The alternative method to animal experiments is based on 3Rs (Replacement, Reduction, Refinement) of animal experiments. The use of an alternative method to animal experiment has become a global trend in chemical substances, pharmaceuticals, medical equipment, agrochemicals, as well as cosmetics for which animal testing within the EU area was prohibited by the EU directive. Here, the progress of alternative method research to animal experiment in Japan, and recent topics on the development of “replacement” in cell culture, non mammalian, non vertebrates and in silico as technical aspects are described.

Non-animal alternative test methods have developed in the field of genotoxicity, endocrine disrupter, irritation and skin sensitization, and these are used the safety evaluation of chemical, pesticide, pharmaceutical and cosmetic for regulatory use. For the systemic toxicological endpoints of repeated dose toxicity, carcinogenicity, immunotoxicity and reproductive toxicity, new test methods are expected to be developed in the future worldwide. I believe Japan will make a significant contribution to these developments.

Animal-free and mechanism-based understanding of human body responses is the ultimate goal of alternative to animal experiments. To achieve this goal, integration of advanced cell-based assays using iPS/ES cell technologies with various numerical methods are required. In this review, from the standpoint of tissue engineering, we focused first on the enhancement of physiological relevance of tissue culture models by overcoming the problem between 3D cellular organization and oxygen/nutrient supply. Second, we summarized the concept and actual systems of microfluidic-based body/organ on-a-chip systems, also called as microphysiological system, MPS, particularly for liver on-a-chip systems. Finally, remaining issues were discussed to realize better physiological relevance in vitro.

Animal experiments have occupied an important position in the safety assessment of chemicals. However, due to the rise in animal welfare as seen in the ban of animal experiments in European cosmetic development, the development of alternative methods for animal experiments has become very important in recent years. Development of in vitro tests for local toxicity such as irritation and sensitization tests is preceded. Meanwhile, alternative tests for systemic toxicity such as chronic and developmental toxicities are under development. In developing alternative methods using cultured cells, we have been focusing on pluripotent stem cells such as ES and iPS cells and studying alternatives to developmental toxicity and neurotoxicity. As an alternative test of developmental toxicity, we developed the Hand 1-Luc EST, which is a simple test utilizing cardiomyocyte differentiation process of mouse ES cells, and Tubb 3- and Reln-Luc ESTs using nerve differentiation process. Recently, it was clarified that the combination of the Hand 1-Luc EST and the Tubb 3- and Reln-Luc ESTs improves the prediction of the developmental toxicity. In the study of in vitro neurotoxicity test using neurons derived from mouse ES cells, evaluation methods for neurite outgrowth using high-content imaging technology and for neural function using multi-electrode arrays were developed. In addition, we introduce differentiation methods for retinal tissues from human ES/iPS cells, which are the results as the collaboration with RIKEN and the present state of an in vitro phototoxicity test using retinal pigment epithelial cells (RPE) derived from human ES cells.

For research and development (R&D) of new drugs, animal experimentation is indispensable, and research institutes, pharmaceutical companies, or contract research organizations routinely conduct preclinical studies of efficacy, safety, or metabolism using laboratory animals. However, animal experimentation entails some organizational risks. One is the suspension of R&D of a new drug, because in the course of clinical studies it becomes apparent that the drug has limited efficacy, unexpected side effects, and/or unexpected metabolites. Another risk is damage to the company image by development of an unfavorable reputation. Society has accepted animal experimentation as a necessary evil, but if such experimentation is not conducted with adequate concern for animal welfare, social sanctions will against that institute, company or organization will result. Once this happens, it is difficult to recover a good public image. Therefore, pharmaceutical companies must conduct animal experiments so as to obtain highly useful data without sacrificing public favor. One way to maintain a good reputation is through third-party accreditation, which verifies that the institute, company or organization and its researchers value animal welfare appropriately.

Sucroferric oxyhydroxide (P-TOL^® chewable tablets, 250 and 500 mg) is a phosphate binder for oral use; it is composed of polynuclear iron (III)-oxyhydroxide, sucrose, and starches, and is currently indicated for alleviating hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis. The results of non-clinical pharmacological studies have suggested that P-TOL consistently decreases serum phosphorus levels in the aqueous environment at pH levels similar to those in the gastrointestinal tract, thereby suppressing the progression of secondary hyperparathyroidism, aberrant calcification, and abnormal bone metabolism associated with hyperphosphatemia. Since the diameter of the P-TOL tablet exceeds 15 mm, it is manufactured with a doughnut-shape to minimize choking hazards. From the results of pharmaceutical studies, it was indicated that the P-TOL tablets promptly disintegrated in the gastrointestinal tract and excessive iron uptake from this product is unlikely to occur. In clinical studies, P-TOL (one tablet/dose, t.i.d.) decreased serum phosphorus levels during treatment Week 1 and allowed stable, long-term control of serum phosphorus levels. Furthermore, P-TOL was expected to reduce the tablet burden on patients and to improve medication adherence. The most common adverse reaction was diarrhea. However, in most cases, the symptoms were mild and oral administration of P-TOL could be continued. Although iron-related parameters tended to increase, iron uptake from this product was low, and the risk of iron overload was considered to be low. These findings confirm the efficacy and safety of P-TOL in CKD patients with hyperphosphatemia. Therefore, sucroferric oxyhydroxide therapy is a potentially useful treatment option for hyperphosphatemia.