RE:Success in trials using mice for human therapies Comparative medicine is built on the ability to use information from one species to understand the same processes in other species. Basic biomedical research involves the characterization of genes/proteins, the study of anatomical and physiological functions and the characterization of normal and pathological states in a variety of animal species. This knowledge is then applied to understanding these same processes in humans. Likewise, information gained in the field of human medicine can be mined to advance veterinary medicine because of the commonalities among species that form the basis of comparative medicine.
Laboratory rats and mice provide ideal animal models for biomedical research and comparative medicine studies because they have many similarities to humans in terms of anatomy and physiology. Likewise, rats, mice, and humans each have approximately 30,000 genes of which approximately 95% are shared by all three species.3–6 The use of rodents for research purposes has economic advantages: mice and rats are relatively small and require little space or resources to maintain, have short gestation times but relatively large numbers of offspring, and have fairly rapid development to adulthood and relatively short life spans. For example, mice have a gestation period of approximately 19–21 days; can be weaned at three to four weeks of age, and reach sexual maturity by five to six weeks of age, allowing large numbers of mice to be generated for studies fairly quickly.
The use of rodents also provides advantages related to the wealth of genetic information available to scientists. The human genome was sequenced in 2001,4, 5 with those of the mouse and rat following in 2002 and 2004 respectively.3, 6 The availability of the complete nucleotide sequences for all three species has enabled genome-wide comparisons across species which have been critical for the identification and characterization of genes. The ability to use sophisticated molecular genetic techniques to manipulate the genes in mice and more recently rats, allows genes to be “knocked out” (no expression) or expressed at designated times of development or in select tissues in order to better understand their normal function and/or role in disease.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987984/