-
Chaoyang Li,
Michael S Ominsky,
Hong-Lin Tan,
Mauricio Barrero,
Qing-Tian Niu,
Franklin J Asuncion,
Edward Lee,
Min Liu,
William S Simonet, Chris Paszty,
Hua Zhu Ke
[show abstract]
[hide abstract]
ABSTRACT: Humans with inherited sclerostin deficiency have high bone mass. Targeted deletion of the sclerostin gene in mice (SOST-KO) causes increases in bone formation, bone mass and bone strength. Inhibition of sclerostin by a monoclonal antibody increases bone formation and enhances fracture healing in rodent and primate models. In this study, we describe the temporal progression of femoral fracture healing in SOST-KO mice compared with wild type (WT) control mice to further characterize the role of sclerostin in fracture healing. Sixty-seven male 9-10 week-old SOST-KO (N=37) and WT (N=30) mice underwent a closed femoral fracture. Weekly radiography was used to monitor the progress of healing. Histologic sections were used to characterize callus composition, evaluate callus bridging, and quantify lamellar bone formation on days 14 and 28. Densitometry and biomechanical testing were utilized to characterize bone mass and strength at the fractured and contralateral femurs on day 45. A significant improvement in time to radiographic healing (no discernible fracture line) was observed in SOST-KO mice, which corresponded to an increase in histologic bony bridging at 14 days (38% versus 0% in WT). Both genotypes appeared to be nearly fully bridged at 28 days post-fracture. The increased bridging at 14 days was associated with 97% greater bone area and 40% lower cartilage area in the callus of SOST-KO mice as compared to WT mice. Bone formation-related endpoints were higher in SOST-KO mice at both 14 and 28 days. At 45 days post-fracture, peak load and bone mass were significantly greater in the fractured femurs of SOST-KO mice as compared to WT mice. In conclusion, fractures in mice lacking sclerostin showed accelerated bridging, greater callus maturation, and increased bone formation and strength in the callus.
Bone 08/2011; 49(6):1178-85. · 4.02 Impact Factor
-
Xiaodong Li,
Michael S Ominsky,
Kelly S Warmington,
Qing-Tian Niu,
Franklin J Asuncion,
Mauricio Barrero,
Denise Dwyer,
Mario Grisanti,
Marina Stolina,
Paul J Kostenuik,
William S Simonet, Chris Paszty,
Hua Zhu Ke
[show abstract]
[hide abstract]
ABSTRACT: Clinical studies have revealed a blunting of the bone anabolic effects of parathyroid hormone treatment in osteoporotic patients in the setting of pre- or cotreatment with the antiresorptive agent alendronate (ALN). Sclerostin monoclonal antibody (Scl-Ab) is currently under clinical investigation as a new potential anabolic therapy for postmenopausal osteoporosis. The purpose of these experiments was to examine the influence of pretreatment or cotreatment with ALN on the bone anabolic actions of Scl-Ab in ovariectomized (OVX) rats. Ten-month-old osteopenic OVX rats were treated with ALN or vehicle for 6 wk, before the start of Scl-Ab treatment. ALN-pretreated OVX rats were switched to Scl-Ab alone or to a combination of ALN and Scl-Ab for another 6 wk. Vehicle-pretreated OVX rats were switched to Scl-Ab or continued on vehicle to serve as controls. Scl-Ab treatment increased areal bone mineral density, volumetric bone mineral density, trabecular and cortical bone mass, and bone strength similarly in OVX rats pretreated with ALN or vehicle. Serum osteocalcin and bone formation rate on trabecular, endocortical, and periosteal surfaces responded similarly to Scl-Ab in ALN or vehicle-pretreated OVX rats. Furthermore, cotreatment with ALN did not have significant effects on the increased bone formation, bone mass, and bone strength induced by Scl-Ab in the OVX rats that were pretreated with ALN. These results indicate that the increases in bone formation, bone mass, and bone strength with Scl-Ab treatment were not affected by pre- or cotreatment with ALN in OVX rats with established osteopenia.
Endocrinology 07/2011; 152(9):3312-22. · 4.46 Impact Factor
-
Michael S Ominsky,
Chaoyang Li,
Xiaodong Li,
Hong L Tan,
Edward Lee,
Mauricio Barrero,
Franklin J Asuncion,
Denise Dwyer,
Chun-Ya Han,
Fay Vlasseros,
Rana Samadfam,
Jacquelin Jolette,
Susan Y Smith,
Marina Stolina,
David L Lacey,
William S Simonet, Chris Paszty,
Gang Li,
Hua Z Ke
[show abstract]
[hide abstract]
ABSTRACT: Therapeutic enhancement of fracture healing would help to prevent the occurrence of orthopedic complications such as nonunion and revision surgery. Sclerostin is a negative regulator of bone formation, and treatment with a sclerostin monoclonal antibody (Scl-Ab) results in increased bone formation and bone mass in animal models. Our objective was to investigate the effects of systemic administration of Scl-Ab in two models of fracture healing. In both a closed femoral fracture model in rats and a fibular osteotomy model in cynomolgus monkeys, Scl-Ab significantly increased bone mass and bone strength at the site of fracture. After 10 weeks of healing in nonhuman primates, the fractures in the Scl-Ab group had less callus cartilage and smaller fracture gaps containing more bone and less fibrovascular tissue. These improvements at the fracture site corresponded with improvements in bone formation, bone mass, and bone strength at nonfractured cortical and trabecular sites in both studies. Thus the potent anabolic activity of Scl-Ab throughout the skeleton also was associated with an anabolic effect at the site of fracture. These results support the potential for systemic Scl-Ab administration to enhance fracture healing in patients.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 05/2011; 26(5):1012-21. · 6.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Sclerostin monoclonal antibody (Scl-Ab) has been shown to increase bone mass and bone strength by stimulating bone formation in an ovariectomy-induced bone loss rat model. The purpose of this study was to determine the effects of Scl-Ab in a rat immobilization/disuse model in which there was both a decrease in bone formation and an increase in bone resorption. Ten-month-old female Sprague Dawley rats were divided into normal weight-bearing (normal-loaded, NL) and right hindlimb-immobilization (under-loaded, UL) groups. Both NL and UL rats were treated with vehicle or Scl-Ab at 5 or 25 mg/kg, twice per week for 4 weeks. Trabecular and cortical bone histomorphometric analyses were performed on the proximal tibial metaphysis (PTM) and tibial shaft (TS). Compared to NL controls, UL rats had reduced body and muscle weights, increased bone marrow fat cells in the PTM, increased trabecular bone resorption and periosteal mineral apposition rate (MAR) as well as decreased trabecular MAR and bone formation rate (BFR/BS). In NL bones, treatment with Scl-Ab significantly increased bone formation and decreased bone resorption, resulting in increased trabecular and cortical bone mass. In UL trabecular bone, treatment with Scl-Ab at 5 or 25 mg/kg induced significant and dose-dependent increases in trabecular bone volume and thickness, mineralized surfaces (MS/BS), MAR and BFR/BS, and a significant decrease in eroded surface (Er.S/BS) compared with UL controls. In UL cortical bone, Scl-Ab treatment induced significant increases in cortical width, periosteal and endocortical MS/BS, MAR and BFR/BS, and significant decreases in endocortical Er.S/BS compared with UL controls. Taken together, these findings suggest that antibody-mediated blockade of sclerostin represents a promising new therapeutic approach for the anabolic treatment of immobilization-induced osteopenia.
Bone 02/2011; 48(2):197-201. · 4.02 Impact Factor
-
Michael S Ominsky,
Chaoyang Li,
Xiaodong Li,
Hong L Tan,
Edward Lee,
Mauricio Barrero,
Franklin J Asuncion,
Denise Dwyer,
Chun-Ya Han,
Fay Vlasseros,
Rana Samadfam,
Jacquelin Jolette,
Susan Y Smith,
Marina Stolina,
David L Lacey,
William S Simonet, Chris Paszty,
Gang Li,
Hua Z Ke
[show abstract]
[hide abstract]
ABSTRACT: Therapeutic enhancement of fracture healing would help prevent the occurrence of orthopaedic complications such as non-union and revision surgery. Sclerostin is a negative regulator of bone formation and treatment with a sclerostin monoclonal antibody (Scl-Ab) results in increased bone formation and bone mass in animal models. Our objective was to investigate the effects of systemic administration of Scl-Ab in two models of fracture healing. In both a closed femoral fracture model in rats and a fibular osteotomy model in cynomolgus monkeys, Scl-Ab significantly increased bone mass and bone strength at the site of fracture. After ten weeks of healing in non-human primates, the fractures in the Scl-Ab group had less callus cartilage and smaller fracture gaps containing more bone and less fibrovascular tissue. These improvements at the fracture site corresponded to improvements in bone formation, bone mass, and bone strength at non-fractured cortical and trabecular sites in both studies. Thus, the potent anabolic activity of Scl-Ab throughout the skeleton was also associated with an anabolic effect at the site of fracture. These results support the potential for systemic Scl-Ab administration to enhance fracture healing in patients. © 2010 American Society for Bone and Mineral Research.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 12/2010; · 6.04 Impact Factor
-
Xiaodong Li,
Kelly S Warmington,
Qing-Tian Niu,
Franklin J Asuncion,
Mauricio Barrero,
Mario Grisanti,
Denise Dwyer,
Brian Stouch,
Theingi M Thway,
Marina Stolina,
Michael S Ominsky,
Paul J Kostenuik,
William S Simonet, Chris Paszty,
Hua Zhu Ke
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to evaluate the effects of sclerostin inhibition by treatment with a sclerostin antibody (Scl-AbII) on bone formation, bone mass, and bone strength in an aged, gonad-intact male rat model. Sixteen-month-old male Sprague-Dawley rats were injected subcutaneously with vehicle or Scl-AbII at 5 or 25 mg/kg twice per week for 5 weeks (9-10/group). In vivo dual-energy X-ray absorptiometry (DXA) analysis showed that there was a marked increase in areal bone mineral density of the lumbar vertebrae (L(1) to L(5) ) and long bones (femur and tibia) in both the 5 and 25 mg/kg Scl-AbII-treated groups compared with baseline or vehicle controls at 3 and 5 weeks after treatment. Ex vivo micro-computed tomographic (µCT) analysis demonstrated improved trabecular and cortical architecture at the fifth lumbar vertebral body (L(5) ), femoral diaphysis (FD), and femoral neck (FN) in both Scl-AbII dose groups compared with vehicle controls. The increased cortical and trabecular bone mass was associated with a significantly higher maximal load of L(5) , FD, and FN in the high-dose group. Bone-formation parameters (ie, mineralizing surface, mineral apposition rate, and bone-formation rate) at the proximal tibial metaphysis and tibial shaft were markedly greater on trabecular, periosteal, and endocortical surfaces in both Scl-AbII dose groups compared with controls. These results indicate that sclerostin inhibition by treatment with a sclerostin antibody increased bone formation, bone mass, and bone strength in aged male rats and, furthermore, suggest that pharmacologic inhibition of sclerostin may represent a promising anabolic therapy for low bone mass in aged men.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 12/2010; 25(12):2647-56. · 6.04 Impact Factor
-
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 09/2010; 25(9):1897-904. · 6.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The current report describes the skeletal effects of a sclerostin monoclonal antibody (Scl-AbIII) treatment at a yellow (fatty) marrow skeletal site in adult female rats. Ten-month-old female Sprague-Dawley rats were treated with vehicle or Scl-AbIII at 5 or 25 mg/kg, twice per week by s.c. injection for 4 weeks. Trabecular bone from a yellow (fatty) marrow site, the 5th caudal vertebral body (CVB), was processed undecalcified for quantitative bone histomorphometric analysis. Compared to vehicle controls, Scl-AbIII at both doses significantly increased bone formation parameters and trabecular bone volume and thickness and decreased bone resorption parameter in the trabecular bone of the CVB. As a reference, we also found that the Scl-AbIII at both doses significantly decreased bone resorption and increased bone formation and bone volume in a red (hematopoietic) marrow site, the 4th lumber vertebral body (LVB). It appears that the percentage of increase in trabecular bone volume induced by Scl-AbIII treatment was slightly larger in the LVB than in the CVB. In summary, these preclinical findings show that antibody-mediated sclerostin inhibition has significant bone anabolic effects at both red and yellow marrow skeletal sites.
Bone 09/2010; 47(3):529-33. · 4.02 Impact Factor
-
Michael S Ominsky,
Fay Vlasseros,
Jacquelin Jolette,
Susan Y Smith,
Brian Stouch,
George Doellgast,
Jianhua Gong,
Yongming Gao,
Jin Cao,
Kevin Graham, [......],
Lei Zhou,
Michael D Hale,
Daniel J Lightwood,
Alistair J Henry,
Andrew G Popplewell,
Adrian R Moore,
Martyn K Robinson,
David L Lacey,
W Scott Simonet, Chris Paszty
[show abstract]
[hide abstract]
ABSTRACT: The development of bone-rebuilding anabolic agents for treating bone-related conditions has been a long-standing goal. Genetic studies in humans and mice have shown that the secreted protein sclerostin is a key negative regulator of bone formation. More recently, administration of sclerostin-neutralizing monoclonal antibodies in rodent studies has shown that pharmacologic inhibition of sclerostin results in increased bone formation, bone mass, and bone strength. To explore the effects of sclerostin inhibition in primates, we administered a humanized sclerostin-neutralizing monoclonal antibody (Scl-AbIV) to gonad-intact female cynomolgus monkeys. Two once-monthly subcutaneous injections of Scl-AbIV were administered at three dose levels (3, 10, and 30 mg/kg), with study termination at 2 months. Scl-AbIV treatment had clear anabolic effects, with marked dose-dependent increases in bone formation on trabecular, periosteal, endocortical, and intracortical surfaces. Bone densitometry showed that the increases in bone formation with Scl-AbIV treatment resulted in significant increases in bone mineral content (BMC) and/or bone mineral density (BMD) at several skeletal sites (ie, femoral neck, radial metaphysis, and tibial metaphysis). These increases, expressed as percent changes from baseline were 11 to 29 percentage points higher than those found in the vehicle-treated group. Additionally, significant increases in trabecular thickness and bone strength were found at the lumbar vertebrae in the highest-dose group. Taken together, the marked bone-building effects achieved in this short-term monkey study suggest that sclerostin inhibition represents a promising new therapeutic approach for medical conditions where increases in bone formation might be desirable, such as in fracture healing and osteoporosis.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 01/2010; 25(5):948-59. · 6.04 Impact Factor
-
Vaclav Veverka,
Alistair J. Henry,
Patrick M. Slocombe,
Andrew Ventom,
Barbara Mulloy, Frederick W. Muskett,
Mariusz Muzylak,
Kevin Greenslade,
Adrian Moore,
Li Zhang,
Jianhua Gong,
Xueming Qian, Chris Paszty,
Richard J. Taylor,
Martyn K. Robinson,
Mark D. Carr
[show abstract]
[hide abstract]
ABSTRACT: The secreted glycoprotein sclerostin has recently emerged as a key negative regulator of Wnt signaling in bone and has stimulated
considerable interest as a potential target for therapeutics designed to treat conditions associated with low bone mass, such
as osteoporosis. We have determined the structure of sclerostin, which resulted in the identification of a previously unknown
binding site for heparin, suggestive of a functional role in localizing sclerostin to the surface of target cells. We have
also mapped the interaction site for an antibody that blocks the inhibition of Wnt signaling by sclerostin. This shows minimal
overlap with the heparin binding site and highlights a key role for this region of sclerostin in protein interactions associated
with the inhibition of Wnt signaling. The conserved N- and C-terminal arms of sclerostin were found to be unstructured, highly
flexible, and unaffected by heparin binding, which suggests a role in stabilizing interactions with target proteins.
Journal of Biological Chemistry 04/2009; 284(16):10890-10900. · 4.77 Impact Factor
-
Vaclav Veverka,
Alistair J Henry,
Patrick M Slocombe,
Andrew Ventom,
Barbara Mulloy,
Frederick W Muskett,
Mariusz Muzylak,
Kevin Greenslade,
Adrian Moore,
Li Zhang,
Jianhua Gong,
Xueming Qian, Chris Paszty,
Richard J Taylor,
Martyn K Robinson,
Mark D Carr
[show abstract]
[hide abstract]
ABSTRACT: The secreted glycoprotein sclerostin has recently emerged as a key negative regulator of Wnt signaling in bone and has stimulated considerable interest as a potential target for therapeutics designed to treat conditions associated with low bone mass, such as osteoporosis. We have determined the structure of sclerostin, which resulted in the identification of a previously unknown binding site for heparin, suggestive of a functional role in localizing sclerostin to the surface of target cells. We have also mapped the interaction site for an antibody that blocks the inhibition of Wnt signaling by sclerostin. This shows minimal overlap with the heparin binding site and highlights a key role for this region of sclerostin in protein interactions associated with the inhibition of Wnt signaling. The conserved N- and C-terminal arms of sclerostin were found to be unstructured, highly flexible, and unaffected by heparin binding, which suggests a role in stabilizing interactions with target proteins.
Journal of Biological Chemistry 03/2009; 284(16):10890-900. · 4.77 Impact Factor
-
Xiaodong Li,
Michael S Ominsky,
Kelly S Warmington,
Sean Morony,
Jianhua Gong,
Jin Cao,
Yongming Gao,
Victoria Shalhoub,
Barbara Tipton,
Raj Haldankar,
Qing Chen,
Aaron Winters,
Tom Boone,
Zhaopo Geng,
Qing-Tian Niu,
Hua Zhu Ke,
Paul J Kostenuik,
W Scott Simonet,
David L Lacey, Chris Paszty
[show abstract]
[hide abstract]
ABSTRACT: The development of bone-rebuilding anabolic agents for potential use in the treatment of bone loss conditions, such as osteoporosis, has been a long-standing goal. Genetic studies in humans and mice have shown that the secreted protein sclerostin is a key negative regulator of bone formation, although the magnitude and extent of sclerostin's role in the control of bone formation in the aging skeleton is still unclear. To study this unexplored area of sclerostin biology and to assess the pharmacologic effects of sclerostin inhibition, we used a cell culture model of bone formation to identify a sclerostin neutralizing monoclonal antibody (Scl-AbII) for testing in an aged ovariectomized rat model of postmenopausal osteoporosis. Six-month-old female rats were ovariectomized and left untreated for 1 yr to allow for significant estrogen deficiency-induced bone loss, at which point Scl-AbII was administered for 5 wk. Scl-AbII treatment in these animals had robust anabolic effects, with marked increases in bone formation on trabecular, periosteal, endocortical, and intracortical surfaces. This not only resulted in complete reversal, at several skeletal sites, of the 1 yr of estrogen deficiency-induced bone loss, but also further increased bone mass and bone strength to levels greater than those found in non-ovariectomized control rats. Taken together, these preclinical results establish sclerostin's role as a pivotal negative regulator of bone formation in the aging skeleton and, furthermore, suggest that antibody-mediated inhibition of sclerostin represents a promising new therapeutic approach for the anabolic treatment of bone-related disorders, such as postmenopausal osteoporosis.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 01/2009; 24(4):578-88. · 6.04 Impact Factor
-
Xiaodong Li,
Michael S Ominsky,
Qing-Tian Niu,
Ning Sun,
Betsy Daugherty,
Diane D'Agostin,
Carole Kurahara,
Yongming Gao,
Jin Cao,
Jianhua Gong, [......],
Kelly Warmington,
Denise Dwyer,
Marina Stolina,
Sean Morony,
Ildiko Sarosi,
Paul J Kostenuik,
David L Lacey,
W Scott Simonet,
Hua Zhu Ke, Chris Paszty
[show abstract]
[hide abstract]
ABSTRACT: Sclerosteosis is a rare high bone mass genetic disorder in humans caused by inactivating mutations in SOST, the gene encoding sclerostin. Based on these data, sclerostin has emerged as a key negative regulator of bone mass. We generated SOST knockout (KO) mice to gain a more detailed understanding of the effects of sclerostin deficiency on bone.
Gene targeting was used to inactivate SOST and generate a line of SOST KO mice. Radiography, densitometry, microCT, histomorphometry, and mechanical testing were used to characterize the impact of sclerostin deficiency on bone in male and female mice. Comparisons were made between same sex KO and wildtype (WT) mice.
The results for male and female SOST KO mice were similar, with differences only in the magnitude of some effects. SOST KO mice had increased radiodensity throughout the skeleton, with general skeletal morphology being normal in appearance. DXA analysis of lumbar vertebrae and whole leg showed that there was a significant increase in BMD (>50%) at both sites. microCT analysis of femur showed that bone volume was significantly increased in both the trabecular and cortical compartments. Histomorphometry of trabecular bone revealed a significant increase in osteoblast surface and no significant change in osteoclast surface in SOST KO mice. The bone formation rate in SOST KO mice was significantly increased for trabecular bone (>9-fold) at the distal femur, as well as for the endocortical and periosteal surfaces of the femur midshaft. Mechanical testing of lumbar vertebrae and femur showed that bone strength was significantly increased at both sites in SOST KO mice.
SOST KO mice have a high bone mass phenotype characterized by marked increases in BMD, bone volume, bone formation, and bone strength. These results show that sclerostin is a key negative regulator of a powerful, evolutionarily conserved bone formation pathway that acts on both trabecular and cortical bone.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 06/2008; 23(6):860-9. · 6.04 Impact Factor
