I haven't used it and seen it in papers very often but my colleague uses it in case of macrophages. So I am just curious about your opinion/experience.
As a result of metabolism, cells keep on producing wastes containing a plenty of radical oxygen. People who work with macrophages know this phenomenon better as under inflammatory stimulus radical oxygen production increases multifold in terms of ROS and Nitric oxide.
The accumulation of radical oxygen in media supernatant may induce oxidative stress to cultured cells. It may interfere with the health of cells and also with the results of any experiment. What I found with BME is that in presence of ~50uM BME, cells are less clumped. Particularly cell lines like THP1 monocytes that can easily form aggregate in suspension, effect of BME addition can be observed easily.
Microglial cells are type of macrophages, and addition of BME should help improve their health.
I have used it at 10-100 uM in mixed neuron-glia cultures, not toxic to glia. Also used it up to 1 mM on differentiated SH-SY5Y cells, was protective against hemin.