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Human-pig embryos pave possible future for transplants

Human-pig embryos could revolutionize our medical industry. For patients hoping for an organ transplant, the wait to get a new heart, liver, or kidney can stretch out for years. To shorten these wait times, doctors are researching ways to grow human organs in a laboratory. Recently, they came one step closer to their goal by successfully growing human cell inside pig and cattle embryos.

Juan Carlos Izpisua Belmonte and his colleagues at the Salk Institute in La Jolla, California published their work in the journal Cell. They made pig embryos in the lab and injected each one with human stem cells. The embryos were only allowed to grow for four weeks, after which they were destroyed.

Animals with cells from different species are called chimeras – named after a creature in Homer’s Iliad that was “lion-fronted and snake behind, a goat in the middle.” Experiments involving chimeras – and particularly those using human cells – have sounded alarm bells amongst those concerned with the ethics of human-animal research. Ethicists wonder if the insertion of human cells into an animal begins to cross a line in which that animal should be given human rights. The U.S. government pulled taxpayer funding of chimera-based scientific experiments in 2015, and any new work must be privately funded.

Scientists at Salk first discovered that they could grow cells from one species inside another when they attempted the procedure on rats and mice. First, they created a mouse embryo without a pancreas. Then, they successfully implanted and grew a rat pancreas inside the mouse embryo. They have also repeated the same experiment with rat hearts and eyes inside mouse embryos.

When the team began researching human stem cells, they realized they needed a larger creature in which to grow them. Although Salk told USA Today that the ability to grow human organs is “far away,” scientists hope to eventually be able to grow human pancreases, livers, and hearts.  

By Dawn Henderson, Staff Writer

Source: Juan Carlos Izpisua Belmonte, Salk Institute


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