Department of Electrical and Computer Engineering, Montana State University, Bozeman, Montana 59717, USA.
Lab Chip. 2021 Mar 21;21(6):1164-1174. doi: 10.1039/d0lc01205j. Epub 2021 Feb 5.
Tangential curvatures are a key geometric feature of tissue folds in the human cerebral cortex. In the brain, these smoother and firmer bends are called gyri and sulci and form distinctive curved tissue patterns imposing a mechanical stimulus on neuronal networks. This stimulus is hypothesized to be essential for proper brain cell function but lacks in most standard neuronal cell assays. A variety of soft lithographic micropatterning techniques can be used to integrate round geometries in cell assays. Most microfabricated patterns, however, focus only on a small set of defined curvatures. In contrast, curvatures in the brain span a wide physical range, leaving it unknown which precise role distinct curvatures may play on neuronal cell signaling. Here we report a hydrogel-based multi-curvature design consisting of over twenty bands of distinct parallel curvature ranges to precisely engineer neuronal networks' growth and signaling under patterns of arcs. Monitoring calcium and mitochondrial dynamics in primary rodent neurons grown over two weeks in the multi-curvature patterns, we found that static calcium signaling was locally attenuated under higher curvatures (k > 0.01 μm). In contrast, to randomize growth, transient calcium signaling showed higher synchronicity when neurons formed networks in confined multi-curvature patterns. Additionally, we found that mitochondria showed lower motility under high curvatures (k > 0.01 μm) than under lower curvatures (k < 0.01 μm). Our results demonstrate how sensitive neuronal cell function may be linked and controlled through specific curved geometric features. Furthermore, the hydrogel-based multi-curvature design possesses high compatibility with various surfaces, allowing a flexible integration of geometric features into next-generation neuro devices, cell assays, tissue engineering, and implants.
切向曲率是人类大脑皮层组织褶皱的关键几何特征。在大脑中，这些更平滑、更坚硬的弯曲被称为脑回和脑沟，它们形成独特的弯曲组织模式，对神经元网络施加机械刺激。这种刺激被假设对正常的脑细胞功能至关重要，但在大多数标准的神经元细胞检测中却缺乏。各种软光刻微图案化技术可用于在细胞检测中整合圆形几何形状。然而，大多数微制造的图案仅集中在一小部分定义的曲率上。相比之下，大脑中的曲率跨度很广，因此不清楚特定的曲率在神经元细胞信号传递中可能扮演什么精确的角色。在这里，我们报告了一种基于水凝胶的多曲率设计，该设计由二十多个不同平行曲率范围的带组成，可精确地在弧形图案下设计神经元网络的生长和信号传递。监测在多曲率图案中生长两周的原代啮齿动物神经元中的钙和线粒体动力学，我们发现，在更高的曲率下（k>0.01 μm），局部钙信号被衰减。相比之下，为了使生长随机化，当神经元在受限的多曲率图案中形成网络时，瞬态钙信号显示出更高的同步性。此外，我们发现线粒体在高曲率下（k>0.01 μm）的运动性低于低曲率下（k<0.01 μm）。我们的研究结果表明，神经元细胞功能可能通过特定的弯曲几何特征而紧密相连和控制。此外，基于水凝胶的多曲率设计与各种表面具有高度兼容性，允许将几何特征灵活地整合到下一代神经设备、细胞检测、组织工程和植入物中。
