In VitroModeling of the Bipolar Disorder and Schizophrenia Using Patient-Derived Induced Pluripotent Stem Cells with Copy Number Variations ofPCDH15 andRELN

Bipolar disorder (BP) and schizophrenia (SCZ) are major psychiatric disorders, but the molecular mechanisms underlying the complicated pathologies of these disorders remain unclear. It is difficult to establish adequatein vitromodels for pathological analysis because of the heterogeneity of these disorders. In the present study, to recapitulate the pathologies of these disordersin vitro, we establishedin vitromodels by differentiating mature neurons from human induced pluripotent stem cells (hiPSCs) derived from BP and SCZ patient with contributive copy number variations, as follows: two BP patients withPCDH15deletion and one SCZ patient withRELNdeletion. Glutamatergic neurons and GABAergic neurons were induced from hiPSCs under optimized conditions. Both types of induced neurons from both hiPSCs exhibited similar phenotypes of MAP2 (microtubule-associated protein 2)-positive dendrite shortening and decreasing synapse numbers. Additionally, we analyzed isogenicPCDH15- orRELN-deleted cells. The dendrite and synapse phenotypes of isogenic neurons were partially similar to those of patient-derived neurons. These results suggest that the observed phenotypes are general phenotypes of psychiatric disorders, and ourin vitromodels using hiPSC-based technology may be suitable for analysis of the pathologies of psychiatric disorders.