Effect of DMSO on lifespan and physiology in C. elegans : Implications for use of DMSO as a solvent for compound delivery

Abstract

Dimethyl sulfoxide (DMSO) is a solvent that has been used for basic and medical research based on its ability to dissolve both polar and non-polar compounds. In order to use DMSO to deliver compounds that may impact longevity or neurodegeneration, it is important to first determine the effects of DMSO on aging and physiology. We examined the effect of different concentrations of DMSO on lifespan and development time in C. elegans. We found that DMSO concentrations up to 2% DMSO did not affect longevity in wild-type worms, while concentrations of up to 0.5% DMSO were compatible with normal development times. 0.5% DMSO also had minimal effect on fertility and movement. In summary, our results show that concentrations of DMSO up to 0.5% can be safely used to deliver compounds to C. elegans with little or no modifying effects on lifespan or physiologic rates.

Figure 1. Effect of DMSO on longevity and physiologic rates

In order to use DMSO as a solvent for compound delivery, the effect of different concentrations of DMSO on aging and physiology was examined. DMSO concentrations of 3% ( A ) or 2.5% ( B ) resulted in a significant decrease in lifespan. In contrast, DMSO concentrations of 2% or less had no effect on longevity ( C-F, extended data ). For panels A-F, exposure to DMSO was initiated at the L1 stage and DMSO was added on top of the plate as described in the methods section. The results are pooled from four biological replicates and have at least 114 animals per condition. At a concentration of 0.5% DMSO, when DMSO exposure was initiated at the L4 stage on plates containing 50 µM FUdR, lifespan was not affected whether the DMSO was added on top of the plate ( G ), or in the plate during plate pouring ( H ). The results from panels G and H are pooled from three biological replicates and have at least 776 animals per condition. Significance of all lifespan experiments was determined using the log-rank test. When synchronized L1 larvae were grown on NGM plates containing DMSO at different concentrations, DMSO concentrations of up to 0.5% resulted in normal post-embryonic development times, while concentrations of 0.75% and above resulted in developmental delay ( I ). There was minimal effect of 0.5% DMSO on either brood size ( J ) or thrashing rate ( K ), while 1.5% DMSO resulted in a significant decrease in both phenotypes. Sample sizes ( n numbers) are indicated in the bars of each graph. Bars indicates the sample mean. Errors bars show the standard error of the mean (SEM). The p-value was determined using a one-way ANOVA with a Dunnett's Multiple Comparison Test. * p < 0.05; **** p < 0.0001 . All assays were performed at 20 ^o C.