Hans Clevers, a group of researchers from the Hubrecht Institute, corrected cystic fibrosis-causing mutations in cultured human stem cell cultures. They used prime editing, a method that replaces the damaged DNA fragment with a healthy one. This was done in collaboration with Oncode Institute and UMC Utrecht. This study was published in Life Science Alliance, August 9th. It shows that prime editing is safer and more secure than the CRISPR/Cas9 method. "We have demonstrated for the first-time that this technique works, and can safely be applied to human stem cells in order to correct cystic Fibrosis.Cystic Fibrosis (CF), one of the most common genetic diseases in the world, can have serious consequences for patients. Mucus buildup in the lungs, throat, and intestines can cause obstructions. While there are treatments that can dilute the mucus or prevent inflammations, CF cannot be curable. A new study by Hans Clevers (Hubrecht Institute), in collaboration with UMC Utrecht, and Oncode Institute provides hope.Correcting CF mutationsResearchers were able to correct the mutations that lead to CF in human intestinal organoids. These organoids are also known as mini-organs and mimic the function of the intestinal tract in patients with CF. These organoids were created from stem cells taken from patients with CF. They were stored in a Utrecht biobank. Prime editing, a method that replaces mutated DNA which causes CF, was used in the study published in Life Science Alliance.Safer than CRISPR/Cas9Prime editing is a more recent version of CRISPR/Cas9. CRISPR/Cas9 corrects the DNA by cutting it. While this fixes the DNA mutation, it can also cause damage to other parts of the genome. Prime editing is safer than CRISPR/Cas9, according to our study. It can add a new piece to the DNA, without causing any damage. This makes the technique attractive for patients," Maarten Geurts (first author of the publication) said.SwellingThe mutations that cause CF are found in the CFTR channel. This channel is found in cells of many organs, including the lungs. The mutations cause the channel to malfunction, resulting in a layer of mucus covering the cells that is too watery. Mucus becomes sticky. Healthy organoids will swell when they are given forskolin. However, this is not the case in organoids that have mutations in CFTR channel. We applied prime editing to the mutations and the treated organoids showed the same response as healthy organoids: they became swelling. Geurts explained that this provided proof that our method worked and the mutated DNA was replaced.Curing genetic diseasesThe researchers have shown that mutations that cause CF are safe to correct, which means that applications for the clinic are now possible. "New CRISPR/Cas9 variants, such as prime editing can correct mutations safely without causing damage to other areas of the DNA. This will allow us to prevent or cure genetic diseases. However, there are still many challenges for researchers. For example, the technique still needs to be safe for humans. Geurts says that this is a significant step in the direction of successfully applying prime editing to the clinic.Hans Clevers is the group leader at the Hubrecht Institute for Developmental Biology & Stem Cell Research as well as at the Princess Mxima Center for Pediatric Oncology. Clevers is also a University Professor at Utrecht University, and an Oncode Investigator.
