Gemcitabine-releasing mesenchymal stromal cells inhibit in vitro proliferation of human pancreatic carcinoma cells

Background aims: Pancreatic cancer (pCa) is a tumor characterized by a fibrotic state and associated with a poor prognosis. The observation that mesenchymal stromal cells (MSCs) migrate toward inflammatory micro-environments and engraft into tumor stroma after systemic administration suggested new therapeutic approaches with the use of engineered MSCs to deliver and produce anti-cancer molecules directly within the tumor. Previously, we demonstrated that without any genetic modifications, MSCs are able to deliver anti-cancer drugs. MSCs loaded with paclitaxel by exposure to high concentrations release the drug both in vitro and in vivo, inhibiting tumor proliferation. On the basis of these observations, we evaluated the ability of MSCs (from bone marrow and pancreas) to uptake and release gemcitabine (GCB), a drug widely used in pCa treatment. Methods: MSCs were primed by 24-h exposure to 2000 ng/mL of GCB. The anti-tumor potential of primed MSCs was then investigated by in vitro anti-proliferation assays with the use of CFPAC-1, a pancreatic tumor cell line sensitive to GCB. The uptake/release ability was confirmed by means of high-performance liquid chromatography analysis. A cell-cycle study and secretome evaluation were also conducted to better understand the characteristics of primed MSCs. Results: GCB-releasing MSCs inhibit the growth of a human pCa cell line in vitro. Conclusions: The use of MSCs as a "trojan horse" can open the way to a new pCa therapeutic approach; GCB-loaded MSCs that integrate into the tumor mass could deliver much higher concentrations of the drug in situ than can be achieved by intravenous injection.