Dietary state and impact of DMSO on Caenorhabditis elegans aging: Insights from healthspan analysis

Caenorhabditis elegans (C. elegans) is a robust model organism in cell biology, physiology, pharmacology, and toxicology. It is widely recognized for its short lifespan (about 30 days), rapid life cycle, and genetic similarities to mammals. Known for their utility in lifespan research, compounds identified in C. elegans studies have shown lifespan-extending effects in higher organisms, making them invaluable for aging research. Recent work has highlighted the importance of food source conditions, specifically whether C. elegans is fed live or dead Escherichia coli (E. coli) OP50, and solvents like dimethyl sulfoxide (DMSO) in evaluating compound efficacy and organismal health. In this study, we employed C. elegans health lifespan auto-monitoring system (C-HAS), an automated imaging technology capable of objectively analyzing lifespan and healthspan by tracking movement patterns in real-time. Our results reveal that C. elegans fed dead bacteria, specifically heat-killed (HK) and freeze-dried (Fd) E. coli, display extended lifespan and healthspan compared to those fed live bacteria, reducing the proportion of short-lived, unhealthy nematodes. Moreover, 0.1 % DMSO treatment, a concentration previously reported as not affecting nematode longevity, notably shortens both lifespan and healthspan in C. elegans under dead bacterial conditions, with similar negative effects observed across different dead bacteria types. These findings highlight the importance of considering bacterial food state and DMSO presence when conducting lifespan and healthspan studies in C. elegans. This work provides foundational insights into how specific experimental conditions impact the health quality of C. elegans, advancing our understanding of environmental influences on organismal aging.