The clinical potential and ethical difficulty posed by gene-editing technology, which can “find and replace” targeted genes, is seemingly endless. But while public attention is focused on whether we should use it to change the genes of embryos, application of the technology to genetically modify pig tissues and organs for transplantation into humans could potentially have a bigger and more immediate impact on human health. The transplantation of living cells, tissues, or organs from one species to another is known as xenotransplantation. It has long been championed as a solution to the shortage of human donor organs. Xenotransplantation could be used either as definitive therapy or to “buy time” while the patient waits for a human donor organ. While progress has been slow, trials have demonstrated benefit in patients with type 1 diabetes who are transplanted with porcine pancreatic cells. And gene-editing research published in October shows incredible promise for making xenotransplantation a reality. Xenotransplantation faces two major challenges: the risk of immune rejection and the risk of transmitting diseases from animals to humans (xenozoonosis)
