The gene, SFTPC, is present in humans as well as mice, coding for a protein that is secreted in the lungs. The protein, surfactant protein C, stops the lungs collapsing during breathing. Harmful versions of the SFTPC gene are usually fatal at birth in both mice and humans. As such, prenatal intervention would be necessary to treat the condition.
'It gets us right in that sweet spot to treat a disease at the very beginning, basically as soon as it's diagnosed,' Dr William Peranteau, a surgeon at the Children's Hospital of Philadelphia, Pennsylvania and a study co-author, told Wired.
The team injected CRISPR/Cas9 into the amniotic fluid of mice to delete a harmful version of the SFTPC gene. Mice are capable of surviving without SFTPC, so they did not need to repair the gene. Seven out of 87 mice survived past 24 hours and five lived to a week.
While the survival percentage was low, Dr Peranteau said that as a proof-of-concept study it showed 'exciting future prospects for prenatal treatments'. All mice with the harmful SFTPC variant that did not receive the genome editing treatment died within six hours of being born.
In addition, the genome editing was specific to the mice fetuses' lung cells in this study, showing that the technique was capable of targeting one tissue type. As a result, the changes made to the lung cells would not be inherited by the next generation, should the mice survive long enough to procreate.
'At some point in the future – not tomorrow or the next day, years from now – I think in-utero editing would provide hope for families that today have none,' said Dr Peranteau.
However, applying the technique to humans is likely to be more complicated. Humans cannot survive without SFTPC. The treatment would need to repair rather than delete the gene to have a chance of success.
'It's wonderful that the field of in utero therapy is moving forward,' Professor Graça Almeida-Porada of Wake Forest University in Winston-Salem, North Carolina, who was not involved in the research, told STAT News. 'For many genetic disorders, there's not a lot that can be offered to the patient [after birth], so it’s important to develop novel therapies that provide a chance at life.'
The research was published in Science Translational Medicine.