Using stem cells in the treatment of cancer has stirred up controversy, with some studies finding that stem cells force tumors to enter a state of programmed cell death. However, other studies discovered that stem cells actually boost tumor proliferation by triggering the creation of new blood vessels. To determine the reality of the situation, researchers examined the impact of stem cells on already established subcutaneous or lung tumors in mice.
In the case of both subcutaneous and lung tumors, injecting stem cells slowed cell proliferation, which subsequently inhibited the rate of tumor growth. Part of the mode of action of stem cells seems to be a result of angiogenesis, but the mechanism behind its function is still unknown.
Lead study author, Claire Rome explains that their discovery of stem cells altering tumor blood vessels resulted in new vasculature but they were longer and fewer when compared to untreated tumors. This could lead to a restriction of oxygen and nutrients to the tumor, thus limiting cell proliferation. She believes her study confirms that stem cells might be one forward-reaching approach to treating cancer.
Celia Gomes from the University of Coimbra comments on the study by stating that it is especially interesting to note that stem cells are capable of both promoting and restricting tumor growth. The main factor in all this appears to be timing – this study examined established tumors, while the others that find stem cells boost growth, were evaluating new tumors. This study is a first step in the direction of pinpointing exactly which patients might benefit most from stem cell therapy and who will not.