New models for cancer research: human cancer stem cell xenografts.

Human cancer stem cells represent promising tools for new approaches to pathway-targeted drug discovery and preclinical screening. Because of their distinctive capability to recapitulate the development of the original tumors in vivo, the study of human cancer stem cells (CSCs) largely relies on models of xenograft transplantation into immunodeficient mice. In this frame, immunity and microenvironment-related issues need careful consideration. Here we shortly revise present knowledge on xenograft-related aspects of human CSCs studies.