Syd M Johnson maintains that we need to consider the ethical implications of growing human organs in pigs.
Earlier this month, Science published a report by researchers who had successfully inactivated porcine endogenous retroviruses (PERVs) in pig kidney cells. Church and colleagues used the gene editing technique CRISPR Cas9 to edit 62 genes in the cells. The ultimate goal of this research is to produce virus-free transgenic pigs to grow organs for humans. The news media worldwide latched on to that aspect of the story, heralding the research as a major development towards using pigs to grow human organs to help meet the demand for transplantation.
To be clear, we are nowhere near being able to grow human organs in pigs, and the current research is at most a very small step towards this ethically questionable goal. The researchers removed PERV DNA, which is present in the genomes of all pigs, from PK15 porcine kidney cells, a cell line commonly used in research. They then cloned the modified kidney cells, and combined them in a petri dish with HEK293 (an immortal cell line of human embryonic kidney cells) to see if PERV infection of the human cells occurred. PERV was not detected in the human cells, leading the researchers to conclude that they had achieved a significant reduction of infectivity. Importantly, this work was entirely limited to lab-grown cultures of kidney cells. It is impossible to conclude that the technique would actually eliminate PERV transmission in living creatures, since the viral DNA is buried in the entire genome of pigs.