Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas.
Tissue Eng Part A. 2019 Oct;25(19-20):1426-1437. doi: 10.1089/ten.TEA.2018.0258. Epub 2019 Aug 20.
Anisotropic biomaterials can affect cell function by driving cell alignment, which is critical for cardiac engineered tissues. Recent work, however, has shown that pluripotent stem cell-derived cardiomyocytes may self-align over long periods of time. To determine how the degree of biomaterial substrate anisotropy impacts differentiating cardiomyocyte structure and function, we differentiated mouse embryonic stem cells to cardiomyocytes on nonaligned, semialigned, and aligned fibrous substrates and evaluated cell alignment, contractile displacement, and calcium transient synchronicity over time. Although cardiomyocyte gene expression was not affected by fiber alignment, we observed gradient- and threshold-based differences in cardiomyocyte alignment and function. Cardiomyocyte alignment increased with the degree of fiber alignment in a gradient-based manner at early time points and in a threshold-based manner at later time points. Calcium transient synchronization tightly followed cardiomyocyte alignment behavior, allowing highly anisotropic biomaterials to drive calcium transient synchronization within 8 days, while such synchronized cardiomyocyte behavior required 20 days of culture on nonaligned biomaterials. In contrast, cardiomyocyte contractile displacement had no directional preference on day 8 yet became anisotropic in the direction of fiber alignment on aligned fibers by day 20. Biomaterial anisotropy impact on differentiating cardiomyocyte structure and function is temporally dependent. Impact Statement This work demonstrates that biomaterial anisotropy can quickly drive desired pluripotent stem cell-derived cardiomyocyte structure and function. Such an understanding of matrix anisotropy's time-dependent influence on stem cell-derived cardiomyocyte function will have future applications in the development of cardiac cell therapies and cardiac tissues for drug testing. Furthermore, our work has broader implications concerning biomaterial anisotropy effects on other cell types in which function relies on alignment, such as myocytes and neurons.
各向异性生物材料可以通过驱动细胞对齐来影响细胞功能，这对于心脏工程组织至关重要。然而，最近的研究表明，多能干细胞衍生的心肌细胞可能会在很长一段时间内自行对齐。为了确定生物材料基底各向异性的程度如何影响分化的心肌细胞结构和功能，我们将小鼠胚胎干细胞分化为非对齐、半对齐和对齐纤维基底上的心肌细胞，并随时间评估细胞对齐、收缩位移和钙瞬变同步性。尽管纤维对齐对心肌细胞基因表达没有影响，但我们观察到心肌细胞对齐和功能存在基于梯度和基于阈值的差异。在早期，心肌细胞的对齐度以基于梯度的方式随着纤维对齐度的增加而增加，而在后期，以基于阈值的方式增加。钙瞬变同步性紧密跟随心肌细胞对齐行为，使高度各向异性的生物材料能够在 8 天内驱动钙瞬变同步性，而在非各向异性生物材料上培养 20 天才能达到这种同步的心肌细胞行为。相比之下，心肌细胞的收缩位移在第 8 天没有方向偏好，但在第 20 天，在对齐纤维上，其收缩位移具有纤维对齐的方向各向异性。生物材料各向异性对分化的心肌细胞结构和功能的影响具有时间依赖性。影响说明 本研究表明，生物材料各向异性可以快速驱动多能干细胞衍生的心肌细胞的结构和功能。这种对基质各向异性对干细胞衍生的心肌细胞功能的时间依赖性影响的理解，将在心脏细胞治疗和用于药物测试的心脏组织的发展中具有未来的应用。此外，我们的工作对于生物材料各向异性对其他依赖于对齐的细胞类型（如心肌细胞和神经元）的影响具有更广泛的意义。
