Compositional and Material Properties of Rat Bone after Bisphosphonate and/or Strontium Ranelate Drug Treatment

PURPOSE: We investigated elemental strontium and/or bisphosphonate drug incorporation upon the compositional and biomechanical properties of vertebral bone, in a rat model of Osteoporosis secondary to ovariectomy. METHODS: Six month old female rats were ovariectomized (OVX) and divided into untreated OVXVehicle, OVX-RIS (Risedronate bisphosphonate [BP] treated), OVX-SrR (Strontium Ranelate [Protos®] treated), combination OVX-RIS+SrR, and sham-operated controls. After 16 weeks of treatment, rats were euthanized and lumbar vertebra were dissected. Micro-Computed Tomography (micro-CT), Electron Probe Micro-Analysis (EPMA), mechanical testing in compression and nano-indentation testing were then undertaken to evaluate bone morphometry, elemental composition, material properties and strength. Results. Bone Volume was significantly reduced in the OVX-Vehicle (133±10mm3) compared with OVX-RIS (169±22mm3), OVXSrR (145±2mm3), and OVX-RIS+SrR (172±8mm3). EPMA mapped elemental Sr deposition to the periosteal surface of cortical bone (50-100 µm thick), endosteal trabecular surfaces (20 µm thick), as well as to both vertebral growth plates. The atomic ratios of (Ca+Sr)/P were significantly reduced with SrR treatment (2.4%- 6.6%), indicating Sr incorporation into bone mineral. No significant differences were measured in vertebral bone reduced modulus by nano-indentation. Conversely, all BP-dosed groups had significantly increased structural bone strength. CONCLUSIONS: Thus, we conclude that BP drugs dominate the conservation of trabecular geometry and structural strength in OP rats, whereas Sr drugs likely influence bone volume and material composition locally

Development and reliability of a multi-modality scoring system for evaluation of disease progression in pre-clinical models of osteoarthritis: celecoxib may possess disease-modifying properties

SummaryObjectiveWe sought to develop a comprehensive scoring system for evaluation of pre-clinical models of osteoarthritis (OA) progression, and use this to evaluate two different classes of drugs for management of OA.MethodsPost-traumatic OA (PTOA) was surgically induced in skeletally mature rats. Rats were randomly divided in three groups receiving either glucosamine (high dose of 192 mg/kg) or celecoxib (clinical dose) or no treatment. Disease progression was monitored utilizing micro-magnetic resonance imaging (MRI), micro-computed tomography (CT) and histology. Pertinent features such as osteophytes, subchondral sclerosis, joint effusion, bone marrow lesion (BML), cysts, loose bodies and cartilage abnormalities were included in designing a sensitive multi-modality based scoring system, termed the rat arthritis knee scoring system (RAKSS).ResultsOverall, an inter-observer correlation coefficient (ICC) of greater than 0.750 was achieved for each scored feature. None of the treatments prevented cartilage loss, synovitis, joint effusion, or sclerosis. However, celecoxib significantly reduced osteophyte development compared to placebo. Although signs of inflammation such as synovitis and joint effusion were readily identified at 4 weeks post-operation, we did not detect any BML.ConclusionWe report the development of a sensitive and reliable multi-modality scoring system, the RAKSS, for evaluation of OA severity in pre-clinical animal models. Using this scoring system, we found that celecoxib prevented enlargement of osteophytes in this animal model of PTOA, and thus it may be useful in preventing OA progression. However, it did not show any chondroprotective effect using the recommended dose. In contrast, high dose glucosamine had no measurable effects

DOX-Vit D, a Novel Doxorubicin Delivery Approach, Inhibits Human Osteosarcoma Cell Proliferation by Inducing Apoptosis While Inhibiting Akt and mTOR Signaling Pathways

This work is licensed under a Creative Commons Attribution 4.0 International License.Doxorubicin (DOX) is a very potent and effective anticancer agent. However, the effectiveness of DOX in osteosarcoma is usually limited by the acquired drug resistance. Recently, Vitamin D (Vit-D) was shown to suppress the growth of many human cancer cells. Taken together, we synthesized DOX-Vit D by conjugating Vit-D to DOX in order to increase the delivery of DOX into cancer cells and mitigate the chemoresistance associated with DOX. For this purpose, MG63 cells were treated with 10 µM DOX or DOX-Vit D for 24 h. Thereafter, MTT, real-time PCR and western blot analysis were used to determine cell proliferation, genes and proteins expression, respectively. Our results showed that DOX-Vit D, but not DOX, significantly elicited an apoptotic signal in MG63 cells as evidenced by induction of death receptor, Caspase-3 and BCLxs genes. Mechanistically, the DOX-Vit D-induced apoptogens were credited to the activation of p-JNK and p-p38 signaling pathway and the inhibition of proliferative proteins, p-Akt and p-mTOR. Our findings propose that DOX-Vit D suppressed the growth of MG63 cells by inducing apoptosis while inhibiting cell survival and proliferative signaling pathways. DOX-Vit D may serve as a novel drug delivery approach to potentiate the delivery of DOX into cancer cells.Canadian Institutes of Health Research [Grant 106665]U.S. National Cancer Institute [Grant R01CA173292

In vivo microfocal computed tomography and micro–magnetic resonance imaging evaluation of antiresorptive and antiinflammatory drugs as preventive treatments of osteoarthritis in the rat

Objective To determine whether treatment with an antiresorptive drug in combination with an antiinflammatory drug reduces periarticular bone and soft tissue adaptations associated with the progression of posttraumatic secondary osteoarthritis (OA). Methods We used in vivo microfocal computed tomography (micro-CT) to map bony adaptations and in vivo micro–magnetic resonance imaging (micro-MRI) to examine joint inflammation in a rat model of surgically induced OA secondary to knee triad injury. We examined the arthroprotective effects of the bisphosphonates alendronate and risedronate and the nonsteroidal antiinflammatory drug (NSAID) meloxicam. Results Micro-CT revealed reduced levels of periarticular trabecular bone loss in animals with knee triad injury treated with the bisphosphonate drugs alendronate or risedronate, or the NSAID meloxicam, compared with untreated animals. Alendronate treatment reduced bony osteophyte development. While risedronate as a monotherapy did not positively impact osteophytogenesis, combination therapy with risedronate and meloxicam reduced osteophyte severity somewhat. Micro-MRI revealed an increased, diffuse water signal in the epiphyses of untreated rats with knee triad injury 8 weeks after surgery, suggestive of a bone marrow lesion–like stimulus. In contrast, meloxicam-treated rats showed a significant reduction in fluid signal compared with both bisphosphonate-treated groups 8 weeks after surgery. Histologic analysis qualitatively confirmed the chondroprotective effect of both bisphosphonate treatments, showing fewer degradative changes compared with untreated rats with knee triad injury. Conclusion Our findings indicate that select combinations of bisphosphonate and NSAID drug therapy in the early stages of secondary OA preserve trabecular bone mass and reduce the impact of osteophytic bony adaptations and bone marrow lesion–like stimulus. Bisphosphonate and NSAID therapy may be an effective disease-modifying drug regimen if administered early after the initial injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78085/1/27595_ftp.pd

A Novel Rat Model of Orthodontic Tooth Movement Using Temporary Skeletal Anchorage Devices: 3D Finite Element Analysis and In Vivo

The aim of this animal study was to develop a model of orthodontic tooth movement using a microimplant as a TSAD in rodents. A finite element model of the TSAD in alveolar bone was built using μCT images of rat maxilla to determine the von Mises stresses and displacement in the alveolar bone surrounding the TSAD. For in vivo validation of the FE model, Sprague-Dawley rats (n=25) were used and a Stryker 1.2 × 3 mm microimplant was inserted in the right maxilla and used to protract the right first permanent molar using a NiTi closed coil spring. Tooth movement measurements were taken at baseline, 4 and 8 weeks. At 8 weeks, animals were euthanized and tissues were analyzed by histology and EPMA. FE modeling showed maximum von Mises stress of 45 Mpa near the apex of TSAD but the average von Mises stress was under 25 Mpa. Appreciable tooth movement of 0.62 ± 0.04 mm at 4 weeks and 1.99 ± 0.14 mm at 8 weeks was obtained. Histological and EPMA results demonstrated no active bone remodeling around the TSAD at 8 weeks depicting good secondary stability. This study provided evidence that protracted tooth movement is achieved in small animals using TSADs

Vascular adaptations after surgical incision of the normal rabbit patellar tendon

Bibliography: p. 65-7

Bisphosphonate antiresorptive drug use in a rabbit model of osteoarthritis

Bibliography: p. 147-159Some pages are in colour.Following anterior cruciate ligament rupture (ACLX) in the knee, rapid periarticular bone loss often occurs prior to the subchondral sclerosis of end-stage osteoarthritis (OA). In a model of knee osteoarthritis, changes were examined in subchondral periarticular bone mineral and microarchitecture (IlCT) and in the femoral insertion of the medial collateral ligament (MCL). Also assessed were whether antiresorptive therapy with a bisphosphonate (BP [risedronate]) altered those bone adaptations in the subchondral plate, at the MCL-insertion, and after ACL-reconstruction, and if BP intervention influenced ligament-complex biomechanics and OA progression. Finally, molecular expression of a bone cytokine (osteoprotegerin [OPG]) in periarticular tissues undergoing remodeling and the influence of BP therapy upon the regulation of that gene were investigated. Early alterations of periarticular bone mineral after ACLX included significant loss in subchondral trabecular bone and in bone at the MCL-insertion. Compared to normal controls, MCL-complex laxity and bone loss at the MCL-insertion were significantly greater in the ACLX cohort at 6 wk and had increased further by 14 wk after ACLX. If ACLX animals were dosed daily with risedronate bisphosphonate for 6 wk, however, MCL-complex laxity was significantly improved, and the loss of MCL insertional bone was significantly less and not significantly different from normal control animals. When animals were dosed up to 24 wk after ACLX with BP, however, the progression of OA was not altered. The transient restabilization of the joint by ACL-reconstruction, in conjunction with BP-dosing, did little to block the progression of OA. The expression of OPG was altered following loss of the ACL, and the BP risedronate countered that effect-resulting in the return of OPG expression in bone and fibrocartilaginous tissues. Such adaptive responses in connective tissues after ACLX may have been necessary for the maintenance and repair of the injured structures. The results suggested a potential therapeutic role for antiresorptive bisphosphonate therapy to inhibit adaptive remodeling early following non-fracture joint trauma. Long-term administration of the BP, however, did not appear to be beneficial, and the ultimate effect of the short-term use of the BP on osteoarthritis progression remains to be determined