FREQUENTLY ASKED QUESTIONS
General Questions

1. What is Science?
2. What is Biomedical Research?
3. What are Biomedical Research Methods?
4. What are Nonhuman Animal Models?
5. What is Clinical Research and What are Human Clinical Trials?
6. What are Epidemiological Studies?
7. What Difference has Biomedical Research Made to Human Health?

FAQ — The Care of Use of Animals in Biomedical Research (8-15)

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4. WHAT ARE NONHUMAN ANIMAL MODELS?
(Taken from Unit I, Chapter 3, of the Rx for Science Literacy teacher manual.)

Introduction: For ethical and other reasons, it is often not feasible to conduct experimental studies of disease and its treatment on humans. Instead, animal models are used. Animals provide the best known surrogate for humans in the laboratory.

Although diseases and drug reactions vary between humans and nonhuman animals, the similarities outweigh the differences. Scientists strive to develop a clear understanding of how animal species differ. By combining what they know about the differences with knowledge of our biological similarities, scientists can apply results from animal experiments to the human condition.

Animals are a vital research model because they provide a whole, complex living system that can interact and react to stimuli much as humans do. They give us an indication of how people may recover from a new surgical technique or respond to the long-term effects of a new medicine. They permit us to discover how a drug, chemical or environmental factor interacts with different organs and systems, and the different routes a substance may take when swallowed, inhaled, injected, absorbed and excreted.

Strengths: Animal models provide an ethical alternative to the use of humans in experimental studies in the search for treatment, cures and prevention of diseases and disabilities.

They also provide a whole, integrated biological system and are the best surrogate for the complexities of the human system. Human and non-human animal similarities far outweigh their differences. Animals share the same structures (cells, tissues, organs and systems), as humans, and they function in much the same way as in humans.

By using animal models scientists can design experiments where they can control for more variables than with humans.

Limitations: Because animals are not identical to humans, the results from experimental animal studies must be extrapolated to humans.

In addition, a whole-animal model introduces more variables than, for example, a cell or tissue culture.

Research animals are also expensive to purchase, house, feed and provide with veterinary care.

The use of animals in research is governed by an extensive, time-consuming and costly system of federal regulation.

Examples of animal models include:

Cystic fibrosis (CF): A mouse has been genetically engineered to provide the first animal model for CF. This breakthrough will allow quicker exploration of new treatments for the deadly disease.

Accidents: Primates have been used to develop ways to restore muscle function to human limbs paralyzed by spinal cord damage.

Heart disease: Dogs have played a crucial role in developing prosthetic devices for replacing congenitally defective heart valves. The pig is an excellent model for evaluating ways to prevent blood vessels from narrowing (restenosis) after they have been opened using a nonsurgical procedure. Rabbits have been very important in the study of hypertension (high blood pressure) and atherosclerosis (hardening of the arteries).

Vaccines and infectious diseases: A variety of animal models, from rodents to primates, have been indispensable in developing and safety-testing vaccines.

AIDS: The recent development of a monkey model is a major advance for vaccine and therapy studies of the AIDS virus.

Hepatitis B and C: Woodchucks infected with the woodchuck hepatitis virus (WHV), a virus closely related to the human hepatitis B virus, develops severe hepatitis and liver cancer. They are an ideal model to test new drugs and other strategies to treat hepatitis B in humans.

Anthrax: Rabbits exposed to anthrax spores develop a disease very similar to humans. The guinea pig is also a useful model for studying the effectiveness of anthrax vaccines.

Wound healing: Pigs are one of the best models for studying the healing process because the repair process is similar to humans.

Leprosy (Hansen’s disease): Naturally occurring leprosy is found in wild armadillos. It is still impossible to grow the bacteria that causes the disease in vitro, so armadillos are the only source of organisms for study and vaccine preparation.

Diabetes: Dogs and humans share similar complications of diabetes, and researchers are using them for transplanting the insulin-producing islet cells of the pancreas to reverse the disease.

Cancer: Scientists have developed mice with leukemia, breast cancer and many other types of cancer, allowing new treatments to be tested.

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