Gaining mechanistic insights into Atrial Fibrillation: Bench to bedside approaches

Description

Atrial fibrillation (AF) is a common arrhythmia with symptoms like irregular heart rate, palpitations, shortness of breath, tiredness, and dizziness. There are four clinical subgroups, namely, Paroxysmal AF, Persistent AF, Long-standing Persistent AF, and Permanent AF. AF occurs when abnormal electrical impulses suddenly begin firing in the atria. These impulses disrupt the heart's natural pacemaker, causing irregular pulse rate due to the inability to control heart rhythm. The cause is not fully understood, but it primarily affects older individuals and those with chronic conditions like heart disease, high blood pressure, or obesity.

Pharmacological therapy aims to control rhythm using drugs targeting ion channels, but its effectiveness is limited. For example, lack of effectiveness and propensity of proarrhythmic complications by antiarrhythmic drugs and bleeding by anticoagulants. Ablation therapy has limitations in safety and effectiveness and is limited to certain patient cohorts. For rate or rhythm control, AF is managed through sinus rhythm restoration and ventricular response control.

Objectives

Atrial IP3 signalling can be pro-arrhythmic. IP3 signalling can cause pro-arrhythmic conditions, but 2-APB an inhibitor of IP3R has shown to reduce AF incidence in rabbits. IP3-dependent stimulation generates Ca2+ events in healthy cells. Inhibitors targeting the renin-angiotensin-system, which stimulates IP3 production, have been found to decrease the prevalence of atrial fibrillation in certain patient groups. In this project, the broad aims include:

1. The study aims to explore the pathophysiological mechanisms of IP3 signalling of a familial form of AF using patient-derived cardiomyocytes (CMs) differentiated from induced pluripotent stem cells (iPSCs)
2. To conduct omics studies on human tissue biopsies to identify pathological IP3 signalling in paroxysmal and persistent AF
3. To identify novel drug candidates and test them on the hiPSC-CMs (developed in Aim 1)

Experimental approach

We will differentiate both male and female sinus rhythm control and AF iPSC-derived stem cells into beating cardiomyocytes (technique well-established in the labs). These terminally differentiated cells have a prolonged longevity of 8 weeks and will allow us to conduct imaging studies and pharmacological interventions. In following approaches will be taken:

1. Tissue culture methods; immunohistochemistry labelling and imaging
2. Calcium imaging, cAMP FRET imaging
3. Maestro Pro 96-well microelectrode array (MEA) system, to track electrical activity and pharmacological drug studies
4. Omics and Bioinformatics studies

Outcome

The experiments aim to determine if increased IP3R expression in AF leads to increased IP3 signalling in human tissue (obtained at cardiac surgery) and if strategies to reduce IP3R expression or signalling have therapeutic potential. Gender is specifically addressed in the bigger research question. This research will open avenues to further research involving genetic manipulations such as knock down or knock out genes in cell lines.

Student experience

This PhD project will involve the use of advanced technology and facilities to develop mechanistic insights and strategies for future treatment of atrial fibrillation. The successful student will gain training in a multitude of techniques, ranging from 2D and 3D cell culture, iPSC generation and differentiation, electrophysiology measurements including live cell imaging. Other techniques include
liquid chromatography mass spectrometry (LC/MS) using Orbitrap QExactive mass spectrometer (UoL) and proteomic analysis using tools such as Ingenuity which will be used to evaluate global gene/protein changes. Validation of biomarkers and differential expressed proteins will be confirmed using western blotting, immunofluorescence and ELISA.

Research Environment

The research outlined will be jointly carried out in the Departments of Pharmacology and Therapeutics and Cardiovascular & Metabolic Medicine (CMM) at the University of Liverpool, with the support of the Liverpool Centre for Cardiovascular Science (LCCS). The latter is a research centre of excellence for UoL, Liverpool John Moores University and Liverpool Heart & Chest Hospital. This unique environment will allow any potential student to use clinical expertise in tandem with fundamental science to tackle a globally growing problem. Working within this interdisciplinary centre will give the student a distinctive outlook in biomedical research and their training in novel techniques. This interdisciplinary centre offers students a unique opportunity to combine clinical expertise with fundamental science to tackle global problems, enhancing their biomedical research outlook and training in cutting-edge techniques.

Applications

Application is by CV and cover letter which must detail your interest in the studentship, related experience, training and suitability for the position. This should be sent to r.a.b.burton@liverpool.ac.uk.