Molecular Characterization of Olfactory Bulb Neural Stem Cells during Proliferation and Differentiation‏

Objective: This study aimed to demonstrate the fate of human olfactory bulb neural stem cells (hOBNSCs). Reportedly,
these cells can be expanded in vitro under prolonged mitogen stimulation without propensity to transform. Material
and methods: We assessed their possible ability to proliferate and differentiate into different neurons, oligodendrocytes
and astrocytes through monitoring changes in expression profile of proliferation (NES, NR4A1, SOX2, MSI1)
and differentiation (FOXO4, CSPG4, MAP2, GFAP)-related genes. Results: In vitro induction of hOBNSCs proliferation
by addition of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and leukemia inhibitory
factor (LIF) to basal serum-free medium (DMEM/F12) resulted in significant up-regulation of proliferation-related
genes. Differentiation of hOBNSCs, which was initiated by replacing bFGF and EGF by triiodothyronine (T3), significantly
increased expression of differentiation-related genes. Among the differentiated cells, GFAP-expressing astrocytes
constituted the highest population of cells followed by CSPGS-expressing immature oligodendrocytes, then
MAP2-expressing immature neurons, and finally FOXO4-expressing mature oligodendrocytes. Conclusion: These
data will enable us to understand the mechanism of proliferation and differentiation of hOBNSCs before and after their
engraftment during cell-based therapy for neurodegenerative diseases.