CRISPR/Cas9 Eliminates Viral Transmission Risk in Xenotransplants

Researchers from  Harvard Medical School in Boston have successfully deactivated 62 viruses in embryo pigs. The achievement was possible thanks to the CRISPR/Cas9 genome editing technology. The study, presented at the National Academy of Sciences meeting in Washington D.C, paves the way to the use of pigs as organ donors without the risk of contracting their viruses.

Shortage of organ donors causes death of up to 35% of people on waiting lists worldwide. Xenotransplantation is an alternative that could supply endless amounts of organs, even if it would raise a bioethical debate. Non-human primates are our closest relatives, but many species are endangered. Other problems are different body size, low numbers of universal blood group donors or the elevated risk of disease transmission. Pigs are more similar in size, produce more offspring and are more distant to humans, so the risk of disease transmission is lower, but still exists. Rejection by the human immune system and viral infection are the most feared problems.

George Church. Credit: Jessica Rinaldi/Reuters

CRISPR/Cas9 eliminates genome embedded viruses and immune response membrane proteins

Porcine endogenous retroviruses (PERVs) are inserted in the pig genome, so there is no possible treatment. It is feared that PERVs could be transmitted to humans, which prevents the use of pigs as organ donors. But the future of xenotransplantation looks brighter now: using CRISPR/Cas9, George Church and his team in Harvard inactivated 62 PERVs in pig embryos. On another group of pig embryos, Dr. Church and colleagues modified more than 20 genes that code for membrane proteins involved in the immune response that rejects donor organs. The identity of the genes will only be revealed when the paper is published.

All the modifications will soon be performed on mother pigs, allowing to see the effects of the gene edits on the pig´s physiology. The results can be specially beneficial for Dr.Church´s eGenesis, a startup that seeks to cheaply produce pigs for organ transplantation.

Source: Medical Daily