Development of a human adipocyte model derived from human mesenchymal stem cells (hMSC) as a tool for toxicological studies on the action of TCDD.

Abstract Efforts were made to develop a human adipocyte model that is useful for toxicological studies in vitro. For this purpose, a stem cell line derived from human bone marrow cells, originally from an adult, was induced to differentiate towards adipocytes by treating them with insulin, dexamethasone, indomethacin and 3-isobutyl-1-methylxanthine for 3 d, followed by additional incubation for 3 d in Dulbecco's modified Eagle's medium supplemented with insulin only. In most cases, thus differentiated cells through such one cycle of differentiation treatment were further subjected to the second cycle of differentiation. The resulting 2-cycle differentiated cells were found to exhibit many characteristics of typical adipocytes. Dioxin (TCDD), when added at the beginning of their treatment with differentiation-inducing hormone cocktail, clearly prevented them from becoming adipocytes, as in the case of TCDD-treated 3T3-L1 cells. Furthermore, TCDD, even when administered to previously differentiated human mesenchymal stem cells (hMSC) adipocytes, consistently induced the sign of inflammatory responses during the early period of TCDD action (24 h), which was followed by gradual loss of adipocyte-specific markers during the 5-d incubation period. In conclusion, hMSC-derived adipocytes appear to offer a promising human cell model suited for future toxicological studies.