Scientists Successfully Grow Human Kidneys Inside Pigs

Saturday - September 9 2023, 08:45 UTC - 1 year ago

A team of Chinese researchers has successfully grown early-stage developing human kidneys inside female pigs using chimeric embryos. The study could provide a bridge between donor organ shortage and large recipient demands, as well as opening up an avenue for regenerative medicine. The researchers used a combination of gene editing, stem cell engineering and optimized environment to create the chimeric embryos.

A team of Chinese researchers has successfully grown early-stage developing human kidneys into female pigs using chimeric embryos. "This is the first time a solid human organ has been grown inside an animal species other than humans," Liangxue Lai, senior study author and a biologist at the Guangzhou Institutes of Biomedicine and Health, told Interesting Engineering. Unlike normal embryos, chimeric embryos contain cells or tissues from two different organisms. In this case, the researchers used human and pig cells to create the chimeric embryos. The researchers claim that the embryos underwent normal development inside pigs for 28 days. During this period, they noticed the formation of tubules and some other renal structures in the developing kidney. "This study demonstrates proof-of-principle of the possibility of producing a humanized organ in organogenesis-disabled pigs, opening an exciting avenue for regenerative medicine and an artificial window for studying human kidney development," Lai added.

In the past, scientists have used a similar process to produce human tissue and muscles inside pigs. However, they couldn’t grow an entire organ because successfully incorporating human stem cells with pig cells is very tricky. For instance, pig cells tend to be more successful or dominant in such embryos because they multiply more rapidly than human cells. This competition can make it challenging for the human cells to survive and develop within the pig embryo. Also, human and pig cells require different nutrients, environmental conditions, or signaling molecules to grow. The differences in their physiological needs further hinder the successful integration of human stem cells into pig embryos, according to the researchers.

Lai and his colleagues employed three techniques to overcome these challenges. First, they used CRISPR to eliminate two genes in pig cells that are required for pig kidney development. This ensured the growth of only human kidneys from human cells in the embryo. Second, they engineered and used human pluripotent stem cells in the chimeric embryo. These cells can renew, grow, and divide into any type of human cells. The researchers turned them into early human embryonic cells. Third, they created an optimized environment for the embryo to accommodate the distinct needs of both human and pig cells. This environment ensured that each cell could receive the nutrients and molecules best suited for their growth.

The researchers used these techniques to create 1,820 chimeric embryos and then transferred those into 13 surrogate pig mothers. When they examined five embryos after 28 days, they found that they had grown into mesonephros, early-stage human kidneys with tubules and cell growths forming the ureter.

There are over 104,000 people listed on the national transplant waiting list in the US. This number could be in millions across the globe, but what’s more unfortunate is that many such individuals die waiting. There is a significant gap between organ donors and people who need organs. The technique proposed by these researchers could be the much-needed bridge between donor organ shortage and large recipient demands.