In a new study published in Science, Massachusetts researchers were able to remove all viruses in the pig genome using a state-of-the-art gene-editing system. This breakthrough clears an important hurdle in cross-species transplantation that brings science one step closer to pig-to-human organ transplants.
How Cloned Pig Cells Can Lead to Animal-to-Human Organ Transplants
Every day, about 22 people in the United States die waiting for an organ transplant with over 116,000 people currently on a transplant wait list. This is all according to the Organ Procurement and Transplant Network (OPTN). For decades, surgeons have hoped to solve this organ shortage using pigs, whose organs are similar100-105 in function and size to humans.
The greatest challenge to the use of pig organs in humans — a process called xenotransplantation — is the concern of virus transmission. Recent advances in gene editing have brought animal-to-human organ transplants one step closer though.
Researchers in Massachusetts announced they were able to use the CRISPR-Cas9 gene-editing system to inactivate the 25 retroviruses in the pig genome that pose a concern to humans. The piglets in the study are currently four months old and appear healthy. This surprised George Church, as the CRISPR technology can be very toxic to cells as it breaks DNA strands. Church is a Harvard Medical School geneticist and co-author of the study.
“We are pushing the envelope of technology day by day. I think that such innovation is required to tackle as challenging a problem as xenotransplantation,” Church said.
Next Steps in Cross-Species Organ Transplants
The next stage of the research is modifying the pigs enough for the organs to function in a human. This involves addressing blood clot issues and tissue compatibility. Other researchers are already working on clearing the path to cross-species transplants. They are also hoping to have the pig organs ready 300-101 for testing within 2 to 3 years.
Researchers are expecting to begin with kidney transplantation, which has the longest wait list, followed by other organs like the liver and heart.
Pigs must typically reach the age of 4 months before their organs are large enough for transplant in humans. The most common organs people on the transplant list are waiting for include the kidneys, liver, heart, and lung.
The new research is a major breakthrough in animal-to-human transplantation and may help pave the way for pig organs ready for testing within the next five years. One concern researchers do hope to address is whether the CRISPR gene editing may lead to cancer. This is a speculation that has not been sufficiently tested yet. To do so, researchers want to see what happens to the pigs when they are allowed to reach old age. Or to reach around 20 years old.
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