South Korean scientists have successfully transplanted organs from a genetically modified pig to monkeys, a state research center said Tuesday, significantly raising the prospect of successful animal-to-human organ transplants.

A heart and a kidney from the engineered pig were given to two separate monkeys on May 31, according to the National Institute of Animal Science, a research arm of the Rural Development Administration.

The pig used in the latest experiment was an offspring of Xeno, the country’s first genetically modified pig developed in 2009 by removing the enzyme alpha-1, 3 galactosyltransferase, which causes hyperacute rejection of animal organs in human bodies.

Both monkeys, however, died this week, after surviving over three weeks since the operation.

“It is a great success even though the monkeys have died as their survival for over 20 days shows the enzyme that causes hyperacute rejection has been successfully eliminated,” an official from the institute told Yonhap News Agency.

The rejection of foreign organs in human bodies takes place in

stages: hyperacute, acute, cell-mediated and chronic. Hyperacute rejection usually results in the mortification of cells or organs within seconds or minutes.

South Korea has two other engineered pigs ― Mideumi and Somang-i, developed in 2010 and 2011, respectively. 

(Yonhap News)