NEWS
HEALTH & WELLBEING Self-repairing heart ANTHONY KING
In a world first, researchers have successfully induced pig hearts to self-repair themselves after damage. Pig hearts that had undergone myocardial infarction or heart attack underwent gene therapy to make the cardiac muscle cells proliferate – a capability generally lost a few days after birth. ‘The cells that we are born with are
more or less the same as those with us when we die, even 80 years later,’ says Mauro Giacca at King’s College London, UK. Pig hearts are very similar to human hearts. Cardiac muscle cells rarely duplicate and proliferate thereafter, leaving the heart with little chance of recovery after a heart attack. In an attempt to restore this lost
capability, Giacca and his team injected the damaged pig cardiac muscle with a virus carrying a gene that instructed heart cells to make a short strand of RNA (Nature, doi:10.1038/ s41586-019-1191-6). ‘In those pigs treated with microRNA, instead of forming scar tissue, they repaired the infarction through the formation of new cardiac muscles,’ Giacca explains. After one month, the damaged heart started functioning as if nothing had happened. ‘This is the first demonstration in a large animal that you
can achieve cardiac regeneration,’ says Giacca, adding that there have been numerous less successful attempts to use stem cells.
HEALTH & WELLBEING Glucosamine and heart health MARIA BURKE
Using glucosamine supplements regularly may be linked to a lower risk of developing cardiovascular disease (CVD). Researchers led by Lu Qi at Tulane University in New Orleans, US, drew on data from the UK Biobank, a large population-based study of more than half a million British people (BMJ, doi:
https://doi.org/10.1136/ bmj.l1628).
Their analysis included 466,039 participants without CVD, who completed a questionnaire on supplement use, including glucosamine, a popular dietary supplement believed by some to relieve osteoarthritis
and joint pain. Almost one in five participants reported glucosamine use. Death certificates and hospital
records were then used to monitor CVD events, including death from CVD, coronary heart disease (CHD) and stroke, over an average period of seven years. The researchers found that glucosamine use was associated with a 15% lower risk of total CVD events, and a 9-22% lower risk of CHD, stroke and CVD death. The association was even stronger in smokers – 37% lower risk – compared with people who had never smoked, 12%, and former smokers, 18%. The team took into account risk factors, such as age, sex, weight, ethnicity,
lifestyle, diet, medication and other supplement use. The authors say regular use
of glucosamine has been linked to lower levels of a chemical associated with inflammation called C-reactive protein (CRP). This would explain the stronger association among smokers, they say, who have higher levels of inflammation and higher risk of CVD than non-smokers. Furthermore, previous data suggest glucosamine may mimic a low carbohydrate diet, which has been linked with lower risk of CVD. However, the team acknowl-
edges that, despite the large sam- ple size, the study is observational only and can’t establish cause.
They also admit to certain limita- tions, such as lack of information on dose, duration, and side- effects of glucosamine use. Sonya Babu-Narayan is
associate medical director at the British Heart Foundation: ‘We don’t know whether people who took glucosamine were less likely to develop CVD because of the glucosamine itself, or if other factors were at play. For example, people who take glucosamine might be more likely to look after their health in general. Ultimately, controlled clinical trials will be needed to uncover whether glucosamine is beneficial in preventing heart and circulatory diseases.’
MicroRNAs work as control switches for other genes. Giacca,
with colleagues in Italy and the UK, screened hundreds of microRNAs to see which ones could push cardiac muscle cells into proliferating. They found eight candidates, including one – miR-199a – which they selected to inject into the damaged pig hearts.
However, the downside to introducing the gene is that it keeps churning out microRNA, which eventually led to the death of most of the treated pigs through heart failure. Work in mice suggests that synthetic
strands of the microRNA, just 23 nucleotides long, could be delivered to heart muscle using lipid nanoparticles. ‘One single injection was enough to stimulate regeneration [in the mice],’ says Giacca. The microRNAs then hang around for only about 10 days, whereupon the proliferative effects end. ‘The results are somewhat surprising in that it appears a single agent is able to effect a result that has for so long eluded scientists,’ comments cardiologist Shin Lin at the University of Washington, Seattle. However, ‘these findings could prove ultimately to be irrelevant clinically for practical, non-scientific reasons. For example, I wonder whether this treatment works in end stage heart failure long after infarction. This aspect could greatly affect how many patients this treatment can ultimately benefit,’ Lin adds.
10 06 | 2019
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