The scariest moment in some parents' life is when a doctor makes a diagnosis of disease or a developmental defect in their unborn child. When this happens one name is usually considered; William Peranteau, a pediatric surgeon who works at Children's Hospital of Philadelphia. Peranteau and pediatric surgeons like him are trying to bring the evolving field of gene editing to the womb. Such editing in humans is a long way off, but a wave of recent advances in mouse studies highlight its potential advantages over other methods of using Crispr to trim away diseases. Parents confronted with an in utero diagnosis are often faced with only two options: terminate the pregnancy or prepare to care for a child who may require multiple invasive surgeries over the course of their lifetime just to survive. Prenatal gene editing may offer a third potential path. "What we see as the future is a minimally invasive way of treating these abnormalities at their genetic origin instead," says Peranteau.
In order to give proof to this idea, Peranteau and colleagues at the University of Pennsylvania injected Crispr editing components, encoded in a virus, into the placentas of pregnant mice whose unborn pups were suffering with a lethal lung-disease-causing mutation. When the fetuses breathed in the amniotic fluid they also inhaled the Crispr bits, which went to work editing the DNA inside their rapidly dividing alveolar progenitor cells. These cells give rise to many types of cells that line the lungs-including ones that secrete a sticky substance that keeps the lungs from collapsing every time you breathe. Mutations to proteins that make up this secretion are a major source of congenital respiratory conditions. All of the mice with the mutation died within a few hours of birth. Of those edited with Crispr, about a quarter survived.
It's a second testimony of theory from the group of scientists in the past year. In October, they published a paper describing a slightly different procedure to edit mutations that lead to a lethal metabolic disorder. By changing a single base pair in the liver cells of prenatal mice, Peranteau's team was able to rescue nearly all of the mouse pups. Other recent successes include unborn mice cured of a blood disorder called beta-thalassemia following a prenatal injection of Crispr, carried out last year by a team at Yale and Carnegie Mellon.
"This is not a panacea for curing every genetic disease that's out there," says Peranteau. But he believes that a Crispr approach may offer a new way forward for at least some of his patients. "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."
