Multiple Poloxamers Improve Membrane Repair Capacity in a Model of Duchenne Muscular Dystrophy

Abstract

Muscular dystrophies, such as Duchenne Muscular Dystrophy (DMD), are characterized by severe muscle degeneration and weakness. A major contributor to this pathology is sarcolemmal membrane fragility, which leads to increased damage to muscle fibers. A potential therapeutic approach is to improve membrane repair, allowing cells to more effectively resist damage that otherwise leads to necrotic cell death. Previous literature demonstrates that use of Poloxamer 188 (P188) can increase membrane repair capacity due to its affinity for damaged cell membranes. P188 is part of a family of poloxamers, all of which consist of a hydrophobic region of polyoxypropylene flanked by two hydrophilic chains of polyoxyethylene. These chains vary in length between different poloxamers. While P188 has been extensively researched in terms of membrane repair, other poloxamers in the same family have not been tested in this capacity. Based on the similarities between these polymers, we hypothesized that other poloxamers in the P188 family will reseal membrane wounds as effectively as P188. To investigate this hypothesis, we first used a rotation damage assay, in which Human Embryonic Kidney (HEK293) cells were exposed to various poloxamers and injured through impact with small glass beads (106 m). After injury, the lactate dehydrogenase (LDH) level in the cell supernatant was measured and compared to no damage and no poloxamer controls. A laser injury assay was subsequently used to investigate the effects of poloxamers on both HEK293 cells and murine muscle fibers. For these experiments, cells were injured with a multiphoton laser in the presence of a lipophilic dye (FM4‐64), which fluoresces when it comes in contact with the lipids of the cell membrane. Change in fluorescence is measured over time to quantify changes in membrane repair capacity. Muscle fibers for the laser injury assay were taken from mdx mice, a mouse model of DMD. Results indicate that multiple poloxamers improve membrane repair capacity similarly to P188. Our results also suggest that certain poloxamers have this effect in a cell‐type specific manner. This investigation improves our understanding of the effect of poloxamer size and composition on membrane repair. Our results support these polymers as promising therapeutics for DMD and other diseases where necrotic cell death contributes to disease progression.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.