Using a patient's own stem cells in a non-invasive procedure may help relieve chest pain caused by angina, research suggests.
The study found that taking a patient's bone marrow stem cells helped relieve symptoms but also boosted how long people could stay fit and active.
Experts hope the finding may help people with difficult-to-control angina who are not suitable for other procedures.
Angina is a common condition among older adults and affects an estimated one in every 12 men and one in every 30 women aged 55 to 64 in England.
This figure rises to one in every seven men and one in every 12 women who are over 65.
Angina occurs when the blood supply to the muscles of the heart is restricted, usually because the arteries have become hardened and narrowed.
The pain feels like a dull, heavy or tight pain in the chest that can spread to the left arm, neck, jaw or back.
It is usually triggered by exercise, walking or stress and the pain usually passes within a few minutes.
The new early-stage research on 15 patients was presented at the American Heart Association's heart sciences meeting.
The patients were injected with a molecule called granulocyte colony stimulating factor (G-CSF) once a day for four days.
G-CSF works by making stem cells migrate into the bloodstream from the bone marrow. Three hours after the last injection, patients had blood taken and the stem cells were separated from other blood components.
Half an hour after the stem cells had been separated, they were injected back into the patient intravenously.
The scientists behind the study said that four weeks after receiving the treatment, patients had significantly fewer angina symptoms and were able to exercise at a higher intensity and for a longer period of time.
Most patients did report mild muscle pains in their backs or legs, but this was controlled with painkillers.
Hadyanto Lim, professor of pharmacology at the Methodist University of Indonesia in Medan, North Sumatra, said: "We injected a 'catalyst' molecule that caused bone marrow stem cells to enter the patient's blood, then harvested them to re-inject into the patient. This is not considered a surgical procedure, is easy to implement, and allows for repeated administrations.
"Using G-CSF to isolate CD34-harbouring stem cells, called CD34+ stem cells, for transplantation back into the patient may be a practical alternative for hard-to-treat patients. The stem cells cause new blood vessels to grow which can improve blood circulation and may help repair the lining of the blood vessels."
