This question is in regards to CNS tissue/cells specifically.

I know Ca++ and Mg++ should be avoided during dissociation when using EDTA and trypsin. I use a papain dissociation but still avoid Ca++ and Mg++ during the actual dissociation process (i.e. do a Ca++ Mg++ -free PBS wash prior). However, during perfusion and for washes before and after the dissociation process, is it preferable to use PBS containing Ca++ and Mg++ to maintain viability?

Also, I know Ca++ and Mg++ can result in cell clumping and adhesion to substrates, so if it is preferable to use PBS with Ca++ and Mg++ once tissue is dissociated, it seems adding BSA would be a good idea to prevent sticking to tubes, etc., correct?