Atrial wall: a 3-D scaffold with formed microvasculature

描述（由申请人提供）：心脏病仍然是发达国家的头号死亡原因，很大程度上是因为目前没有治疗方法来替代因心肌梗死而损失的心肌细胞。如何最好地在宿主体内实现早期血管化是迄今为止限制所有工程心脏组织成功的最重要问题。心房附件是唯一可消耗的自体心脏组织，几乎每个病人都可以使用。自体心房组织作为一种新的心肌梗死修复细胞来源，其独特之处在于它不仅具有三维支架中的自体心肌细胞，而且具有固有而广泛的毛细血管微血管。在这里，我们将研究心房组织是否可以像裂厚皮肤移植物一样，通过接合（形成的宿主血管和移植物血管之间的吻合）快速重建血管，而不需要重新合成微血管网络。虽然我们已经证明心房肌细胞在心室的自然支架上植入至少可以存活四周，但大多数心肌细胞的损失发生在植入后的第一周。几个互补的策略，旨在改善早期血运重建将探讨在皮下植入模型。我们将动员网膜进入皮下空间，以检查靠近较大的动脉流入源是否会加速或增强血管化。然后，将再血管化组织旋转到心脏，维持其血管（大网膜）动脉供应的潜力将被探索，这是一种临床适用的方案。我们将研究局部提供VEGF-165对早期血管形成的影响，比较水凝胶输送VEGF-165直接向心房贴片输送AAV基因的效果。AAV基因疗法也将被用于将热休克蛋白直接输送到贴片上，旨在增加血管重建前心肌细胞对缺血的耐受性。最后，我们将检查是否有效的策略的综合将允许我们建立第二层心房心肌细胞在皮下床。我们已经开发了一种新的AAV载体构建心肌基因转移和一个器官培养系统，使心房壁存活长达2周，以促进基因传递。目标是制造一个活的、动态的三维心脏结构，可以在体外进行工程设计，并在体内快速重建血管。利用成人自体心房心肌作为活体工程组织进行心肌梗死修复是一种新的生物工程概念，具有潜在的临床应用前景。

DESCRIPTION (provided by applicant): Heart disease remains the number one cause of death in the developed world, in large part because there is no current therapy to replace cardiac myocytes lost to myocardial infarction. The issue of how best to achieve early vascularization in the host is the most important problem limiting the success of all engineered cardiac tissues to date. The atrial appendage is the only expendable autologous cardiac tissue that would be available in virtually every patient. As a new cell source for myocardial infarct repair, autologous atrial tissue is unique in that it has not only autologous cardiomyocytes in a three dimensional scaffold, but also an inherent and extensive capillary microvasculature. Here we will examine whether, like a split thickness skin graft, atrial tissue could be revascularized rapidly by inosculation (anastomoses between formed host and graft vessels), without requiring synthesis of a de novo microvascular network. Although we have shown that atrial myocytes implanted on the ventricle in their natural scaffold survive to at least four weeks, most myocyte loss that occurs is in the first week post implantation. Several complementary strategies designed to improve early revascularization will be explored in a subcutaneous implant model. We will mobilize omentum into the subcutaneous space to examine whether proximity to a larger arterial inflow source would accelerate or augment vascularization. Then, the potential for rotating the re-vascularized tissue to the heart, maintaining its vascular (omental) arterial supply will be explored, a clinically applicable protocol. We will examine the effect on early vascularization of providing local VEGF-165, comparing the efficacy of hydrogel delivery of VEGF-165 to direct AAV gene delivery to the atrial patch. AAV gene therapy will also be used to deliver a heat shock protein directly to the patch, designed to increase myocyte tolerance to ischemia in the period before revascularization. Finally, we will examine whether a synthesis of efficacious strategies would allow us to build a second layer of atrial cardiomyocytes in the subcutaneous bed. We have developed a new AAV vector construct for myocardial gene transfer and also an organ culture system to keep atrial wall alive for up to 2 weeks to facilitate gene delivery. The goal is to produce a living, dynamic three-dimensional cardiac structure that can be engineered in vitro and revascularized rapidly in vivo. Making use of autologous adult atrial myocardium as a living engineered tissue for myocardial infarct repair is a novel bioengineering concept that has potential for imminent clinical applicability.