A number of companies have attempted to develop alternatives to transfusions, generally based on modifications of the red cell oxygen transport protein hemoglobin. However, toxic side effects have been seen in a range of clinical trials. Therefore no product is currently licensed for use in the major healthcare markets of the world.
The “intrinsic toxicity” of the hemoglobin molecule is likely to be responsible for these side effects. Oxidative stress produces highly reactive “ferryl” intermediates at the heme iron and free radicals elsewhere in the protein.
“Engineering a range of hemoglobin molecules that are less likely to induce oxidative damage.”
At the University of Essex basic science funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) has revealed that introducing specific amino acid residues (tyrosine) on the hemoglobin protein can detoxify the protein. This is achieved by enabling the body’s own defences - vitamin C and uric acid - to better reduce the potentially damaging oxidative intermediates.
The University of Essex has engineered a range of novel hemoglobin molecules that have additional tyrosine residues; consequently they are less likely to induce oxidative damage. Patents have been granted in the USA and Australia and are pending in other territories.