Creating a prevascularized thick implantable human tissue

描述（申请人提供）：植物和动物都有适应的血管或通道网络，用于营养物和废物的对流运输，以克服扩散的限制。因此，大的（1厘米或更大的数量级）可植入组织的成功创建将必然需要的运输机制，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巨大的了解，因此，旨在替换或修复受损组织的新疗法也有了希望。这一领域被称为“再生医学”或“组织工程”，尽管潜力巨大，但进展缓慢，这在很大程度上是由于缺乏在较厚组织中实现营养物质和废物充分运输的解决方案。虽然已经提出了几种方法，但我们的前提是，生物导向的策略将被证明是最成功的。我们建议在植入前，用成熟的完全形成的人微血管（具有支持周细胞）的互连网络在体外预血管化厚组织。在植入宿主后，微血管的连续网络被准备用于组织的快速吻合和灌注，从而保持活力。由真正的人类微血管组成，动态血管网络然后可以响应组织的代谢需要而重塑（修剪或延伸，成为小动脉或小静脉）。我们发表的和初步的数据证明了这种方法的可行性，包括在植入后约24小时内用宿主血液灌注预血管化组织。然而，我们还没有证明在含有缺氧敏感细胞的真正厚（约1 cm）组织中的疗效。因此，我们的建议有两个具体的目的：1）使用来自脐带血或成人外周血的内皮前体细胞（EPC-EC）衍生的内皮细胞，和适当的基质细胞（例如，成纤维细胞），产生厚的（~ 1cm）组织，该组织用由周细胞支持的良好形成的微血管的连续互连网络预血管化，含有缺氧敏感性指示细胞（例如，心肌细胞）分布在各处，并且适合于植入; 2）建立与宿主（免疫受损小鼠）循环和灌注的快速（<24小时）吻合，以维持组织活力。如果成功，R21的结果将为许多更大规模的项目奠定基础，包括组织特异性功能的整合。 公共卫生相关性：该项目将设计一种厚（1 cm）的可植入预血管化组织，其包含1）成熟的人类微血管互连网络，2）支持周细胞，以及3）缺氧敏感细胞（例如，心肌细胞）。我们试图证明与宿主循环的快速（<24小时）吻合和上级细胞存活能力，这将在再生医学领域具有广泛的应用。

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.