BACKGROUND: Pulmonary hypertension is high blood pressure in the arteries leading to the lungs. There are treatments to help the symptoms of the disease, but there is no cure. In patients with pulmonary hypertension, the vessels that carry blood from the heart to the lungs become hard and narrow. That makes it harder for the heart to pump blood, and over time, the heart will weaken and may result in heart failure. Drugs, oxygen and even lung transplantation may be used to treat the disease.

Pulmonary hypertension is a relatively rare disease. In 2002, there were 15,668 deaths from the disease and 260,000 hospital visits among people with the disease. Between 2000 and 2002, there were 807,000 people hospitalized with pulmonary hypertension. Sixty-one percent of those hospitalizations were among women, and 34 percent were younger than age 65.

A BREAKTHROUGH TREATMENT: An innovative approach to treating pulmonary hypertension is making waves in the medical world. Doctors are combining gene and cell therapy to treat the condition. It's the first time that combined gene and cell therapy has ever been used to treat any heart or blood vessel disease.

HOW IT WORKS: Researchers from St. Michael's Hospital in Toronto are using adult stem-like cells called endothelial progenitor cells (EPC). In patients with pulmonary hypertension, the endothelial cells, which line the blood vessels of the lungs, are damaged. Michael Kutryk, M.D., from St. Michael's Hospital, says, "The one thing that all endothelial cells have in common is that they are replaced by circulating endothelial progenitor cells. We all have in our blood a very small proportion of cells that circulate freely in our blood that have the capacity to become healthy endothelial cells when they are in the right environment. We think that those cells are there to repair blood vessels that are damaged."

In the study, doctors are harvesting EPCs from a patient's blood. Those cells are then genetically altered by loading them with extra copies of a gene called endothelial nitric oxide synthase (eNOS). The gene eNOS plays a vital role in maintaining healthy blood vessels. After the cells are genetically modified and grown in the lab, doctors re-inject them into the patient. The hope is that the cells will then reverse the damage that has been done to the lung's blood vessels.

Dr. Kutryk says, "It's a very, very novel and first in the world application of this technology. This will be very exciting if we can halt the progression of the disease ... we're hoping we can, in fact, reverse the disease in many cases."

The study is still in the early phases with increasing doses being given to subsequent patients. Dr. Kutryk says, "We're certainly seeing positive results at the moment, but we expect to see much better results as we increase the doses of genetically modified cells."

The study is currently ongoing in Toronto and Montreal.