Oligodendrocyte Precursor Cell Viability, Proliferation, and Morphology is Dependent on Mesh Size and Storage Modulus in 3D Poly(ethylene glycol)-Based Hydrogels

Oligodendrocytes in the central nervous system (CNS) are responsible for generating myelin, an electrically insulating layer around neuronal axons. When myelin is damaged, neurons are incapable of sustaining normal communications, which can manifest in patients as pain and loss of mobility and vision. A plethora of research has used biomaterials to promote neuronal regeneration, but despite the wide implications of a disrupted myelin sheath, very little is known about how biomaterial environments impact proliferation of oligodendrocyte precursor cells (OPCs) or their differentiation into myelinating oligodendrocytes. This work investigates how the storage modulus and mesh size of a polyethylene glycol (PEG)-based hydrogel, varied via two different mechanisms, directly affect the proliferation of two OPC lines encapsulated and cultured in 3D. Viability and proliferation of both OPC lines was dependent on hydrogel swelling and stiffness, where the concentration of ATP increased more in the more compliant gels. OPCs multiplied in the 3D hydrogels, creating significantly larger spheroids in the less cross-linked conditions. Stiffer, more highly cross-linked materials lead to greater expression of PDGFRα, an OPC receptor, indicating that fewer cells were committed to the oligodendrocyte lineage or had dedifferentiated in compliant materials. Laminin incorporation in the 3D matrix was found to have little effect on viability or proliferation. These findings provide valuable information on how mesh size and stiffness affect OPCs where more compliant materials favor proliferation of OPCs with less commitment to a mature oligodendrocyte lineage. Such information will be useful in the development of translational biomaterials to stimulate oligodendrocyte maturation for neural regeneration.