Batten disease is a fatal childhood neurodegenerative disease. In CLN3 type Batten disease, children are born healthy and then develop neurodegenerative symptoms from age 4 until death in teenage years. Batten disease significantly effects the quality of life of affected children and their families with main symptoms being blindness, loss of speech and mobility, and seizures. Currently there are no approved treatments for CLN3 Batten disease with the BBB posing a major challenge for treatment design. Despite this, little research effort has been directed to understanding its physiology and overcoming drug permeability challenges. This project will use a patient-derived lab grown living models of the blood brain barrier (BBB) to investigate how brain cell health is affected by CLN3 Batten disease and test potential new treatments such as drugs and focused ultrasound waves. Firstly, we will grow 2D monolayer models of BBB cells and then conduct experiments to measure how CLN3 Batten disease affects inflammatory markers, toxin build-up, barrier permeability, and integrity compared to healthy cells. Therapeutic investigations will involve drug repurposing and Focused Ultrasound. Drugs with repurposing potential (used in other diseases but may have unknown benefits in Batten disease), will be tested for their permeability across the BBB monolayer and effects on disease pathology (e.g. reductions in inflammation and toxin build-up). Then, focused ultrasound waves will also be applied to see if this enhances drug permeability or reduces any disease pathology. This project will provide essential information on the effects of Batten disease on the BBB, which is crucial for determining effective treatment targets. Furthermore, this project is a significant contribution to personalised medicine innovation.