Anemia, Author Interviews, Genetic Research, Hematology / 27.10.2016
Minimally Invasive Gene Editing Cured Thalassemia in Mice
MedicalResearch.com Interview with:
Peter M. Glazer, MD, PhD
Robert E. Hunter Professor of Therapeutic Radiology and Professor of Genetics; Chair, Department of Therapeutic Radiology
Yale University
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: It is generally recognized that gene editing in blood stem cells could provide a strategy for treatment of inherited disorders such as sickle cell disease and thalassaemia. Recent excitement has focused on CRISPR/Cas9 technology because of it is so easy to use. However, the CRISPR approach introduces an active DNA cutting enzyme into cells, which can lead to off-target cuts in the genome. As an alternative, we have pursued triplex-forming peptide nucleic acids (PNAs) designed to bind site-specifically to genomic DNA via strand invasion and formation of PNA/DNA/PNA triplexes. PNAs consist of a charge-neutral peptide-like backbone and nucleobases enabling hybridization with DNA with high affinity. PNA/DNA/PNA triplexes recruit the cell’s own DNA repair machinery to initiate site-specific editing of the genome when single-stranded ‘donor DNAs’ are co-delivered as templates containing the desired sequence modification.
We found that triplex-forming PNAs substituted at the gamma position yielded high levels of gene editing in blood stem cells in a mouse model of human β-thalassaemia. Injection of thalassemic mice with nanoparticles containing gamma PNAs and donor DNAs ameliorated the disease phenotype, with sustained elevation of blood hemoglobin levels into the normal range and up to 7% β-globin gene correction in stem cells, with extremely low off-target effects. We conclude that the combination of nanoparticle delivery and next generation PNAs may offer a minimally invasive treatment for genetic disorders of the blood that can be achieved safely and simply by intravenous administration.
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