Groove-aided sacrificial molding for fabrication of an <i>in vitro</i> vascular model with branches using ECM-derived materials

This paper describes a fabrication method of an <i>in vitro</i> branched vascular model using extracellular matrix (ECM)-derived materials (transglutaminase crosslinked gelatin, TG-gelatin). Mechanical stresses, such as disturbed blood flow derived from vascular branches, are a significant cause of cardiovascular disease. To study cardiovascular diseases, a perfusion and stretching culture platform with an ECM-based <i>in vitro</i> vascular model with branches has been essential. Among the proposed microchannel fabrication methods, sacrificial molding with a template made of soluble material is attractive for fabricating branched microchannels. However, the soluble template remained an issue of undesired deformation due to the swelling caused by the moisture in the hydrogel. Here, we propose groove-aided sacrificial molding (GAS molding) to suppress the deformation of the soluble template in the TG-gelatin. By preparing a channel-shaped groove on the TG-gelatin, the shape retention of the soluble template is assisted. We experimentally evaluated the deformation of the microchannels fabricated by the proposed GAS molding. The vascular endothelial cells were seeded into microchannels fabricated by GAS molding for perfusion and stretching culture. The effects of mechanical stress were visualized by immunofluorescence staining of PECAM1 and integrin α9 in the endothelial cells. Overall, our method would suggest a platform to spatially elucidate the cellular responses to irregular mechanical stresses, such as triggers of cardiovascular disease.