In the study, a team led by Juan Carlos Izpisúa Belmonte, of the Salk Institute in La Jolla, California, extracted cells from six patients with a rare genetic disease called Fanconi anemia. This recessive genetic disorder, which causes bone marrow failure, luekemia and other cancers, is often fatal unless the patient is able to undergo a bone marrow transplant from a perfectly matched donor.
To correct the gene that causes the disease, the researchers infected the extracted cells with a genetically modified virus, which were then reprogrammed into an embryo-like state to create induced pluripotent stem cells (IPS cells). When the IPS cells were grown in culture, they developed into the type of blood progenitor cells that are required for transplant in therapies used with Fanconi anemia patients. Because the IPS cells had been corrected, they no longer had the genetic defect that causes the disease - yet were genetically identical to the patient's own tissue and should be able to be transplanted without the risk of rejection by the body's immune system. Their work was recently published online in the journal, Nature.
"We haven't cured a human being, but we have cured a cell. In theory we could transplant it into a human and cure the disease," says Professor Belmonte, who notes that their work has taken more than two years already. "In principle, our approach could be used with any disease that could be corrected by gene therapy and where there is loss or alteration of a specific cell type," he adds.
Additional work needs to be done to improve the technology in order to produce cells that can be safely transplanted into patients. As Chris Mathew, a molecular geneticist at King's College London, writes in a statement: "The current reprogramming and gene therapy techniques - which both involve introducing foreign DNA with potentially cancer-causing viruses - are not suitable for therapeutic application, but researchers are working on developing safer reprogramming methods."
News Release: Patched-up human cells� � www.the-scientist.com� May 31, 2009News Release: Stem cells without genetic defects heralded as breakthrough
www.timesonline.co.uk � June 1, 2009