CCL5 and teratoma: Indeed, previous work has demonstrated that although MSC themselves do not develop teratoma even when derived from a teratoma-forming human embryonic stem cell line [141], a close vicinity to neoplastic breast epithelial cells within the tissue microenvironment can stimulate growth and metastasis of breast cancer cells by cytokines including CCL5 (Rantes) [142] and may most probably also influence the exchange of miR-containing micro vesicles.