460307 Oligodendrocyte Survival, Proliferation, and Intracellular Redox State Is Dependent on 3D Hydrogel Mechanics

Friday, November 18, 2016: 10:00 AM
Continental 6 (Hilton San Francisco Union Square)
Lauren Russell and Kyle Lampe, Chemical Engineering, University of Virginia, Charlottesville, VA

Oligodendrocyte precursor cells (OPCs) differentiate into oligodendrocytes, which in the central nervous system are responsible for generating the myelin sheath, an electrically insulating layer around neuronal axons. This myelin sheath enables neurons to send quick and efficient electrical signals to surrounding neurons. Diseases or injuries to the myelin sheath, such as multiple sclerosis, are highly debilitating diseases that have a large impact on the patient’s quality of life. Multiple sclerosis is an autoimmune disorder where inflammation occurs and oligodendrocyte myelin segments are disrupted and impaired. Following relapses, stem cells are capable of migrating to the damaged area, however OPCs are often unable to survive or differentiate into functional, myelinating oligodendrocytes. Biomaterials may be a potential method of repair following these insults or injuries, however little is known about what biomaterial factors stimulate OPC proliferation, differentiation, and functional myelination. Research indicates that there is a correlation between a cell’s ability to proliferate or mature and its intracellular redox state, which can be modulated by both soluble antioxidants and microenvironmental stiffness.

Here, we investigate how simply tuning the mechanical stiffness of a polyethylene glycol (PEG) based hydrogel affects the proliferation and intracellular redox state of two different oligodendrocyte precursor cell lines. PEG-dimethacrylate hydrogels with storage moduli from 230 to 1000 Pa were formed by tuning the concentration and molecular weight from 6% to 10% (wt/v) and 4600 to 8000 Da, respectively. When cells were encapsulated in the hydrogels, they proliferated in a stiffness dependent trend, where the largest increases in ATP and DNA concentrations were found in the most compliant hydrogel formulation. In gels with storage moduli of 230 Pa, the concentration of ATP was found to increase 12 fold over seven days while DNA increased 44% over seven days. To test the influence of antioxidants, we incorporated lactic acid into the hydrogel both as a soluble factor or into the polymer backbone where it can be released through hydrolytic degradation. As a measure of intracellular redox state, glutathione content within cells was measured in its reduced GSH form and in its oxidized GSSG disulfide form. Results from determining the ratio of reduced GSH to total glutathione (GSH and GSSG) suggest that incorporating lactic acid further reduces the intracellular redox state and increases cellular proliferation. These findings suggest the potential use of tunable PEG hydrogel systems to promote OPC growth, increase oligodendrocyte maturation, and repair the myelin sheath.

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See more of this Session: Stem Cells in Tissue Engineering
See more of this Group/Topical: Food, Pharmaceutical & Bioengineering Division