Stock solutions for tissue culture

The kitchen makes Tris, TD, Tryp/TD, PBS, and VE.

Tris is a fairly complex, Tris-buffered physiological saline solution. It is used to wash cells and is preferable to TD, unless you need a Ca++/Mg++ free solution.

It is:

136.8 mM NaCl 5 mM KCl 0.9 mM CaCl2 0.7 mM MgCl2 (6H20) 0.7 mM Na2HPO4 25 mM Tris-HCl, pH 7.4

TD is a variant of Tris that lacks the calcium and magnesium. It is used to wash cells prior to trypsinization. Calcium and magnesium inhibit cell dispersal. Tryp/TD is 0.25% Bacto trypsin in TD. It is stored frozen. PBS is a phosphate-buffered physiological saline solution. It is useful if you want to avoid Tris buffer. Like Tris, it contains calcium and magnesium. There is a rarely used variant lacking calcium and magnesium called PBSa.

PBS is:

136.8 mM NaCl 2.5 mM KCl 0.8 mM Na2HPO4 1.47 mM KH2PO4 0.9 mM CaCl2 0.5 mM MgCl2 (6H2O)

VE is TD that contains EDTA. One very old brand name for EDTA is Versene, hence the acronym. VE is helpful in trypsinizing very adherent cells. Note that EDTA inhibits the growth of some cells, so it must be gotten rid of in many cases.