Furthermore, recent studies have identified biological processes that are specific to the human body and cannot be modelled in other animals. Nevertheless, extrapolating results from model systems to humans has become a major bottleneck in the drug discovery process.

The common principles of animal development and organ physiology derived from this approach have led to a detailed mechanistic understanding of many human diseases. Historically, the investigation of disease mechanisms in animal models has progressed along a common discovery pipeline, whereby biological processes were initially investigated by genetic screens in invertebrates, followed by an analysis of evolutionary conservation in mammalian model systems, eventually leading to clinical translation to humans. The value of the achievements these model systems have made possible is proved by the fact that their use has become near universal in biomedical research today. The use of classical cell line and animal model systems in biomedical research during the late twentieth and early twenty-first centuries has been successful in many areas, such as improving our understanding of cellular signalling pathways, identifying potential drug targets and guiding the design of candidate drugs for pathologies including cancer and infectious disease.

Pros of adult stem cells