Patient-derived stem cell models of brain endothelial-neuron interactions in early course psychosis

Early-course psychosis (ECP) exhibits marked heterogeneity in illness trajectories, with a substantial subset of individuals developing progressive symptomatic, cognitive, and functional decline. Although growing evidence implicates blood-brain barrier (BBB) and neurovascular unit (NVU) dysfunction in psychosis spectrum disorders, direct links between longitudinal clinical trajectories and disease-related cellular phenotypes remain insufficiently characterized.

This protocol describes a standardized stem cell-based framework to model BBB and NVU dysfunction in ECP using induced pluripotent stem cells (iPSCs) derived from peripheral blood mononuclear cells (PBMCs) within a longitudinally characterized clinical cohort. The approach integrates donor-specific ex vivo cellular assays with repeated clinical, cognitive, and functional assessments for up to 5 years. Procedures are detailed for iPSC reprogramming from PBMCs, differentiation of iPSCs to brain microvascular endothelial cells (BMECs) and cortical neurons, and functional assessment of BBB integrity using trans-endothelial electrical resistance (TEER), paracellular permeability, and tight junction protein expression. NVU effects are examined by exposing cortical neurons to BMEC-conditioned media under matched and cross-culture conditions, with quantification of dendritic spine morphology, synaptic puncta, and neuronal activity using micro-electrode arrays. The protocol further incorporates modular mechanistic perturbations, including pharmacological and genetic modulation of matrix metalloproteinase 1 (MMP1), tumor necrosis factor alpha (TNFα)-related signaling, and evaluation of antipsychotic effects on barrier function.

Ethical approval and informed consent for this study was obtained and the findings will be disseminated through publication in peer-reviewed journals and presentations at scientific conferences.