Schumacher, Y. O., & Ashenden, M. (2004). Doping with artificial oxygen carriers. Sports Medicine, 34(3), 141-150.

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There is a long history of science seeking to develop artificial substitutes for body parts damaged by disease or trauma. While defective teeth and limbs are commonly replaced by imitations without major loss of functionality, the development of a substitute for red blood cells has proved elusive.

There is a permanent shortage of donor blood in western societies. Nevertheless, despite whole blood transfusions carrying measurable risks due to immunogenicity and the transmission of blood-borne infectious diseases, red blood cells are still relatively inexpensive, well-tolerated and widely available. Researchers seeking to develop products that are able to meet and perhaps exceed these criteria have responded to this difficult challenge by adopting many different approaches. Work has focused on two classes of substances: modified hemoglobin solutions and perfluorocarbon emulsions. Other approaches include the creation of artificial red cells, where hemoglobin and supporting enzyme systems are encapsulated into liposomes.

Hemoglobin is ideally suited to oxygen transport when encased by the red cell membrane; however, once removed, it rapidly dissociates and is cleared by the kidney. Therefore, it must be stabilized before it can be safely re-infused into humans. Modifications concomitantly alter the vascular half-life, oxygen affinity, and hypertensive characteristics of raw hemoglobin, which can be sourced from outdated blood stores, genetically-engineered Escherichia coli, or even bovine herds. In contrast, perfluorocarbons are entirely synthetic molecules that are capable of dissolving oxygen while being biologically inert. Since they dissolve rather than bind oxygen, their capacity to serve as a blood substitute is determined principally by the oxygen pressure gradients in the lung and at the target tissue.

Blood substitutes have important potential areas of clinical application including red cell replacement during surgery, emergency resuscitation of traumatic blood loss, oxygen therapeutic applications in radiography (oxygenation of tumor cells is beneficial to the effect of certain chemotherapeutic agents), other medical applications such as organ preservation, and finally to meet the requirements of patients who cannot receive donor blood because of religious beliefs.

Given elite athletes' historical propensity to experiment with novel doping strategies, it is likely that the burgeoning field of artificial oxygen carriers has already attracted their attention. Scientific data concerning the performance benefits associated with blood substitutes are virtually nonexistent; however, international sporting federations have been commendably proactive in adding this category to their banned substance lists. The current situation is vulnerable to exploitation by immoral athletes since there is still no accepted methodology to test for the presence of artificial oxygen carriers.

Implication. While there are speculative theoretical benefits of doping with artificial oxygen carriers, there are no scientific studies that show they are performance-enhancing. The procedures are banned by WADA as performance-enhancing despite there being no evidence to support such a spurious assumption. And yet, Draconian punishments are handed athletes found using the procedures associated with artificial oxygen carriers. That is socially irresponsible.

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