Haematogenous Models of Metastases

Abstract

Animal models of cancer and of metastasis in particular, provide a critical link between in vitro studies and the treatment of human disease. Animal models allow scientists to understand and interpret disease pathogenesis in an environment in which metastatic cells are constantly bombarded by autocrine, paracrine, and endocrine signals from a multitude of sources. Disease pathogenesis can only be elucidated through observation of organs, organ systems, and, ultimately, whole organisms. In addition to contributing to our knowledge of disease pathogenesis, animal models also provide an avenue for testing both the safety and efficacy of various anti-metastatic drugs and biological compounds. Animal models allow interpretation of the physiological effects of administrating a drug or biological compound in a complex organism. In this respect, animal models are critical to the drug development process and are a required element of the drug approval process. Within the umbrella term ‘animal models’, there are various types of models that present unique advantages and disadvantages to understanding metastasis and the ability to test anti-metastatic compounds. Ideally, animal models that closely mimic human cancers, with respect to disease duration, progression, mode of dissemination, and metastatic location, are desirable. However, due to the often inefficiency that is inherent in the metastatic process, animal models in which metastasis takes many years to develop are impractical. To overcome this innate obstacle, several different types of animal models have been developed to expedite the metastatic process: there are ectopic models, in which malignant cells are explanted into foreign locations on the animal, and there are haematogenous models of metastasis, in which cells are dispersed into circulation with the intention of simulating a natural course of dissemination.