Oropeza Beu P, Adams Jason R, Furth Michael E, Chessa Jack, Boland Thomas
Biomedical Device, Delivery and Diagnostic Laboratory, Metallurgical, Materials and Biomedical Engineering Department, The University of Texas at El Paso, El Paso, TX, United States.
Aerospace and Mechanical Engineering, The University of Texas at El Paso, El Paso, TX, United States.
Front Bioeng Biotechnol. 2022 Mar 10;10:855186. doi: 10.3389/fbioe.2022.855186. eCollection 2022.
Bioprinting is an emerging technique used to layer extrudable materials and cells into simple constructs to engineer tissue or arrive at organ models. Although many examples of bioprinted tissues exist, many lack the biochemical complexity found in the native extracellular matrix. Therefore, the resulting tissues may be less competent than native tissues-this can be especially problematic for tissues that need strong mechanical properties, such as cardiac or those found in the great vessels. Decellularization of native tissues combined with processing for bioprinting may improve the cellular environment for proliferation, biochemical signaling, and improved mechanical characteristics for better outcomes. Whole porcine hearts were decellularized using a series of detergents, followed by lyophilization and mechanical grinding in order to produce a fine powder. Temperature-controlled enzymatic digestion was done to allow for the resuspension of the decellularized extracellular matrix into a pre-gel solution. Using a commercial extrusion bioprinter with a temperature-controlled printhead, a 1:1 scale model of a human ascending aorta and dog bone shaped structures were printed into a reservoir of alginate and xanthium gum then allowed to crosslink at 37C. The bioengineered aortic construct was monitored for cell adhesion, survival, and proliferation through fluorescent microscopy. The dog bone structure was subjected to tensile mechanical testing in order to determine structural and mechanical patterns for comparison to native tissue structures. The stability of the engineered structure was maintained throughout the printing process, allowing for a final structure that upheld the dimensions of the original Computer-Aided Design model. The decellularized ECM (Ē = 920 kPa) exhibited almost three times greater elasticity than the porcine cardiac tissue (Ē = 330 kPa). Similarly, the porcine cardiac tissue displayed two times the deformation than that of the printed decellularized ECM. Cell proliferation and attachment were observed during the cell survivability assessment of human aortic smooth muscle cells within the extracellular matrix, along with no morphological abnormalities to the cell structure. These observations allow us to report the ability to bioprint mechanically stable, cell-laden structures that serve as a bridge in the current knowledge gap, which could lead to future work involving complex, large-scale tissue models.
生物打印是一种新兴技术，用于将可挤出材料和细胞分层制成简单结构，以构建组织或获得器官模型。尽管存在许多生物打印组织的实例，但许多缺乏天然细胞外基质中发现的生化复杂性。因此，所得组织可能不如天然组织功能强大——对于需要强大机械性能的组织，如心脏组织或大血管中的组织，这可能尤其成问题。天然组织的去细胞化与生物打印处理相结合，可能会改善细胞增殖、生化信号传导的细胞环境，并改善机械特性以获得更好的结果。使用一系列去污剂对整个猪心脏进行去细胞化处理，然后进行冻干和机械研磨以制成细粉。进行温度控制的酶消化，以使去细胞化的细胞外基质重新悬浮在预凝胶溶液中。使用带有温度控制打印头的商用挤出式生物打印机，将人升主动脉的1:1比例模型和狗骨形状的结构打印到藻酸盐和黄原胶储库中，然后在37℃下交联。通过荧光显微镜监测生物工程主动脉构建体的细胞粘附、存活和增殖情况。对狗骨结构进行拉伸力学测试，以确定结构和力学模式，以便与天然组织结构进行比较。在整个打印过程中，工程结构的稳定性得以维持，从而得到一个最终结构，该结构保持了原始计算机辅助设计模型的尺寸。去细胞化的细胞外基质（E = 920 kPa）的弹性几乎是猪心脏组织（E = 330 kPa）的三倍。同样，猪心脏组织的变形是打印的去细胞化细胞外基质的两倍。在细胞外基质内对人主动脉平滑肌细胞进行细胞活力评估期间，观察到细胞增殖和附着，并且细胞结构没有形态异常。这些观察结果使我们能够报告生物打印机械稳定、负载细胞结构的能力，这在当前的知识空白中起到了桥梁作用，可能会导致未来涉及复杂、大规模组织模型的工作。
