Creating a prevascularized thick implantable human tissue

描述(申请人提供)：植物和动物都适应了对流输送营养物质和废物的容器或通道网络，以克服扩散的限制。因此，成功制造大型(1厘米或更大)可植入组织必然需要传输机制，而不是简单的扩散。在过去的二十年里，人们对基本的生物学机制有了极大的了解，因此，旨在替换或修复受损组织的新疗法的前景变得光明起来。这一领域被称为“再生医学”或“组织工程学”，尽管潜力很大，但进展缓慢，很大程度上是因为缺乏在较厚的组织中实现足够的营养和废物运输的解决方案。虽然已经提出了几种方法，但我们的前提是，以生物为导向的策略将被证明是最成功的。我们建议在植入之前，在体外预置一个厚厚的组织，该组织由成熟的完全形成的微血管(带有支持的周细胞)组成的相互连接的网络组成。在植入宿主后，连续的微血管网络为组织的快速吻合和灌流做好了准备，从而维持了生存能力。由真正的人类微血管组成的动态血管网络可以根据组织的新陈代谢需求进行重塑(修剪或延伸，成为小动脉或小静脉)。我们已发表的和初步的数据证明了这种方法的可行性，包括在植入后24小时内用宿主血液灌流未血管化的组织。然而，我们还没有在含有缺氧敏感细胞的真正厚(~1厘米)的组织中证明这种效果。因此，我们的建议有两个具体目标：1)使用来自脐带血或成人外周血的内皮前体细胞(EPC-EC)和适当的基质细胞(如成纤维细胞)，创建厚(~1厘米)的组织，该组织由周细胞支持的连续互联的微血管网络预先血运丰富，包含分布于全身的缺氧敏感指标细胞(如心肌细胞)，并适合植入；2)与宿主(免疫低下小鼠)建立快速(24小时)吻合，以维持组织的活力。如果成功，这项拟议的R21的结果将为许多更大规模的项目奠定基础，包括纳入组织特异性功能。 与公共卫生相关：该项目将设计一种厚(1厘米)的可植入的预血管组织，其中包含1)成熟的相互连接的人类微血管网络，2)支持周细胞，以及3)低氧敏感细胞(例如，心肌细胞)。我们寻求展示快速(24小时)与宿主循环的吻合和卓越的细胞存活率，这将在再生医学领域有广泛的应用。

DESCRIPTION (provided by applicant): Both plants and animals have adapted networks of vessels or channels for convective transport of nutrients and waste to overcome the limits of diffusion. Hence, the successful creation of large (order 1 cm or larger) implantable tissues will necessarily require mechanisms of transport other than simple diffusion. The past two decades have brought enormous understanding of basic biological mechanisms, and, as a result the promise of new therapies aimed at replacing or repairing damaged tissues. This field has been dubbed "regenerative medicine" or "tissue engineering", and, although bursting with potential, progress has been slowed due, in large part, to a lack of solutions for achieving adequate transport of nutrients and waste in thicker tissues. While several approaches have been proposed, it is our premise that a biology-directed strategy will prove the most successful. We propose to prevascularize in vitro a thick tissue with an interconnected network of mature fully-formed human microvessels (with supporting pericytes) prior to implantation. Upon implantation to the host, the continuous network of microvessels is primed for rapid anastomosis and perfusion of the tissue thereby maintaining viability. Being composed of true human microvessels, the dynamic vascular network can then remodel (prune or extend, become arterioles or venules) in response to the metabolic needs of the tissues. Our published and preliminary data demonstrate the feasibility of this approach including perfusion of the prevascularized tissue with host blood within ~ 24 hours of implantation. However, we have yet to demonstrate the efficacy in a truly thick (~ 1 cm) tissue that contains hypoxia-sensitive cells. Hence, our proposal has two specific aims: 1) using endothelial cells derived from endothelial precursor cells (EPC-EC) from either cord or adult peripheral blood, and an appropriate stromal cell (e.g., fibroblast), create a thick ( ~ 1 cm) tissue that is prevascularized with a continuous interconnected network of well-formed microvessels supported by pericytes, containing a hypoxia-sensitive indicator cell (e.g., cardiac myocyte) distributed throughout, and suitable for implantation; 2) establish rapid (<24 hours) anastomosis with the host (immune- compromised mouse) circulation and perfusion to maintain tissue viability. When successful, the results of this proposed R21 will lay the groundwork for numerous larger scale projects including the incorporation of tissue specific functionality. PUBLIC HEALTH RELEVANCE: This project will design a thick (1 cm) implantable prevascularized tissue which contains 1) a mature interconnected network of human microvessels, 2) supporting pericytes, and 3) a hypoxia-sensitive cell (e.g., cardiac myocyte). We seek to demonstrate rapid (<24 hours) anastomosis with the host circulation and superior cell survivability, which will have broad applications in the field of regenerative medicine.