Human mesenchymal stem cells and their paracrine factors for the treatment of brain tumors.

Glioblastoma multiforme (GBM or World Health Organization (WHO) grade IV) is the most malignant tumor of the brain. Despite conventional combination treatment of surgery, radiotherapy and chemotherapy, the survival of patients with GBM is generally <1 year. It is a great challenge to identify an effective drug that could efficiently inhibit (i) the growth of cancer cells; (ii) angiogenesis; (iii) metastasis; (iv) tumor-associated inflammation; (v) inactivate proliferative signal, (vi) induce specific apoptosis, and yet causes minimal harm to normal cells. Mesenchymal stem cells (MSCS) do possess some unique features (inherent tumor tropism; anti-inflammatory and immunosuppressive properties) that are not commonly found in current anticancer agents. These cells are known to secrete a vast array of proteins including growth factors, cytokines, chemokines and so on that regulate their biology in an autocrine or paracrine manner in accordance to the surrounding microenvironment. This review briefly summarizes the biology of MSCs and discusses their properties and new development for brain cancer treatment.