Special cells, special considerations: The challenges of bringing embryonic stem cells from the laboratory to the clinic

Human embryonic stem (ES) cells are an attractive tool for cell-based therapies because of their limitless capacity for proliferation and their ability to differentiate into all cell types of the body. However, these features introduce certain unique risks that must be considered in developing transplantation strategies for clinical use. We outline these risks and examine current approaches to address them, both before and after transplantation.