Gene-Editing Program Advanced in Pigs
By Ahmad Sabbagh '17
Scientists have once again made remarkable progress in improving the celebrated yet controversial gene-editing technique known as CRISPR. At a recent gathering at the National Academy of Sciences, a pioneer of the technique, Dr. George Church of Harvard Medical School, presented a new experiment in which he and his colleagues were able to alter 62 genes at once. This remarkable feat overcame CRISPR’s previous limitations of editing only a single gene per CRISPR molecule at a time.
Dr. Church’s experiment was inspired by a search for a way to solve the shortage of human organs needed for transplant operations. It had been suggested that pig organs could be harvested to address the need; however, it was soon discovered in 1998 that pig DNA contained viral genes called porcine endogenous retroviruses (PERVs) that could infect human cells. In 2013, Dr. Church began looking for ways to edit these PERVs so that they could become harmless to pigs and thus harmless to humans as well. Dr. Church and his colleagues found 62 PERV genes and caught a lucky break when they found the DNA was nearly identical virus to virus. The researchers were then able to use a single CRISPR molecule to edit all 62 genes within the cell.
Not only does this discovery bring scientists closer to making pig organs safe for human transplants, but it carries with it greater implications of being able to treat human diseases through gene-editing. However, despite its rapid development and successes on animal specimen, the CRISPR technology will need some time before it is brought to clinics to treat human diseases and will likely experience some setbacks as it continues to develop. The immediate results of the new improvement in CRISPR, however, are promising, as it adds new tools to the genome-editing toolbox.
The promising prospects of gene-editing also bring with them concerns as pertaining to issues of ethics and safety practices. Besides curing diseases, gene-editing could be utilized to enhance desirable qualities in embryo genomes. This brings forth an issue of ethics, as the modified genes would be passed on to generations of humans without the consent of those effected. It also raises an issue of safety, as mutations may occur at locations other than those targeted, creating unintended consequences and potentially causing disease. These concerns have led to a group of biologists, including the inventor of CRISPR, to call for a worldwide moratorium on such modifications to human embryos. With power comes responsibility, urging the controlled use of such powerful technology, lest our urge for control of the future spirals our future out of control.
Sources:
http://www.nature.com/news/gene-editing-record-smashed-in-pigs-1.18525
http://www.nature.com/news/ethics-of-embryo-editing-divides-scientists-1.17131