The number of animals used in preclinical studies is continuously increasing. Each year millions of experimental animals across the world are sacrificed in the name of scientific research.
The pain, distress and death experienced by the animals during scientific experiments have been an issue of debate since long. Besides the major concern of ethics, there are few more disadvantages of using animals for scientific experiments, like requirement of skilled manpower, time consuming protocols, and high cost.
Considering these disadvantages, many alternatives to animal testing have been proposed. Currently, a strategy of 3Rs (reduction, refinement, and placement) is being applied for using animals in research labs.
But, what are these 3Rs?
Here, we give a brief account of these alternatives and the advantages associated with them.
The strategy of 3Rs was first suggested by Russell and Burch in 1959 to make animal experiments more human and ethical. Their approach motivates to use minimum number of animals in an experiment, plan and refine experiments to minimize pain and distress to the animals, and finally replace higher animals with alternative methods and lower organisms.
In vitro cell cultures have provided a safe alternative to reduce the use of animals in lab testing. By using in vitro cell cultures like human hepatocyte culture, embryonic stem cell culture etc., you can easily get relevant information about the metabolism and excretion of drugs from the body.
Inclusion of these methods in study design and sharing of the discovered data will eliminate unsuitable drug compounds in preliminary stages and minimize the use of animals in further research.
When the cage environment of the animals used in experiments is not suitable, it adds to the stress on animals. Their hormone levels fluctuate and the results are not satisfactory. Thus, the experiments have to be repeated causing an increase in the use of experimental animals.
The experiments can be refined by enriching the cage environment of the experimental animals. This not only reduces the pain and discomfort in animals, but will also improve the quality of research.
Various alternatives like in vitro cell cultures, computer models, and new imaging techniques are now being used in place of experimental animals. Besides reducing the use of animals, these alternative methods are time-effective, cost-effective, and require less manpower.
a.Cell and tissue cultures
Use of in vitro cell and tissue cultures involves the growth of cells outside the body in a laboratory environment and offer an important alternative for animal experiments.
The cells and tissues from the liver, kidney, brain, skin etc. are removed from an animal and kept outside the body in a suitable growth medium for few days to several months or years.
Cell cultures are routinely used in preclinical studies to know the toxicity and efficacy of potential drug molecules. They are cost and time-effective and easy to follow.
Computers help us to understand the basic principles of biology. Specialized computer models and software programs have been designed to predict the various possible biological and toxic effects of a chemical or potential drug candidate without animal dissection.
This way unsuitable drug gets eliminated in primary screening and only the most promising ones are used for animal experimentation.
These software programs give speed and cost-effectiveness to the preclinical studies.
Owing to the ethical issues regarding the use of experimental animals like pigs, rats, dogs, and monkeys, use of alternative organisms has been proposed.
Different model organisms that can be used as alternatives to animals include micro-organisms such as bacteria and fungi, lower vertebrates like zebra fish, and invertebrates like flies.
These alternative organisms reduce the required working space, cost of laboratory solutions, test chemicals and the manpower besides the use of experimental animals.
Thus, the issue of animal ethics can’t be ignored and more efforts must be undertaken to effectively implement the 3 Rs strategy during laboratory use of animals. For this, various computer models, in vitro cell cultures, enzymatic screens, and alternative model organisms must be integrated. The integrated approach would result in minimum involvement of animals in preclinical research.