DMSO Usage in Cell Culture
Dimethyl sulfoxide (DMSO) is an organic compound with the formula of (CH3)2SO. DMSO is frequently used in cell banking applications as a cryoprotectant. DMSO prevents intracellular and extracellular crystals from forming in cells during the freezing process. For most cryopreservation applications, DMSO is used at 10% concentration and is usually combined with saline or serum albumin.
Hydrophobic peptides can be easily dissolved in DMSO. However, peptides in DMSO could be cytotoxic to the cells although DMSO increases cell permeability. A high concentration of DMSO should never be used for cell culture. 5% is very high and will be dissolving the cell membranes. Most cell lines can tolerate 0.5% DMSO and some cells can tolerate up to 1% without severe cytotoxicity. However, primary cell cultures are far more sensitive. So if it is the primary cell you are using then do a further dose/response curve (viability) at concentrations below 0.1%.
So for very hydrophobic peptides, try to dissolve the peptide in a small amount of DMSO (30-50ul, 100%), and then slowly drop the solution to a stirred aqueous buffer solution like PBS or your desired buffer to the desired concentration. If the resulting peptide solution begins to show turbidity, you have reached the limit of solubility. Sonication will help to dissolve the peptides.
Rule of thumb:
- 0.1% DMSO is considered to be safe for almost all cells.
- 0.5% DMSO as the final concentration has been used widely for cell culture without cytotoxicity.
- 1% DMSO doesn't cause any toxicity to some cells but 0.5% DMSO is recommended.
- 5% DMSO was used successfully for some cells.
To keep the final concentration to 0.5%, you can make 200x stock in 100% DMSO.