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A new trial therapy, called autologous cellular heart transplant, is being carried out at National Heart Centre Singapore (NHCS). It involves using a patient’s own stem cells rather than from a donor to help heal weakened hearts.
The therapy is not for those with chronic heart failure but specifically for those with weak hearts after a heart attack.
It cannot replace whole heart transplant for patients with chronic heart failure, but it could be another bridging option while patients wait for a transplant.
The 10-patient trial in Singapore is part of a larger international experiment to test the safety of the therapy.
The trial is also underway in the UK and France, and limited to patients who, despite primary angioplasty (emergency stenting of blocked arteries) after a heart attack, still have poor heart function.
NHCS is the first specialised cardiac centre in Asia-Pacific to run the trial, and was selected because of its experience and technical expertise in primary angioplasty and working with stem cells. The centre is working with French biotechnological firm CellProthera, which harvests and processes the stem cells of patients.
Why a patient’s own stem cells?
Associate Professor Philip Wong, Senior Consultant, Department of Cardiology, NHCS, who is the principal investigator in the trial, said of the 300 or so heart attack patients that NHCS treats every year, 30 per cent develop heart failure or weakened hearts that never return to normal.
“The heart is like a balloon. Once it is stretched and this becomes chronic, it loses its ability to contract and cannot go back to its original form. Heart failure is hard to reverse even with conventional medical treatment. About half of the patients with advanced stage heart failure do not survive beyond five years.”
He said that many types of stem cells, including muscle stem cells from other patients, have been used for weakened hearts in the last 10 to 20 years, but they have not been very effective in patients with longstanding heart failure.
“So, the thinking has moved to new therapies such as replacing dying heart cells in the acute phase of damage with the patient’s own stem cells. The advantage here is that there is no need to give the patient any immune-suppression therapy, which has its own set of issues.
“This exciting field of ‘self-repair’ holds promise for the heart, and removes a major stumbling block of having to give immune-suppression therapy over the long term,” he added.
Dr Wong said there is greater potential for this therapy to work on the heart because it is more amenable to receiving cell transplants, compared to other organs such as the liver or brain.
“The liver is a complex, static organ with many cell types. And brain cells have a very short lifespan – it only takes a few minutes before they die – compared to heart cells,” he said.
“The heart is made up of many of the same type of beating cells grouped together. If we replace these cells, or boost their contracta bility, there may be a chance it could improve the function of the heart, or at least prevent further deterioration.”
Research shows that heart cells under duress, for example in a heart attack, can “hibernate” with a lower metabolic rate and go into a deep sleep. “They are not functioning but still alive, and if the environment is corrected, these cells can potentially recover.”
It will take three to five years to find out if the new treatment is effective. “If it is, autologous stem cell therapy may one day become the standard of care for some of these patients.”
How it works
The procedure starts after primary angioplasty – the standard of care for patients with a heart attack. The surgeon inserts a coronary stent in the blocked heart artery through a special catheter, and inflates it to widen blocked areas and improve blood flow to the heart.
If the heart function test shows the heart is still weak after the procedure, the patient may be recruited for the trial’s stem cell therapy. The entire therapy takes around two weeks and is as follows:
1. The patient who is recruited for the trial will be given injections for five days to boost his supply of stem cells. Everyone has stem cells made in his bone marrow, but these injections help to increase stem cell production.
2. After this, 200cc of blood will be taken from the patient.
3. The blood is sent to CellProthera, which processes and harvests pure stem cells from the blood. This takes three to four days.
4. Using a special device, these pure stem cells are injected directly around the area where the heart attack occurred.
5. It is a minimally invasive procedure done under local anaesthesia. The patient gets 10 to 20 injections, each containing one to 10 million stem cells.
6. These “helper cells” may be able to produce hormones and other nutrients that the heart needs to repair damage from the heart attack.
Dr Philip Wong says the heart is more responsive to this therapy compared with other organs.