosis and infiltration, neovascularization, and perfusion in a hindlimb ischemia model, and 3) To determine the effects of exogenous muscle progenitors in the milieu of injectable muscle ECM derived hydrogels on neovascularization, and cell transplant retention, survival, and maturation.