Images of sprouting GFP+ and tdTomato+ HUVEC spheroids at day 7 were taken on the Zeiss Axiozoom microscope at a magnification of ×20 to capture the spheroids bioprinted at various distances. Images of sprouts at days 2 and 5 were taken using the EVOS FL Cell Imaging System. Sprouting behavior of spheroids was analyzed using AngioTool (41). To obtain the cross-sectional view of the capillary-like structures formed by GFP+ and tdTomato+ HUVEC spheroids at day 7, samples were imaged using a 40× oil lens on the Olympus FV1000 confocal microscope. For the study with GFP+ HDF/MSC coculture and HUVEC spheroids, samples were imaged on the EVOS microscope using fluorescent (4×) channels at days 2 and 5. Images of those samples on day 7 were taken using fluorescent (16× and 40×) and phase (16×) channels by the Axiozoom microscope.