Cell viability and imaging. The viability of 3T3 fibroblasts embedded within cast constructs and bioprinted constructs was assessed on days 1, 3, 7, and 14 using a live/dead assay (LIVE/DEAD TM Cell Imaging Kit, 488/570, Life Technologies Corp., CA, USA) following the manufacturer's instructions. Fluorescence images were taken with an inverted confocal microscope (Nikon A1R HD25, Nikon Canada, Mississauga, ON, Canada) using a 10X/0.45NA objective. Image J (National Institute of Health, Bethesda, MD, USA) software was used to process the images and calculate the cell viability.