Biopure is one of the leading companies in the development and manufacture of oxygen carrying solutions. Biopure’s first-in-class product for human use is Hemopure, which is a Hemoglobin-based oxygen carrying solution (HBOC). It is also known as Hemoglobin Glutamer-250 (bovine) or HBOC 201.
Hemopure is made of chemically stabilized, cross-linked bovine (cow) hemoglobin situated in a salt solution. Hemoglobin by itself is toxic to the kidneys because it contains stroma lipids, which are contaminated with endotoxins. If the stroma lipids are removed, however, then the Hemoglobin has too high an affinity for oxygen, which means less oxygen off-loading to the tissues. In order to assure that the Hemoglobin is not toxic, but still therapeutically useful, it must be stabilized. Stabilization can be achieved through a number of methods, but Hemopure stabilizes the hemoglobin by cross-linking it. This is done by cross-linking the two alpha, and the two beta subunits. This then stabilizes the alpha-beta dimers, which in turn makes the hemoglobin molecule more stable, and also reduces its affinity for oxygen, making it easier to deliver oxygen to the tissues. A picture of the structure of hemoglobin is presented below, including the positions of the alpha and beta subunits.
Since the Hemoglobin used in Hemopure is derived from cows, Biopure goes through extensive lengths to make sure that Hemopure is: free of pathogens, infectious agents (BSE), and chemically pure, including:
Advantages of Hemopure vs. RBC’s
Hemopure is smaller in size (up to 1,000 times smaller than a typical red blood cell) and has less viscosity than human red blood cells (which contain hemoglobin). This means that it can carry more oxygen at a lower blood pressure than red blood cells. Also, because of its smaller size, it can carry oxygen through partially obstructed or restricted blood vessels, where RBC’s cannot reach, as seen in the diagrams below.
Inadequate tissue oxygenation resulting from occluded arteries can result in heart attack, angina, or transient ischemic attack, which is a precursor to stroke. Traditionally, these conditions have been treated by blood transfusions, but RBC’s are often too big to pass through the occlusion, which is why Hemopure can potentially be very helpful. Some of the trials done to demonstrate the benefits of Hemopure are below:
Where is Hemopure Now?
Hemopure is currently approved in South Africa for the use of surgical patients who are anemic, thereby reducing or eliminating the need of blood transfusions for these patients. It is currently in Phase III Clinical Trials in South Africa and Europe. In the U.S. Hemopure, is currently under review by the F.D.A. and is conducting animal studies. In March, 2003, the U.S. Naval Medical Research Center (NMRC) signed a collaborative research and development agreement with Biopure to help fund and conduct a trial on the effects of Hemopure in out-of-hospital resuscitation of patients with severe hemorrhagic shock. This trial, named “Restore Effective Survival in Shock” (RESUS) and over $14 million in Congressional, Navy, Army, and Air Force funding has been given so far to support the trauma development program for Hemopure. Hemopure has also been approved for compassionate use.