The effect of the alendronate on OPG/RANKL system in differentiated primary human osteoblasts

Abstract

Alendronate is a well-established treatment for osteoporosis and suppresses bone resorption by a direct effect on osteoclasts and their precursors. The effect of alendronate on osteoclasts is produced, at least in part, by the receptor activator of nuclear factor kappaB ligand (RANKL) and the osteoprotegerin (OPG) synthesized by the osteoblasts. This study analyzes the effect of alendronate in cell viability, alkaline phosphatase (ALP) activity and RANKL and OPG expression in primary human osteoblasts (hOB). Alendronate at concentrations lower than 10⁻⁵ M did not have a toxic effect on hOB in vitro and did not modify the ALP activity at least for 72 h. Alendronate did not change OPG expression in basal, 10% fetal bovine serum (FBS), and vitamin D-treated cultures. Similar results were observed at the protein level. Unexpectedly, alendronate at 10⁻⁷ and 10⁻⁵ M concentrations increased the RANKL expression with the presence of vitamin D in differentiated hOB, and this induction of RANKL mRNA levels by alendronate was dose-dependent. However, this effect was not observed in basal and 10% FBS culture conditions. Thus, we conclude that alendronate does not affect the ALP activity and OPG gene expression in differentiated hOB, but may increase RANKL gene expression induced by vitamin D.

The Susceptive Alendronate-Treatment Timing and Dosage for Osteogenesis Enhancement in Human Bone Marrow-Derived Stem Cells

“…In previous study, hMSCs treated with 40 µM FPP or 10 µM GGPP alone showed no significant effect on cell proliferation and apoptosis [34]. Five to 20 µM of FPP treatments were also used in the inhibition of zoledronic acid [5] induced mineralization in osteoblasts [31], which indicated FPP (lower than 40 µM) and GGPP (lower than 10 µM) did not affect cell proliferation individually, and GGPP (higher than 5 µM) inhibited ZA-induced mineralization. In the results of BMP-2 and Runx-2 expression, also showed no significant difference between control and 10 µM FPP or GGPP treated hBMSCs (Figure S3).…”

“…In previous studies, Aln inhibited cellular proliferation at high dose in MG-63 osteoblastic cells (10 −4 M) [7] and primary human osteoblasts (<10 −5 M) [5]. The toxic doses of Aln were usually greater than 1 µM in differentiated cells, such as chondrosacrcoma cell [21], epidermal cell [22], endothelial cell [23], fibroblast [24], intestinal epithelial cell [25], or macrophage [3], [26], [27].…”

“…Moreover, Aln was also found to enhance osteogenic activities, including cell proliferation and osteo-differentation. The osteogenic effects of Aln were suggested due to increased alkaline phosphatase (ALP) activity, mineralization and osteogenic genes, such as bone morphogenetic protein-2 (BMP-2), type I collagen (Col I) and osteocalcin (OC) in osteoblasts [5], [6], [7], [8], bone marrow-derived stem cells (BMSCs) [9], [10] and human adipocyte-derived stem cells (human ADSCs) [11]. Previous studies suggested that Aln is uptaken by endocytosis of macrophages, osteoclasts and osteoblasts, the similar way may also happen in hBMSCs [12], [13].…”

“…In contrast, aminobisphosphonate concentrations greater than 10 µM exerted strong inhibitory effects on both osteoblast proliferation and bone formation [6], [14]. Moreover, the Aln treatment periods for stem cells are typically less than four days [5], [7], [8], [9] or five days in osteo-induction medium [11]. The effective dose, treatment time and duration of Aln required for enhancing osteogenesis among different cell types were varied and those in mesenchymal stem cells have not been well characterized.…”

A case of hepatitis C-associated osteosclerosis: accelerated bone turnover controlled by pulse steroid therapy

“…It has been suggested that HCV alone or in combination with other unknown factor(s) may infect and alter bone cells or their precursors in predisposed individuals. Abnormalities have been demonstrated by previous studies in the insulin-like growth factor (IGF) system (3), the receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) system imbalance (4, 5), and the transforming growth factor (TGF)–β-Smad signaling (6). With regards to therapeutic approaches to the disease, the hallmarks are the changes in deep, torturing bony pain, bone markers, thickening of the long bone cortices and BMD.…”