DMSO – Cryopreservation Comes With a Cost
Dimethyl sulfoxide (DMSO) is frequently used in cell banking applications as a cryoprotectant. When added to media, DMSO prevents intracellular and extracellular crystals from forming in cells during the freezing process. Without a cryoprotectant, these crystals cause cell death, thus rendering the cells useless for transplant.
DMSO is almost always used in the banking of cord blood cells. Cord blood is collected from the umbilical cords of infants at birth. Many parents choose to save these valuable cells and preserve them for future use or opt to donate them to a public bank where they can be used by anyone who needs them. Cord blood cells are frequently used in the treatment of childhood leukemia and are being explored as treatment for many other diseases including cerebral palsy and traumatic brain injury. By banking their child’s cord blood cells, parents are taking out a kind of insurance policy. If their child becomes ill with a disease that can be treated with cord blood cells, there will be a donor cell match available. Since these cells often aren’t used until several years in the future, they need to be preserved in a way that ensures the maximum number of healthy cells after thawing. This is where cryopreservation with DMSO is critical. For most cryopreservation applications, DMSO is used at 10% concentration and is usually combined with saline or serum albumin.
After the cells are thawed they are washed to remove the DMSO, but some still remains and is injected into patients during cell transplant. While DMSO has been declared safe and non-toxic to stem cells, there have been several reports from transplant centers of serious side effects in patients as a result of DMSO toxicity. According to Berz, et. al. 2007, nausea, vomiting and abdominal cramps occur in about half of all cell transplant cases. Serious side effects have also been reported in patients’ cardiovascular, respiratory, and renal systems including some fatalities.
So if there are serious side effects and even fatalities attributed to DMSO toxicity, why is it still being used? The main issue is that without a cryoprotectant, the cells can’t survive the freezing process. If the cells don’t survive cryopreservation, there is no therapy and these therapies save lives. Other cryoprotectant possibilities are being explored including using lower concentrations of DMSO. Scientists have also explored the possibility of using propylene glycol instead of DMSO. While having cells for transplant is better than having none at all, the ideal would be to be able to conduct transplants without any negative side effects from DMSO toxicity.
Please comment on the use of DMSO in cellular therapy and cell transplants or on any other novel solutions to eliminate DMSO toxicity.