Adipose tissue-derived mesenchymal stem cells cultured at high density express IFN-β and TRAIL and suppress the growth of H460 human lung cancer cells

Although mesenchymal stem cells (MSCs) have been reported to inhibit tumor growth, the mechanism controlling this tumor suppression function is unclear. Here, we report that high-density (40,000 cells/cm(2)) cultured adipose tissue-derived MSCs (40K-ASCs) expressed interferon (IFN)-beta and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL); we also found that serum deprivation during cell culture induced the expression of IFN-beta and TRAIL. In addition, the mRNA expression of IFN-beta, but not TRAIL, was increased during the washing step required for the transplantation of normal-density (5000 cells/cm(2)) cultured ASCs (5K-ASCs). When the human lung cancer cell line H460 was co-cultured with 40K-ASCs, necrotic cell death was dramatically increased in vitro. When ASCs were injected after four washes, both 5K-ASCs and 40K-ASCs substantially reduced tumor weight in H460-derived cancer animal models. These results suggest that serum deprivation during the culture of 40K-ASCs or during the washing step of 5K-ASCs can induce IFN-beta and/or TRAIL expression, ultimately leading to the tumor suppression capability of ASCs.