On World Day for Laboratory Animals (24th April 2024), we recognize the invaluable contributions of animals to science and medicine by serving as a bridge between laboratory experiments and human clinical trials. However, the use of animals in medical research remains a topic of ethical debate and concern. In this blog, we will explore the reasons behind using animals in medical studies, the ethical considerations surrounding this practice, and the ongoing efforts to refine and reduce animal experimentation.
Animal models in medical research
Animal models have long been the cornerstone of biomedical research and continue to be so. They have contributed to numerous medical breakthroughs and are crucial to understanding drug development and disease processes. The discovery of insulin by Banting and Best in the 1920s exemplifies the impact of animal research on medical progress, revolutionizing diabetes treatment and saving countless lives. Nobel Prize-winning studies on the immunological basis of organ rejection, utilizing dogs, and on eye disorders such as strabismus and amblyopia, utilizing cats, further underscore the significant role of animal models in scientific progress. Since the 1970s, there has been a notable decline in the use of dogs and cats, with rodents comprising the majority (around 95%) of research animals in the U.S., while dogs, cats, and primates collectively account for less than 1%.
Limitations of animal models
Although valuable, animal models present ethical, practical, and predictive limitations. Their translation into human biology can be challenging; they are expensive to maintain, and they raise ethical concerns. The reliability of animal testing in predicting human responses to substances is questionable due to species-specific differences. Human diseases artificially induced in laboratory animals may not accurately reflect the human condition, influencing the reliability of test results. Additionally, variations in experimental conditions such as age, sex, diet, and environment within laboratory settings contribute to inconsistent results across different facilities.
In vitro 3D modeling: A promising alternative
In recent years, there has been a growing shift towards developing advanced in vitro models to replace traditional animal models. One of the most promising advancements in this area is the development of 3D cell cultures, leveraging human-derived cells or tissues obtained directly from patients. These models mimic the 3D structure, functions, and mechanical properties of human organs or tissues, providing a more physiologically relevant environment. By enabling personalized medicine, disease modeling, and predictive drug testing, patient-derived in vitro models hold promise for optimizing treatment outcomes and improving patient care. Moreover, in vitro models reduce animal use, lower costs, and speed up drug discovery.
Shifting from animal models to 3D in vitro models aligns with the 3Rs, first defined by Russell and Burch over 50 years ago:
- Replace animals in research where possible.
- Reduce their use.
- Refine procedures to minimize suffering.
The 3Rs concept has since been expanded in some contexts to include a fourth R: responsibility, advocating for a responsible attitude towards the care and use of animals in research.
Notably, the FDA no longer requires animal testing for all drugs before human trials. The Modernization Act 2.0 eliminates the requirement for medicine development to undergo animal testing. However, making the switch will take time. Addressing challenges such as sample availability, standardization, and scalability is essential to unlock their full potential in pre- and clinical applications.
Animal models in drug development
Despite advancements in in vitro models, animal models remain indispensable in drug development. They play critical roles in preclinical safety assessment, providing insights into potential toxic effects and guiding dosage determination. They also enable pharmacokinetics and pharmacodynamics studies, offering valuable information on drug behavior in living organisms that cannot be replicated in vitro. Additionally, they replicate human disease complexity and test novel treatments within a physiological context, providing comprehension of systemic effects and treatment outcomes in complex disease areas such as neurological disorders.
Conclusion
World Day for Laboratory Animals is a poignant reminder of our responsibility to protect and respect animal rights, especially in scientific and medical research. Although animal study is still essential for many complex areas of medicine, advances in in vitro models offer a promising path to reducing our reliance on traditional animal models. By embracing the principles of the 4Rs, scientific and medical research can make significant strides in ethical practices while advancing our understanding of diseases and the development of life-saving treatments. It is a testament to our commitment to science and compassion for all living beings.
References
https://www.understandinganimalresearch.org.uk/what-is-animal-research/myths-and-facts
https://med.stanford.edu/animalresearch/facts-and-myths.html
