Departments of Cardiothoracic Surgery (D.v.B., H.W., M.J.P., A.B.G., A.E., A.T., L.S., A.N.S., V.N.T., K.J., C.H., Y.J.W.), Stanford University, CA.
Bioengineering (L.S., A.N.S., Y.J.W.), Stanford University, CA.
Circulation. 2018 Nov 6;138(19):2130-2144. doi: 10.1161/CIRCULATIONAHA.118.035231.
Cardiovascular bypass grafting is an essential treatment for complex cases of atherosclerotic disease. Because the availability of autologous arterial and venous conduits is patient-limited, self-assembled cell-only grafts have been developed to serve as functional conduits with off-the-shelf availability. The unacceptably long production time required to generate these conduits, however, currently limits their clinical utility. Here, we introduce a novel technique to significantly accelerate the production process of self-assembled engineered vascular conduits.
Human aortic smooth muscle cells and skin fibroblasts were used to construct bilevel cell sheets. Cell sheets were wrapped around a 22.5-gauge Angiocath needle to form tubular vessel constructs. A thin, flexible membrane of clinically approved biodegradable tissue glue (Dermabond Advanced) served as a temporary, external scaffold, allowing immediate perfusion and endothelialization of the vessel construct in a bioreactor. Subsequently, the matured vascular conduits were used as femoral artery interposition grafts in rats (n=20). Burst pressure, vasoreactivity, flow dynamics, perfusion, graft patency, and histological structure were assessed.
Compared with engineered vascular conduits formed without external stabilization, glue membrane-stabilized conduits reached maturity in the bioreactor in one-fifth the time. After only 2 weeks of perfusion, the matured conduits exhibited flow dynamics similar to that of control arteries, as well as physiological responses to vasoconstricting and vasodilating drugs. The matured conduits had burst pressures exceeding 500 mm Hg and had sufficient mechanical stability for surgical anastomoses. The patency rate of implanted conduits at 8 weeks was 100%, with flow rate and hind-limb perfusion similar to those of sham controls. Grafts explanted after 8 weeks showed a histological structure resembling that of typical arteries, including intima, media, adventitia, and internal and external elastic membrane layers.
Our technique reduces the production time of self-assembled, cell sheet-derived engineered vascular conduits to 2 weeks, thereby permitting their use as bypass grafts within the clinical time window for elective cardiovascular surgery. Furthermore, our method uses only clinically approved materials and can be adapted to various cell sources, simplifying the path toward future clinical translation.
心血管旁路移植术是治疗动脉粥样硬化疾病复杂病例的重要手段。由于自体动脉和静脉移植物的可用性受到患者限制，因此已经开发出自组装的细胞仅移植物，作为具有现成可用性的功能性移植物。然而，生成这些移植物所需的不可接受的长生产时间目前限制了它们的临床应用。在这里，我们介绍了一种显著加速自组装工程血管移植物生产过程的新技术。
用人主动脉平滑肌细胞和皮肤成纤维细胞构建双层细胞片。将细胞片包裹在 22.5 号 Angiocath 针周围，形成管状血管构建体。一层薄而灵活的临床认可的可生物降解组织胶（Dermabond Advanced）膜作为临时外部支架，允许在生物反应器中立即对血管构建体进行灌注和内皮化。随后，将成熟的血管移植物用作大鼠股动脉间置移植（n=20）。评估了爆裂压力、血管反应性、流动动力学、灌注、移植物通畅性和组织学结构。
与没有外部稳定化形成的工程血管移植物相比，使用胶膜稳定化的移植物在生物反应器中的成熟时间缩短到五分之一。仅经过 2 周的灌注，成熟的移植物就表现出与对照动脉相似的流动动力学，以及对血管收缩和扩张药物的生理反应。成熟的移植物的爆裂压力超过 500 毫米汞柱，具有足够的机械稳定性用于手术吻合。8 周时植入移植物的通畅率为 100%，流量和后肢灌注与假手术对照相似。8 周后取出的移植物显示出类似于典型动脉的组织学结构，包括内膜、中膜、外膜和内、外弹性膜层。
我们的技术将自组装、细胞片衍生的工程血管移植物的生产时间缩短至 2 周，从而使其能够在心血管择期手术的临床时间窗内用作旁路移植物。此外，我们的方法仅使用临床认可的材料，并且可以适应各种细胞来源，简化了未来临床转化的途径。
