Fig. 4.

Quantitative in-droplet cell growth and survival. The integrated viability assay was used to optimize cell encapsulation and storage conditions to achieve maximum survival of encapsulated cells. Human monocytic U937 cells were encapsulated inside droplets, collected into a glass syringe, and incubated in a standard cell incubator. (A) After different incubation times, the encapsulated cells were assayed for viability using the integrated viability chip. Encapsulated cells maintained >80% survival up to 4 days post-encapsulation. (B) To assess the balance between cell growth and cell death, we analyzed the distribution of the total number of cells per droplet over time. During the first 24 h, the distribution of number of cells contained in each droplet showed a partial shift toward droplets containing more cells, the distribution remained very constant after this initial period. The results show that only limited cell growth occurred during the first 24 hours.