Alendronate promotes bone formation by inhibiting protein prenylation in osteoblasts in rat tooth replantation model

Abstract

Bisphosphonates (BPs) are a major class of antiresorptive drug, and their molecular mechanisms of antiresorptive action have been extensively studied. Recent studies have suggested that BPs target bone-forming cells as well as bone-resorbing cells. We previously demonstrated that local application of a nitrogen-containing BP (N-BP), alendronate (ALN), for a short period of time increased bone tissue in a rat tooth replantation model. Here, we investigated cellular mechanisms of bone formation by ALN. Bone histomorphometry confirmed that bone formation was increased by local application of ALN. ALN increased proliferation of bone-forming cells residing on the bone surface, whereas it suppressed the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in vivo. Moreover, ALN treatment induced more alkaline phosphatase-positive and osteocalcin-positive cells on the bone surface than PBS treatment. In vitro studies revealed that pulse treatment with ALN promoted osteocalcin expression. To track the target cells of N-BPs, we applied fluorescencelabeled ALN (F-ALN) in vivo and in vitro. F-ALN was taken into bone-forming cells both in vivo and in vitro. This intracellular uptake was inhibited by endocytosis inhibitors. Furthermore, the endocytosis inhibitor dansylcadaverine (DC) suppressed ALN-stimulated osteoblastic differentiation in vitro and it suppressed the increase in alkaline phosphatase-positive bone-forming cells and subsequent bone formation in vivo. DC also blocked the inhibition of Rap1A prenylation by ALN in the osteoblastic cells. These data suggest that local application of ALN promotes bone formation by stimulating proliferation and differentiation of bone-forming cells as well as inhibiting osteoclast function. These effects may occur through endocytic incorporation of ALN and subsequent inhibition of protein prenylation.

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

“…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].…”

Annexin A5 Involvement in Bone Overgrowth at the Enthesis

“…Immunohistochemistry of Anxa5 and pSMAD1/5/8 were carried out using anti‐human Annexin V antibody (1:100, BioVision, Milpitas, CA, USA), anti‐phospho SMAD1/5/8 (Ser463/465) antibody (1:100, Millipore, Temecula, CA, USA), Alexa Fluor 594‐conjugated chicken anti‐rabbit IgG (Thermo Fisher Scientific, Waltham, MA, USA), and Alexa Fluor 488‐conjugated goat anti‐rabbit IgG (Thermo Fisher Scientific), and the sections were counterstained with 4′,6‐diamidino‐2‐phenylindole (DAPI). Alkaline phophatase (ALP) and tartrate‐resistant alkaline phosphatase (TRAP) activities as markers of bone formation and bone resorption, respectively, were detected by staining assay as previously described …”

Development of nanomaterials for bone-targeted drug delivery

“…Previous studies have demonstrated that the antiresorptive drug alendronate (Alen) can promote new bone formation by stimulating OB proliferation and/or differentiation, and inhibiting OC function [46]. However, there is a need to develop novel materials for the controlled release of this drug because of toxicity issues at high doses [46].…”

“…However, there is a need to develop novel materials for the controlled release of this drug because of toxicity issues at high doses [46]. Shen et al .…”