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，这在很大程度上是因为目前没有替代心肌梗死导致的心肌细胞损失的疗法。如何最好地在宿主中实现早期血管化的问题是迄今为止限制所有工程化心脏组织成功的最重要问题。心房附件是唯一的消耗性自体心脏组织，几乎每个患者都可以使用。自体心房组织作为心肌梗死修复的一种新的细胞来源，其独特之处在于它不仅具有三维支架中的自体心肌细胞，而且还具有固有的和广泛的毛细血管微血管。在这里，我们将研究是否可以像一个分裂的厚度皮肤移植，心房组织可以通过吻合（形成的宿主和移植血管之间的吻合），而不需要重新合成一个微血管网络的快速血运重建。虽然我们已经证明，心房肌细胞在其天然支架中植入心室至少存活四周，但大多数肌细胞损失发生在植入后第一周。将在皮下植入模型中探索旨在改善早期血运重建的几种补充策略。我们将大网膜移动到皮下空间，以检查靠近较大动脉流入源是否会加速或增加血管化。然后，将探索将再血管化组织旋转到心脏，维持其血管（网膜）动脉供应的可能性，这是一种临床适用的方案。我们将检查提供局部VEGF-165对早期血管形成的影响，比较VEGF-165的水凝胶递送与直接AAV基因递送至心房补片的功效。腺相关病毒基因疗法还将用于将热休克蛋白直接输送到贴片，旨在提高心肌细胞在血运重建前对缺血的耐受性。最后，我们将研究是否有效的策略的合成将允许我们建立第二层的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，也是一个器官培养系统，以保持心房壁存活长达2周，以促进基因传递。其目标是产生一个活的、动态的三维心脏结构，该结构可以在体外工程化并在体内快速血管重建。利用自体心房肌作为活的工程组织修复心肌梗死是一种新的生物工程概念，具有潜在的临床应用价值。

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.