Toronto researchers say they have developed a promising new experimental gene and cell therapy for a rare, devastating cardiovascular disease that predominantly affects young women.

It's the first therapy of this kind in the world for a disease called pulmonary arterial hypertension (PAH) -- a condition in which the arteries that carry blood from the heart to the lungs become progressively blocked, weakening the heart until the patient eventually suffers severe cardiac arrest.

There are about 500 new cases each year in Canada, and no cure.

Although there are drug treatments available, the vast majority of patients will die within five years of diagnosis.

"In a nutshell, (the patients) don't have enough blood vessels in the lungs," lead researcher Dr. Duncan Stewart told CTV News.

"What has happened for reasons we don't fully understand is they've lost, particularly, the small, most fragile blood vessels."

Stewart and his team of researchers at Toronto's St. Michael's Hospital developed a way to inject genetically engineered, stem-like cells -- called endothelial progenitor cells (or EPCs) -- into the lungs.

EPCs are essentially adult stem cells which are created in the bone marrow and that circulate in our blood. Doctors then add a gene called eNOS, which produces nitric oxide (NO), a powerful vasodilator that plays a key role in the growth and repair of blood vessels.

Then, the genetically engineered EPC cells are injected through a vein in the neck and into the patient's heart, where they filter into the lungs. There, researchers believe they will trigger blood vessels to repair and regrow.

Animal studies suggest these souped-up cells boost the regenerative power by 10 to 100 times normal.

Since the cells come from the patient, they won't be rejected, which is why some consider it as potentially the ultimate form of self-healing.

"It's the first time that there's been any such therapy for this disease," said Stewart.

"This is a very difficult disease to manage, it belongs to what we call orphan diseases because it's not a very common disease -- therefore there hasn't been as much interest in terms of the private sector developing treatments."

Stewart says even a modest effect in a patient with pulmonary hypertension could have a dramatic impact on the blood pressure in the lungs.

His team calculates that about 75 to 80 per cent of the lung vessels are lost by the time someone develops symptoms of pulmonary hypertension.

"If we can even open up five per cent of the circulation that would have a huge effect on the lungs," said Stewart.

The first patient

Junne Page is the first patient with pulmonary hypertension in the world to test what could become a revolutionary treatment. A month ago, doctors gave her an injection of her own blood cells.

There's no sign yet if it is working, but Page said she is honoured to be part of this trial.

"I hope they will achieve something through this research that will help others if not me," she said.

"Someone's got to be the first and in a way I feel sort of privileged to be into this research because it is very exciting."

Early tests on animals have shown promising results, with evidence that Stewart's cell therapy stopped and actually reversed the progression of the disease.

Stewart's efforts have caught the attention of physicians around the world.

Dr. Robert Levy, head of the division of Respirology at St. Paul's Hospital in British Columbia, called Stewart's work "exciting and highly innovative."

It's a "great example of 'translational research' -- applying basic science discoveries in the clinical arena. And this for a devastating disease we have very few (and largely unsatisfactory) treatment options for," he told CTV News in an email.

Stewart's experiment is triggering excitement that his technique could be used to treat other forms of heart disease -- even cancer.

"The imagination begins to explode, which is I think the real exciting aspect of this," Dr. John Granton, head of the critical care medicine program at the University of Toronto, told CTV News.

Doctors plan to test the therapy on 18 patients over the next year-and-a-half, hoping that cells don't migrate to other parts of the body or that they don't trigger any unwanted side effects.

UPDATE: Patients interested in the trials can contact:

Nancy Camack, RN BScN MBA CCRP
Clinical Trials Officer,
Cell and Gene Therapy Research
Division of Cardiology
St. Michael's Hospital
30 Bond St. Room 3-007 Bond Wing
Toronto, Ont. M5B 1W8
416-864-6060 ext. 2857
416-864-5686 fax
camackn@smh.toronto.on.ca