The O’Brien lab within the Stem Cell Institute has been involved in the development, characterization, and translational applications of adult stem cells including mesenchymal stem cells and multipotent adult progenitor cells and in the development of induced pluripotent stem cells in large animal species. More recently, in collaboration with the Modiano lab, we have become involved in the characterization of cancer stem cells in canine non-Hodgkin lymphoma. The cancer stem cell theory postulates that cancers ultimately arise from cells with stem cell-like characteristics, and that it is these cells which are responsible for propagating the tumors and giving rise to all of the cellular components of the tumor. Stem cells in general tend to be slowly dividing and this and other metabolic features they possess make them more resistant to chemotherapeutic agents and radiation. Thus, it is likely that the cancer stem cells, in particular, are responsible for cancer relapses and for resistance to conventional therapies. It is our goal to understand the basic biology of these cells in canine lymphoma with the ultimate aim of applying this knowledge to the development of new therapeutic modalities targeted at the lymphoma cancer stem cells. Such therapies offer the promise of actually curing this devastating disease by destroying the cells at the root of the cancer.