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The children are Sheila, an 18-month Palestinian, and a girl from Colombia. Bordignon and his colleagues removed some of the bone marrow from the pelvises of the two patients in the study. Next, they isolated the blood stem cells, which have the potential to develop into the body's various red and white blood cells. When researchers exposed the stem cells to an engineered virus carrying a healthy version of the ADA gene, the virus inserted the gene into the stem's cell's genome.
Before injecting the engineered stem cells into the patients, the science authors performed an additional step, which they believed would make their efforts more successful than previous efforts to treat SCID with gene therapy. Until now, Bordignon says, these efforts have not established enough healthy stem cells in the body for the results to last. This time around, a process called "non-myeloblative conditioning" may make the difference, according to the researchers.
"Non-myeloblative condition means you don't really wipe out the bone marrow, you just give one of the drugs used for a transplant, at a much lower dose to make space for engineered marrow to size, expand and grow better," Bordignon explained.
Within weeks of being injected into the patients, the engineered stem cells migrated to the bone marrow, and began spawning key types of immune cells, such as B cells, T cells and NK cells. Within months, antibodies appeared and the patients responded normally to small amounts of certain pathogens, such as the tetanus vaccine. One year later, one of the patients no longer had the respiratory infections, chronic diarrhoea or scabies that were common before the therapy.
Teacher: Michael
Many articles taken from 'A word with the doctor', by Dr. John Windsor.
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