Scientists say difficulty lies in extrapolating animal data to humansWashington—Research on traumatic spinal cord
injuries is hampered by a reliance on animal experiments that
don’t accurately predict human outcomes, says a new study in the
upcoming edition of the peer-reviewed journal Reviews in the
Neurosciences. The review was written by scientists with the Physicians
Committee for Responsible Medicine.
“Despite
decades of animal experiments, we still don’t have a drug to cure
spinal cord injury in humans,” says Aysha Akhtar, a neurologist
with PCRM and the lead author. “According to the Journal of the
American Paraplegic Society, at least 22 agents were found to improve
spinal cord injury in animals, but not one of these was helpful in
humans,” says Dr. Akhtar.
The paper
outlines the numerous problems with translating animal data into
effective human treatments, including the many variations between
laboratory-induced injuries in animals and human injuries, the
difficulties in interpreting Functional outcomes in animals, and the
multitude of inter-species differences in physiology and anatomy.
The
extrapolation problem, in general, has been widely acknowledged by
scientists of many disciplines and affiliations. According to data from
the Food and Drug Administration, more than 90 percent of drugs that
proved successful in animal tests are not approved for wider use after
clinical trials in humans. In February, three U.S. government agencies,
including the National Institutes of Health, the Environmental
Protection Agency, and the National Toxicology Program announced a
major new program aimed at ending the use of animals in safety testing
of new chemicals and drugs.
Because of the extrapolation
challenge, some fields, such as cancer research and toxicity testing,
are moving toward a greater use of alternatives. Unfortunately, spinal
cord research, a relatively newer endeavor, is not yet learning from
the failure of other fields of inquiry. As Dr. Akhtar warns, “We
need to develop new, more effective research techniques.”
Although
scientists have just begun to develop alternatives to the use of
animals in spinal cord injury research, several techniques show great
promise. Researchers at the University of Miami, for example, are
collaborating on the Human Spinal Cord Injury Model Project which uses
imaging techniques, post-mortem analysis, and nerve conduction methods
to understand human spinal cords. Other promising directions involve
computer modeling, studies on human nerve tissues, and the study of
human cadavers.
At least 250,000 Americans are living with spinal cord injuries; an estimated 10,000 Americans are diagnosed each year.
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Journalists: For a copy of the paper or an interview with Dr. Akhtar, please contact Ms. Simon Chaitowitz at 202-527-7309.
Founded
in 1985, the Physicians Committee for Responsible Medicine is a
nonprofit health organization that promotes preventive medicine,
especially good nutrition. PCRM also conducts clinical research
studies, opposes unethical human experimentation, and promotes
alternatives to animal research.