2.8. Cell viability

The distribution of viable and dead cells within PEG-4MAL hydrogels was assessed at day 7 of cell culture using a live/dead assay. Cell-hydrogel matrices were rinsed with warm PBS pH 7.4 and incubated with 4 μM calcein AM (Life Technologies) and 6 μM propidium iodide (PI; Life Technologies) at 37 °C for 30 min, for detection of viable and dead cells, respectively. After incubation, the samples were rinsed twice with PBS pH 7.4, transferred to the culture medium, and immediately observed under confocal laser scanning microscopy (CLSM, Leica TCS SP5). Quantitative analysis of live and dead cells was also conducted using immunocytometry (See Supplementary Materials and Methods).