Interferon-α-secreting mesenchymal stem cells exert potent antitumor effect in vivo

Mesenchymal stem cells (MSCs) are a kind of adult stem cells that can be isolated easily from bone marrow, adipose tissue, umbilical cord and many other tissues. MSCs have been shown to specifically migrate to inflammatory sites, including tumors, and hold great promise as tumor-specific vectors to deliver antitumor agents. Interferon-alpha (IFN alpha) has been used in clinic to treat various types of tumors; however, because of its short half-life, significant therapeutic effects require high doses that often results in serious side effects. Here, we tested whether MSCs continuingly secreting IFN alpha can exert a persistent antitumor effect and eliminate the side effects associated with high clinical doses of recombinant IFN alpha. We found that even a small number of IFN alpha-secreting MSCs could potently halt B16 tumor growth in vivo. The antitumor activity of IFN alpha-secreting MSCs was largely abolished in immunodeficient mice, an effect largely attributed to natural killer cells and CD8(+) T cells. Therefore, IFNa-secreting MSCs provide an innovative strategy for tumor therapy.