Alpha-thalassemia, a form of blood diseases caused by deletions in the α-globin gene cluster, is a candidate for stem cell based gene therapy combined with cell replacement therapy. This is because the mutant genes are well-known and scientists have the ability to produce certain blood cells from stem cells in the lab. Now, Dr. Eric Bouhassira, Ph.D., and graduate student Chan-Jung Chang, at the Albert Einstein College of Medicine, report in Blood the introduction of functional α-globin genes into induced pluripotent stem cells (iPSCs) from α-thalassemia patients. When differentiated into erythroblasts (immature red blood cells), α-globin expression was detected at near physiological levels. Dr. Bouhassira’s approach used zinc finger nucleases (ZFNs) to target a “safe harbor” site in the human genome that allows robust expression of the α-globin genes with minimal affects on other nearby genes. This approach may be broadly applicable in the future, as a single set of ZFNs could be validated to insert functional genes for a wide variety of diseases. However, iPSCs and other pluripotent stem cells do not yet yield transplantable blood cells. This research was supported by NYSTEM individual and shared facility awards to Dr. Bouhassira (C024405 and C024172).
Chang CJ, Bouhassira, EE. Zinc-finger nuclease mediated correction of α-thalassemia in iPS cells. Blood. 2012 Sep 21. (Epub ahead of print).