Engineered Collagen Hydrogel Scaffold

Collagen hydrogels (10H and 5Ø mm in dimension) were prepared as previously described.45 (link) Briefly, RatCol^® Rat Tail Collagen for 3D Hydrogels (Advanced BioMatrix, Carlsbad, CA, USA) and its neutralization solution were mixed in the proportion 9:1 keeping the solution in ice to prevent polymerization. Then cell suspension containing 10⁵ cells was added to a final volume of 300 µL. Hydrogels were let polymerize in 96 well plates for 1 h at 37 °C and then transferred in 2 mL medium/scaffold (well) in the 12-well custom PMMA culture chambers. These were then connected to the bioreactor system operating for up to 7 days, supplying fresh medium three times/week.