Effect of macromer weight percent on neural cell growth in 2D and 3D nondegradable PEG hydrogel culture.

Neural precursor cells (NPCs) are a renewable cell source that may be useful for neural cell transplant therapies. Their expansion and differentiation potential have traditionally been explored by culturing them on stiff tissue culture polystyrene. Here we describe advantages of an alternative culture system: bio-inert poly(ethylene glycol) (PEG) hydrogels. Specifically this work reports the effect that macromer weight percent has on the metabolic and apoptotic activity, proliferation, and cellular composition of a mixed population of neurons and multipotent NPCs grown both on 2D and within 3D PEG hydrogels. In 2D culture, hydrogel properties did not affect metabolic or apoptotic activity but did impact cell proliferation and composition leading to an increase in glial cell reactivity as stiffness increased. In 3D culture, low weight percent hydrogels led to greater metabolic activity and lower apoptotic activity with significant proliferation observed only in hydrogels that closely matched the stiffness of native brain tissue. PEG hydrogels therefore provide a versatile in vitro culture system that can be used to culture and expand a variety of neural and glial cell types simply by altering the material properties of the hydrogel.