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Denosumab increases total, trabecular, and cortical estimated hip and spine strength in postmenopausal women with osteoporosis
Bone 48 (2011) S86–S90
Contents lists available at ScienceDirect
Bone j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / b o n e
Oral Posters 1: Clinical OPC01 (for more information visit the Amgen/GlaxoSmithKline scientific booth) Denosumab increases total, trabecular, and cortical estimated hip and spine strength in postmenopausal women with osteoporosis H.K. Genant a,⁎, J.R. Zanchetta b, D. Kendler c, J.P. Brown d, S. Goemaere e, C. Recknor f, M.L. Brandi g, R. Eastell h, D. Kopperdahl i, K. Engelke j, T. Fuerst k, H.-S. Radcliffe l, C. Libanati m, T. Keaveny n a UCSF/Synarc, Tiduron, USA b Instituto de Investigaciones Metabolicas, Buenos Aires, Argentina c University of British Columbia, Vancouver, Canada d Laval University, Quebec, Canada e Ghent University Hospital, Gent, Belgium f United Osteoporosis Centers, Gainesville, USA g University of Florence, Florence, Italy h University of Sheffield, Sheffield, UK i O.N. Diagnostics, Berkeley, USA j Institute of Medical Physics, University of Erlangen, Erlangen, Germany k Synarc Inc, San Francisco, USA l Amgen, Inc, Cambridge, UK m Amgen, Inc, Thousand Oaks, USA n UC Berkeley, Berkeley, USA
Abstract: Denosumab (DMAb), a fully human monoclonal antibody to RANKL, increased bone mineral density, decreased bone resorption, and significantly reduced the risk of new vertebral, nonvertebral, and hip fractures in the FREEDOM trial (Cummings et al, NEJM, 2009:361:756). FREEDOM was a phase 3 trial in women 60–90 years old with postmenopausal osteoporosis randomized to 60 mg DMAb or placebo (Pbo) every 6 months plus daily calcium and vitamin D. In a substudy of FREEDOM, hip and spine quantitative computed tomography scans were obtained at baseline, 12, 24 and 36 months. These scans were used to analyze patient-specific estimated hip strength for a simulated sideways fall and L2 spine strength for a simulated compression overload, using non-linear 3D finite element analysis (51 DMAb; 48 Pbo). All analyses were exploratory. For women treated with DMAb, hip strength increased significantly compared with baseline by 5.4% (p < 0.0001) at 12 months, and this strength was augmented over time reaching 8.4% (p < 0.0001) at 36 months (Fig. 1). In contrast, for women receiving Pbo, hip strength did not change at 12 months and decreased at 36 months compared with baseline (− 5.4%, p < 0.0001). The same temporal trends were seen at the spine but the changes were much larger than at the hip at 36 months, spine strength increased by 18.1% (p < 0.0001) for the DMAb group and decreased by − 4.1% (p = 0.004) for the Pbo group. For both the hip and spine, DMAb subjects displayed increases in cortical strength, estimated from the outer 3 mm of bone at the hip and the outer 2 mm at the spine, as well as in trabecular strength (for both, p < 0.0001 vs placebo and baseline at 36 months). Pbo subjects exhibited a preferential loss of trabecular strength. Additionally, DMAb-related improvements in strength at the hip and spine were significantly correlated (r = 0.38, p = 0.02, Fig. 2). At 36 months, all DMAb subjects had increased spine strength, and all but 2 had increased hip strength from baseline; while strength decreases were observed for the majority of Pbo subjects. In summary, DMAb treatment significantly increased both hip and spine strength at 12 months compared with both baseline and Pbo, and positively influenced the trabecular and cortical compartments. Hip and spine strength continued to improve over 36 months of treatment. These improvements in total strength, in particular cortical strength, extend the understanding of the impact of DMAb in vertebral and nonvertebral fracture reductions. This article is part of a Special Issue entitled ECTS 2011.
8756-3282/$ – see front matter
Fig. 1. FEA Total Hip and Spine Estimated Strength.
Fig. 2. Hip and Spine Estimated Strength Change Relationship.
Disclosure of interest: H. Genant Shareholder of Synarc, Grant / Research Support from Merck, GSK, BMS, Roche, Lilly, Amgen, Novartis, Servier, Genentech, Medtronic, Takeda, Consulting fees from Synarc, Merck, GSK, BMS, Roche, Lilly, Amgen, Novartis, Servier, Genentech, Medtronic, Takeda, J. Zanchetta Grant / Research Support from Amgen, Eli Lilly, Merck, Pfizer, Advisory Board Membership of Amgen, Eli Lilly, GSK, Merck, Pfizer, Servier, Consulting fees from Amgen, Eli Lilly, GSK, Merck, Pfizer, Servier, D. Kendler Grant / Research Support from Amgen, Lilly, Novartis, Pfizer, Biosante, GSK, Roche, Consulting fees from Amgen, Lilly, Merck, Novartis, Pfizer, Warner Chilcot, Speaker Fees from Amgen, Lilly, Novartis, Pfizer, Warner Chilcott, J. Brown Grant / Research Support from Abbott, Amgen, BMS, Eli Lilly, Pfizer, Roche, Advisory Board Membership of Abbott, Amgen, Eli Lilly, Novartis, Merck, Warner Chilcott, Consulting fees from Abbott, Amgen, Eli Lilly, Novartis, Merck, Warner Chilcott, Speaker Fees from Eli Lilly, Amgen, Novartis, Merck, Warner Chilcott , S. Goemaere Grant / Research Support from MSD, Amgen, Servier, Nycomed, Advisory Board Membership of Eli Lilly, Consulting fees from Amgen, Speaker Fees from MSD, Roche, Servier,
Abstracts / Bone 48 (2011) S86–S90 Warner Chillcott, Amgen, C. Recknor Consulting fees from Zelos, Takeda, Dramatic Health, Novartis, Eli Lilly, Lecture Fees from Amgen, Novartis, Publicis Meetings, M. L. Brandi Grant / Research Support from Amgen, Eli Lilly, NPS, GSK, Roche, Servier, Stroder, Nycomed, Advisory Board Membership of Amgen, MSD, Servier, Eli Lilly, NPS, Nycomed, R. Eastell Grant / Research Support from Novartis, Advisory Board Membership of Novartis, D. Kopperdahl Employee of O.N. Diagnostics, K. Engelke Employee of Synarc, Grant / Research Support from German Research Society, NIH, Paid Instructor for German Osteology Society, T. Fuerst Shareholder of Synarc, Employee of Synarc, H.-S. Radcliffe Employee of Amgen, C. Libanati Shareholder of Amgen, Employee of Amgen, T. Keaveny Shareholder of O.N. Diagnostics, Grant / Research Support from Amgen, Merck, Lilly, Novartis, Advisory Board Membership of Merck, Consulting fees from Merck, Novartis. doi:10.1016/j.bone.2011.03.116
OPC02 Daily nitroglycerin increases bone formation, bone mass, bone structure, and indices of bone strength: A two-year randomized trial S.A. Jamal a, C.J. Hamilton b, R. Eastell c, S.R. Cummings d,⁎ a Department of Medicine, University of Toronto, Toronto, Canada b Department of Exercise Sciences, University of Toronto, Toronto, Canada c University of Sheffield, Sheffield, UK d San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, USA Abstract: Nitric oxide acts on osteoclasts and osteoblasts in vitro. Nitroglycerin (NTG), a nitric oxide donor, prevented bone loss in ovariectomized and steroid-treated mice. Small trials have found that NTG, stimulates bone formation and inhibits bone resorption. Observational studies suggest that intermittent use of nitrates may increase BMD and decrease fracture risk. To determine the effect of NTG on bone turnover, mass, structure and strength, we randomized 243 postmenopausal women with lumbar spine T-scores between 0 and −2.0 to receive 15 mg of NTG ointment or placebo once daily at bedtime for 24 months. Of those randomized, 76% adhered to NTG and 85% to placebo and, overall, 93% completed all 2-year assessments. Bone formation was assessed by serum bone-specific alkaline phosphatase (BALP) and resorption by concentrations of N-telopeptide in urine (uNTX). Bone structure and trabecular density in the tibia and radius were measured by pQCT (Norland/Stratec XCT 2000), and indices of bone strength were calculated with the manufacturer's software (Version 6.00). Compared with placebo, daily nitroglycerin increased B-ALP by 21.3% at 1 and 36% at 2 years; it decreased uNTX levels by 31.0% at 12 months and 51% at 2 years (P < 0.001 for all). Two years of nitroglycerin increased spine BMD 6.7% (95% CI, 5.2 to 8.2%) and femoral neck BMD 7.0% (5.5 to 8.5%) at 24 months (P < 0.001). At the radius and tibia, respectively, NTG increased trabecular BMD 11.9% and 8.5%, cortical thickness 13.9% and 24.6%, and periosteal circumference 7.4% and 2.9% (P < 0.001 for all comparisons). NTG increased polar section modulus 10.7% and 9.8% and polar moment of inertia 7.3% and 14.5%. Headache was reported by 35% with NTG vs 5% with placebo in the 1st month, but only 5% vs 1% at 1 year. We conclude that daily use of NTG ointment for 2 years uncouples bone formation from bone resorption, forms bone on the periosteal surface, and increases bone density, cortical thickness and indices of bone strength. These results suggest that nitroglycerin may substantially reduce the risk of vertebral and nonvertebral fractures, but this should be tested in a randomized trial. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: None declared. doi:10.1016/j.bone.2011.03.117
OPC03 Strontium ranelate positively affects the response of osteocytes to mechanical loading and osteocyte signalling towards osteoclasts A.D. Bakker ⁎, B. Zandieh-Doulabi, J. Klein-Nulend Oral Cell Biology, ACTA–University of Amsterdam and VU University Amsterdam, Research Institute MOVE, Amsterdam, Netherlands Abstract: Strontium ranelate (SrRan) is a successful treatment for postmenopausal osteoporosis, based on its efficacy in stimulating osteoblasts and inhibiting osteoclasts. Signalling molecules produced by osteocytes in response to mechanical loading, such as nitric oxide (NO) or prostaglandin E2 (PGE2), mediate the number and activity of osteoblasts and osteoclasts. The aim of this study was to assess the effect of SrRan on paracrine signalling from mechanically stimulated osteocytes towards osteoclasts. MLO-Y4 osteocytes were cultured for 24 h in the presence of SrRan up to 3 mM, and either or not stimulated with 60 min of pulsating fluid flow (PFF). Treatments effects were assessed by quantification of NO (Griess), adenosine tri-phosphate (ATP; Luminescence) and
S87
PGE2 (ELISA) in the culture medium, and by quantification of mRNA expression (taqman PCR) of COX2 (key enzyme for PGE2 production), cx43 (constituent of gap junctions and hemichannels), RANKL, OPG and M-CSF (mediating osteoclast formation). Apoptosis was assessed using Caspase-Glo 3/7 Assay, since apoptotic osteocytes can stimulate osteoclastogenesis. Medium from SrRan and/or PFF-treated osteocytes was added to cultured mouse bone marrow cells. After 7 days TRACP-positive multinucleated cells (osteoclasts) were counted. SrRan did not affect apoptosis or ATP release by osteocytes. 3 mM SrRan stimulated NO and PGE2 production by osteocytes in both static (1.6 and 2.8-fold, respectively) and PFF-stimulated conditions (1.3 and 2.6-fold, respectively), showing that SrRan enhances osteocyte signalling. SrRan did not affect COX2, cx43 or M-CSF expression at any concentration tested. Conditioned medium from osteocytes treated with 3 mM SrRan inhibited osteoclastogenesis by 1.9-fold compared to conditioned medium from non-treated osteocytes. The combination of 3 mM SrRan and PFF strongly inhibited osteocyte-stimulated osteoclastogenesis (4.3 fold), concomitantly with an enhanced osteocyte OPG/RANKL ratio (2.9-fold). In conclusion, SrRan positively affects paracrine signalling between osteocytes and osteoclasts. The positive effects of SrRan on bone mass may be at least partly explained by improved paracrine signalling by the most abundant cell in bone, the osteocyte. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: A. Bakker Grant / Research Support from Servier, France, B. ZandiehDoulabi Grant/Research Support from Servier, France, J. KleinNulend Grant/Research Support from Servier, France. doi:10.1016/j.bone.2011.03.118
OPC04 Transmenopausal changes in osteocyte lacunar volume in adult human trabecular bone D.B. Kimmel a,⁎, M.P. Akhter a, R. Recker a, T. Fong b, J. Coats b a Osteoporosis Research Center, Creighton University, Omaha, NE, USA b Xradia, Inc., Pleasanton, CA, USA Abstract: Osteocytes (Ot) respond to pharmacologic/mechanical stimuli by altering their lacunar volume. Synchrotron radiation (SR) scanning (0.7 μm pixel resolution [PR]) allows 3D imaging of whole Ot lacunae (Ot.La). The smallness of Ot.La causes current laboratory 3D imaging devices difficulty in resolving them in intact bone samples. Here, we quantify the effect of estrogen status on Ot.La volume (Ot.LaV) in various trabecular bone microarchitectural regions with a lab-based 3D imaging instrument that achieves SR-like resolution. Transilial biopsy specimens were taken from opposite sides of a healthy woman before menopause and at one year after her last menses. Each was embedded undecalcified in plastic. Histomorphometry showed seven-fold higher remodeling after menopause. A portion of each specimen remaining after sectioning was trimmed to 2 × 2 × 8 mm and scanned at 5 μm PR with a 3D X Ray Microscope. 3D images were reconstructed. Ten volumes of interest (VOIs; 0.9 mm diameter × 0.5 mm long; 4 pre- and 6 post-menopausal) containing trabecular nodes or struts were selected and scanned at ~ 0.6 μm PR. The 3D image of each VOI was analyzed by segmentation software (Ratoc; Tokyo, JP) for individual Ot.LaV (iOt.LaV). Ot.La were taken as discrete bone tissue voids > 50 and < 500 μm³. All Ot.La of like menopausal status and microarchitectural location were pooled and analyzed by two factor ANOVA. 9093 Ot.La were examined. iOt.LaV was 11% lower in post-menopausal specimen struts than pre-menopausal struts (P < .0001) (Table 1). Ot.LaV did not change in nodes. Struts and nodes differ significantly in their Ot.LaV behavior across menopause. Study of these and other transmenopausal pairs continues.
Table 1 Location
Pre-Meno iOt.LaV
Post-Meno iOt.LaV
Struts Nodes
170 ± 117 (2 [1848]) 172 ± 119 (2 [2394])
151 ± 107 (4 [3431])* 170 ± 109 (2 [1420])
Units(iOt.LaV) = μm 3; Mean ± SD; (# of VOIs [total number of Ot.La in sample]). *Diff from Pre-Meno (P < .0001). These data suggest that Ot.LaV in bone tissue decreases with menopause in trabecular struts, but not nodes. Bone tissue with smaller Ot.La could have less ability to intercept propagating microcracks, creating decreased toughness on a sub-microscopic level not detectable by current methods. These results also parallel rat data that indicate smaller Ot. LaV in trabecular bone of OVX than intact rats. Decreased toughness concentrated in trabecular struts may also be an additional reason why struts are preferentially lost with menopause and aging. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: D. Kimmel Consulting fees from Xradia, Inc., M. Akhter Consulting fees from Xradia, Inc., R. Recker: None Declared, T. Fong Employee of Xradia, Inc., J. Coats Employee of Xradia, Inc. doi:10.1016/j.bone.2011.03.119
Contents lists available at ScienceDirect
Bone j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / b o n e
Oral Posters 1: Clinical OPC01 (for more information visit the Amgen/GlaxoSmithKline scientific booth) Denosumab increases total, trabecular, and cortical estimated hip and spine strength in postmenopausal women with osteoporosis H.K. Genant a,⁎, J.R. Zanchetta b, D. Kendler c, J.P. Brown d, S. Goemaere e, C. Recknor f, M.L. Brandi g, R. Eastell h, D. Kopperdahl i, K. Engelke j, T. Fuerst k, H.-S. Radcliffe l, C. Libanati m, T. Keaveny n a UCSF/Synarc, Tiduron, USA b Instituto de Investigaciones Metabolicas, Buenos Aires, Argentina c University of British Columbia, Vancouver, Canada d Laval University, Quebec, Canada e Ghent University Hospital, Gent, Belgium f United Osteoporosis Centers, Gainesville, USA g University of Florence, Florence, Italy h University of Sheffield, Sheffield, UK i O.N. Diagnostics, Berkeley, USA j Institute of Medical Physics, University of Erlangen, Erlangen, Germany k Synarc Inc, San Francisco, USA l Amgen, Inc, Cambridge, UK m Amgen, Inc, Thousand Oaks, USA n UC Berkeley, Berkeley, USA
Abstract: Denosumab (DMAb), a fully human monoclonal antibody to RANKL, increased bone mineral density, decreased bone resorption, and significantly reduced the risk of new vertebral, nonvertebral, and hip fractures in the FREEDOM trial (Cummings et al, NEJM, 2009:361:756). FREEDOM was a phase 3 trial in women 60–90 years old with postmenopausal osteoporosis randomized to 60 mg DMAb or placebo (Pbo) every 6 months plus daily calcium and vitamin D. In a substudy of FREEDOM, hip and spine quantitative computed tomography scans were obtained at baseline, 12, 24 and 36 months. These scans were used to analyze patient-specific estimated hip strength for a simulated sideways fall and L2 spine strength for a simulated compression overload, using non-linear 3D finite element analysis (51 DMAb; 48 Pbo). All analyses were exploratory. For women treated with DMAb, hip strength increased significantly compared with baseline by 5.4% (p < 0.0001) at 12 months, and this strength was augmented over time reaching 8.4% (p < 0.0001) at 36 months (Fig. 1). In contrast, for women receiving Pbo, hip strength did not change at 12 months and decreased at 36 months compared with baseline (− 5.4%, p < 0.0001). The same temporal trends were seen at the spine but the changes were much larger than at the hip at 36 months, spine strength increased by 18.1% (p < 0.0001) for the DMAb group and decreased by − 4.1% (p = 0.004) for the Pbo group. For both the hip and spine, DMAb subjects displayed increases in cortical strength, estimated from the outer 3 mm of bone at the hip and the outer 2 mm at the spine, as well as in trabecular strength (for both, p < 0.0001 vs placebo and baseline at 36 months). Pbo subjects exhibited a preferential loss of trabecular strength. Additionally, DMAb-related improvements in strength at the hip and spine were significantly correlated (r = 0.38, p = 0.02, Fig. 2). At 36 months, all DMAb subjects had increased spine strength, and all but 2 had increased hip strength from baseline; while strength decreases were observed for the majority of Pbo subjects. In summary, DMAb treatment significantly increased both hip and spine strength at 12 months compared with both baseline and Pbo, and positively influenced the trabecular and cortical compartments. Hip and spine strength continued to improve over 36 months of treatment. These improvements in total strength, in particular cortical strength, extend the understanding of the impact of DMAb in vertebral and nonvertebral fracture reductions. This article is part of a Special Issue entitled ECTS 2011.
8756-3282/$ – see front matter
Fig. 1. FEA Total Hip and Spine Estimated Strength.
Fig. 2. Hip and Spine Estimated Strength Change Relationship.
Disclosure of interest: H. Genant Shareholder of Synarc, Grant / Research Support from Merck, GSK, BMS, Roche, Lilly, Amgen, Novartis, Servier, Genentech, Medtronic, Takeda, Consulting fees from Synarc, Merck, GSK, BMS, Roche, Lilly, Amgen, Novartis, Servier, Genentech, Medtronic, Takeda, J. Zanchetta Grant / Research Support from Amgen, Eli Lilly, Merck, Pfizer, Advisory Board Membership of Amgen, Eli Lilly, GSK, Merck, Pfizer, Servier, Consulting fees from Amgen, Eli Lilly, GSK, Merck, Pfizer, Servier, D. Kendler Grant / Research Support from Amgen, Lilly, Novartis, Pfizer, Biosante, GSK, Roche, Consulting fees from Amgen, Lilly, Merck, Novartis, Pfizer, Warner Chilcot, Speaker Fees from Amgen, Lilly, Novartis, Pfizer, Warner Chilcott, J. Brown Grant / Research Support from Abbott, Amgen, BMS, Eli Lilly, Pfizer, Roche, Advisory Board Membership of Abbott, Amgen, Eli Lilly, Novartis, Merck, Warner Chilcott, Consulting fees from Abbott, Amgen, Eli Lilly, Novartis, Merck, Warner Chilcott, Speaker Fees from Eli Lilly, Amgen, Novartis, Merck, Warner Chilcott , S. Goemaere Grant / Research Support from MSD, Amgen, Servier, Nycomed, Advisory Board Membership of Eli Lilly, Consulting fees from Amgen, Speaker Fees from MSD, Roche, Servier,
Abstracts / Bone 48 (2011) S86–S90 Warner Chillcott, Amgen, C. Recknor Consulting fees from Zelos, Takeda, Dramatic Health, Novartis, Eli Lilly, Lecture Fees from Amgen, Novartis, Publicis Meetings, M. L. Brandi Grant / Research Support from Amgen, Eli Lilly, NPS, GSK, Roche, Servier, Stroder, Nycomed, Advisory Board Membership of Amgen, MSD, Servier, Eli Lilly, NPS, Nycomed, R. Eastell Grant / Research Support from Novartis, Advisory Board Membership of Novartis, D. Kopperdahl Employee of O.N. Diagnostics, K. Engelke Employee of Synarc, Grant / Research Support from German Research Society, NIH, Paid Instructor for German Osteology Society, T. Fuerst Shareholder of Synarc, Employee of Synarc, H.-S. Radcliffe Employee of Amgen, C. Libanati Shareholder of Amgen, Employee of Amgen, T. Keaveny Shareholder of O.N. Diagnostics, Grant / Research Support from Amgen, Merck, Lilly, Novartis, Advisory Board Membership of Merck, Consulting fees from Merck, Novartis. doi:10.1016/j.bone.2011.03.116
OPC02 Daily nitroglycerin increases bone formation, bone mass, bone structure, and indices of bone strength: A two-year randomized trial S.A. Jamal a, C.J. Hamilton b, R. Eastell c, S.R. Cummings d,⁎ a Department of Medicine, University of Toronto, Toronto, Canada b Department of Exercise Sciences, University of Toronto, Toronto, Canada c University of Sheffield, Sheffield, UK d San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, USA Abstract: Nitric oxide acts on osteoclasts and osteoblasts in vitro. Nitroglycerin (NTG), a nitric oxide donor, prevented bone loss in ovariectomized and steroid-treated mice. Small trials have found that NTG, stimulates bone formation and inhibits bone resorption. Observational studies suggest that intermittent use of nitrates may increase BMD and decrease fracture risk. To determine the effect of NTG on bone turnover, mass, structure and strength, we randomized 243 postmenopausal women with lumbar spine T-scores between 0 and −2.0 to receive 15 mg of NTG ointment or placebo once daily at bedtime for 24 months. Of those randomized, 76% adhered to NTG and 85% to placebo and, overall, 93% completed all 2-year assessments. Bone formation was assessed by serum bone-specific alkaline phosphatase (BALP) and resorption by concentrations of N-telopeptide in urine (uNTX). Bone structure and trabecular density in the tibia and radius were measured by pQCT (Norland/Stratec XCT 2000), and indices of bone strength were calculated with the manufacturer's software (Version 6.00). Compared with placebo, daily nitroglycerin increased B-ALP by 21.3% at 1 and 36% at 2 years; it decreased uNTX levels by 31.0% at 12 months and 51% at 2 years (P < 0.001 for all). Two years of nitroglycerin increased spine BMD 6.7% (95% CI, 5.2 to 8.2%) and femoral neck BMD 7.0% (5.5 to 8.5%) at 24 months (P < 0.001). At the radius and tibia, respectively, NTG increased trabecular BMD 11.9% and 8.5%, cortical thickness 13.9% and 24.6%, and periosteal circumference 7.4% and 2.9% (P < 0.001 for all comparisons). NTG increased polar section modulus 10.7% and 9.8% and polar moment of inertia 7.3% and 14.5%. Headache was reported by 35% with NTG vs 5% with placebo in the 1st month, but only 5% vs 1% at 1 year. We conclude that daily use of NTG ointment for 2 years uncouples bone formation from bone resorption, forms bone on the periosteal surface, and increases bone density, cortical thickness and indices of bone strength. These results suggest that nitroglycerin may substantially reduce the risk of vertebral and nonvertebral fractures, but this should be tested in a randomized trial. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: None declared. doi:10.1016/j.bone.2011.03.117
OPC03 Strontium ranelate positively affects the response of osteocytes to mechanical loading and osteocyte signalling towards osteoclasts A.D. Bakker ⁎, B. Zandieh-Doulabi, J. Klein-Nulend Oral Cell Biology, ACTA–University of Amsterdam and VU University Amsterdam, Research Institute MOVE, Amsterdam, Netherlands Abstract: Strontium ranelate (SrRan) is a successful treatment for postmenopausal osteoporosis, based on its efficacy in stimulating osteoblasts and inhibiting osteoclasts. Signalling molecules produced by osteocytes in response to mechanical loading, such as nitric oxide (NO) or prostaglandin E2 (PGE2), mediate the number and activity of osteoblasts and osteoclasts. The aim of this study was to assess the effect of SrRan on paracrine signalling from mechanically stimulated osteocytes towards osteoclasts. MLO-Y4 osteocytes were cultured for 24 h in the presence of SrRan up to 3 mM, and either or not stimulated with 60 min of pulsating fluid flow (PFF). Treatments effects were assessed by quantification of NO (Griess), adenosine tri-phosphate (ATP; Luminescence) and
S87
PGE2 (ELISA) in the culture medium, and by quantification of mRNA expression (taqman PCR) of COX2 (key enzyme for PGE2 production), cx43 (constituent of gap junctions and hemichannels), RANKL, OPG and M-CSF (mediating osteoclast formation). Apoptosis was assessed using Caspase-Glo 3/7 Assay, since apoptotic osteocytes can stimulate osteoclastogenesis. Medium from SrRan and/or PFF-treated osteocytes was added to cultured mouse bone marrow cells. After 7 days TRACP-positive multinucleated cells (osteoclasts) were counted. SrRan did not affect apoptosis or ATP release by osteocytes. 3 mM SrRan stimulated NO and PGE2 production by osteocytes in both static (1.6 and 2.8-fold, respectively) and PFF-stimulated conditions (1.3 and 2.6-fold, respectively), showing that SrRan enhances osteocyte signalling. SrRan did not affect COX2, cx43 or M-CSF expression at any concentration tested. Conditioned medium from osteocytes treated with 3 mM SrRan inhibited osteoclastogenesis by 1.9-fold compared to conditioned medium from non-treated osteocytes. The combination of 3 mM SrRan and PFF strongly inhibited osteocyte-stimulated osteoclastogenesis (4.3 fold), concomitantly with an enhanced osteocyte OPG/RANKL ratio (2.9-fold). In conclusion, SrRan positively affects paracrine signalling between osteocytes and osteoclasts. The positive effects of SrRan on bone mass may be at least partly explained by improved paracrine signalling by the most abundant cell in bone, the osteocyte. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: A. Bakker Grant / Research Support from Servier, France, B. ZandiehDoulabi Grant/Research Support from Servier, France, J. KleinNulend Grant/Research Support from Servier, France. doi:10.1016/j.bone.2011.03.118
OPC04 Transmenopausal changes in osteocyte lacunar volume in adult human trabecular bone D.B. Kimmel a,⁎, M.P. Akhter a, R. Recker a, T. Fong b, J. Coats b a Osteoporosis Research Center, Creighton University, Omaha, NE, USA b Xradia, Inc., Pleasanton, CA, USA Abstract: Osteocytes (Ot) respond to pharmacologic/mechanical stimuli by altering their lacunar volume. Synchrotron radiation (SR) scanning (0.7 μm pixel resolution [PR]) allows 3D imaging of whole Ot lacunae (Ot.La). The smallness of Ot.La causes current laboratory 3D imaging devices difficulty in resolving them in intact bone samples. Here, we quantify the effect of estrogen status on Ot.La volume (Ot.LaV) in various trabecular bone microarchitectural regions with a lab-based 3D imaging instrument that achieves SR-like resolution. Transilial biopsy specimens were taken from opposite sides of a healthy woman before menopause and at one year after her last menses. Each was embedded undecalcified in plastic. Histomorphometry showed seven-fold higher remodeling after menopause. A portion of each specimen remaining after sectioning was trimmed to 2 × 2 × 8 mm and scanned at 5 μm PR with a 3D X Ray Microscope. 3D images were reconstructed. Ten volumes of interest (VOIs; 0.9 mm diameter × 0.5 mm long; 4 pre- and 6 post-menopausal) containing trabecular nodes or struts were selected and scanned at ~ 0.6 μm PR. The 3D image of each VOI was analyzed by segmentation software (Ratoc; Tokyo, JP) for individual Ot.LaV (iOt.LaV). Ot.La were taken as discrete bone tissue voids > 50 and < 500 μm³. All Ot.La of like menopausal status and microarchitectural location were pooled and analyzed by two factor ANOVA. 9093 Ot.La were examined. iOt.LaV was 11% lower in post-menopausal specimen struts than pre-menopausal struts (P < .0001) (Table 1). Ot.LaV did not change in nodes. Struts and nodes differ significantly in their Ot.LaV behavior across menopause. Study of these and other transmenopausal pairs continues.
Table 1 Location
Pre-Meno iOt.LaV
Post-Meno iOt.LaV
Struts Nodes
170 ± 117 (2 [1848]) 172 ± 119 (2 [2394])
151 ± 107 (4 [3431])* 170 ± 109 (2 [1420])
Units(iOt.LaV) = μm 3; Mean ± SD; (# of VOIs [total number of Ot.La in sample]). *Diff from Pre-Meno (P < .0001). These data suggest that Ot.LaV in bone tissue decreases with menopause in trabecular struts, but not nodes. Bone tissue with smaller Ot.La could have less ability to intercept propagating microcracks, creating decreased toughness on a sub-microscopic level not detectable by current methods. These results also parallel rat data that indicate smaller Ot. LaV in trabecular bone of OVX than intact rats. Decreased toughness concentrated in trabecular struts may also be an additional reason why struts are preferentially lost with menopause and aging. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: D. Kimmel Consulting fees from Xradia, Inc., M. Akhter Consulting fees from Xradia, Inc., R. Recker: None Declared, T. Fong Employee of Xradia, Inc., J. Coats Employee of Xradia, Inc. doi:10.1016/j.bone.2011.03.119