Meso-scale topological cues to promote endothelial cell proliferation on macro-scale, blood-contacting polymeric substrates

Abstract

OBJECTIVE: Mesoscopic-topological-cues are a challenging and promising alternative to promote a stable endothelial cell layer formation able, long-term, to impact the thrombogenicity of medical devices. The use of polydimethylsiloxane (PDMS)-micropatterned-films and substrates has shown limitations, such as slow degradation rate, low surface-to-volume ratio, low permeability, and a rather limited scalability which all affected biocompatibility. In this preliminary study, we introduce a hybrid lithography/electrodeposition method to fabricate permeable, large, fiber-based substrates with mesoscale patterns putatively able to mimic basement membrane and promote functional endothelium formation. METHODS: Lithography was performed through a direct-laser-writing-system(LW405E, Microtech srl) that selectively removed the photoresist and engraved the pattern on a three-layer substrate composed of soda-lime-glass, AZ1518-photoresist, and chrome. The conductive chrome-layer enabled the wafer to serve directly as a collector for the electrodeposition. The alternated conductive/non-conductive regions of the target were designed to attract the electrospun fibers selectively, processing values were investigated in the range V(Δ14kV),d(10cm),t(30min), T(22°C),HR(35%),Q(0,4ml/hr),needle(21G). Two different patterns depths were evaluated: 1µm, and 4µm. Patterns were investigated via SEM and quantitative analysis (%patterns on polymer substrate/patterns on CAD model) to prove the method capacity to prescribe a mesoscale pattern regardless of its shape: square and honeycombs both with a side of 60µm and 20µm gaps. Scaffolds were seeded with vascular smooth muscle cells to assess topological cues impact on cellular metabolic activity via Alamar blue test. RESULTS: Qualitative and quantitative analysis of SEM images confirmed the ability to transfer a pattern geometry regardless of its shape with an accuracy of 84% and 98% respectively for 1µm and 4µm. This proprietary technique (US2024/0016983A1) demonstrates higher cellular activity than casted-non-fibrous patterns. CONCLUSIONS: This study showed how photolithography and electrodeposition can be combined to process micro-fiber-based substrates 4cmx4cm with mesoscale-patterns of desired shape feasible for applications at organ level scale enhancing cellular viability.