Human embryonic stem cells (hESCs) have a potential for differentiation into neuronal cells. Neural differentiation of hESCs is currently used in many fields of neurological study. Therefore, evaluation of developmental neurotoxicity in hESCs is possible during the embryonic period. In the current study, we investigated the neuronal toxicity of hydroxyurea, cytosine arabinoside, and penicillin G at multiple doses (low, medium, high) for 28 days for neural differentiation. For assessment of neural toxicity, we examined the expression of marker genes that represent neural cell development. The mRNA levels of the marker genes were evaluated by real-time PCR in hESCs. Morphological changes of hESCs during neuronal differentiation were also estimated. The results for low and medium doses of hydroxylurea showed a significant increase of dopaminergic neuron marker gene (NR4A2) and GABA neuron marker gene (GAD2). However, glutamartergic neuron marker gene (SLC1A2) and oligodendrocyte marker gene (CNP) showed a significant decrease. Results for another drug, cytosine arabinoside, showed a significant decrease of glutamartergic neuron marker gene (SLC1A2) and oligodendrocyte marker gene (CNP) at a high dose. In addition, cytosine arabinoside caused a significant decrease of dopaminergic neuron marker gene (NR4A2) without significant change in GAD2. For the control, penicillin G, no significant difference in expression of neural specific-genes was observed at all tested doses. These findings suggest that neural-specific genes are perturbed by hydroxyurea and cytosine arabinoside, which may be involved in abnormal neural development during the embryonic neurogenesis period in hESCs.
Midbrain dopaminergic neuron fate specification: Of mice and embryonic stem cells
