Microcarrier expansion of mouse embryonic stem cell-derived neural stem cells in stirred bioreactors.

Neural stem cells (NSCs) are self-renewing multipotent cells, able to differentiate into the phenotypes present in the central nervous system. Applications of NSCs may include toxicology, fundamental research, or cell therapies. The culture of floating cell clusters, called "neurospheres," is widely used for the propagation of NSC populations in vitro but shows several limitations, which may be circumvented by expansion under adherent conditions. In particular, the derivation of distinct populations of NSCs from embryonic stem cells capable of long-term culture under adherent conditions without losing differentiation potential was recently described. However, the expansion of these cells in agitated bioreactors has not been addressed until now and was the aim of this study. Selected microcarriers were tested under dynamic conditions in spinner flasks. Superior performance was observed with polystyrene beads coated with a recombinant peptide containing the Arg-Gly-Asp (RGD) motif (Pronectin F). After optimization of the culture, a 35-fold increase in cell number was achieved after 6 days. High cellular viability and multipotency were maintained throughout the culture. The study presented here may be the basis for the development of larger scale bioprocesses for expansion of these and other populations of adherent NSCs, either from mouse or human origin.