Effect of monocytes/macrophages on the early osteogenic differentiation of hBMSCs

Heterotypic cell interactions are essential for the homeostasis of bone tissue, in particular the widely studied interaction between osteoblasts and osteoclasts. Closely related with osteoclasts are monocytes/macrophages. These have been shown to produce osteogenic factors, e.g. BMP-2, which plays a key role in bone metabolism. However, the mechanisms through which monocytes/macrophages interact with osteoblasts are still elusive. The aim of this work was to assess the influence of human peripheral blood monocytes/macrophages over the early osteogenic differentiation of human bone marrow stromal cells (hBMSCs) in the presence of dexamethasone-supplemented medium. The co-cultures were performed using porous transwells that allowed the interaction between both cell types through the production of paracrine factors. The potential effect of BMP-2 produced by monocytes/macrophages was addressed by adding an anti-BMP-2 antibody to the co-cultures. hBMSCs cultured in the presence of monocytes/macrophages had a higher proliferation rate than hBMSCs monocultures. The quantification of early osteogenic marker alkaline phosphatase (ALP) revealed higher activity of this enzyme in cells in the co-culture throughout the time of culture. Both of these effects were inhibited by adding an anti-BMP-2 antibody to the cultures. Moreover, qRTPCR for osteocalcin and osteopontin transcripts showed overexpression of both markers. Once again, the effect of monocytes/macrophages over hBMSC osteogenic differentiation was completely inhibited in the co-cultures by blocking BMP-2. The present report confirmed that monocytes/macrophages produce BMP-2, which promotes osteogenic differentiation and proliferation of hBMSCs cumulatively to dexamethasone-supplemented medium. This potentially implies that monocyte/macrophages play a stronger role in bone homeostasis than so far supposed

Gene-enhanced tissue engineering for dental hard tissue regeneration: (1) overview and practical considerations

Gene-based therapies for tissue regeneration involve delivering a specific gene to a target tissue with the goal of changing the phenotype or protein expression profile of the recipient cell; the ultimate goal being to form specific tissues required for regeneration. One of the principal advantages of this approach is that it provides for a sustained delivery of physiologic levels of the growth factor of interest. This manuscript will review the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. Part 2 will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration

Use and efficacy of bone morphogenetic proteins in fracture healing

Signal transduction in aging related disease

Estrogens and antiestrogens stimulate release of bone resorbing activity by cultured human breast cancer cells.

Patients with advanced breast cancer may develop acute, severe hypercalcemia when treated with estrogens or antiestrogens. In this study, we examined the effects of estrogens and related compounds on the release of bone resorbing activity by cultured human breast cancer cells in vitro. We found that the estrogen receptor positive breast cancer cell line MCF-7 releases bone resorbing activity in response to low concentrations of 17 beta-estradiol. Bone resorbing activity was also released in response to the antiestrogen nafoxidine. Other steroidal compounds had no effect on the release of bone resorbing activity. Estrogen-stimulated release of bone resorbing activity occurred with live bone cultures, but not with devitalized bones, indicating that the effect was bone cell mediated. The breast cancer cell line MDA-231, which does not have estrogen receptors, did not release bone resorbing activity in response to 17 beta-estradiol or nafoxidine. Release of the bone resorbing activity by MCF-7 cells incubated with 17 beta-estradiol was inhibited by indomethacin (10 microM) and flufenamic acid (50 microM), two structurally unrelated compounds that inhibit prostaglandin synthesis. Concentrations of 17 beta-estradiol and nafoxidine that caused increased release of bone resorbing activity by the breast cancer cells caused a four- to fivefold increase in release of prostaglandins of the E series by MCF-7 cells. These data may explain why some patients with advanced breast cancer develop acute hypercalcemia when treated with estrogens or antiestrogens, and why bone metastases are more common in patients with estrogen receptor positive tumors