Unfortunately, a broken heart, more accurately termed cardiovascular disease, is responsible for 10,000 deaths each year in Ireland. Nearly half of these deaths are a result of Myocardial Infarction, or heart attack and 20% of those who survive are left with scar tissue that can ultimately lead to heart failure. Prof Noel Caplice and his team in University College Cork have recently managed to improve the outcome for these patients in a world first clinical trial. The researchers have discovered that Insulin-like growth factor 1 (IGF-1), a naturally occurring protein, can improve the integrity of the heart muscle cells that are deprived of oxygen following a blockage associated with heart attacks.
The heart is one of the hardest working organs in the body. Well before you are born the heart begins to beat and doesn’t stop until you take your last breath. It is responsible for pumping oxygenated blood around the body but has its own blood network that covers the surface of the heart, these vessels are known as coronary arteries. Certain lifestyle choices can cause a build-up of fatty deposits in these arteries resulting in narrowing and restricted blood flow. The complete blockage of a coronary artery can result in a heart attack. With blood flow completely blocked the heart muscle cells are deprived of oxygen. After 20 minutes without oxygen these cells will begin to die: where enough cells die, functional heart muscle is replaced with inactive scar tissue leading to long term strain on the remaining healthy muscle.
Prof Caplice and his team in University College Cork began looking at muscle damage from heart attack by determining whether stem cells could be used to help rebuild the damaged muscle. Throughout the course of their work they discovered that IGF-1, a protein secreted by the stem cells was ultimately responsible for the positive effects they observed. IGF-1 is a naturally occurring protein called a cytokine. It is produced by a variety of cells in the body and is helpful in preventing cell death, encouraging the enlargement of healthy heart cells at sites of damage and encouraging the spread of new blood vessels.
In a world first clinical trial, 47 patients who had suffered large heart attacks were recruited. The patients were treated with 12 hours of the heart attack, this involved having an artery opened and stented. They were then injected with IGF1, within half an hour of the surgery. Patients received two different, low-dose preparations of IGF1, or a placebo and were closely monitored. Those that received the higher dose of IGF-1 showed an improvement in the remodelling of the heart tissue after 8 weeks. The next step for the study is to run a much larger clinical trial involving multiple centres and thousands of patients worldwide.