Blood transfusion may differ now

Blood transfusion may never be the same again. Researchers at the University of Copenhagen have used newly discovered enzymes to eliminate the incompatibility of blood groups.

Blood transfusion may differ now

Bloodtransfusion may never be the same again. Researchers at the University of Copenhagenhave used newly discovered enzymes to eliminate the incompatibility of bloodgroups.

A life-saving method of converting blood from one group to another has beenpioneered by scientists. The breakthrough could potentially mean the end ofblood-donor shortages and boost supplies of sought-after group O negativeblood.

O negative blood is known as "universal" because it can be given to anyonein a blood transfusion. Giving patients the wrong type of blood can causesevere immune system reactions and can be fatal.

Writing in the journal Nature Biotechnology, aninternational team of researchers described how they converted blood from groupA, B or AB to group O.

The process uses bacterial enzymes found in fungi, which can be used asbiological "scissors" to cut sugar molecules from the surface of red blood cells.

People inherit blood type through their parents' genes, and the system ofcategorising groups as A, B, AB or O dates back to 1900. Those in groups A andB have blood containing one of two different sugar molecules that can triggeran immune response. People in group O, the most common group, have neither ofthese "antigens", while those in group AB have both. 

 Patients produce antibodies against the antigens they lack. For thisreason, AB individuals, who lack neither, can receive blood safely from anygroup. But group A patients cannot be given a transfusion of group B blood, andvice versa.

Group O patients react badly against A, B or AB blood. However, their ownblood, having neither of the sugar antigens, is suitable for people from allthe ABO groups. Group O donors are therefore always in demand, and O blood isoften in short supply.

A further antigen that can trigger an immune response, a protein called RhD,exists in blood labelled "rhesus positive". Truly "universal" group O blood isrhesus negative, meaning that it is also missing this antigen, but at themoment this type makes up only 4 per cent of stocks for the National BloodService (NBS).

 The scientists, led by Henrik Clausen, from the University of Copenhagen,screened 2,500 types of fungi and bacteria looking for useful proteins. Theyfound two bacteria, Elizabethingia meningosepticum and Bacterioides fragilis,that yielded enzymes capable of removing A and B antigens from red blood cells.

In tests, the antigens were found to vanish from 200ml samples of A, B andAB blood after an hour's exposure to the appropriate enzyme. The researcherswrote: "Clinical translation of this approach may allow improvement of theblood supply and enhancement of patient safety in transfusion medicine." 

 Group O blood created using the new method will have to be tested onhuman beings before it can be used in hospitals. 

 To create supplies of group O negative blood, rhesus negative A, B andAB blood would have to be selected. No way has yet been found to turnrhesus-positive blood into rhesus-negative.

 The present system of blood transfusions is wasteful, with 10 per centof donations in the UKnever reaching patients. It is also expensive, with each unit costing more than£120 to extract, screen and store. * The NBS, which serves England and North Wales,holds 40,000 units of blood in stock — enough to last about 5½ days. A unit isa single blood donation, or two thirds of a pint. Red blood cells can be storedfor only 35 days, and stocks must be replenished continuously by donors.

Time / Nature Biotechnology


Güncelleme Tarihi: 20 Eylül 2018, 18:16