During bone development, FasL acts not only through the traditional apoptotic mechanism regulating the amount of boneresorbing osteoclasts, but there is also growing evidence about its effect on cell differentiation. Expression of osteoblastic factors was followed in non-differentiated and differentiating primary calvarial cells obtained from FasL-deficient (gld) mice. The gld cells showed decreased expression of the key osteoblastic molecules osteocalcin (Ocn), osteopontin (Opn), and alkaline phosphatase (Alpl) in both groups. Notably, receptor activator of nuclear factor kappa-B ligand (Rankl) was unchanged in nondifferentiated gld vs. wild type (wt) cells but decreased in differentiating gld cells. Osteoprotegerin (Opg) in the gld samples was increased in both groups. Opg vs. Rankl expression levels favored Opg in the case of non-differentiated cells but Rankl in differentiating ones. These results expand information on the involvement of FasL in non-apoptotic cell pathways related to osteoblastogenesis and consequently also osteoclastogenesis and pathologies such as osteoporosis.
Over the past decades, the in vitro use of pluripotent cell lines gained a crucial role in toxicology, preclinical drug testing and developmental biology. NTERA2 clone D1 cells were identified as pluripotent cells with high potential for neural differentiation. Although they are commonly used cellular sources in neuropharmacology and neurodevelopmental studies, their endodermal and mesodermal differentiation potential awaits further characterization. Here, we devised improved protocols for hepatogenic and osteogenic differentiation of NTERA2 clone D1 cells. Our in vitro differentiation assays showed significant up-regulation of multiple hepatogenic markers. We also observed robust mineralization and osteogenic marker expression of NTERA2 clone D1 cells upon in vitro osteogenic induction. These results suggest that NTERA2 clone D1 cells may be utilized as an in vitro model system to study various aspects of liver biology and osteogenesis. In addition, tri-lineage differentiation of NTERA2 clone D1 cells may serve as a simple experimental control system when validating pluripotency of other cell types.