Your transplant organs will soon come from a pig

Scientists have ushered the world into a new biological era by developing an organism that is part-human, part-pig with the aim of growing human organs in it for transplant patients. This means it could soon be possible to use pigs to grow organs that are not only similar to humans’, but also of the appropriate size.

Creation of the hybrid animal, also known as a chimera as it contains cells from two different species, involved injecting human stem cells into pig embryos that were in early development into surrogate sows and growing them up to four weeks old. Shortly after, the embryos were terminated before any human-animal mixture could form.

The research on the human-pig hybrid, funded entirely by private donors, also raises the possibility of viruses jumping from one species to the next as well as the likelihood that, at some point, there might be mixing of human and animal tissues, leading to hybrid pigs with brains that are more human and, by extension, human intelligence.

The team of researchers from the Salk Institute of Biological Studies’ Gene Expression Laboratory in the US tested the safety and effectiveness of the study, and discovered that some cells in the embryos were starting to specialise and had the precursors of human organs, including the heart and liver. However, they contained a small amount of human cells, about one in every 100,000 pig cells.

That low percentage of human cells is the only remaining challenge in the quest to grow human organs in animals as such organs could be rejected by human bodies because of the high percentage of pig tissue.

THE INNOVATION

The innovation — in which human stem cells are introduced into a non-human organism, survive, and grow inside the uterus of the host animal — promises to revolutionise organ transplantation at a time when human organs are hard to come by, resulting in long transplant waiting lists.

The study, published January 26 in the science journal Cell, however cautions that the research is at its infancy stage and might take a while to actually live up to its expectations of providing functional human organs.

Nevertheless, it has stroked controversy, particularly within religious circles, as critics question why scientists want to “play God” without a clear understanding of where the animal ends and when the human being begins.

Reverend Tadeusz Pacholczyk, director of education at the US National Catholic Bioethics Center, last year questioned the ethics of the cause, saying there was need to “reflect carefully on the morally appropriate use of these novel and powerful technologies, so that human dignity will not be harmed, subjugated, or misappropriated in any way”.

But science, on the other hand, argues that this is a novel path towards advanced bio-engineering that, if conducted within the accepted ethical standards, will not only address organ shortage, but also help researchers study early embryo development and organ formation.

'INTERESTING BREAKTHROUGH'

Dr Marianne Mureithi of the University of Nairobi’s Department of Medical Microbiology said the study is an “interesting breakthrough”, but warned that “chimeric contribution is random and the resulting chimera could have ‘human’ tissues strewn all over the animal”.

She said if this new technology is ultimately developed and verified, diseased organs ravaged by non-communicable ailments such cancers or autoimmune disorders could be replaced. This knowledge would also set the stage for stem-cell and gene-editing technologies which will generate genetically-matched human tissues and organs.

The research began on the foundation of a prior similar study on mice and rats in which researchers were able to grow a mouse pancreas in a rat. After that, islets — tissue from the pancreases — were transplanted into mice with diabetes, helping control the mice’s blood sugar levels.

The research on the human-pig hybrid, funded entirely by private donors, also raises the possibility of viruses jumping from one species to the next as well as the likelihood that, at some point, there might be mixing of human and animal tissues, leading to hybrid pigs with brains that are more human and, by extension, human intelligence.

Another untoward outcome would be if human cells should come to compose the pig’s reproductive tissues. Few people want to see what might result from the union between a pig with human sperm and a sow with human eggs.