I-Corps: Tissue-engineering vascular grafts using autologous cell sheets

在美国大约有1000万人患有外周血管疾病（PVD），每年有46万例血管搭桥手术使用合成或自体静脉移植。隐静脉是最常用的自体移植物材料，由于内膜增生，18个月内的失败率为50%。对于不再有静脉可供搭桥的患者，血管外科医生必须使用合成移植物（聚四氟乙烯或涤纶），这与较高的并发症发生率相关，如闭塞和感染。此外，这些合成移植物通常只能用于搭桥内径大于6mm的血管。提出的技术/产品由一种新型的细胞片衍生的工程自体血管移植物组成，可以满足这种迫切的临床需求，即生物反应性血管移植物。这有可能克服目前自体和合成移植物的问题：供应有限；自体移植物长度受限，合成移植物生物相容性差。所提出的细胞片培养和堆叠系统被优化，以低成本生产生物反应，活血管移植物。任何与生理相关的细胞类型、大小和二维模式的融合和自组装的细胞片可以在播种后10天内实现。水凝胶底物刚度从根本上影响细胞表型和行为，可以准确地匹配血管各层的刚度，例如中膜或外膜。在水凝胶基质平台上生长的细胞片显示出高细胞活力和高度的天然组织再现性（如血管），如细胞排列、细胞外基质组成和机械强度。细胞片的堆叠和滚动过程保留了单个细胞片的模式和细胞活力（99%），以产生结构和生物学上相似的血管移植物。该系统可扩展到高通量制造过程，以降低成本和制造时间。完全血管化的三维活组织在组织工程中仍然是一个未解决的挑战。所提出的系统可用于需要复杂结构以实现适当组织功能的组织替代物的设计。这种多功能技术可能会进一步扩展，超越目前的心血管应用，为其他疾病状态创建组织工程解决方案。

There are approximately 10 million people in the US with peripheral vascular disease (PVD), and 460,000 vascular bypass surgeries are performed annually using either synthetic or autologous venous grafts. Saphenous vein, the most commonly used autograft material, has a 50% failure rate within 18 months due to intimal hyperplasia. For patients who no longer have veins available for bypass, the vascular surgeon must use synthetic grafts (PTFE or Dacron) which are associated with a higher rate of complications such as occlusion and infection. Furthermore, these synthetic grafts can typically only be used to bypass vessels with an internal diameter greater than 6 mm. The proposed technology/product consists of a novel cell sheet-derived engineered autologous vascular graft that can meet this urgent clinical need for biologically responsive vascular grafts. This has the potential to overcome the current problems of autologous and synthetic grafts: limited supply; restricted length of autologous grafts, and poor biocompatibility of synthetic grafts. The proposed cell sheet culture and stacking system was optimized to produce biologically responsive, living vascular grafts at low-cost. Confluent and self-assembled cell sheets of any physiologically relevant cell type, size and 2D pattern can be achieved within 10 days after seeding. Hydrogel substrate stiffness, which fundamentally affects cell phenotype and behavior, can be accurately matched to the stiffness of individual layers of the vessel, e.g. tunica media or tunica adventitia. Cell sheets grown on a hydrogel substrate platform demonstrate high cell viability and a high degree of native tissue recapitulative properties (e.g. blood vessel) such as cell alignment, extracellular matrix composition, and mechanical strength. The cell sheet stacking and rolling process preserves individual cell sheet patterns and cell viability (99%) to produce structurally and biologically similar vascular graft. This system is scalable for high throughput manufacturing processes to lower the cost and fabrication time. Fully vascularized three-dimensional living tissue remains an unsolved challenge in tissue engineering. The proposed system can be utilized for the design of tissue replacements that require complex structures for proper tissue function. This versatile technology may be further expanded beyond the current cardiovascular application to create tissue engineered solutions for other disease states.