Abstract Body (Do not enter title and authors here): Introduction: Atrial Fibrillation (AF), the most common cardiac arrhythmia in clinical practice is associated with a higher risk for progressive cognitive decline and dementia independent of clinical stroke and other comorbid conditions. While the pathophysiological mechanisms by which AF is linked with cognitive decline remain unclear, increasing evidence suggests that aging-related increase in inflammation and endothelial dysfunction may be a common etiology. Caveolin-1 (CAV-1), a membrane protein expressed in endothelial cells (ECs), fibroblasts, cardiomyocytes and neurons, plays a vital role in maintaining EC functions including caveolae-mediated transcellular transport and cell signaling. While genome wide association studies have associated common variants in CAV1 with AF, the underlying mechanisms are not known. Here, we explored the role of CAV-1 depletion in AF and cognitive decline utilizing CAV-1 knockout (KO) human iPSC-derived cellular models of atrial cardiomyocytes (aCMs), ECs and neurons.
Hypothesis: Depletion of CAV-1 causes increased vascular permeability and endothelial dysfunction which promotes inflammatory remodeling in atrial cardiomyocytes and neurons.
Methods: Human iPSC-aCMs, microvascular ECs, brain-like microvascular (BMECs) and cortical neurons (CN) were generated from CAV-1 KO and wild-type (WT) iPSCs. Optical voltage mapping was performed using the voltage sensitive dye Fluovolt, followed by imaging with a IONOPTIX system. Trans endothelial electrical resistance was measured using an ECIS system. Neuron morphology analysis was performed using Neuron J, an Image J plugin. All experiments were performed with a minimum of three replicates.
Results: Co-culture of CAV-1 KO iPSC-ECs with WT-iPSC-aCMs induces action potential duration (APD) prolongation (Fig. A). CAV-1KO-iPSC-BMECs have reduced expression of tight junction protein Claudin 5 (Fig. B-C) and decreased recovery of resistance on stimulation with thrombin (Fig. D) while CAV1- KO iPSC-CN exhibit increased neurite lengths compared to WT (Fig. E).
Conclusion: Endothelial dysfunction due to CAV-1 depletion prolongs APD in human iPSC-aCMs creating an electrophysiological substrate for AF and increases vascular permeability in iPSC-BMECs. Our results suggest CAV-1 as a novel therapeutic target for improving vascular dysfunction underlying AF and cognitive decline.