Stem Cells and Dynamic Materials Improve Cardiac Function Post-mycardial Infarcti

描述（由申请人提供）：心肌梗死（MI）后产生的纤维化疤痕是僵硬的细胞外基质（ECM），这是由于组织变薄和坏死时胶原蛋白分泌增强所致。先前改善MI后心肌功能的方法，例如心脏补片和细胞注射，不能充分模拟基质的固有性质，例如刚度（表示为E）。此外，他们经常使用尚未显示具有显著重塑能力的成体干细胞，而是对异常基质条件更敏感;因此，已经观察到细胞不适当地分化成成骨细胞样细胞或在3倍太硬的梗死心肌中完全不能分化，即EARct>> ECARDIO。我们最近开发了一种动态的、基于巯基改性的透明质酸（HA-S）的水凝胶，其通过时间依赖性交联随着时间的推移显示发育适当的刚度。我们还表明，这可以提高心脏祖细胞分化成熟心肌细胞近一个数量级的软基质，不重塑。 在这项提议中，我们将首先将我们的发现扩展到胚胎干细胞（ESC），这应该比以前的干细胞类型在基质重塑方面更有效。将首先在ESC中监测2D和3D HA-S水凝胶中心脏特异性基因的表达，以确定相对于心脏祖细胞和年龄匹配的对照动物，HA-S是否可以诱导心肌发生，如果不能，至少确保它增强了HA-S水凝胶的分化，HA-S水凝胶已经通过碘乙酰胺处理去除了其时间依赖性交联。还将测量基质分泌、组装和重塑（通过透明质酸酶降解）并与心脏祖细胞进行比较，以确保ESC确实可以有效地重塑基质，并且细胞可以在材料中充分迁移。随后将在皮下大鼠模型中使用细胞和HA-S水凝胶，以确保生物相容性并监测体内水凝胶特性，例如时间依赖性硬化。最后，在MI的大鼠模型中，ESC和/或心脏祖细胞将与HA-S结合使用，以确定我们的HA-S水凝胶相对于常规治疗（例如细胞注射）可以在多大程度上改善MI后的心肌功能。

DESCRIPTION (provided by applicant): The fibrotic scar that results after a myocardial infarction (MI) is stiff extracellular matrix (ECM), owing to the enhanced secretion of collagen as the tissue thins and undergoes necrosis. Pervious methods to improve myocardial function post-MI, e.g. cardiac patches and cell injections, do not sufficiently mimic the intrinsic properties of the matrix, such as stiffness (denoted E). Moreover, they often employ adult stem cells which have not been shown to have significant remodeling capacity and instead are more responsive to aberrant matrix conditions; thus cells have been observed to improperly differentiate into osteoblast-like cells or to fail to differentiate altogether in infarcted myocardium that is 3-fold too stiff, i.e. EInfarct >> ECARDIO. We have recently developed a dynamic, thiol-modified hyaluronic acid (HA-S)-based hydrogel that displays developmentally appropriate stiffness over time via time-dependent crosslinking. We have also shown that this can improve cardiac progenitor differentiation in mature cardiomyocytes by nearly an order of magnitude over soft matrix that does not remodel. In this proposal, we will first extend our findings to embryonic stem cells (ESCs), which should be even more effective at matrix remodeling than previous stem cell types. Expression of cardiac-specific genes in 2D and 3D HA-S hydrogels will first be monitored in ESCs to determine if HA-S can induce cardiomyogenesis relative to cardiac progenitor cells and age-matched control animals, and if not, at least ensure that it enhances differentiation over HA-S hydrogels that have had their time-dependent crosslinking removed by treatment with iodacetamide. Matrix secretion, assembly, and remodeling (via degradation by hyaluronidase) will also be measured and compared to cardiac progenitor cells to ensure that ESCs can indeed remodel matrix effectively and that cells can migrate sufficiently in the material. Cells and HA-S hydrogels will subsequently be used in a subcutaneous rat model to ensure biocompatibility and monitor hydrogel properties in vivo, e.g. time-dependent stiffening. Finally in a rat model of MI, ESCs and/or cardiac progenitor will be used in conjunction with the HA-S to determine to what degree our HA-S hydrogel can improve myocardial function post-MI versus convention treatments, e.g. cell injection.