title: Jaw bone marrow-derived osteoclast precursors internalize more bisphosphonate than long-bone marrow precursors.
abstract: Bisphosphonates (BPs) are widely used in the treatment of several bone diseases, such as osteoporosis and cancers that have metastasized to bone, by virtue of their ability to inhibit osteoclastic bone resorption. Previously, it was shown that osteoclasts present at different bone sites have different characteristics. We hypothesized that BPs could have distinct effects on different populations of osteoclasts and their precursors, for example as a result of a different capacity to endocytose the drugs. To investigate this, bone marrow cells were isolated from jaw and long bone from mice and the cells were primed to differentiate into osteoclasts with the cytokines M-CSF and RANKL. Before fusion occurred, cells were incubated with fluorescein-risedronate (FAM-RIS) for 4 or 24h and uptake was determined by flow cytometry. We found that cultures obtained from the jaw internalized 1.7 to 2.5 times more FAM-RIS than long-bone cultures, both after 4 and 24h, and accordingly jaw osteoclasts were more susceptible to inhibition of prenylation of Rap1a after treatment with BPs for 24h. Surprisingly, differences in BP uptake did not differentially affect osteoclastogenesis. This suggests that jaw osteoclast precursors are less sensitive to bisphosphonates after internalization. This was supported by the finding that gene expression of the anti-apoptotic genes Bcl-2 and Bcl-xL was higher in jaw cells than long bone cells, suggesting that the jaw cells might be more resistant to BP-induced apoptosis. Our findings suggest that bisphosphonates have distinct effects on both populations of osteoclast precursors and support previous findings that osteoclasts and precursors are bone-site specific. This study may help to provide more insights into bone-site-specific responses to bisphosphonates.
authors: Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands. Electronic address: j.vermeer@acta.nl.
authors: Jenny A F
authors: JA
authors: Vermeer
authors: Ineke D C
authors: ID
authors: Jansen
authors: Matangi
authors: M
authors: Marthi
authors: Fraser P
authors: FP
authors: Coxon
authors: Charles E
authors: CE
authors: McKenna
authors: Shuting
authors: S
authors: Sun
authors: Teun J
authors: TJ
authors: de Vries
authors: Vincent
authors: V
authors: Everts
mesh_terms: D000818:Animals; D050071:Bone Density Conservation Agents / Q000378:metabolism* / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000378:metabolism*; D004164:Diphosphonates / Q000378:metabolism / Q000494:pharmacology; D004705:Endocytosis; D005434:Flow Cytometry; D007568:Jaw / Q000166:cytology*; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D010010:Osteoclasts / Q000378:metabolism; D010020:Osteonecrosis / Q000378:metabolism
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates
keywords: ALP; BP; Bisphosphonates; Endocytosis; FPPS; Irf8; Jaw; MFI; MafB; ONJ; Osteoclast heterogeneity; Osteonecrosis; PAM; PBGD; RIS; TRACP; V-maf musculoaponeurotic fibrosarcoma oncogene homolog B; alkaline phosphatase; bisphosphonate; farnesyl pyrophosphate synthase; interferon regulatory factor 8; median fluorescence intensity; osteonecrosis of the jaw; pamidronate; porphobilinogen deaminase; risedronate; tartrate-resistant acid phosphatase