An international team of researchers have announced on 27 January that they have created the first successful human-animal hybrids. The project - though controversial - proves that human cells can be introduced into a non-human organism, survive, and develop inside a host animal, in this case, pigs.

This advancement has long thought to be beyond reach and scientists, who were hoping to address a critical shortage of donor organs globally, are ecstatic.

Led by Salk Institute, the team created what is scientifically known as a chimera: an organism that contains cells from two different species. Naive pluripotent human stem cells were injected into pig embryos before they were placed into adult pigs for development. They were then extracted after 28 days and analysed.

Research only offers future possibilities

186 later-stage chimeric embryos survived and the team estimates that each had 0.0001% human cells. This low percentage could present a problem for the method in the long run, says Ke Cheng, a stem cell expert at the University of North Carolina at Chapel Hill and North Carolina State University. 

This is because human tissue slows down the growth of the embryo and organs grown from such embryos are highly likely to be rejected by humans, since they would contain more pig tissue, Cheng noted.

Cheng calls the work a breakthrough: “There are other steps to take,” he concedes. “But it’s intriguing. Very intriguing.”

Therefore the next step is to explore the possibility of increasing the number of human cells the embryos can tolerate - and it could take years and be expensive. Currently these experiments have been funded privately as they are ineligible for public funding in the United States and public opinion too, have been against the creation of such organisms - and they have reason to be.

Many bioethical dilemmas to consider

The experiment presents a preliminary step into developing pigs and cows as living containers for an unlimited supply of human organs.

If successful in the future, this means that key organs such as the heart, liver, kidney, pancreas, lungs and brains, could be easily produced and harvested for organ transplantations, research on human disease, development, evolution, and models for drug development.

Many researchers are thrilled with the prospects of what this experiment could offer, but it also raises ethical dilemmas about the moral status of these chimeras. To be effective models for health research, the chimeras need to be human enough, but not so much that they qualify for the rights of protection from research.

Possibility of self-awareness in chimeras is dangerous

Particularly concerning is the possible creation of chimeras with human brain cells. This presents a possibility that the organisms might develop self-awareness, therefore understanding their identity and circumstances, which would lead to major complications.

This chimeric research only proves that researchers have crossed a huge number of moral lines. Every day, tens of millions of animals are deliberately sickened, injured, genetically manipulated and then tested with a drug before they are analysed and then killed, despite a growing evidence showing that some animals are indeed more self-aware and emotionally and cognitively complex than previously thought.

If chimeric research continues to be pursued - and it most probably will - , researchers might have to think about the ethical issues and moral values at stake before realising that their unrestricted efforts to save the human race, may result in the loss of humanity. MIMS

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