Modulation of Planaria Regeneration by Resolvin D1 and the Omega-3 Fatty Acid Precursor 17-Hydroxy Docosahexaenoic Acid

Omega-3 fatty acids (FA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have long been consumed as medical supplements for their far-reaching health benefits, ranging from alleviating asthma symptoms to mitigating kidney and inflammatory diseases like colitis and diabetes. These fatty acids produce a variety of lipid mediator metabolites including maresins, protectins, and resolvins, and are essential for aiding the resolution pathways in inflammation. However, their roles in regenerative responses are relatively unknown. We decided to investigate the effect of Resolvin D1 (RvD1) in Dugesia dorotocephala regeneration, as RvD1is the most widely studied lipid mediator. We foundthat regenerating planaria released significantly higher amounts of RvD1 in water than control and that D. dorotocephala could synthesize their own RvD1 from the omega-3 FA precursor 17-hydroxy docosahexaenoic acid (17-HDHA). We also observed that both RvD1 and 17-HDHA enhanced regeneration responses in planaria by using eye scoring and a modified cell metabolism assay (MTT). We conclude that planarians may utilize similar biosynthetic pathways to mammals in producing resolvins and that resolvins hold immense potential in enhancing regenerative responses in tissues.