Sickle cell disease is a family of inherited blood disorders afflicting millions worldwide, primarily those with ancestors from Africa, the Mediterranean and India. The disorders involve the production of abnormal forms of hemoglobin, the oxygen-carrying component of red blood cells. When depleted of oxygen, this sickle hemoglobin forms rigid polymers that cause the normally pliable blood cells to stiffen and contort into jagged shapes. These sickle-shaped cells block small vessels and cause vascular inflammation and other changes that further inhibit blood transport. Lack of blood flow results in ischemia, the damage and death of cells and tissues deprived of oxygen and nutrients, and acute episodes of severe pain in the chest, back, abdomen or extremities.
Experts say repeated crises result in damage to such organs as the kidneys and blood vessels.
To reduce the impact of sickle episodes, the CytRx Corporation of Norcross, Ga., is testing a compound called Flocor that it says improves blood flow in ischemic tissue by inhibiting adhesive interactions and lowering blood viscosity. The company says early tests indicate the chemical can shorten crises by acting as a lubricant, allowing sickled blood cells to flow more easily through tight vessels. Dr. R. Martin Emanuele, the company's vice president for research, said Flocor was a highly purified version of poloxamer 188, an emulsifying chemical used in food products and other drugs to change the surface tension of oil-water mixtures. Flocor is being tested at 46 hospitals around the country in a trial involving sickle cell patients in crisis. The study is expected to be completed by the end of the year.