Oxygen carrier promising for sickle cell disease

NEW YORK, Ag 31 (Reuters) A new red blood cell substitute improved the survival of mice with sickle cell disease that were subjected to conditions to simulated a sickle cell crisis, Canadian researchers report in the medical journal Anesthesiology.

The new drug candidate, HRC 101 from Henosol, is a hemoglobin-based oxygen carrier that improved survival in mice genetically modified to have a condition similar to sickle cell disease. Reducing levels of oxygen simulated a sickle cell crisis in these animals.

Dr Mark W Crawford and colleagues at the Hospital for Sick Children and the University of Toronto note that there are risks associated with the use of red blood cell transfusions to treat children during a sickle cell crisis.

Sickle cell disease, also called sickle cell anemia, is an inherited condition in which the body produces red blood cells that have a sickled, rather than an oval, appearance. Because these sickle cells are not efficient, patients become anemic and the cells periodically obstruct blood flow. This affects blood flow to major organs and other parts of the body, depriving them of oxygen and causing a sickle cell crisis.

To investigate the protective effect of HRC 101 in such circumstances, the researchers administered 0.02 mL/g of the agent or placebo to regular mice and sickle cell mice.

The animals, which were breathing freely under anesthesia, were given normal 30-percent oxygen (controls) or 6-per cent oxygen to induce oxygen deprivation for 60 minutes.

All of the control mice survived, but all of the sickle cell mice given placebo died in an average of 9 minutes.

However, after receiving the 6-per cent oxygen plus HRC 101, four of the 12 mice with sickle cell disease survived. Although the remaining eight mice died, their average survival time was extended to 48 minutes.

These results, conclude the investigators, show that HRC 101 ''protects sickle mice from the lethal effects of acute, severe'' oxygen deprivation. ''Further studies are needed to define the mechanisms responsible for this effect,'' the team added.

REUTERS SV ND0846