South Korean researchers have successfully treated diabetic monkeys using pigs’ pancreatic islets, parts of the organ that contain cells which secrete hormones, including insulin.

A team led by Seoul National University professor Park Seong-hoe said on Monday that his team has transplanted pancreatic islets from pigs to monkeys afflicted with diabetes. Park said the monkeys have survived for more than six months without rejection symptoms.

The team said that the monkeys did not show rejection symptoms even after they were taken off immunosuppressants, which it said is very rare for even transplant cases between the same species.

The achievement is expected to aid in treating the three-and-a-half million diabetic patients in the nation and contribute to research on bone marrow transplants or the medical use of stem cells.