Blood shortages to be passé?

Hallelujah! Blood shortages may be passé!

Such were the headlines this past week with a flurry of news items about bacterial enzymes that can cut antigen-bearing sugar molecules from the surface of red blood cells. The enzymes can render A and B rbc into group O rbc, producing so-called "universal donor" cells that can be transfused to recipients of any ABO group, providing the rbc are Rh-negative and providing recipients lack unexpected antibodies.

The news was based on this recent publication by Danish researchers:

• Qiyong P Liu QP et al. Bacterial glycosidases for the production of universal red blood cells. Nature Biotechnology 2007 Mar;25(3):327-37.

Was it really news given that the concept has been around for about 25 years? For example:

• Goldstein J, Siviglia G, Hurst R, Lenny L, Reich L. Group B erythrocytes enzymatically converted to group O survive normally in A, B, and O individuals. Science 1982 Jan 8;215(4529):168-70.
• Dybus S, Aminoff D. Action of alpha-galactosidase from Clostridium sporogenes and coffee beans on blood group B antigen of erythrocytes. The effect on the viability of erythrocytes in circulation.Transfusion 1983 May-Jun;23(3):244-7.

Editorials back then were similar to today:
Cowart VS. Green coffee beans may solve a blood bank problem. JAMA 1982 Jan 1;247(1):12.

Similar research followed in the 1990s:

• The conversion of group B red blood cells into group O by an alpha-D-galactosidase from taro (Colocasia esculenta). Carbohydr Res 1991 Sep 18; 217:191-200.

Looking back, I think that I first became aware of the possibility of enzymes to cleave ABO blood group antigens in this 1994 paper and accompanying editorial:

• Goldstein J, Galbraith RA. Transfusions to group O subjects of 2 units of red cells enzymatically converted from group B to group O. Transfusion 1994 Mar; 34(3):209-14.
• Wilson RB, Spitalnik SL. Designer red cells. (editorial)Transfusion 1994 Mar; 34(3):189-91.

These early papers made nice discussion papers for students as they dealt with enzymes from coffee beans, soybeans, and taro (novelty) and helped reinforce the sugars responsible for group A and B antigens.

My joke when teaching ABO blood group chemistry was that no one in the transfusion service ran around asking for a crossmatch for two alpha-D-galactose red cells. <8-)

One problem was that the research dealt with converting B cells into group O red cells (stripping the terminal alpha-D-galactose) and would be more useful if A rbc could be converted using a naturally occurring alpha-N-acetylgalactosaminidase, since group A has a higher frequency in Western Europe and North America.

Another was that the research could not be applied to large scale production despite in vivo studies such as this one:

• Lenny LL, Hurst R, Goldstein J, Benjamin LJ, Jones RL. Single-unit transfusions of RBC enzymatically converted from group B to group O to A and O normal volunteers. Blood 1991 Mar 15;77(6):1383-8. (note link to full free text)

In a way, the current headlines remind me of the unmet promise of "artificial blood substitutes" (perfluorocarbons and hemoglobin-based oxygen carriers) whose history dates back to the 1960s. We have been waiting a long time!

Many of the news items on the possibility of converting other blood groups to group O include precautions. As noted by Ian Franklin, the national medical and scientific director of the Scottish National Blood Transfusion Service, in the Scotsman:

• "There are many hurdles to overcome, from changing the blood groups of samples in the laboratory to making this technique available to patients."

Quite an understatement by Dr. Franklin. Moreover, the conversion process would need to be cost-effective when applied to large-scale production (millions of blood donors annually).

So, will blood shortages may be passé any time soon? My guess is that this French saying applies:

• Plus ça change, plus c'est la même chose.

Keep on donating!

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