A team from the University of California, San Francisco, devised a new electroporation-based CRISPR-Cas9 method, eliminating viruses from the gene editing process and laying the groundwork for safer, more precise and more efficient editing for CAR-T cancer treatments and other cell therapies.
The researchers believe the approach could address the shortcomings of virus-based editing, a time-consuming process that inserts genes into the T-cell genome with limited predictability. Producing viruses for cell therapies—such as lentiviruses for CAR-Ts—can take as long as a year, which slows down research and increases the time a patient must wait before receiving treatment, they said in a statement.
But a major barrier to the nonviral editing of T cells has been the toxicity of the DNA sequences to be inserted into the target genome. The researchers found that using electroporation—a process that makes cell membranes temporarily more permeable—reduced toxicity, allowing them to cut and paste specific sequences precisely at the site of a CRISPR-programmed cut in the genome.
Along with colleagues from UCLA’s Parker Institute for Cancer Immunotherapy, the team used the method to replace a native receptor in human T cells with a new receptor engineered to hunt down a specific subtype of melanoma cells. The modified T cells targeted and attacked melanoma cells in a lab dish while leaving other types of cells unharmed.