Designer Babies: Delivering Soon in the United States
Aug 03 2017 by Kristina Bennett
The latest effort, led by Shoukhrat Mitalipov of Oregon Health & Science University, with researchers from South Korea, China, the Salk Institute for Biological Studies in California and others, involved editing the DNA of single-cell embryos with CRISPR-Cas9, a tool for genome engineering that is much simpler, faster and cheaper than earlier methods, and which has sparked an explosion of interest in possible applications.
The embryos were editing using a powerful gene-editing tool called Crispr-Cas9, which works by precisely snipping away the defective piece of DNA from embryos containing the mutation.
In early attempts, the introduction of genome editing constructs into one-cell embryos (zygotes), resulted in multicellular embryos or offspring with mosaic outcomes in individual cells13, 14. The study that was conducted in USA comes just months after a national scientific committee recommended new guidelines for modifying embryos, easing blanket prescriptions but urging the technique be used only for dire medical problems, the report added. "Of course, even as the science moves forward, there will still be a need for ongoing societal discussion and debate about the kinds of genetic corrections that should be allowed or perhaps even promoted". As a result, only 28% of the resulting embryos carried genes for hypertrophic cardiomyopathy.
"This information will help to guide ongoing research, and it demonstrates that research on early-stage human embryos will be necessary to establish safe and effective procedures in the long run", he said.
The procedure was successful in 42 out of 58 embryos that underwent gene editing.
"The embryos are really looking for the blueprint", Mitalipov, who directs OHSU's Center for Embryonic Cell and Gene Therapy, said in an interview.
In the mean time, though, scientists still have a lot to work out.
This study was a pre-clinical test created to examine the technique's safety and effectiveness, and while further optimization is needed before clinical trials can be considered, the results are promising. The work is not likely to spread to fertility clinics either, he said.
Researchers used CRISPR to prevent an embryo from inheriting a fatal heart condition.
Embryos have been genetically edited before in China, in a series of small studies in 2015 which were met with widespread condemnation.
"It may be that some countries never permit germline genome editing because of moral and ethical concerns", said Professor Joyce Harper from University College London.
Not everybody is in favour of gene editing being used to prevent heritable conditions in the future.
"We would like to explore a correction for cancer genes particularly BRCA, which is inherited the same way and a single copy can cause breast cancer", he says.
Increasing the number of embryos without the defect from 50 percent to 72.4 percent may not seem to be a huge advance, but co-author Paula Amato, associate professor of obstetrics and gynecology in the OHSU School of Medicine said the need for fewer IVF cycles to generate embryos suitable for implantation would be a significant benefit, especially for older women with fewer eggs. Food and Drug Administration is prohibited from considering any clinical trials involving genetic modifications that may be inherited.
The scientists in OR obtained the eggs for the research and brought their expertise in embryo biology to the study. The disease, which leads to a thickening of the heart's muscular wall, affects one in 500 people and is a common cause of sudden cardiac arrest in young people.
The human embryos used in the research were created using eggs collected from healthy women and sperm from a man carrying a DNA error.
Now, when it comes to using CRISPR to correct gene mutations in embryos, Mitalipov said Tuesday, "We've done some ground work".
Instead of fixing mutant genes, doctors can simply remove the problematic embryos and only inject the healthy ones during in-vitro fertilization.
Echoing similar concerns, Fr. Pacholczyk pointing as well to the guidance from the National Academies of Sciences' 2017 report on human gene editing.
Currently, the United States permits privately funded research involving embryonic genetic modification in laboratory settings while prohibiting clinical applications. How would you regulate this, and make sure that it's equally accessible?
Building on previous research from other groups, in the new research Ma and colleagues improve the success rates of DNA editing by changing the timing. The argument means that children born from such embryos might not, strictly speaking, be considered genetically modified.