Ape-to-human, pig-to-human blood donations: Could xenotransfusions work?

Playing to be GOD……

Would you accept a transfusion of blood products from a chimpanzee or a gorilla? Or what about a pig? One person did back in 1667 when French physician Jean-Baptiste Denis successfully transfused blood from a lamb into 15 year-old human boy. This may surprise many people as most are aware that even humans are not universally transfusion-compatible. Instead, humans are divided into blood groups that determine who can receive blood from whom without suffering a severe immune reaction that can be fatal. That’s because our immune system senses molecules on the surface of red blood cells and reacts aggressively to certain surface molecules, or markers, in an individual whose on red blood cells don’t have the same kind.

But while there are literally hundreds of different surface markers that make red blood cells different between people, only a handful of markers act as strong antigens to the immune system. The main ones are the ABO and Rh antigens (the positive or negative seen after the more commonly known A, B, O types) and for people to receive blood products they must be appropriately ABO and Rh matched. It turns out, however, that the ABO and Rh blood groups are not limited just to human populations. They also apply to our close relatives in the animal kingdom, especially other primates. Indeed, Rh stands for rhesus, because it was identified on the red blood cells of rhesus monkeys before it was found on human red blood cells.

All of this means that a human can be ABO and Rh matched for blood products from a monkey, or even better, a great ape such as a gorilla or chimpanzee (who are closer to us on the evolutionary tree than monkeys). And, since the ABO and Rh antigens are the most critical factors to match to avoid fatal transfusion reactions, it means that xenotransplantation from an ape is feasible theoretically. But some hurdles may exist to making it a reality.

Drawbacks to ape blood and benefits of using pigs

Work with blood and non-human primates goes back to Karl Landsteiner, who not only co-discovered the rhesus factor in monkeys in 1937, but also discovered the ABO groups in 1900. The blood group commonality between humans and other animals thus is not a new revelation, but this raises question of why xenotransfusion was not seriously decades ago.

One reason is because, despite ABO and Rh commonality, there are minor differences between the blood of humans, apes, and other animals whose effects on transfusion would have to be understood completely. Humans also may still have some lingering superstitions about blood from non-humans that make xenotransfusion unpalatable. Also, when it comes to great apes, they are endangered. They’re not like cows and pigs that simply are bred in industrial quantities to serve humans. So, even while it might be no more trouble for an ape to donate blood than for a hen to lay eggs, the supply of ape blood would be fairly small anyway.

Thus, as we consider xenotransfusion pigs might actually be a more feasible option, and in fact that’s what’s happening. Xenotransfusion research currently focusses on pigs, not apes, and it’s not just because pigs are abundant. They’re blood actually is quite similar to human blood. The size of red blood cells is similar. So is the typical red blood cell life span, the hemoglobin content and structure, and other factors, plus pigs can be genetically modified to produce red blood cells that are equivalent to human type O negative. As noted earlier, that’s the universal donor blood, and this makes xenotransfusion sound very attractive, although, other ways to make O negative blood also beckon.

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