Gene therapy for bubble babies

Immunodeficiency of the bubble babies can be treated by gene therapy

25/08/2011

Gene therapy can be used to detect the extremely rare immunodeficiency SCID („severe combined immunodeficiency“) in so-called „Bubble babies“ may be fixed. Bobby Gaspar and Adrian Thrasher from University College London (UCL) report in the latest issue of the journal „Science Translational Medicine“ from two studies in which several children suffering from the extremely rare disease of the immune system were able to live relatively symptom-free for at least nine years with the help of experimental gene therapies.

SCID patients suffer from, among other things, a malfunction or a deficiency of T lymphocytes, which causes a significant weakening of the immune system, the UCL scientists report. The disease is caused by a congenital genetic defect and has the effect of almost completely eliminating the immune system of those affected, making them extremely susceptible to any form of infection. For their own protection, patients are therefore already isolated in childhood in a sterile bladder, hence the name „Bubble baby“ stir. Without medical care, SCID disease usually leads to death within a few months, according to the British researchers. Typical signs of SCID include developmental and growth delays, recurrent infections, especially in the respiratory tract (pneumonia) and chronic diarrhea.

In their recent publication, Bobby Gaspar and Adrian Thrasher report two studies that assess the disease progression at 16 „Bubble babies“ studied during experimental gene therapy. To correct the immune deficiency, the researchers took blood-forming stem cells from the child's bone marrow and inserted intact genes into the cells. The genetically modified stem cells were then replanted to patients between four months and four years old, hoping to correct the immune system disorders. According to UCL researchers, the novel treatment method has been successful in 13 of the 16 children. Although their immune system did not reach normal levels of performance, susceptibility to infections was significantly reduced and patients were able to lead a relatively symptom-free life, the British scientists report. The children no longer had to live in a sterile bladder, could attend a normal school and enjoy their everyday life with their friends, according to Bobby Gaspar and Adrian Thrasher. In two of the 16 study participants, however, the novel treatment had to be discontinued for technical reasons and today they receive an artificially administered enzyme that lacked their immune system to stabilize their health status, the researchers report in the journal „Science Translational Medicine“.

One of the children, according to the scientists in the gene therapy treatment developed a leukemia (blood cancer), which is to be regarded as a serious contraindication. Similar difficulties have already emerged in gene therapy treatment trials in France and are in the novel process, apparently a generally not to be underestimated risk, so the statement of study authors in their recent publication. The child affected by the current studies was promptly given chemotherapy to stop the growth of cancer cells. Despite the risk of leukemia, research in the treatment of SCID places great hope in gene therapy. Thus, according to the presentation in the comments on the current studies, it is already being used in France, Italy and the USA. Not only is it possible to transplant genetically modified blood-forming stem cells from patients' own bone marrow, but the stem cells of a donor can also be used, according to the UCL scientists. However, according to the experts, this may not be completely unproblematic, as there is a risk that the body will reject the foreign cells. A use of the body's own stem cells would bring significant benefits here, according to the assessment of Bobby Gaspar and Adrian Thrasher. (Fp)

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Image: Gabi Schoenemann