Blood Substitute Made From Cattle Is Tested in Humans
DALLAS (AP) _ A blood substitute derived from cows has been tested successfully in humans and could be used to prevent transmitting AIDS, hepatitis and other diseases in blood transfusions, competing researchers said Friday.
The first tests took place on volunteers in Guatemala last spring, said Dr. Ted Jacobs, medical director of Biopure Corp. of Boston, which has received permission to begin the test on humans in the United States.
Humans also successfully received a blood substitute derived from cows in tests last fall in Zaire, said Dr. Mario Feola, a researcher at Texas Tech Health Science Center who developed the competing product.
However, Dr. S. Gerald Sandler, chief medical officer of blood service at the American Red Cross, cautioned: ″Bovine hemoglobin and other hemoglobin solutions are limited to the function of carrying oxygen and carbon dioxide″ and have yet to offer the same needs of other blood components.
″They do not provide the treatments for which we use plasma and platlets. They are substitutes for red blood cells,″ he said. ″The No. 1 use of these products would be in the emergency situation where the demand for blood exceeds that stored in a hospital or where ... a rare or uncommon blood type is not readily available.″
Researchers have been searching for a blood substitute for a century to help patients whose blood has trouble carrying oxygen, Jacobs said.
″Approximately 70 percent to 80 percent of people who receive blood transfusions do so for oxygen-transport reasons,″ he said.
A blood substitute also could provide protection from AIDS transmission, the researchers said.
Feola said the blood substitute could lead to safer blood transfusions, especially in countries where AIDS testing is not routinely done. Cattle blood is not susceptible to diseases such as hepatitis and acquired immune deficiency syndrome, which can be transmitted by human blood.
The bovine hemoglobin, purified and modified through a process developed at Texas Tech, was tested on nine children suffering from sickle cell anemia at the Center for Sickle Cell Anemia in Kinshasa, Zaire, Feola said.
The modified hemoglobin produced no immunologic or toxic reaction, nor any kidney malfunction in the nine, said Feola.
The patients were tested several times during a six-month period after the infusions. Their blood samples showed no antibodies against the solution. Feola said the substance appeared to stimulate bone marrow to develop new red blood cells for about three months.
″It served as a blood transfusion in the immediate sense and prolonged effect of stimulated bone marrow,″ he said.
Feola said clinical tests are expected to be conducted in Europe this summer.
The Food and Drug Administration-approved U.S. tests of Biopure’s product will begin this month or next, Jacobs said in a telephone interview from Boston.
He would not discuss details of the Guatemala testing, saying, ″The study has not been completed in terms of its final form, and it is premature to comment on it.″
Hemoglobin is the same among all mammals, but additional proteins attached to the hemoglobin results in blood differences among mammals and varied blood types among humans. Blood typing in humans prevents human blood from being interchangeable without severe reactions.
The process developed by the Texas Tech researchers makes a ″generic″ hemoglobin by stripping the cow blood of red cells, white cells, plasma and other biological matter. The hemoglobin, extracted from Hereford cattle, is then purified and combined with chemical compounds that enhance its oxygen- carrying capacity and prevent kidney damage.
Feola had previously tested the bovine hemoglobin solution successfully in rabbits, dogs and monkeys. He has been working on the blood substitute for 15 years, the last seven with Dr. Jan S. Simoni of Poland. He also spent time with the Biopure researchers, Jacobs said.
He concentrated his research on cattle blood because of its large-scale availability, the existence of a uniform type of hemoglobin in Hereford cattle, the similarity of molecular structure with human hemoglobin and a greater capacity for oxygen transport than found in human blood.