Researchers at Northwestern University, Chicago, USA, have
reported that the injection of stem cells into heart tissue can significantly
improve the symptoms of people with severe angina. They found that exercise
tolerance was increased and the number of pain episodes was halved compared to
those not given the injections.
The new multi-centre study, published in the journal
Circulation Research, investigated the safety and clinical benefit of using a
patient's own CD34+ stem cells as a treatment.
CD34+ stem cells circulate in the blood and have previously been shown
to be able to create new blood vessels and improve function in diseased heart
Angina affects around 250,000 people in
the UK and can make even very light exercise difficult. The chest pains, usually associated
with heart disease, occur when there is not enough oxygen in the
blood. Normal therapeutic measures include lifestyle changes, medication and
surgery, but for some patients these treatments fail, leaving limited options.
Researchers took 167 patients with 'refraction' angina, which
is unresponsive to treatment, and separated them into three groups. All
patients were given a growth stimulation drug to increase the numbers of
circulating stem cells, before these cells were extracted and purified. Each
group then received either a low dose stem cell infusion, a high dose or a
After six months, patients in the low dose group showed a
significantly reduced number of painful angina episodes during an average week -
around six, compared to 11 in those given the placebo. The amount of exercise
tolerated in patients also significantly increased in the low-dose group, at 139
seconds compared to 69 seconds in the control group. A similar improvement was
seen in the high-dose group, but the team found no real advantage in receiving the
high dose over the low dose.
Dr Douglas Losordo, the lead author of the study, said: 'While
we need to validate these results in phase 3 studies before definitive
conclusions can be drawn, we believe this is an important milestone in
considering whether the body's own stem cells may one day be used to treat
chronic cardiovascular conditions'.
He continued: 'One exciting potential of this procedure is
that it will offer these folks an opportunity to get part of their lives back',
adding that it could make the difference between being able to walk slowly and
being able to ride a bike.
However, owing to the lack of research into the long term
benefits of the treatment, and poorly understood underlying mechanisms,
Professor Jeremy Pearson from the British Heart Foundation remained cautious: 'Until
these uncertainties are resolved, it remains unclear how successful this
treatment will prove to be'.