Stem cells are identified as real culprit behind heart attacks after case of mistaken identity that could revolutionise treatmentsScientists previously thought heart attacks and strokes were caused by smooth muscle cellsStem cells multiply and caused arteries to hardenHeart attacks affect 90,000 and strokes 150,000 in Britain every year

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UPDATED:

16:17 GMT, 6 June 2012

The real culprit behind heart attacks and strokes is stem cells, researchers have claimed in a landmark study that could revolutionise treatment.

Until now, scientists thought vascular health problems were triggered by smooth muscle cells.

Now a team from the University of California in Berkeley have found a previously unknown stem cell, which causes the arteries to harden when it multiplies.

Real hope: The cells can multiply and cause arteries to harden, blocking the blood's route to the heart or brain

Real hope: The cells can multiply and cause arteries to harden, blocking the blood's route to the heart or brain

The groundbreaking work is set to completely change how heart attacks and strokes are treated, dramatically cutting the number of deaths, according the study published today in the journal Nature Communications.

Heart attacks are the most common reason for people to need emergency treatment. Around 90,000 people in Britain have one each year – of whom around a third will die as a result.

More than 150,000 people a year have a stroke and it is the third largest cause of death after heart disease and cancer.

Strokes occur when the blood supply to part of the brain is cut off, while heart attacks happen when the supply of blood to the heart is blocked, usually by a blood clot.

Landmark moment: The discovery of the new type of stem cell could dramatically cut the number of deaths from strokes and heart attacks

Landmark moment: The discovery of the new type of stem cell could dramatically cut the number of deaths from strokes and heart attacks

'For the first time, we are showing
evidence that vascular diseases are actually a kind of stem cell
disease,' said Professor Song Li, from the university.

HOW STEM CELLS HARDEN ARTERIES

The build-up of artery-blocking plaque
results from the body’s immune response to vessel damage.

Vessel damage is caused by
low-density lipoproteins – the 'bad' cholesterol many people try to
eliminate from their diets.

It attracts white blood cells,
causing the formation of fibrous scar tissue, which narrows the blood flow.

The scar tissue has certain characteristics of
smooth muscle, the main type of tissue found in the blood vessel wall, but it is actually dormant stem cells that are activated and multiply.

'This work should revolutionise
therapies for vascular diseases because we now know that stem cells
rather than smooth muscle cells are the correct therapeutic target.'

'This is groundbreaking and provocative work, as it challenges existing dogma,' added his colleague Dr Deepak Srivastava.

The newly discovered vascular stem cells
are multipotent – or capable of changing into various cell types, including smooth muscle, nerve, cartilage, bone and fat
cells – explaining why previous studies misidentified the cells involved
in vessel clogs.

'In the later stages of vascular
disease, the soft vessels become hardened and more brittle,' said
Professor Li.

'Previously, there was controversy about how soft tissue
would become hard. The ability of stem cells to form bone or cartilage
could explain this calcification of the blood vessels.'