An engineered platform to study the influence of extracellular matrix nanotopography on cell ultrastructure

Nanoscale fabrication techniques have played an essential role in revealing the impact of extracellular matrix (ECM) nanotopography on cellular behavior. However, the mechanisms by which nanotopographical cues from the ECM influence cellular function remain unclear. To approach these questions, we have engineered a novel class of nanopatterned ECM constructs suitable for cryogenic electron tomography (cryo-ET), the highest resolution modality for imaging frozen hydrated cells in 3D. We electrospun aligned and randomly oriented ECM fibers directly onto transmission electron microscopy (TEM) supports to generate fibrous scaffolds that mimic physiological ECM in healthy (organized ECM) and diseased (disorganized ECM) states. We produced fibers from gelatin without toxic additives and crosslinked them to maintain structural stability in aqueous environments. The electrospun fibers had an average fiber diameter of hundreds of nanometers, within the physiological range. We confirmed that the TEM supports can serve as viable cell culture substrates that can influence cell organization and demonstrated their compatibility with plunge freezing and cryo-ET. By enabling nanoscale structural analysis inside cells on substrates with programmable topographies, this platform can be used to study the physical cues necessary for healthy endothelial tissue formation and pathologies that are linked to endothelial dysfunction in diseases such as peripheral arterial disease.