Department of Mechanical and Aerospace Engineering, The George Washington University, Washington District of Columbia 20052, United States.
Department of Civil and Mechanical Engineering, The United States Military Academy, West Point, New York 10996, United States.
ACS Appl Mater Interfaces. 2020 Oct 14;12(41):45904-45915. doi: 10.1021/acsami.0c14871. Epub 2020 Oct 2.
Blood vessel damage resulting from trauma or diseases presents a serious risk of morbidity and mortality. Although synthetic vascular grafts have been successfully commercialized for clinical use, they are currently only readily available for large-diameter vessels (>6 mm). Small-diameter vessel (<6 mm) replacements, however, still present significant clinical challenges worldwide. The primary objective of this study is to create novel, tunable, small-diameter blood vessels with biomimetic two distinct cell layers [vascular endothelial cell (VEC) and vascular smooth muscle cell (VSMC)] using an advanced coaxial 3D-bioplotter platform. Specifically, the VSMCs were laden in the vessel wall and VECs grew in the lumen to mimic the natural composition of the blood vessel. First, a novel bioink consisting of VSMCs laden in gelatin methacryloyl (GelMA)/polyethylene(glycol)diacrylate/alginate and lyase was designed. This specific design is favorable for nutrient exchange in an ambient environment and simultaneously improves laden cell proliferation in the matrix pore without the space restriction inherent with substance encapsulation. In the vessel wall, the laden VSMCs steadily grew as the alginate was gradually degraded by lyase leaving more space for cell proliferation in matrices. Through computational fluid dynamics simulation, the vessel demonstrated significantly perfusable and mechanical properties under various flow velocities, flow viscosities, and temperature conditions. Moreover, both VSMCs in the scaffold matrix and VECs in the lumen steadily proliferated over time creating a significant two-cell-layered structure. Cell proliferation was confirmed visually through staining the markers of alpha-smooth muscle actin and cluster of differentiation 31, commonly tied to angiogenesis phenomena, in the vessel matrices and lumen, respectively. Furthermore, the results were confirmed quantitatively through gene analysis which suggested good angiogenesis expression in the blood vessels. This study demonstrated that the printed blood vessels with two distinct cell layers of VECs and VSMCs could be potential candidates for clinical small-diameter blood vessel replacement applications.
创伤或疾病导致的血管损伤会带来严重的发病和死亡风险。虽然合成血管移植物已成功商业化并应用于临床，但目前仅可用于大直径血管（>6 毫米）。然而，小直径血管（<6 毫米）的替换在全球范围内仍然存在重大的临床挑战。本研究的主要目标是使用先进的同轴 3D 生物打印机平台，创建具有仿生双层结构的新型、可调谐的小直径血管，其包含血管内皮细胞（VEC）和血管平滑肌细胞（VSMC）。具体来说，VSMCs 负载在血管壁中，VECs 在管腔中生长，以模拟血管的自然组成。首先，设计了一种由负载 VSMCs 的明胶甲基丙烯酰（GelMA）/聚乙二醇（二丙烯酸酯）/海藻酸钠和溶菌酶组成的新型生物墨水。这种特定的设计有利于在环境中进行营养物质交换，同时在不限制基质孔内物质包封的空间限制的情况下，改善基质中负载细胞的增殖。在血管壁中，随着溶菌酶逐渐降解海藻酸钠，负载的 VSMCs 稳定生长，为基质中的细胞增殖留出更多空间。通过计算流体动力学模拟，该血管在各种流速、流粘度和温度条件下均表现出显著的可灌注性和力学性能。此外，支架基质中的 VSMCs 和管腔中的 VECs 随着时间的推移稳定增殖，形成显著的双层结构。通过分别对血管基质和管腔中的标志物 alpha-平滑肌肌动蛋白和分化群 31 进行染色，可以直观地观察到细胞增殖。此外，通过基因分析对细胞增殖进行了定量确认，结果表明血管中具有良好的血管生成表达。本研究表明，具有 VEC 和 VSMC 双层结构的打印血管可能是临床小直径血管替代应用的潜在候选者。
