Photo by Hope on the Horizon for Cystic Fibrosis Sufferers
Cystic fibrosis, a devastating genetic disorder, has long plagued millions of people worldwide. However, a recent breakthrough in gene-editing technology has brought new hope to those afflicted. Researchers in the U.S. have successfully used prime editing to correct the most common mutation that causes the disease in human lung cells.
The mutation, known as F508del, is responsible for the malfunctioning or complete absence of the CFTR protein, which regulates the flow of salt and water in and out of cells. This malfunction leads to the buildup of thick mucus in various organs, causing respiratory problems and other complications.
A one-time, permanent treatment for cystic fibrosis might be within reach.
– David Liu, PhD
The researchers, led by David Liu, PhD, director of the Merkin Institute of Transformative Technologies in Healthcare at the Broad Institute, optimized prime editing to selectively correct the F508del mutation in cells that line the airways. This achievement marks a significant milestone in the development of a potential cure for cystic fibrosis.
The corrective edit persists through cellular proliferation and differentiation.
The team applied six optimizations to enhance prime editing’s efficacy, including improving the RNA molecule that guides the DNA-editing enzyme to its proper location in the genome. In addition, the editing enzyme itself was modified, and the target site was made more accessible.
Before optimization, prime editing corrected the F508del mutation in less than 0.5% of lung cells. After applying the six enhancements, 58% of cells were edited – a 140 times improvement.
In airway cells isolated from three cystic fibrosis patients with F508del, the mean F508del correction rate across all treated cells was 25% – a 59 times improvement with optimization.
The proportion of corrected cells remained constant over the three-week ALI growth period.
To test their functional abilities, edited cells were grown in an air-liquid interface (ALI) that modeled human airways. The team confirmed that the proportion of corrected cells remained constant over the three-week ALI growth period, demonstrating the corrective edit persists through cellular proliferation and differentiation.
CFTR protein was then stimulated, and the flow of salt was measured. Compared to unedited cystic fibrosis cells, stimulation substantially increased the flow of salt in prime-edited cystic fibrosis cells to levels exceeding 50% of those found in healthy non-cystic fibrosis airway cells.
This breakthrough has far-reaching implications for the treatment of cystic fibrosis and potentially other genetic diseases. As Liu noted, ‘Developing a strategy to efficiently correct this challenging mutation also provided a blueprint for optimizing prime editing to precisely correct other mutations that cause devastating disorders.’
A one-time, permanent treatment for cystic fibrosis might be within reach.
