One approach is to take cells from the patient, introduce the therapeutic genes into them and reinject the treated cells back into the patient. The other approach is to inject the payload-carrying vehicle directly into patients. BPEC researchers hope to find ways to facilitate both approaches. The best delivery vehicle researchers have found so far are retroviruses, which normally infect cells by copying parts of their DNA into the genetic code of the host cell. By removing harmful parts of the retrovirus and replacing them with therapeutic genes, researchers tried to design ways to treat diseases like cystic fibrosis or cancer.
Retroviruses also can set off the human immune response, causing inflammation in patients.
At BPEC, researchers plan to work around this problem by using stem cells as gene delivery vehicles. Stem cells are attractive targets for gene delivery because these cells can make more of themselves and give rise to a set of differentiated cells. The most accessible stem cells are in the bone marrow, where they give rise to blood-forming cells, but stem cells also exist in liver, skin, muscle and bone. Researchers say that if stem cells could be engineered to carry therapeutic genes, they might be able to repopulate diseased cells with a continuous supply of normal cells. However, researchers have to solve some technical problems before this becomes a possibility.