AP Biology Ending Type O Blood Shortages

Ending Type O Blood Shortages

Every year in the United States, 5 five million patients receive “approximately 14 million units of red blood cells (RBCs) according to the American Association of Blood Banks”.[5] However, seven out of ten incidents classified as a serious hazard of transfusion (SHOT) are categorized as IBCT or incorrect blood component transfused.[3] IBCT occurs when Type A blood is transfused into someone incompatible with Type A, e.g. a person with Type B. The result of this error is acute hemolytic transfusion reaction (HTR) and according to the Food and Drug Administration, it has accounted for up to 51% of transfusion-related fatalities at one time.[1,6] Since then, IBCT-related deaths have fallen and now average around 10%, but even at this reduced rate, it is still unacceptable. Fortunately, in 2007, a multinational group of scientists discovered two bacterial glycosidases that have the ability to cleave the ABO antigens on any type of blood and efficiently produce Type O blood and thus, potentially eliminate all fatalities associated with the problem of IBCT.
The problem is caused by the presence of ABO antigens (which define blood type) on red blood cells. For Type A blood, it is the monosaccharide N-acetylgalactosamine (GalNAc), for Type B, it is galactose (Gal), but for Type O there is none.[4] To avoid the issue of HTR, in 1982, Dr. Jack Goldstein of the Kimbell Research Institute first came up with the solution of cleaving these antigens using glycolytic enzymes.[5] He used the enzyme -N-acetylgalactosidase derived from chicken liver to remove A antigens and galatcosidase from coffee beans for removing B antigens. Although his experiments proved the feasibility of converting blood cells to Type O, the enzymes he used were not very efficient and required an acidic pH optimum of 5.5.
Less than twenty-five years later, a group of scientists in collaboration with ZymeQuest Inc. began searching for bacterial glycosidases from an array of 2500 bacterial and fungal specimens.[5] In April 2007, they found the two that would remove the problematic antigens from RBCs efficiently, and at a neutral pH. The process for converting regular RBCs to enzyme converted to group O (ECO) RBCs would involve three steps. First, the enzyme is added to a unit containing either A, B, or AB cells. Then, the solution is incubated at room temperature for one hour. Finally, the unit containing the ECO RBCs is washed to remove excess enzyme and monosaccharides. The entire process would take only 90 minutes to complete. The the new ECO RBCs would have different serological properties, i.e. they would lack A, B, or AB antigens, but would function as normal type O blood.
Currently, ECO RBCs are shown to be just as effective as natural type O blood. After the 1991 Phase I clinical trials were conducted successfully, the study went into Phase II which involved transfusing full units as opposed to small infusions.[5] So far, tests have revealed that ECO RBCs are not attacked by antibodies and are very safe.
This discovery is a remarkable landmark in human medicine. Now that a cost-efficient way of converting any type of blood to the universal blood type at a neutral pH has been found, no longer will blood banks have to worry about shortages of type O. Since the military and hospitals constantly use type O blood, demand is great and this new achievement will serve to alleviate it. However, the reason why this hasn't been implemented yet, according to Professor Henrik Clausen, one of the original researchers, is that “it is generally predicted that drugs take 10-15 yrs [sic] from discovery to market” due to clinical trials.[2] Despite this delay, once the process is complete, this discovery will help save many lives not only in the United States but all over the world.

References
1. “Blood Transfusion Related Fatalities.” BloodBook.com. 5 Feb. 2001. Center for Biologics Evaluation and Research (CBER). 23 May 2009 <http://www.bloodbook.com/death-notify.html>.
2. Clausen, Henrik. E-mail interview. 21 May 2009.
3. Cohen, Hannah, and Dorothy Stainsby. “Summary of Annual Report 2004.” Serious Hazards of Transfusion. 2004. Manchester Blood Transfusion Centre. 23 May 2009 <http://www.shotuk.org/SUMMARY%202004.pdf>.
4. Liu, Qiyong P, et al. “Bacterial glycosidases for the production of universal red blood cells.” Nature Biotechnology 25.4 (2007): 454-464.
5. Olsson, Martin L., and Henrik Clausen. “Modifying the red cell surface: towards an ABO-universal blood supply.” British Journal of Haematology 140 (Oct. 2007): 3-12.
6. Sazama, K. “Reports of 355 transfusion-associated deaths: 1976 through 1985.” Transfusion 30 (1990): 583-590.