Mesenchymal Stem Cells and Cancer — for Better or for Worse?

The importance of the microenvironment and stroma in the evolution and progression of solid tumors has re-emerged in the past few years. Recently, mesenchymal stem cells (MSCs), which are the progenitors of stromal cells and fibroblasts, have also been found to interact with cancer cells. Most commonly isolated from the bone marrow, MSCs are multipotent adult stem cells with immunomodulatory effects and the ability to home to sites of injury. These properties, clearly useful for therapeutic purposes, have recently been found to be abused by cancer cells for their own end. However, reports also show that MSCs can inhibit tumor growth under certain circumstances. This review briefly describes what is currently known about this emerging field of cancer-MSC biology, which is bringing new knowledge to an old disease and may hopefully reveal new ideas and targets for treatment.