UK patients have been cut from an international clinical trial to test a new heart attack drug because of uncertainties about registering new medicines after Brexit.

The drug, dutogliptin, is being tested to see if it can help regenerate cardiac muscle after a heart attack and patients in Exeter, Leeds and Clydebank in Scotland were due to take part.

However, Recardio, the US-based company developing the drug, has shelved the UK arm of the trial over fears that data in Britain will no longer be acceptable to the European Medicines Agency (EMA) – which licenses drugs for EU use – after Britain quits the bloc.

Under the skin – best of the British Heart Foundation 2018 image prize Show all 10 1 /10 Under the skin – best of the British Heart Foundation 2018 image prize Under the skin – best of the British Heart Foundation 2018 image prize Subarachnoid vessels The runner-up image came from Matt MacGregor Sharp, a PhD student at the University of Southampton. The super-high resolution image shows a normal artery at the surface of a rat’s brain and was taken with a powerful scanning electron microscope. These ‘subarachnoid vessels’ supply blood to the brain and also act like a drain to remove toxic waste products. Matt Macgregor’s team are trying to show that failure to remove waste by these vessels is one of the underlying causes of vascular dementia. The researchers took the image using a technique called ‘freeze fracture’, where tissue or cell samples are frozen and then split apart to reveal the hidden layers within the sample so they can be studied in extreme detail. Sitting above the brown brain tissue, the artery appears blue, and its surrounding layer, the pia mater, is shown in purple. Matt MacGregor Sharp, University of Southampton, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Explosive beginnings Winner: Endothelial cells line all blood vessels in the body, forming a barrier between the circulating blood and the vessel wall. They also help to protect blood vessels from damage and release important chemical messengers which help to control blood pressure. The winning researcher, Courtney Williams, is a Masters student and PhD candidate at Leeds University. Her lab are developing new ways to map the growth of new blood vessels within their surrounding landscape in 3D. Understanding the complex secrets of blood vessel formation could be harnessed to boost the regrowth of damaged blood vessels after a heart attack, and halt blood vessel growth when it’s counterproductive. Courtney Williams, Leeds University, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize A snapshot of platelet production - Reflections of Research Supporters’ Favourite This image from Abdullah Obaid Khan, a PhD student at the University of Birmingham, won the supporters’ favourite. What look like precious jewels are actually platelets forming within the bone marrow. Platelets are the smallest of our circulating blood cells with a hugely important role in preventing bleeding. However, they also play a role in the formation of clots, which can lead to heart attacks and strokes. Abdullah Obaid Khan and his team are studying rare bleeding disorders. Abdullah Obaid Khan, University of Birmingham, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Cardiac collagen web - Shortlist This colourful image shows the web-like, network of the smallest blood vessels in the heart – the microvessels. Magenta marks the outer collagen layer of the vessels; while orange marks their inner lining and blue the cell nuclei. Dr Neil Dufton, Imperial College London Dr Neil Dufton, Imperial College London, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Heart to Heart - Shortlist This piece shows four ventricles (from a mouse) arranged into the shape of the hearts four normal chambers. The researchers have used fluorescent markers to recognise certain proteins and created the image using of hundreds of images assembled together. Dr Elisa Avolio and Dr Zexu Dang, University of Bristol Dr Elisa Avolio and Dr Zexu Dang, University of Bristol, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Loving artery - Shortlist This image shows a cross section of an artery and the different layers which make up the artery wall. Affiliate Professor Silvia Lacchini, University of Glasgow Silvia Lacchini, University of Glasgow, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Oxidative inkblot - Shortlist This colour explosion shows one of the culprits in cardiovascular disease – an enzyme called NADPH oxidase. The enzyme is considered ‘Janus faced’ because it is important in health, as well as disease. This picture shows the active enzyme in patients who have high blood pressure. Dr Livia de Lucca Camargo, University of Glasgow Dr Livia de Lucca Camargo, University of Glasgow, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Neon skeleton - Shortlist This image shows the developing blood vessel system of a two day old zebrafish embryo. The researchers used gene enhancers (the on-off switches of genes) to switch on fluorescent markers in different types of endothelial cells – the important cells which line all blood vessels. All blood vessels switch on the red marker, while the veins also switch on the green marker, resulting in yellow veins and red arteries. Dr Svanhild Nornes, University of Oxford Dr Svanhild Nornes, University of Oxford, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Calcium reef - Shortlist This image shows calcium in blood vessel cells from people who have high blood pressure and resembles Australia’s Great Barrier Reef. Dr Rheure Alves-Lopes, University of Glasgow Dr Rheure Alves-Lopes, University of Glasgow, British Heart Foundation - Reflections of Research Under the skin – best of the British Heart Foundation 2018 image prize Budding blood vessels - Shortlist This image shows the growing blood vessels in the mouse retina. In red you can see all the blood vessels and in yellow/green you can see the blood vessels that are actively growing (a process called sprouting). PhD candidate Kira Chouliaras, University of Oxford Kira Chouliaras, University of Oxford, British Heart Foundation - Reflections of Research

Experts have repeatedly warned that leaving the EU means the UK will be put to the “back of the queue” for new drugs as manufacturers prioritise the large EU market, and half a million patients in clinical trials will be put at risk.

The lack of progress in addressing these issues ahead of the 29 March 2019 deadline is creating a “very difficult” situation for companies such as Recardio, its founder and president, Dr Roman Schenk, told the BBC.

But the government said it was “confident” the UK would still be a good base for trials after the March deadline.

The Independent’s own Final Say campaign is calling on Theresa May to guarantee a second referendum before the UK quits for voters to have their say on the deal.

The dutogliptin trial is running in hospitals in Poland, Austria, Belgium, Bulgaria, Hungary, the Netherlands and the US.

The Golden Jubilee Research Institute, near Glasgow, had been due to take part as well but was informed by Recardio by email on 17 September that this had been put on hold.

“According to the company, uncertainty due to EU withdrawal, particularly drug and data release to the EMA, are completely unresolved and represent a significant risk,” a spokesman for the institute said.

“However, this may change when the regulatory situation has clarity.”

While it was “disappointing” the trial would not go ahead as planned, they added that patients would still receive the same safe, effective, innovative care.

A Scottish government spokesman said: “This is the first clinical study we are aware of to be suspended in Scotland as a result of Brexit – and a very concerning sign of what could happen.

“We are working hard to protect Scotland’s interests in spite of a lack of clarity and meaningful engagement from the UK government over our future.

“With Brexit only six months away, we are doing all we can to plan and mitigate against as many of the significant uncertainties that exist for our health service.”

A spokeswoman for the Department of Health said: “We are confident of reaching a deal with the EU that benefits patients and continues to deliver the best possible environment in which to support clinical trials.

“We want to ensure that patients in the UK and across the EU are still able to access the most innovative and effective medicines.”