Both chronic excess of PTH, as in hyperparathyroidism, and intermittent elevation of PTH (by daily injections) increase the number of osteoblasts. However, whereas the former condition can lead to bone catabolism, intermittent administration of PTH causes bone anabolism. The striking difference between bone loss and bone gain in the two conditions might result from a negative vs. positive balan...

AIMS To analyse osteoblast function in 153 cases of established osteoporosis as previous work has indicated that osteoporosis is a heterogeneous condition characterised by different patterns of osteoclast and osteoblast dysfunction. METHODS Histomorphometric data from 153 cases with established osteoporosis was used to analyse osteoblast function, using the following parameters: osteoblast nu...

The last 5 yr have witnessed major progress in skeleton biology. One of these areas of progress has been the partial elucidation of the transcriptional mechanisms of osteoblast differentiation and their conservation between mouse and human. Cbfal, or runx2, a homolog of the Drosophila Runt protein serves both as the earliest transcriptional regulator of osteoblast differentiation and as control...

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) either inhibit or enhance IGF-stimulated cellular effects. While inhibition occurs by sequestration of IGF from cell-surface receptors, the exact mechanism of IGF-enhancement remains undefined. Human osteoblast-like bone cells in culture secrete several IGF-binding proteins, one of which we have previously identified as IGFBP-5. In this...

Cell proliferation on the actively growing periosteal surface of the femur of rabbits aged 2 weeks has been investigated using autoradiographic techniques. Injections of tritiated glycine and tritiated thymidine were given simultaneously and the animals sacrificed at intervals from 1 hour to 5 days after injection. The glycine labeled the position of the bone surface at the time of injection an...

The osteoblast is the bone-forming cell. The molecular basis of osteoblast-specific gene expression and differentiation begin to be understood. Following the characterization of OSE2, an osteoblast-specific cis-acting element present in the Osteocalcin promoter Osf2/Cbfa1, the protein that binds to OSE2, was identified. Osf2/Cbfa1 is a member of the runt family of transcription factors. Its exp...

A screen of microRNAs preferentially expressed in osteoblasts identified members of the miR-34 family as regulators of osteoblast proliferation and/or differentiation. Osteoblast-specific gain- and loss-of-function experiments performed in vivo revealed that miR-34b and -c affected skeletogenesis during embryonic development, as well as bone mass accrual after birth, through two complementary c...

BACKGROUND/AIMS The antigen phenotype of human osteoblast-like cells suggests that they are related to other cellular populations and may also have immunologic functions in common. METHODS Flow cytometry and transmission electron microscopy were used to show the phagocytotic activity of osteoblast-like cells in culture. The allogeneic stimulation of T cells by human osteoblast-like cells was ...

Introduction: IIron oxide nanoparticles (IO NP) have an increasing number of biomedical applications. To date, the potential cytotoxicity of these particles remains an issue of debate. Little is known about the cellular interaction or toxic effects of IO NP on differentiation of stem cells. The aim of the present study was to investigate the possible toxic role of different doses of IO NP in di...

The differentiation of pluripotent mesenchymal stem cells to mature osteoblasts is crucial for the maintenance of the adult skeleton. In rheumatic arthritis, osteoblast differentiation is impaired by the overproduction of cytokine tumor necrosis factor (TNF)‑α. It has been demonstrated that TNF-α is able to inhibit osteoblast differentiation through the activation of nuclear factor (NF)-κB sign...