The scientific and logistical limitations incurred by the use of animal models of humans within biomedical research and toxicity testing are substantial, and increasingly recognized; as is social concern about, and consequent regulatory restriction of, laboratory animal use. In defiance of these factors, such use remains enormous. Based on best estimates, 11,154,961 living non-human vertebrates were subjected to fundamental or medically-applied biomedical research, toxicity testing, or educational use, within Japan, in 2004; which was second only to the US. Additionally, the use of genetically-modified animals, and the implementation of large-scale chemical testing programs, are increasing laboratory animal use internationally. These trends demonstrate the need for considerably greater awareness of, and compliance with, the principles of the 3Rs—namely, the replacement, reduction and refinement of laboratory animal use—within governmental, academic and commercial sectors. These principles are widely recognized as essential to good laboratory animal practice. They may increase research quality and the robustness of outcomes, result in reduced timeframes and resource consumption, and jointly benefit consumers, industry and laboratory animals. An overview of 3Rs principles, and of strategies likely to increase their implementation, is therefore provided. Combinations of such strategies may have synergistic effects, improving both scientific outcomes and animal welfare
The embryonic stem cell test (EST) is an in vitro assay that has been developed to assess the embryotoxic potential of chemicals and biomaterials. It is based on the capacity of the mouse embryonic stem cell line D3 (ES-D3 cells) to differentiate into contracting myocardial cells. However, the EST method cannot fully test the embryotoxicity of mercury vapor. We tried to apply the rotary culture bottle containing mercury vapor and culture medium was slowly turned and the cells come into direct contact with the gaseous phase containing mercury vapor. At the mercury exposure concentrations tested in this study, no cell pulsations were observed. The cell viability was affected to some extent in the 5.0μg mercury concentration group, whereas in the 2.0μg group little difference was observed from that of the control group. Although mercury vapor was observed to strongly impair the differentiation of EBs in this study, the test results this time did not prove that mercury vapor has a strong embryotoxic effect on humans. We think it important to develop a device that closely mimics the actual exposure conditions of the human body, including an exposure method that is different from that used in this study, as an alternative to animal experiments.