Transcriptional regulation of the human bone sialoprotein gene by fibroblast growth factor 2

Toxicity and developmental effects of Arctic fuel oil types on early life stages of Atlantic cod (Gadus morhua)

Due to the heavy fuel oil (HFO) ban in Arctic maritime transport and new legislations restricting the sulphur content of fuel oils, new fuel oil types are continuously developed. However, the potential impacts of these new fuel oil types on marine ecosystems during accidental spills are largely unknown. In this study, we studied the toxicity of three marine fuel oils (two marine gas oils with low sulphur contents and a heavy fuel oil) in early life stages of cod (Gadus morhua). Embryos were exposed for 4 days to water-soluble fractions of fuel oils at concentrations ranging from 4.1 - 128.3 µg TPAH/L, followed by recovery in clean seawater until 17 days post fertilization. Exposure to all three fuel oils resulted in developmental toxicity, including severe morphological changes, deformations and cardiotoxicity. To assess underlying molecular mechanisms, we studied fuel oil-mediated activation of aryl hydrocarbon receptor (Ahr) gene battery and genes related to cardiovascular, angiogenesis and osteogenesis pathways. Overall, our results suggest comparable mechanisms of toxicity for the three fuel oils. All fuel oils caused concentration-dependant increases of cyp1a mRNA which paralleled ahrr, but not ahr1b transcript expression. On the angiogenesis and osteogenesis pathways, fuel oils produced concentration-specific transcriptional effects that were either increasing or decreasing, compared to control embryos. Based on the observed toxic responses, toxicity threshold values were estimated for individual endpoints to assess the most sensitive molecular and physiological effects, suggesting that unresolved petrogenic components may be significant contributors to the observed toxicity.

Stepwise strategy for generating osteoblasts from human pluripotent stem cells under fully defined xeno-free conditions with small-molecule inducers

Clinically relevant human induced pluripotent stem cell (hiPSC) derivatives require efficient protocols to differentiate hiPSCs into specific lineages. Here we developed a fully defined xeno-free strategy to direct hiPSCs toward osteoblasts within 21 days. The strategy successfully achieved the osteogenic induction of four independently derived hiPSC lines by a sequential use of combinations of small-molecule inducers. The induction first generated mesodermal cells, which subsequently recapitulated the developmental expression pattern of major osteoblast genes and proteins. Importantly, Col2.3-Cherry hiPSCs subjected to this strategy strongly expressed the cherry fluorescence that has been observed in bone-forming osteoblasts in vivo. Moreover, the protocol combined with a three-dimensional (3D) scaffold was suitable for the generation of a xeno-free 3D osteogenic system. Thus, our strategy offers a platform with significant advantages for bone biology studies and it will also contribute to clinical applications of hiPSCs to skeletal regenerative medicine.

Tonsil-Derived Mesenchymal Stem Cells Promote Bone Mineralization and Reduce Marrow and Visceral Adiposity in a Mouse Model of Senile Osteoporosis

Osteoporosis is a disease that affects 35% women and 20% men aged more than 65 years. Reduction in bone formation and increased bone resorption are known factors that drive osteoporosis, but recent studies suggest a positive correlation between bone marrow adipose tissue (MAT) and osteoporosis. Previously, we have observed that tonsil-derived mesenchymal stem cells (T-MSCs) reduce MAT in a mouse model of bone marrow depletion. That prompted us to investigate on the senile osteoporosis to characterize the bone-forming effect, as well as MAT-reducing effect of T-MSCs. In a mouse model of senescence-accelerated mouse prone 6 (SAMP6), we injected T-MSCs or T-MSC conditioned medium (CM) through tail vein and examined changes in bone microstructure using micro-CT scan and hematoxylin & eosin (H&E) staining. Biochemical markers of osteoporosis, deoxypyridinoline (DPD) and osteocalcin, were examined by ELISA. Results demonstrated attenuation in the progression of osteoporosis, in part, by sustaining osteocalcin production and by blocking MAT accumulation. Increase in matrix mineralization was determined using in vitro culture of murine preosteoblast cell line by treatment of T-MSC CM. Interestingly, T-MSC CM induced continuous weight loss and selectively reduced visceral adipose tissue mass. Finally, antiadipogenic effects of T-MSC CM were determined in vitro. In conclusion, regulation of bone together with MAT could be considered as a new therapeutic option for the treatment of senile osteoporosis and this report may provide a framework for future cell therapy using T-MSCs.

Combined effects of simvastatin and fibroblast growth factor-2 on the proliferation and differentiation of preosteoblasts

Simvastatin reportedly promotes osteoblastic and inhibits osteoclastic activity. It increases bone formation when injected subcutaneously over the calvaria in mice. It also increases cancellous bone volume in rats following oral administration. Fibroblast growth factor-2 (FGF-2), a member of the FGF family, is expressed by cells of the osteoblastic lineage. FGF-2 promotes osteoblast proliferation and it is secreted during the healing process of fractures or at bone surgery sites. FGF-2 reportedly regulates bone formation and osteoblast differentiation. In this study, the combined effects of simvastatin and FGF-2 on the proliferation and differentiation of preosteoblasts were investigated and an alkaline phosphatase (ALP) activity test was performed to assess the differentiation. Moreover, the expression of proteins associated with bone formation were measured using western blot analysis. The results demonstrated that the protein content of the cultures grown in osteogenic differentiation media in the presence of FGF-2 at a concentration of 20 ng/ml was higher compared to that of the untreated control cultures. ALP activity was decreased when cells were treated with FGF-2 (2 and 20 ng/ml) and increased when cells were treated with simvastatin. The cultures grown in the presence of 1 μM of simvastatin and 2 ng/ml of FGF-2 exhibited increased ALP activity when compared to that in the 2 ng/ml FGF-2-only group. The combination of 1.0 μM simvastatin and 2 ng/ml FGF-2 achieved a higher estrogen receptor-α expression compared to the 2 ng/ml FGF-2-only group. Within the limits of this study, simvastatin enhanced osteoblast differentiation. However, the combined treatment with simvastatin and FGF-2 did not exert synergistic effects on osteoblast differentiation under the current experimental conditions. Future studies are required to evaluate divergent conditions and determine the selective timing and optimal dosage for the delivery of the agents.