(630f) Oligodendrocyte Precursor Cell Intracellular Redox State Is Dependent on 3D Hydrogel Properties

The intracellular redox state of a cell is indicative not only of a cell’s proliferation or differentiation capabilities, but the cell’s ability to build and maintain cellular structures as well. In the central nervous system, this could correlate to an oligodendrocyte’s ability to generate the myelin sheath, the electrically insulating layer around neuronal axons. This myelin sheath enables neurons to send quick and efficient electrical signals to surrounding neurons, and is the main tissue component that is damaged in demyelinating diseases like multiple sclerosis. Biomaterials may be a potential method of repair following insults or injuries to the central nervous system and the myelin sheath, however little is known about what biomaterial factors stimulate functional regrowth and subsequent remyelination of oligodendrocytes from their parent cells: oligodendrocyte precursor cells.

Here we investigate how tuning the biomaterial properties of a polyethylene glycol based hydrogel affects the intracellular redox state and myelin production of an oligodendrocyte precursor cell line. PEG-dimethacrylate hydrogels with storage moduli from 230-1900 Pa were formed by tuning the concentration and molecular weight from 6 to 10% and 4600 to 8000 Da, respectively. When cells are encapsulated in the hydrogels, not only do cells proliferate in a stiffness dependent trend¹, but the cellular redox state appears to be modulated as well. The cellular redox state can be calculated by measuring the amounts of glutathione in the reduced, GSH, and oxidized GSSG form through a simple assay kit. Cells in the more compliant materials are found to have a more reduced intracellular redox state, observed by increased ratios of reduced glutathione, GSH, to total glutathione in reduced and oxidized forms (GSH and GSSG), compared to a more oxidized intracellular redox state in the least compliant, or stiffer materials. After 1 day in 3D culture, cells in the more compliant material had a 40% increase in reduced glutathione compared to the stiffer material, and a 60% increase at 7 days. When poly(lactic acid) is built into the PEG backbone, lactic acid, a powerful antioxidant and metabolite, can be slowly released as the polymer backbone hydrolytically degrades. Doping in soluble lactic acid as well as the release of lactic acid from the polymer backbone were also found to increase the amount of glutathione in the reduced form (40% with 5μmol/mL of soluble lactic acid) as compared to the total amount of glutathione in both the GSH and GSSG form. Further research investigates how the incorporation of electrospun fibers as topographical cues for myelination will further modulate the intracellular redox state and promote subsequent myelin production by differentiated oligodendrocytes in the 3D biomaterial. These results together suggest the potential use of an engineered PEG hydrogel environment to promote OPC growth, maturation, and repair of the myelin sheath.

¹Russell, LN & Lampe, KJ, Cells Tissues and Organs, 2016.