(Dimethyl Sulfoxide (DMSO
DMSO (dimethyl sulfoxide) is a polar organic solvent that is used as a cryoprotectant due to its membrane-penetrating properties and water displacement. It is added to cell culture media to reduce ice crystal formation and thereby prevent cell death caused by the freezing process.
Experimental studies report that during the initial freezing step, a temperature decrease of approximately 1°C/min is optimal. In vitro, DMSO has been reported to induce membrane pore formation and apoptosis through the activation of caspase 9 and 3 at concentrations above 10%. The response induced depends on the cell type or cell line.
The timing of freezing and thawing of cells is a critical factor, as it must minimize the amount of cell contact with DMSO. The toxic effects of DMSO occur at temperatures above 4°C. For this reason, during cell culture differentiation, it must be neutralized or diluted before reaching 4°C. DMSO can be diluted with the complete medium used for cell culture or with PBS (prepared in double distilled water). For example, the prepared cell suspension can be diluted in 6–8 ml of PBS.
DMSO is a cryoprotectant. Water freezes at 0°C and DMSO at 19°C. A mixture of the two has a lower freezing point. Also, a mixture of the two forms fewer disruptive crystals when frozen. The solid form of water (ice) is less dense than its liquid state, so ice crystals take up more space than liquid water. Individual water crystals can become very large, especially when they merge with smaller crystals. Water crystals tend to form hexagonal crystals (snowflakes). DMSO, even at the 10% by weight that is commonly used, prevents the formation of such large, destructive crystals, especially when the temperature drops to -80°C.
For this purpose, DMSO is used instead of other water-soluble liquids such as ethanol because it is much less toxic. However, hematopoietic cells, embryonic stem cells, and many hybridoma cell lines are vulnerable to DMSO.
Comments
Your Comments
Comments