A naturally occurring protein that protects heart cells against damage after a heart attack has been discovered, BBC News has reported. The protein, called nerve growth factor (NGF), was “thought to act only on nerve cells in the body, but mounting evidence suggests it acts on heart muscle cells too”, the website said. BBC News reported that the authors of the study are hopeful that the treatment would also benefit humans; the main author of the study is quoted as saying "This is the first time that a pro-survival effect of NGF in the heart has been found.”
During a heart attack, cells are deprived of oxygen, and this causes damage or cell death and can lead to heart failure. The story is based on research carried out in rats which shows that NGF can prevent damage to cells after a heart attack. This is a promising and exciting development, but, as always, it is important not to assume that results in animals will be the same when applied to humans. Further animal studies and, eventually, human studies will need to be completed before any potential benefits of this treatment are realised.
Dr Andrea Caporali from the Bristol Heart Institute and colleagues from the Pathology Department at the University of Palma in Italy carried out this research. The study was supported by the British Heart Foundation and was published in the (peer-reviewed) medical journal: Cell Death and Differentiation.
This was a nine-part "proof of concept" study that aimed to show that the idea of injecting the gene for nerve growth factor (NGF) into the hearts of rats having a heart attack to stop the cells dying off was worth doing more research on. The researchers showed changes in several parts of the pathway and suggested ways in NGF might improve the survival of heart cells.
First, the researchers confirmed that the protein NGF was produced by newborn rat heart cells and demonstrated that there was a receptor for this protein on the surface of the cells.
In four subsequent parts to the experiment, they looked at the signalling mechanism in these newborn rat heart cells. The researchers investigated the idea that three of the proteins, which usually stimulate cell death, could be prevented from doing so by the addition of the protein NGF. This was shown to be successful and confirmed the researchers’ idea that NGF can control heart cell survival.
Other parts of the study looked at the same pathway in adult heart cells and at an “animal model” of heart disease. In this animal model, a heart attack was induced in an adult rat by tying off the arteries supplying oxygen to the heart. The damaged heart muscle was injected either with the NGF gene carried by a virus or with an inert control. After seven days, the heart muscle was examined under the microscope and the researchers were able to show that there was less cell death in the hearts of those rats who had been injected with the NGF gene.
The researchers discussed the fact that despite the assumption that nerve growth factors may only act in nerves, they have been shown, over the last 10 years, to be active in heart muscle too. They claim that in this study they are reporting for the first time that: “NGF possess a direct antiapoptotic effect (an effect reducing cell death) on the cardiomyocyte (heart muscle cell)” and they suggest the underlying mechanism.
This is a major piece of work that helps to improve scientists’ understanding of the mechanisms behind cell death. The value of this for the development of human treatments and the possibility that NGF (or a derivative) may turn out to be a cure or effective treatment for heart disease is a long way in the future. As with all animal studies, much further research is needed before the technique can even be considered for use in humans.
However, as the authors acknowledge, this piece of work is also important for encouraging further research aimed at unravelling the actions of nerve growth factors on heart cells.