The effects of cannabidiol and its main metabolites on human neural stem cells

Cannabidiol (CBD) has been used for different purposes by different populations in recent years. When consumed by pregnant women, CBD can pass through the placenta and enter the fetal blood stream. There is concern over adverse effects of fetal exposure to CBD and its major metabolites (7-OH-CBD and 7-COOH-CBD). In the present study, human neural stem cells (NSCs) were treated with CBD and its metabolites at different concentrations for various durations to understand how the drug may affect fetal brain development. NSCs were also treated with delta-9 tetrahydrocannabinol (THC) for comparison purposes. CBD, 7-OH-CBD and 7-COOH-CBD dose-dependently reduced NSC viability. CBD and 7-OH-CBD reduced NSC number at the G1 phase. A 24 h exposure did not cause significant change in NSC proliferation. At concentrations comparable to those detected in human blood, longer exposures to CBD, 7-OH-CBD and 7-COOH-CBD caused more obvious cell death. After NSCs differentiation, CBD treatment reduced GFAP and cannabinoid receptor 2 (CB2) expression. THC treatment reduced the GFAP expression, but the change in CB2 expression did not reach statistical significance. The expression of cannabinoid receptor 1 (CB1) and beta-tubulin III were not significantly altered by drug exposures. The study demonstrated that clinically relevant concentrations of CBD, 7-OH-CBD and 7-COOH-CBD affect basic physiological features of human NSCs. After NSC differentiation, the reduced expression of CB2 receptors and GFAP on differentiated cells further indicated the vulnerability of developing central nervous system to CBD and THC. These data will help to contextualize <i>in vivo</i> neurodevelopmental studies that may not accurately model human metabolite profiles of CBD.