ABSTRACT
This chapter focuses on some inherent limitations of the nude mouse-human tumor model, particularly those disadvantages that have received most attention in the literature. Human tumor xenografts in nude mice are regarded as the best model available for the study of human tumor biology. A tumor's blood supply is generally regarded as one of the main limiting factors for tumor expansion and growth. Hormones, various enzymes, and other physiological host factors may also be of influence on the growth and the biological characteristics of the human tumor cells in xenografts. One major argument against the validity of biological studies in human tumor xenografts has been the changes observed in tumor characteristics during consecutive transfer. Tumorigenicity in nude mice is regarded as the most stringent criterion for successful malignant transformation of non-tumorigenic cells. Xenografts in nude mice provide the best available model for studies on human tumor biology in vivo.
