Zebrafish have a rare capacity to regenerate their own hearts if they get damaged. Now scientists hope to learn from them
The British Heart Foundation turned 50 earlier this year and launched its Mending Broken Hearts Appeal – one of its most ambitious projects ever. The goal is to spend £50m on research that could begin to literally mend broken hearts in as little as 10 years.
Hope for success rests partly on the amazing zebrafish, which have the ability to regenerate heart muscle – something that tens of thousands of people in the UK living with debilitating heart failure caused by a heart attack can't do. By unlocking the biological secrets of the zebrafish, scientists funded by the Mending Broken Hearts Appeal aim to identify and harness the key genes and chemical messengers that allow the fish to regenerate heart muscle, and find a way to help human hearts damaged by heart attacks heal themselves.
Without this vital research, the growing number of patients surviving heart attacks will remain without hope of an end to the debilitating symptoms of heart failure, such as breathlessness, tiredness, palpitations, swollen ankles, lack of appetite, anxiousness and depression. Drugs and surgery can help alleviate symptoms, but currently the only cure for heart failure is a heart transplant. And even if a donor is found, a heart transplant may not fully restore quality of life for recipients who require a lifetime of immunosuppressant drugs to prevent organ rejection.
How much better it would be to be able to regenerate healthy heart tissue and replace heart muscle destroyed by heart attacks. The zebrafish is already providing vital clues about how this could be done in human hearts. If part of its heart is damaged, it can repair it in a matter of weeks, just like we are able to mend a broken bone.
Because zebrafish are transparent early in their life cycle, it is relatively easy for researchers to see their hearts and blood vessels grow. Their hearts begin to develop after just 12 hours, and they reach adult size – about 3cm long – in about three months, so they can provide quick research results.
Dr Tim Chico, consultant cardiologist at the University of Sheffield, whose work is partly funded by the British Heart Foundation (BHF), explains: "The same pathways and genes that made my heart and your heart are responsible for switching on heart development in zebrafish. At that fundamental level we share more common mechanisms than you might imagine.
"We have a library of many thousands of compounds that might be the next best drug. With zebrafish we can very quickly screen them to see if the compounds have an effect.
"We can switch off genes and see how the zebrafish regrows vessels to repair damage. If we could switch the right genes on in humans then we could live longer and survive better after a heart attack."
By spending £50m, the BHF aims to fund world-leading scientists in stem cell research, regenerative medicine and developmental biology to find ways to repair or replace damaged or dead heart tissue with new, healthy, functioning heart tissue.
"The aim of the Mending Broken Hearts Appeal is to start early clinical trials within five years and full trials within another five so that in 10 years people with heart failure would have a brighter future," says the BHF's medical director, Professor Peter Weissberg.
Stem cells, for example, offer hope because they have the potential to turn into any specialist cell. Scientists think they can harness stem cells from elsewhere in the patient's body to repair damaged heart muscle – or find out what can trigger stem cells already present in the heart to repair themselves.
Fifty years of research by the British Heart Foundation
1961 The BHF is launched and funds research that results in the first UK pacemaker to correct irregular heart rhythm at St George's Hospital in London. Half a million pacemakers have been fitted in the past 50 years.
1963 The BHF starts funding early heart transplant research.
1968 The BHF part funds the UK's first heart transplant
1973 Transplants halted by the Department of Health because of poor survival rates so the BHF funds research into overcoming transplant rejection.
1976 BHF Professor Michael Davis demonstrates that blood clots cause heart attacks.
1979 Transplants restart with a BHF five-year grant to surgeon Terence English at the Papworth Hospital.
1998 Earlier BHF-funded mega-trials reveal that aspirin and clot-busting drugs are very effective forms of heart attack treatment.
1997 BHF professor Steve Humphries launches first DNA test for Familial Hypercholesterolaemia, a common genetic cause of high cholesterol.
2002 A specialist BHF training course in echocardiography leads to a pioneering operation on the heart of an unborn baby.
2008 Four BHF Centres of Research Excellence are established.
2011 The BHF launches the Mending Broken Hearts Appeal, which aims to spend £50m to develop new treatments for heart failure
Dive into the Hope Tank
The British Heart Foundation has built a digital aquarium, which they hope will become the world's largest virtual fish tank. The aim is to raise awareness of their scientific research into the treatment of cardiovascular disease
Visit the site, where you'll be met by a charismatic talking zebrafish who will explain how the aquarium works
• Explore the tank by moving through the water with your mouse
• Watch videos of researchers in their labs and an animation of how the heart works
• Find surprise guests
• Hear emotive stories of heart patients
• Learn about the pioneering science
• Discover other zebrafish – find those created by your Facebook friends or others from your home town or county
Dive into the world of the zebrafish
Create your own fish and show your support for the Mending Broken Hearts Appeal at hopetank.org.uk