Animal models are becoming obsolete with the development of new technologies and improvements in traditional methodologies (like epidemiological studies and clinical trials) that can greatly add to our knowledge pool. The methodologies we will describe in this section hold the promise of being more predictive than animal models ever could be because they have more direct relevance to humans from the start.
In the medical realm, modern science has produced a myriad of technological innovations and methodologies without sacrificing animals, including:
- Functional MRI and PET scanners that can peer into living, functioning tissue and organs noninvasively.
- Microscopes that can view three-dimensional images of the inner workings of a cell.
- Microarrays – high-throughput (rapidly produces a substantial amount of data) screening methods that can be used for multiple purposes, from measuring expression levels for thousands of genes to testing thousands of chemicals as potential drug targets faster, cheaper, and with greater relevance.
- Microchips that simulate the activities and mechanics of entire organs.
- Polymerase chain reaction – a molecular biology technique that amplifies DNA and is used for multiple purposes, including the functional analysis of genes, the diagnosis of hereditary diseases, and the detection of infectious diseases.
- Sophisticated new statistical methods for analyzing epidemiological data.
- Mathematical and computer models to study disease and develop new drugs.
These methods give us relevant, invaluable data that animal models can never provide.
Modification of traditional human studies, like clinical trials, can enable the collection of more human-relevant data about response to drugs, while minimizing animal use. Introduction of another phase to clinical trials -- “phase zero” -- would enable just a few human volunteers to receive sub-therapeutic amounts of new drugs (microdosing). From these studies, the fate of the compound in the human body can be determined over time. Because the microdose of the new compound is so low, the risk to the human volunteer is very small. And this kind of testing paradigm holds great potential for substantially reducing the number of animals used in safety, pharmacologic, and toxicity studies of new compounds, because if a new compound does not have a desired effect in humans, than the compound would not have to undergo additional safety studies in animals. Also, microdosing has the added benefit of using the most relevant testing platform for people, humans; therefore, this testing methodology should turn out to be more predictive than the animal models currently used. The phase zero studies can also be extended to determine individual responses to drugs, which can be integrated as an essential part of individualized medicine.
The National Institutes of Health (NIH) has recognized that animal models may not accurately predict drug efficacy in people, and they are supporting the generation of more reliable and predictive models. Dr. Francis Collins, Director of the NIH, recently stated that transitioning to models which rely on human tissues and stem cells, combined with improvements in assay validation, may make it “justifiable to skip the animal model assessment of efficacy altogether.” One of the most ambitious projects in this area of research involves generating micro-sized models of human physiological systems for use in toxicology studies. The use of different human cell types, in combination, will generate micro-sized physiological systems which can "talk to each other" and better address the biological complexities of whole living organisms. This “human body on a chip” technology would allow scientists to look for specific profiles in cells that would help identify safe compounds to test in people. This technology represents significant advantages over animal models because it would rely on human cells, and is more likely to be predictive of what happens in people.
Personalized Medicine: The Future Is Now
Recent advances in genetics and genomics have made it possible for scientists to begin to understand the molecular basis of human disease, and how genetic differences between human beings can influence disease diagnosis, prognosis, prevention, and response to treatments. Doctors have long known that the “one size fits all” approach to healthcare is not as accurate (or safe) as it could be. The promise of personalized medicine is that an individual patient’s healthcare can be customized, taking into account their specific genetic makeup. The notion that improving our knowledge of what our DNA encodes for, how it is regulated, and which changes in DNA sequences or expression are correlated to specific medical conditions, (e.g., disease states, rate of drug metabolism, etc.) may be beneficial to improving health care has caught the attention of many of the most prestigious medical institutions around the world, as they already have or are developing personalized medicine programs. This alone speaks to the great potential that scientists see in this line of investigation and its ability to customize preventive, diagnostic, and therapeutic interventions to optimize healthcare.
Traditionally, personalized medicine has been limited to the consideration of a patient's family history, social circumstances, environment, and behaviors in tailoring individual care. But today, we are on the verge of appreciating how a patient’s genetic makeup may influence their disease susceptibility, progression, and response to treatment. Genomics, proteomics, metabolomics, pharmacogenomics and other emerging developments hold the promise of basing treatment on the individual signature of each patient’s specific disease.
While personalized medicine has not had a direct impact on the health care of most individuals yet, there are some impressive advances that have been made in the realm of clinical medicine:
- New cancer therapeutics have been developed.
- Genetic tests have been developed which can determine if people with breast cancer need chemotherapy and if so which therapies would be the most appropriate.
- The DNA variations that correlate to the risk of developing many common diseases have been identified.
- An individual’s response to drugs can be accurately predicted for some medicines.
- Direct-to-consumer genetic testing is available to the general public at an affordable rate.
The field of personalized medicine is really still in its infancy, but it holds great potential of being successful as long as scientists focus their time and resources on identifying genetic and environmental risk factors and determining how to translate this information to human health and well being. Amazing progress has been made in genetics in the last few years and has brought the promise of personalized medicine closer than it has ever been. As the Director of the NIH, Dr. Francis Collins, said, “Only time will tell how deep and how far that power will take us. I am willing to bet that the best is yet to come.”
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