Department of Chemical Engineering, University of California, Davis, California, USA.
Department of Microbiology and Molecular Genetics, University of California, Davis, California, USA.
Biotechnol J. 2024 Jan;19(1):e2300071. doi: 10.1002/biot.202300071. Epub 2023 Nov 9.
Light-inducible regulation of cellular pathways and gene circuits in mammalian cells is a new frontier in mammalian genetic engineering. Optogenetic mammalian cell cultures, which are light-sensitive engineered cells, utilize light to regulate gene expression and protein activity. As a low-cost, tunable, and reversible input, light is highly adept at spatiotemporal and orthogonal regulation of cellular behavior. However, light is absorbed and scattered as it travels through media and cells, and the applicability of optogenetics in larger mammalian bioreactors has not been determined. In this work, we computationally explore the size limit to which optogenetics can be applied in cylindrical bioreactors at relevant height-to-diameter ratios. We model the propagation of light using the radiative transfer equation and consider changes in reactor volume, absorption coefficient, scattering coefficient, and scattering anisotropy. We observe sufficient light penetration for activation in simulated bioreactors with sizes of up to 80,000 L at maximal cell densities. We performed supporting experiments and found that significant attenuation occurs at the boundaries of the system, but the relative change in intensity distribution within the reactor was consistent with simulation results. We conclude that optogenetics can be applied to bioreactors at an industrial scale and may be a valuable tool for specific biomanufacturing applications.
光诱导调控哺乳动物细胞中的细胞通路和基因回路是哺乳动物基因工程的一个新前沿。光遗传学哺乳动物细胞培养物是对光敏感的工程细胞，利用光来调控基因表达和蛋白活性。作为一种低成本、可调谐且可还原的输入，光非常擅长于对细胞行为进行时空和正交调控。然而，光在穿过介质和细胞时会被吸收和散射，并且光遗传学在更大的哺乳动物生物反应器中的适用性尚未确定。在这项工作中，我们通过计算探索了在相关的高径比下，光遗传学在圆柱形生物反应器中可以应用的尺寸极限。我们使用辐射传输方程来模拟光的传播，并考虑了反应器体积、吸收系数、散射系数和散射各向异性的变化。我们观察到，在模拟生物反应器中，在最大细胞密度下，光穿透足以激活，尺寸可达 80000L。我们进行了支持性实验，发现系统边界处会发生显著衰减，但反应器内的强度分布的相对变化与模拟结果一致。我们得出结论，光遗传学可以应用于工业规模的生物反应器，并且可能是特定生物制造应用的有价值的工具。
