I have mouse testicular cells, from which I isolate spermatogonia (non-stem) using MACS. The buffer I use in MACS is 1xPBS supplemented with 0.5% BSA (bovine serum albumin) and 2mM EDTA.

After magnetic isolation, I take a fraction of the sample (isolated spermatogonia, and everything-but-the-spermatogonia) for flow cytometric processing, but the rest stays in the fridge in MACS buffer, at temperatures of 2-8 degrees Celsius. I've noticed (with flow cytometry) that after 4 days in the fridge with the aforementioned buffer, I have a significant number of cells falling apart.

Is there any better medium for short term storage, for example DMEM or alpha-MEM, not necessarily for cell cultivation, but simply for cell preparation?