Modified Stem Cells to be Used in Landmark Test on Lung Patients

Eighteen Canadians with debilitating lung disease will soon be asked to test a new medical marvel -- genetically engineered stem cells.

Researchers at the University of Toronto expect to begin the long-awaited project in March to test the cells as a treatment for an incurable and fatal lung condition called pulmonary arterial hypertension. The disease makes breathing difficult and exercise impossible.

The $2.5-million project, funded in part by the federal government and approved by Health Canada more than a year ago, is the first in the world to take "stem-like" cells from patients' blood, load them up with extra genes, and then return the cells to the body.

The hope is the cells will take up residence deep in the patients' lungs and stimulate growth of new blood vessels to help them breathe.

"What we're doing is not trivial," says Dr. Duncan Stewart, director of cardiology at the University of Toronto and chief scientific officer of the biotech firm Northern Therapeutics that is involved in the trial.

"We've never done it before. No one has ever done it before," he says, "so it has taken a bit longer than expected to get it running."

The project builds on recent advances in genetics and stem cells, potent cells found throughout the body that seem to be able to morph into different kinds of cells as needed. If successful, the experiment could pave the way for similar treatments to mend damaged hearts. Failure, however, would be another setback for gene therapy, which has been hobbled by the deadly side effects of experiments in Europe and U.S.

The Canadian project grows out of years of work that shows the genetically enhanced cells can do wonders for laboratory animals with lung and heart disease.

The plan for the upcoming trial is to harvest stem-like cells from the blood of 18 patients. Unlike stem cells from human embryos that can grow into any tissue in the body, these cells are limited in what they can do.

"The thing they do best is stimulate growth of new blood vessels," Dr. Stewart says. This makes them ideal for treating pulmonary arterial hypertension, which chokes off blood vessels in the lungs.

To enhance their regenerative capacity, the cells will be loaded up with hundreds of extra copies of a gene that produces a protein called endothelial nitrous oxide synthase, which stimulates blood-vessel growth.