Scientists from the Weizmann Institute in Israel managed to successfully transplant embryonic pancreatic tissue from a pig into a monkey, growing a new pancreas, and effectively treating the primate with type 1 diabetes. As radioimmunoassay tests showed, the technique led to the production of porcine insulin while the vessels running through the new pancreas were the monkey’s own.
MIT Technology Review reports:
In an earlier study, the researchers found evidence that semiformed pancreatic tissue taken from pig embryos at 42 days of gestation appeared to offer the best combination of characteristics for xenotransplantation. According to Reisner [Yair Reisner], if they’re harvested too early, there may not be enough partially differentiated pancreatic cells. But if taken too late, the tissues’ ability to grow into a new organ is diminished, perhaps because they contain too few stem cells, while their ability to cause immune rejection increases.
In the latest study, the researchers transplanted 42-day-old pig pancreatic tissue into monkeys with induced type 1 diabetes. The first pair of animals involved in the study died soon after transplantation from an infection caused by too much immunosuppressive therapy.
The second pair of animals received milder immunotherapy and survived for a year. Furthermore, within five months of treatment, the animals had grown new pancreases and were no longer reliant on insulin injections. This indicates that the replacement organs had sufficient islets–tiny, insulin-producing structures consisting of around 1,500 beta cells, which have their own intricate vascular systems.
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Abstract in PNAS: Embryonic pig pancreatic tissue for the treatment of diabetes in a nonhuman primate model
Image: Fluorescent red markers show that blood vessels in a transplanted pancreas are of monkey origin. Limited green coloring suggests that few pig blood vessels are present. Credit: PNAS