The origin of vascular cells in tumors is unknown, but it is believed that tumors use cells from the host to build new vessels. To determine whether adipose tissue stem cells (ASCs) could be attracted by cancer cells, we performed migration assays in which ASCs were seeded on a transwell migration system top chamber and tumor-conditioned medium was placed in the bottom chamber. Our data showed that a significant number of ASCs migrated toward the tumor-conditioned medium (p < 0.0001), and migration of human ASCs significantly (p < 0.0001) increased in response to increased concentrations of recombinant PDGF-BB. In addition, neutralizing antibodies to PDGF receptor (PDGFR)-beta decreased migration of ASCs toward a breast cancer-conditioned medium to the level of serum-free control. These data suggest that tumor cell-derived PDGF-BB is an important factor in governing the microenvironment interaction between tumor cells and local tissue-resident stem cells. (C) 2010 Elsevier Inc. All rights reserved.