Tissue-Engineered Skin with Built-in Capillary Flow Newtworks

组织工程（TE）产品有可能彻底改变医疗保健。体内的许多组织和器官 人体如软骨、骨骼、心脏瓣膜、血管、皮肤和肝脏正被研究作为TIS靶， 苏工程。然而，其中只有少数如TE皮肤目前在临床上使用。此外，几乎所有 目前正在使用或正在进行临床试验的TE产品针对无血管组织（例如心脏瓣膜和心肌）， 拉格），或在临床使用之前没有血管化（例如皮肤替代物）。应用的主要障碍 针对更高功能的靶向组织的TE工程缺乏开发具有整合功能的TE产品的通用方法， 格栅微血管系统用于对流输送营养物和清除代谢废物。我们的战略- gic的目标是制定这样一种方法。在这个建议中，我们描述了一种方法来建立'血管化' TE皮肤连接， 结构。我们提出了四个具体目标，解决了从传质要求到 组织的制造，以及具有内置毛细流动网络的组织的体外测试。具体目标1。 使用微加工和微流体方法评估细胞的传质要求。这将 导致随后的合理设计的毛细管流动网络和更好地了解传质极限， 在组织构建中的作用。具体目标2。设计和制造最佳的平面微血管模拟系统， 生物聚合物基质。在这个特定的目标，最佳的毛细血管网络设计，以满足代谢的需求 的靶组织将包埋在胶原-糖胺聚糖（胶原-GAG）中，以形成微血管支架， 真正使用微加工方法。具体目标3。通过内皮化使毛细血管网络“血管化”- 和微流体，并在体外评估它们。这将导致胶原蛋白-GAG支架与'微血管' 这些网络可以通过对流方式提供营养并去除废物。具体目标4。发展 在灌注生物反应器中的复合TE皮肤，并评估集成对流转运系统的功效， tem对TE复合皮生长和分化的影响。在这个特定的目标中，复合蒙皮替代了 集成的流动网络将在灌注生物反应器中开发，以测试对流运输的假设， 基质提高了分化表皮的形成速率。成功实现这些目标将导致 该产品是可放大的并且可以容易地在体内测试。

Tissue engineered (TE) products have the potential to revolutionize health care. A number of tissues and organs in the human body such as cartilage, bones, heart valves, blood vessels, skin and liver are being investigated as targets for tis- sue engineering. However, only a handful of them such as TE skin are currently in clinical use. In addition, almost all TE products currently in use or undergoing clinical trials are targeted at avascular tissues (e.g. heart valves and carti- lage), or are not vascularized before their use in the clinics (e.g. skin substitutes). A major obstacle in the application of TE engineering to target tissues of higherfunction is the lack of a general approach to develop TEproducts with inte- grated microvascular systemfor convective delivery of nutrients and removal of metabolic waste products. Our strate- gic goal is to develop such an approach. In this proposal, we describe a method to build 'vascularized' TE skin con- structs. We propose four specific aims, which address several specific issues that range from mass transfer requirements of tissues to fabrication, and in vitro testing of tissues with built-in capillary flow networks. These are: Specific Aim 1. To assess mass transfer requirements of cells, using microfabrication and microfluidic methodologies. This will lead to subsequent rational design of the capillary flow networks and to better understanding of mass transfer limita- tions in tissue constructs. Specific Aim 2. To design and fabricate optimal planar microvascular analog systems in biopolymeric matrices. In this specific aim, optimal capillary networks designs tailored to meet the metabolic demand of target tissue will be embedded in collagen-glycosaminoglycans (collagen-GAG) to form scaffolds for microvascula- ture using microfabrication methodologies. Specific Aim 3. To 'vascularize' capillary networks by endothelializa- tion and by microfluidics, and to assess them in vitro. This will lead to collagen-GAG scaffolds with 'microvascular' networks that can supply nutrients and remove waste products via convective means. Specific Aim 4. To develop composite TE skin in a perfusion bioreactor and to assess the efficacy of an integrated convective transport sys- tem on the growth and differentiation of composite TE skin. In this specific aim, composite skin substitutes with integrated flow networks will be developed in a perfusion bioreactor to test the hypothesis that convective transport of substrate improves the rate of formation of a differentiated epidermis. Successful completion of these aims will result in a product that is scalable and that can readily be tested in vivo.