Researchers Have Finally Found A Way To Save The Northern White Rhinos

Turning frozen skin into sperm and egg cells could bring back northern white rhinos from endangered status
Javan Rhino Moleskine wrap-around cover art, 2/2011 by steve loya is licensed under CC BY-NC-ND 2.0
“Javan Rhino Moleskine wrap-around cover art, 2/2011” by steve loya is licensed under CC BY-NC-ND 2.0

Just two northern white rhinos remain on the planet. Both of them are female, named Najin and her daughter Fatu. The last male, Sudan, died in 2018. All rhino species are endangered because of poaching and their horns, but the northern white rhino has suffered the greatest among species. But researchers say there is hope, as the San Diego Zoo Wildlife Alliance in California examined skin cells extracted from 12 distinct northern white rhinos preserved in their Frozen Zoo. Using a computer model, they simulated the outcome of utilizing the genetic material from these rhinos to produce sperm and egg cells. The cells, transformed into embryos, could be carried by a closely related subspecies, the southern white rhino, creating more northern white rhinos and repopulating the species.

What Are The Northern White Rhinos?

White rhinos are the second-largest land mammal and is also known as the square-lipped rhinoceros. White rhinos have a square upper lip with almost no hair. Two genetically different subspecies exist the northern and southern white rhino, and are found in two different regions in Africa. As of March 2018, there are only two rhinos of the northern white rhino left, both of which are female. They live in the Ol Pejeta Conservancy in Kenya and are protected round-the-clock by armed guards. Their near extinction is due to decades of rampant poaching for rhino horn, which is falsely believed to cure cancer and mental disorders. This species is extinct in the wild and has two unfertile females left to its name.

How Does This Process Work?

Skin cells are first collected and stored in a bank. These cells can then be reprogrammed into induced pluripotent stem cells (iPSCs). iPSCs are unique because of their ability to differentiate into any type of cell in the body. Once they generate iPSCs, researchers can direct them to differentiate into primordial germ cells. To provide evidence, the research team sequenced the genes of both northern and southern white rhinos as a way to measure the degree of diversity in both subspecies. They then used a computer model to mimic the creation of a set number of northern white rhinos with the expected degree of genetic diversity. The team then turned their attention to the likelihood of genetic mutations in the engineered animals and their offspring and found no evidence of fitness declines over 10 generations. This process has many flip sides though, with the many challenges including chemically inducing frozen skin cells into functional sperm and egg stem cells and uncertainty about whether surrogates from the closely related southern white rhino species will be capable of carrying embryos to term successfully. This is a significant concern because success depends on the ability to gestate and birth healthy offspring.


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