Tissue-Engineered Skin with Built-in Capillary Flow Newtworks

描述(由申请人提供)：组织工程(TE)产品有可能给医疗保健带来革命性的变化。人体内的许多组织和器官，如软骨、骨骼、心脏瓣膜、血管、皮肤和肝脏，都被作为组织工程的目标进行研究。然而，目前只有少数几种药物在临床上使用，如TE Skin。此外，目前正在使用或正在进行临床试验的几乎所有TE产品都是针对无血管组织(例如心脏瓣膜和心脏瓣膜)，或者在临床使用之前没有被血管化(例如皮肤替代品)。TE工程应用于高功能靶组织的一个主要障碍是缺乏一种通用的方法来开发具有集成的微血管系统的TE产品，用于对流输送营养物质和清除代谢废物。我们的战略目标就是开发这样一种方法。在这项建议中，我们描述了一种建立“血管化”TE皮肤结构的方法。我们提出了四个具体目标，解决了几个具体问题，从组织的质量传输要求到制造，以及利用内置毛细管流动网络对组织进行体外测试。具体目标：1.使用微细加工和微流控方法评估细胞的传质要求。这将导致随后的毛细管流动网络的合理设计，并更好地理解组织结构中的传质限制。具体目的2.在生物聚合物基质中设计和制备最佳的平面微血管模拟系统。在这个特定的目标中，为满足靶组织的代谢需求而量身定做的最佳毛细血管网络设计将被嵌入到胶原-糖胺聚糖(胶原-GAG)中，以使用微制造方法形成用于微血管构建的支架。具体目的3.通过内皮化和微流体法使毛细血管网络“血管化”，并在体外对其进行评估。这将导致具有微血管网络的胶原蛋白-Gag支架，这些支架可以通过对流方式提供营养并清除废物。具体目的4.在灌流生物反应器中制备复合TE皮肤，并评价集成对流输送系统对复合TE皮肤生长和分化的影响。为此，将在灌流生物反应器中开发具有完整流动网络的复合皮肤替代物，以验证基质的对流输送提高分化的表皮形成速度的假说。成功完成这些目标将产生一种可扩展且易于在体内测试的产品。

DESCRIPTION (provided by applicant): 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 higher function is the lack of a general approach to develop TE products with inte- grated microvascular system for convective delivery of nutrients and removal of metabolic waste products. Our strategic goal is to develop such an approach. In this proposal, we describe a method to build 'vascularized' TE skin constructs. 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.