Pulmonary hypertension is a serious, often fatal disease that causes the lung's delicate blood vessels to become smaller and disappear.

Eventually, the heart has to work so hard that many patients die of heart failure.

Now, Canadian doctors are using gene therapy to heal the damaged vessels.

Junne Page is the first patient to get the therapy. She lived a healthy life until seven years ago.

"I had been short of breath," she said. "I thought it was due to a medication I was taking."

It turned out to be pulmonary hypertension -- an often fatal disease.

"Most commonly, the disease is rapidly progressive such that the survival is only about 50 percent at three years if left untreated," said Michael Kutryk, cardiologist.

Pulmonary hypertension constricts the lung's blood vessels, making it tough for the heart to get oxygen-rich blood to the lungs.

"And there are no therapies or treatments now that are designed to replace those blood vessels," Kutryk said.

Given that dim prognosis, he is excited about a new gene therapy.

"We're hoping that we can slow down the progression, halt the progression and in fact, we feel confident that we may be able to reverse the disease in most incidents," he said.

In the first ever trial of a gene-cell therapy for cardiovascular disease, doctors take cells from the patient's blood and grow them in the lab. The cells are altered with a gene that promotes healing and then injected back into the patient.

"We're certainly seeing positive results at the moment, but we expect to see much better results as we increase the doses," Kutryk said.

Junne's disease is stable, and her spirits are up.

"It's giving me hope that things are going ahead and they are doing things that are working and they're working on it ... and there is promise."

Junne says she's happy to be holding her own.

Kutryk says the therapy could pave the way for a new approach to treat heart, lung and kidney failure.

The therapy is currently under study in Toronto and Montréal.