HUVECs (C2519A; Lonza) were used in experiments. The cells were cultured in endothelial growth medium and supplements (CC‐3162; Lonza) with a 50 mg/ml Gentamicin Sulfate Solution (11980‐14; Nacalai Tesque, Inc.) at 37°C in a humidified atmosphere with 5% CO2. Cell passaging was performed by trypsinization in 0.05% trypsin‐EDTA (25300062; Thermo Fisher Scientific).
To reconstitute a pre‐gel collagen solution, 50 mM sodium hydroxide, 200 mM HEPES, and 260 mM sodium hydrogen carbonate were mixed to prepare a reconstitution buffer. The reconstitution buffer, ×10 Hanks balanced salt solution and acid‐solubilized collagen solution (IAC‐50), was then mixed on ice at a volume ratio of 1:1:8 to reconstitute the collagen pre‐gel solution. In this step, cells were included in the solution at 7 × 106 cells/ml. Then, 90 µl of the prepared suspension was introduced into the culture chamber, and 3 ml of the medium was introduced.
To reconstitute a pre‐gel collagen solution, 50 mM sodium hydroxide, 200 mM HEPES, and 260 mM sodium hydrogen carbonate were mixed to prepare a reconstitution buffer. The reconstitution buffer, ×10 Hanks balanced salt solution and acid‐solubilized collagen solution (IAC‐50), was then mixed on ice at a volume ratio of 1:1:8 to reconstitute the collagen pre‐gel solution. In this step, cells were included in the solution at 7 × 106 cells/ml. Then, 90 µl of the prepared suspension was introduced into the culture chamber, and 3 ml of the medium was introduced.