Scientists create blood cells that could be friendly to all.
Scientists have created a “stealth” red blood cell that camouflages its immune status, meaning it could potentially be transfused into anybody in an emergency, regardless of their blood type.
The finding, published in Science Advances, promises to shake up my own former field of emergency medicine, where treating people who have lost litres of blood from shootings, stabbings and road trauma is all in a day’s work.
The resuscitation team has to quickly get an IV in the patient’s vein and infuse salt water to get their blood pressure back up, otherwise you’re looking at cardiac arrest and death.
But even if blood pressure is normalised there’s still an issue – salt water can’t carry oxygen around the body, so your patient might die anyway. The answer is to transfuse oxygen-carrying red blood cells, supplied by a very kind person who has donated blood.
But that comes with its own complications.
Red blood cells are host to a range of different antigens, signposts on their surface that tell antibodies and other immune cells whether they are yours or somebody else’s.
Some of those antigens are household names – A and B antigens are found on the red cells of people with blood types A and B (there’s also blood type AB, which has both).
Give a person with type A blood a transfusion of type B, or vice versa, and you get something called a transfusion reaction that makes the red cells burst and the person gets very sick or dies.
Which is where blood type “O” comes in. It hasn’t got A or B antigens and so you can give it to someone of any blood type without a reaction.
That’s helpful, but it comes with a bit of fine print.
Some blood cells also have rhesus or “D” antigens on their surface. If you have those, your blood type gets an additional “positive” moniker: A+, B+, AB+ or O+. If you don’t have the Rh antigen you are “negative”: A-, B-, AB- or O-.
Put Rh positive blood into someone who is Rh negative and you also risk a transfusion reaction.
Which is why O negative blood is so special. It is the “universal donor” that can be transfused into anyone – emergency doctors like to have plenty of it on hand because it takes time to crossmatch a person’s exact blood type, and in a trauma you need blood STAT.
But “O neg” blood is annoyingly rare – only about nine per cent of people have it. And when people stop donating blood, during a coronavirus epidemic for example, stockpiles can plummet.
Enter a team of researchers led by Ben Wang at Zhejiang University School of Medicine in Hangzhou, China.
Read the full story in Cosmos magazine here