Growth cones of oligodendrocyte progenitor cells (OPCs) are challenging to investigate with conventional light microscopy due to their small size. Especially substructures such as filopodia, lamellipodia and their underlying cytoskeleton are difficult to resolve with diffraction limited microscopy. Light microscopy techniques, which surpass the diffraction limit such as stimulated emission depletion microscopy, often require expensive setups and specially trained personnel rendering them inaccessible to smaller research groups. Lately, the invention of expansion microscopy (ExM) has enabled super-resolution imaging with any light microscope without the need for additional equipment. Apart from the necessary resolution, investigating OPC growth cones comes with another challenge: Imaging the topography of membranes, especially label- and contact-free, is only possible with very few microscopy techniques one of them being scanning ion conductance microscopy (SICM). We here present a new imaging workflow combining SICM and ExM, which enables the visualization of OPC growth cone nanostructures. We correlated SICM recordings and ExM images of OPC growth cones captured with a conventional widefield microscope. This enabled the visualization of the growth cones’ membrane topography as well as their underlying actin and tubulin cytoskeleton.

中文翻译：

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结合扫描离子电导和四倍放大显微镜观察少突胶质细胞祖细胞生长锥的膜表面和细胞骨架

由于少突胶质细胞祖细胞 (OPC) 的生长锥尺寸较小，因此用传统光学显微镜进行研究具有挑战性。尤其是诸如丝状伪足、板状伪足及其底层细胞骨架等子结构很难用衍射极限显微镜来解析。光学显微镜技术超越了衍射极限，例如受激发射损耗显微镜，通常需要昂贵的设备和经过专门培训的人员，这使得较小的研究小组无法使用它们。最近，膨胀显微镜（ExM）的发明使得任何光学显微镜都可以进行超分辨率成像，而无需额外的设备。除了必要的分辨率之外，研究 OPC 生长锥还面临另一个挑战：对膜的形貌成像，尤其是无标记和无接触的膜形貌成像，只能通过极少数的显微镜技术实现，其中之一是扫描离子电导显微镜 (SICM)。我们在此提出一种结合 SICM 和 ExM 的新成像工作流程，可实现 OPC 生长锥纳米结构的可视化。我们将 SICM 记录和用传统宽视野显微镜捕获的 OPC 生长锥的 ExM 图像关联起来。这使得生长锥的膜形貌及其底层肌动蛋白和微管蛋白细胞骨架的可视化成为可能。