Recently, the UK’s Human Fertilization and Embryology Authority gave scientists the green light to use the CRISPR-Cas9 gene-editing technique in human embryos. The scientists will not be using the method for any direct therapeutic purpose, but instead will investigate the genes that guide human development.
George Q. Daley, a Harvard Medical School professor and director of the stem cell transplantation program at Children’s Hospital Boston and Dana Farber Cancer Institute says CRISPR is basically a bacteria's immune system, adapted to human cells.
"Just like we are bombarded with viruses, bacteria has developed a way of fighting off viruses," Daley says. "They recognize the invader and chop it up. So scientists have been able to adapt this to human cells in a way that allows us to very specifically identify a gene, recognize it, and either chop it up, deleting its activity, or repair it. [This is] a process we call gene editing. What [we] now want to do is employ this very powerful method for gene editing in human embryos."
Gene editing has already been done in mice, but Daley says the results of those experiments can't provide enough insight into the problems of human health.
"We really can't answer the critical questions about human development [using] mice," Daley says. "It turns out that mice develop differently. The principles we've discovered in mice don't seem to work in humans. ... This is going to shed important light on questions like infertility, miscarriages and birth defects."
CRISPR is currently illegal in the US, and Congress has banned all funding for the FDA to even consider doing this sort of research. But Daley is an enthusiastic supporter and wants to see it in the US.
"It's now swept the international biomedical community. I mean virtually every laboratory is taking advantage of this. It's so powerful, so efficient and so easy to use that it's finding all sorts of very exciting new applications," Daley says. "We do hope that this work gets done in the United States. It'll have to be done with private funding, but it's essential. It's going to teach us a tremendous amount about the earliest days of human development."
Still, there are some who are calling into question the scientific, legal and ethical aspects of editing the genetic material of human embryos. Some critics have called it the first steps toward designer babies.
"The longer term question [that] arises is whether this technique could ever be used to eradicate disease in an embryo, that is to prevent a baby from coming into the world with a particular disease. Could we treat it at that embryonic stage?" Daley says. "There are some who think that's a very laudible goal. But it also raises this thornier question of modifying human heredity. You know, if we intervene in an embryo and and cure a disease in an embryo, that means that that person's offspring has to carry this genetic change. It's very controversial."
Hank Greely, a law professor at Stanford and the director of the Center for Law and the Biosciences at Stanford, hopes the obvious ethical and legal implications of bringing a genetically modified child into the world will prevent scientists from doing something inappropriate with CRISPR.
"Really, when you think about trying to make a baby using a previously unknown technique, the potential downside is enormous," Greely says, "The idea of bringing seriously disabled or deformed or dead children into the world is a serious constraint. There are legal ramifications, there are medical licensure ramifications. The woman who's a necessary part of it would have to consent to it. It doesn't mean that it's impossible, that in some strange corner of the world somebody might try something inappropriate. But I think it's not very likely dealing with humans."