Development of a Collagen-Coated Microfluidic Device to Evaluate Tubular Structure Formation of RF/6A Cells Under Static and Dynamic Flow Conditions

This study presents the development of a collagen-coated microfluidic device to model retinal angiogenesis, with a focus on the choroid layer of the outer blood-retina barrier (oBRB). A PDMS-glass microchannel (2 cm × 2 mm × 85 μm) was fabricated and simulated using COMSOL Multiphysics to evaluate shear stress levels under flow rates of 15–45 µL/min. The device generated physiological wall shear stress (0.77–3.16 dyn/cm²) comparable to human choroid microvasculature. RF/6A endothelial cells were cultured within the device under both static and dynamic conditions for 96 hours using VEGF-enriched media. Tubular structures were visualized using phase-contrast microscopy and analyzed with ImageJ (Angiogenesis Analyzer plugin). Results revealed significantly increased vessel complexity—measured via master segment length, number of branches, and junction points—in dynamic cultures compared to static ones (p < 0.01). The findings highlight the pivotal role of shear stress in promoting in vitro angiogenesis and validate the potential of this device as a functional platform for retinal vascular studies.