Figure 7.

Bulk vs. granular 3D encapsulation of cells. A) Bulk hydrogels supported 3D cell culture with an average viability of 80% across the thickness of the sample. B) After three days of culture, viability in bulk hydrogels decreased to ~60%, with pronounced cell death at the core of the hydrogel where nutrient diffusion is most limited. Inset: view of entire ~4 mm scaffold with visualized region outlined. C) 3D encapsulation of cells within microgels in annealed porous scaffolds afforded comparable viability; most dead cells were poorly encapsulated and retained in the voids between microgels. D) In contrast to bulk hydrogels, viability in granular scaffolds improved over three days of culture to >80% and did not depend on location within the 3D superstructure. Scale bars = 500 μm. Bin widths for all histograms are ~0.01. Labeled black lines in viability histograms represent population-wide average. Dashed blacked lines in population histograms represent modeling of a homogenous distribution of cells throughout the scaffold. Live and dead cells were respectively stained with calcein AM (green) and ethidium homodimer (red).