Chief Science Correspondent
Animal testing has been an extremely controversial issue for both science and animal rights activists for decades. However, some argue that trends within research have made the need for live animal subjects less critical than ten years ago.
Scientists have two general options when studying organismal biology: in vivo or in vitro. In vivo research involves whole organisms. If a cancer biologist studies melanoma in rats, there will be rats with skin cancer. If the biologist is studying melanoma in vitro, they will be studying the cancer in either infected cell or tissue culture.
In vitro testing generally tends to be less controversial than in vivo testing because the study does not inflict pain or death on its “subjects.” Although animals are generally killed to obtain cell and tissue cultures, the death of one organism results in a culture line that can be maintained almost indefinitely and sold commercially to researchers. In some ways, in vitro culturing appears more efficient.
However, in vitro research cannot replace the value of studying an animal. Additionally, in vivo is not necessarily superior to in vitro. Both offer their own advantages and disadvantages.
In vitro testing is ideal for testing a single factor within a conserved system. It provides an efficient way to see answer a basic question, such as how the density of cells, affects cell death. Often, studying whole organisms can present a challenge because signaling networks are so complex that often a single factor can prompt numerous unintended effects. Additionally, it can be difficult to completely control an in vivo experiment.
However, in vitro testing can be limiting because it does not necessarily tell the whole story. The results from the rat tissue culture cancer study will not provide the researchers with information on how treatments can impact the physical progression of the disease. A whole-organism study, on the other hand, would provide physiological, physical and behavioral symptoms of the disease when the organisms are held under certain treatments and conditions.
As an undergraduate, I worked for a professor who was interested in how aquatic organisms are affected by changes in temperature. For my project, I studied how a population of fish adjusted various physiological processes in response to temperature changes in tanks, which I controlled within the laboratory. (My study would not technically be considered in vivo, because I actually tested the tissues of the organism after extracting and freezing them. However, it did involve the handling and sacrifice of a group of animals)
Our laboratory is also interested in how temperature affects fish cells at a more basic level. Therefore, other students in our group have performed temperature experiments on a line of fish cells. Together, these results provide us with two different aspects of fish physiology: How temperature affects an entire system, and the mechanism of how temperature affects one isolated component of the system.
My professor once told me that I should not feel badly about sacrificing an organism (whether it was a plant, an animal or a bacterium) as long as I used it to the fullest extent. Scientists generally do not undertake in vivo experiments unnecessarily, as they often offer the most relevant information.
Even as we find new ways to perform research, we should not forget that it is in vivo experiments that have provided the answer to many of our scientific inquiries, especially in relation. to human medicine. However, the number of methods through which a scientist can perform research is rapidly expanding.
As time passes, we will likely continue to discover more and more ways to answer the world’s biological questions. We should therefore make every effort to use the best ways possible to maximize our overall progression for biology and medicine based on the tools we have worked to develop.