HI,

 for sure you can use EdU or BrdU in order to test cle proliferation, otherwise you can use immunofluorescence with Ki67  that works very well. In parallel you can check viutality using Calcein or live-dead commercial kit likewise 04511-1KT-F.

Good luck

Simple techniques like MTT will tell if the cell are viable. You can also stain with DAPI or PI and check. or prestain your cells with vital dyes and see how long they survive in hydrogel...many more 

MTT will work. Calceim Am stain works too.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5855117/