Research & Development

BLOOD. Ask a four-year-old about blood and they’ll tell you blood is red and that it shows up when you scrape your knee. Ask a freshman biology student about blood and they might tell you blood carries oxygen and comes in different types – A, B, AB, and O. Ask a chronically transfused patient about blood and they’re likely to say that while it keeps them alive, it can also sometimes make them feel sick.

While all of these statements are true, they don’t necessarily paint the whole picture about blood. Indeed, red blood cells are red, do carry oxygen, and do come in the ABO and also RhD types, the major blood group antigens that most people are aware of. What is unknown to most people, however, is that there are hundreds of additional blood group antigens that can sometimes result in a negative reaction in patients who receive repeated transfusions. In this scenario, patients can make antibodies that recognize and attack antigens present in a donor’s blood, which can cause fever and illness, and ultimately means there are fewer and fewer donors whose blood will be compatible for their treatment.

In order to help combat this issue and improve the safety of blood transfusion overall, Canadian Blood Services has been funding research for nearly a decade on a method that camouflages the surface of red blood cells from the immune system, thereby limiting the chance of negative reaction in transfused patients.

These “stealth” red cells are made by chemically gluing a compound called methoxypolyethylene glycol (mPEG) to the cell membrane. The membrane-bound mPEG physically camouflages the blood group antigens thereby preventing the blood recipient’s immune system from seeing and reacting to them. The mPEG itself is safe and non-toxic and is commonly used in medicine as well as in the food industry.

Experiments with red blood cells from humans and mice have shown that this technology efficiently camouflages a majority of blood group antigens, preventing the body from making an immune – or antibody – response to it. Studies have also shown that these camouflaged cells circulate and deliver oxygen within the body just as long as normal red blood cells.

By successfully applying this technology, blood transfusion may become much safer for those patients who face chronic transfusions and are at an increased risk of developing potent immune responses to the transfused blood.

To date, research by Canadian Blood Services’ research team at the University of British Columbia’s Centre for Blood Research in Vancouver is getting very close to trials in humans. This is an important next step in determining the viability of camouflaged red blood cells in the Canadian hospital system.

Research findings have been published in Proceedings of the National Academy of Sciences of the United States of America, Blood, Transfusion, American Journal of Hematology, Acta Biomaterialia, and Biomaterials, among many others.