Image by Tom Ellenberger
Researchers say they have discovered a more efficient way to edit the genomes of hematopoietic stem and progenitor cells (HSPCs).
The approach involves adeno-associated virus (AAV) serotype 6 and zinc finger nuclease (ZFN) messenger RNA (mRNA).
Combining these delivery techniques allowed the team to “achieve high levels of precise genome editing” in HSPCs, including the most primitive cell population.
Paula Cannon, PhD, of the University of Southern California in Los Angeles, and her colleagues described this work in Nature Biotechnology.
The researchers have been using ZFNs to cut a cell’s DNA at a precise location or sequence. The cell normally uses a copy of the cut DNA sequence as a template to repair the DNA break.
During this process, there is the opportunity to introduce new DNA sequences or to repair mutations, effectively fooling the cell into making a genetic edit.
To provide the cell with both the targeted nuclease and the new DNA template, researchers can use a variety of delivery vehicles or vectors, including viruses and mRNA.
With this study, Dr Cannon and her colleagues found they could deliver the DNA repair template using AAV6, which can naturally enter HSPCs.
At the same time, they found that delivering the ZFNs as short-lived mRNA molecules allowed the DNA cutting and repair process to occur without disrupting the HSPCs.
By combining these delivery methods, the researchers were able to insert a gene at a precise site in even the most primitive human HSPCs, with efficiency rates ranging from 17% to 43%.
The team then transplanted these edited HSPCs into immune-deficient mice and found the cells thrived and differentiated into many different blood cell types, all of which retained the edits to their DNA.
“Our results provide a strategy for broadening the application of genome editing technologies in HSPCs,” said study author Michael C. Holmes, PhD, vice president of research at Sangamo BioSciences in Richmond, California.
“This significantly advances our progress towards applying genome editing to the treatment of human diseases of the blood and immune systems.”
