Detecting early bone changes using in vivo micro-CT in ovariectomized, zoledronic acid-treated, and sham-operated rats

Arctiin alleviates knee osteoarthritis by suppressing chondrocyte oxidative stress induced by accumulated iron via AKT/NRF2/HO-1 signaling pathway

Iron overload (IO) was considered to be a risk factor for cartilage degradation in knee osteoarthritis (KOA) advancement. However, few drugs were found to improve cartilage degeneration by alleviating multiple cell death induced by the impaired iron level of the knee joints. We aimed to elucidate that Arctiin (ARC) plays a role in managing KOA caused by accumulated iron levels by restoring chondrocyte apoptosis and ferroptosis. Single-cell RNA sequencing analysis was used to discover the disparities in chondrocytes between KOA patients and non-KOA individuals. CCK-8 assay was performed to detect chondrocyte viability. Annexin V-FITC/PI staining determined the cell apoptosis rate. The fluorescence density reflected the iron content, ROS, lipid-ROS, and mitochondrial membrane potential. Q-RTPCR and Western Blotting were used to detect the expression levels of genes and proteins expression. Micro-CT and Safranin O-Fast Green staining were used to detect the phenotype of the knee joints. ARC increased cell viability and inhibited chondrocyte apoptosis. Further, ARC acts as an anti-ferroptosis effect by reducing the intracellular iron, ROS, and lipid-ROS content and restoring mitochondrial damage. Based on the results of scRNA-seq, we found that ARC can play a role by activating AKT/NRF2/HO-1 signaling pathway. In vivo, ARC can significantly improve the severity of KOA caused by IO. ARC alleviates oxidative stress in chondrocytes via the AKT/NRF2/HO-1 signaling pathway, suggesting the potential application of ARC in KOA.

Combining PTH(1-34) and mechanical loading has increased benefit to tibia bone mechanics in ovariectomised mice

Combined treatment with PTH(1-34) and mechanical loading confers increased structural benefits to bone than monotherapies. However, it remains unclear how this longitudinal adaptation affects the bone mechanics. This study quantified the individual and combined longitudinal effects of PTH(1-34) and mechanical loading on the bone stiffness and strength evaluated in vivo with validated micro-finite element (microFE) models. C57BL/6 mice were ovariectomised at 14-week-old and treated either with injections of PTH(1-34), compressive tibia loading or both interventions concurrently. Right tibiae were in vivo microCT-scanned every 2 weeks from 14 until 24-week-old. MicroCT images were rigidly registered to reference tibia and the cortical organ level (whole bone) and tissue level (midshaft) morphometric properties and bone mineral content were quantified. MicroCT images were converted into voxel-based homogeneous, linear elastic microFE models to estimate the bone stiffness and strength. This approach allowed us for the first time to quantify the longitudinal changes in mechanical properties induced by combined treatments in a model of accelerated bone resorption. Both changes of stiffness and strength were higher with co-treatment than with individual therapies, consistent with increased benefits with the tibia bone mineral content and cortical area, properties strongly associated with the tibia mechanics. The longitudinal data shows that the two bone anabolics, both individually and combined, had persistent benefit on estimated mechanical properties, and that benefits (increased stiffness and strength) remained after treatment was withdrawn.

Modelling the Effects of Growth and Remodelling on the Density and Structure of Cancellous Bone

A two-stage model is proposed for investigating remodelling characteristics in bone over time and distance to the growth plate. The first stage comprises a partial differential equation (PDE) for bone density as a function of time and distance from the growth plate. This stage clarifies the contributions to changes in bone density due to remodelling and growth processes and tracks the rate at which new bone emanates from the growth plate. The second stage consists of simulating the remodelling process to determine remodelling characteristics. Implementing the second stage requires the rate at which bone moves away from the growth plate computed during the first stage. The second stage is also needed to confirm that remodelling characteristics predicted by the first stage may be explained by a realistic model for remodelling and to compute activation frequency. The model is demonstrated on microCT scans of tibia of juvenile female rats in three experimental groups: sham-operated control, oestrogen deprived, and oestrogen deprived followed by treatment. Model predictions for changes in bone density and remodelling characteristics agree with the literature. In addition, the model provides new insight into the role of treatment on the density of new bone emanating from the growth plate and provides quantitative descriptions of changes in remodelling characteristics beyond what has been possible to ascertain by experimentation alone.

Temporal changes in cortical microporosity during estrogen deficiency associated with perilacunar resorption and osteocyte apoptosis: A pilot study

Osteocytes can actively regulate bone microporosity, through either perilacunar resorption or micropetrosis following apoptosis. Osteocyte apoptosis is more prevalent in estrogen deficiency and changes in the lacunar-canalicular network of osteocytes have been reported. Temporal changes in bone mineralisation and osteocytes cellular strains occur, which might be associated with osteocyte-driven microporosity changes, although time dependant changes in bone microporosity are not yet fully understood. In this pilot study we conducted micro-CT analysis, backscatter electron imaging and histological analysis of femoral cortical bone form an ovariectomized rat model of osteoporosis to investigate whether estrogen deficiency causes temporal changes in lacunar and vascular porosity. We also assessed MMP14 expression, lacunar occupancy and mineral infilling, as indicators of perilacunar resorption and micropetrosis. We report temporal changes in cortical microporosity in estrogen deficiency. Specifically, canalicular and vascular porosity initially increased (4 weeks post-OVX), coinciding with the period of rapid bone loss, whereas in the longer term (14 weeks post-OVX) lacunar and canalicular diameter decreased. Interestingly, these changes coincided with an increased prevalence of empty lacunae and osteocyte lacunae were observed to be more circular with a mineralised border around the lacunar space. In addition we report an increase in MMP14+ osteocytes, which also suggests active matrix degradation by these cells. Together these results provide an insight into the temporal changes in cortical microporosity during estrogen deficiency and suggest the likelihood of occurrence of both perilacunar resorption and osteocyte apoptosis leading to micropetrosis. We propose that microporosity changes arise due to processes driven by distinct populations of osteocytes, which are either actively resorbing their matrix or have undergone apoptosis and are infilling lacunae by micropetrosis.

Gegen Qinlian Decoction ameliorates type 2 diabetes osteoporosis via IGFBP3/MAPK/NFATc1 signaling pathway based on cytokine antibody array

BACKGROUND

Osteoporosis affects more than half the patients with type 2 diabetes mellitus (T2DM). Up to data, there is no effective clinical practice in managing type 2 diabetes osteoporosis (T2DOP) because of its complex pathogenesis. Gegen Qinlian Decoction (GQD) has been used for the long-term management of T2DM. However, the underlying mechanism of GQD in the treatment of T2DOP remains unknown.

PURPOSE

To reveal the role of GQD in T2DOP and its potential therapeutic targets in the management of T2DOP.

STUDY DESIGN

The effect of GQD on T2DOP was observed in db/db mice in four groups: model group, GQD low-dose group (GQD-L), GQD high-dose group (GQD-H), and metformin (positive control) group. C57BL/6J mice were used as the negative control group.

METHODS

Quantitative phytochemical analysis of GQD was performed using high-performance liquid chromatography (HPLC). Micro-CT and hematoxylin-eosin (H&E) staining were used to evaluate bone histomorphometry. To screen for candidate targets of GQD, a cytokine antibody array was used, followed by bioinformatics analysis. Quantitative real-time PCR (qRT-PCR) and western blotting (WB) were used to determine expression levels.

RESULTS

The major active components of GQD were confirmed by HPLC. Micro-CT and H&E staining showed that bone mass was significantly increased in the GQD-H group compared with the model group. Antibody arrays revealed that the expression of insulin-like growth factor binding protein 3 (IGFBP3) was elevated in the GQD-H group. The MAPK pathway was identified using bioinformatics analysis. Additionally, the levels of osteoclastogenesis-related genes, including cathepsin K (Ctsk), acid phosphatase 5 (Acp5), matrix metallopeptidase 9 (Mmp9), and ATPase H+ transporting V0 subunit D2 (Atp6v0d2) were significantly decreased in the GQD-H group. Compared with the model group, high-dosage GQD inhibited phosphorylation of extracellular signal-regulated kinases (ERKs) and P38 mitogen-activated protein kinase (MAPK) and the expression of c-Fos and nuclear factor of activated T cells 1 (NFATc1).

CONCLUSION

GQD plays a protective role in T2DOP by upregulating IGFBP3 expression and downregulating the IGFBP3/MAPK/NFATc1 signaling pathway. IGFBP3 in serum may also be a novel biomarker in the treatment of T2DOP. Our current findings not only expand the application of GQD, but also provide a theoretical basis and guidance for T2DOP.

Effects of Soft Tissue Closure on Medication-Related Osteonecrosis of the Jaw in a Rabbit Model with Tooth Extraction: A Pilot Study

Objectives

The study investigated the effect of soft tissue closure after tooth extraction on the prevention of medication-related osteonecrosis of the jaw in a rabbit model.

Materials and Methods

Twenty female New Zealand white rabbits were randomly assigned into the experimental group administrated with zoledronic acid (ZA) and control groups treated with saline. Bilateral lower premolar extraction was performed 4 weeks after ZA/saline administration. Immediately after extraction, the wound on the right mandible was closed by suture while the other side was left open. Animals were sacrificed 4 weeks and 8 weeks after tooth extraction. Fluorochrome labeling solutions were injected subcutaneously to evaluate the bone growth rates. The mandibles were harvested and subjected for microcomputed tomography, confocal microscope, and histomorphological examinations.

Results

All extraction sites healed well without any signs of infection. Trabecular thickness (Tb.Th) was significantly higher in the ZA-treated group than in the control group at both week 4 and week 8, while no significant difference was detected in the rest of the assessed parameters. The bone growth rate in mandibles showed gradual reduction in the ZA-treated group. Histological analysis showed that at week 8, the animals in the ZA-treated group had significantly higher incidence of osteonecrosis than that in the control group, while no significance was revealed between the sutured and nonsutured side.

Conclusions

ZA treatment significantly reduces bone growth rates but does not reveal a significant effect on bone mineral density and bone microarchitecture. Soft tissue closure of the extraction socket does not reduce the incidence of ONJ in the ZA-treated rabbit model.

Effects of Bisphosphonates on Osseointegration of Dental Implants in Rabbit Model

This study is to investigate the effect of bisphosphonates on the osseointegration of dental implants in a rabbit model. Twenty female New Zealand White rabbits were equally assigned into control and experiment groups which received saline or zoledronic acid treatment 4 weeks prior to surgery. Titanium dental implant was placed on the calvarial bone. Zoledronic acid or saline treatment continued after surgery for 4 weeks (short-term subgroup) or 8 weeks (long-term subgroup) until sacrifice. Three different fluorochrome labeling solutions were administrated for assessing bone growth rates. Samples of the calvarial bone and mandible were subjected to microcomputed tomography (micro-CT), confocal microscope, and histology analysis. Zoledronic acid treatment significantly reduced bone growth rates in the calvarial bone, but had no significant influence in bone mineral density and trabecular microarchitecture. Significantly lower bone-to-implant contact ratios were found in zoledronic acid-treated animals compared to controls at week 4 but not at week 8. Oncologic dose zoledronic acid suppresses the bone growth rates of the calvarial bone; ZA may have an adverse effect on osseointegration of dental implant in short term, but this effect tends to diminish in long term.

Protective Effect of Oxytocin Against Bone Loss in a Female Rat Model of Osteoporosis

Background

Introduction: Oxytocin (OT) has been proposed to assist in the regulation of bone remodeling and to exert an antiosteoporotic effect. We evaluated the possible protective effect of OT against bone degeneration in ovariectomized (OVX) rats.

Methods

The study was performed on three groups of adult female rats; group I was subjected to sham operation, group II was subjected to ovariectomy, and group III was subjected to ovariectomy and intraperitoneal injection with OT for eight successive weeks. At the end of the study, bone mass density (BMD) was measured; then the rats were euthanized and their blood and bone tissues were examined.

Results

The group II rats had significantly less BMD and greater serum bone-specific alkaline phosphatase (bALP), osteocalcin (OC), and tartrate-resistant acid phosphatase (TRAP) levels than the group I rats. Furthermore, group II rats had fewer osteocytes and osteoblasts, and less OPG/RANKL mRNA expression than group I rats. The groups I and III and rats showed no significant differences in BMD, bALP, OC, TRAP, OPG/RANKL mRNA expression, or osteocyte and osteoblast numbers.

Conclusion

Oxytocin may have an antiosteoporotic effect in OVX rats.

PTH(1-34) treatment and/or mechanical loading have different osteogenic effects on the trabecular and cortical bone in the ovariectomized C57BL/6 mouse

In preclinical mouse models, a synergistic anabolic response to PTH(1–34) and tibia loading was shown. Whether combined treatment improves bone properties with oestrogen deficiency, a cardinal feature of osteoporosis, remains unknown. This study quantified the individual and combined longitudinal effects of PTH(1–34) and loading on the bone morphometric and densitometric properties in ovariectomised mice. C57BL/6 mice were ovariectomised at 14-weeks-old and treated either with injections of PTH(1–34); compressive loading of the right tibia; both interventions concurrently; or both interventions on alternating weeks. Right tibiae were microCT-scanned from 14 until 24-weeks-old. Trabecular metaphyseal and cortical midshaft morphometric properties, and bone mineral content (BMC) in 40 different regions of the tibia were measured. Mice treated only with loading showed the highest trabecular bone volume fraction at week 22. Cortical thickness was higher with co-treatment than in the mice treated with PTH alone. In the mid-diaphysis, increases in BMC were significantly higher with loading than PTH. In ovariectomised mice, the osteogenic benefits of co-treatment on the trabecular bone were lower than loading alone. However, combined interventions had increased, albeit regionally-dependent, benefits to cortical bone. Increased benefits were largest in the mid-diaphysis and postero-laterally, regions subjected to higher strains under compressive loads.

Secondary alterations in bone mineralisation and trabecular thickening occur after long-term estrogen deficiency in ovariectomised rat tibiae, which do not coincide with initial rapid bone loss

This study delineates the time sequence of changes in bone tissue mineralisation in ovariectomised rats. We report that changes in bone mineral distribution arise secondary to the initial rapid bone loss but coincide with trabecular thickening. We propose that these changes compensate for elevated stresses in remaining trabeculae after bone resorption.

INTRODUCTION

Recent studies have shown that osteoporosis is not simply a disease of bone loss and microarchitectural degradation but that important changes in tissue composition also occur. Such changes may be a secondary response to early bone loss, but the time sequence of changes in bone mineral distribution is not fully understood. The objective of this study was to quantify the temporal effects of estrogen deficiency on trabecular mineral distribution in the tibia of ovariectomised (OVX) rats.

METHODS

Weekly in vivo micro-CT scans and morphometric and bone mineral density distribution analyses of the proximal tibia were conducted for the first 4 weeks of estrogen deficiency and then at 8, 14 and 34 weeks.

RESULTS

Here we report that although trabecular bone volume and architecture are significantly deteriorated within the first 4 weeks of estrogen deficiency, there is no change in the distribution of bone mineral within trabeculae during this initial period. The rate of bone loss in OVX animals dramatically reduced between week 4 and week 14, which coincided with the initiation of increases in trabecular thickness and mineralisation in the OVX group.

CONCLUSIONS

Together this study reveals for the first time that alterations in bone mineralisation and trabecular thickening arise secondary to the initial rapid bone loss. We propose that these secondary mineralisation changes act to reinforce the trabecular network in an attempt to compensate for the increased loading that ensues after severe bone loss. This study provides an insight into temporal changes in bone mineral distribution in estrogen deficiency.

Bone microarchitectural parameters can detect oxytocin induced changes prior to bone density on mitigating bone deterioration in rabbit osteoporosis model using micro-CT

Background

This study is aimed to determine the efficacy of X-Ray Microtomography (micro-CT) in predicting oxytocin (OT) treatment response in rabbit osteoporosis(OP) model.

Methods

Sixty-five rabbits were randomly divided into three groups: control group, ovariectomy (OVX) -vehicle and OVX-oxytocin group. The controls underwent sham surgery. OVX-vehicle and OVX-oxytocin groups were subjected to bilateral OVX. The rabbits in OVX-oxytocin group were injected with oxytocin. In the 0th, 4th, 8th, 10th and 12th weeks post OVX operation, bone mineral density (BMD) and bone micro-architectural parameters were measured in three groups.

Results

Bone mineral density (BMD), bone volume fraction (BV/TV), Trabecular Number (Tb.N), and Trabecular Thickness (Tb.Th) decreased, while Trabecular Spacing (Tb.Sp) and Structure Model Index (SMI) increased overtime in all the three groups. In OVX-oxytocin group, the bone deterioration tendency is slowing down compared with that of the OVX-vehicle group. The BMD of the OVX-oxytocin group was significantly lower than those in the OVX-vehicle group at 12th week (P = 0.017). BV/TV and Tb.Sp in OVX-oxytocin group changed significantly from 8th week (P = 0.043) and 12th week (P = 0.014), which is earlier than that of BMD and other bone micro-architectural parameters.

Conclusion

BV/TV and Tb.Sp changed prior to BMD and other bone micro-architectural parameters with oxytocin intervention, which indicate that they are more sensitive markers for predicting early osteoporosis and treatment monitoring when using micro-CT to evaluate osteoporosis rabbit model.

The longitudinal effects of ovariectomy on the morphometric, densitometric and mechanical properties in the murine tibia: A comparison between two mouse strains

Oestrogen deficiency-related bone loss in the ovariectomized (OVX) mouse is a common model for osteoporosis. However, a comprehensive in vivo assessment of intervention-related changes in multiple bone properties, and in multiple mouse strains, is required in order to identify an appropriate model for future evaluation of novel anti-osteoporotic therapies. The aim of this study was to evaluate the effect of OVX on the morphometric and densitometric properties measured in the microCT images and the mechanical properties estimated with finite element models of the tibia in two mouse strains, C57BL/6 and BALB/c. 14-weeks-old female C57BL/6 and BALB/c mice were divided into two groups per strain: (1) ovariectomized, (2) non-operated control. The right tibia was scanned at baseline (14 weeks) and then every two weeks thereafter, until 24-weeks-old, using in vivo microCT. Changes in trabecular and cortical bone morphometry, spatiotemporal changes in densitometric properties and in mechanical properties (from micro-finite element (μFE) analysis) were computed. Differences between OVX and non-operated controls were evaluated by ANCOVA, adjusted for 14-weeks baseline. In morphometry, trabecular bone mass was significantly reduced in both C57BL/6 and BALB/c from four weeks following surgery. Though the OVX-effect was transient in BALB/c as bone mass reached skeletal homeostasis. OVX inhibited the age-related thickening of cortical bone only in C57BL/6. In both strains, increments in bone mineral content were significantly lower with OVX only in the proximal tibia, with intervention-related differences increasing with time. OVX had no effect on μFE estimates of stiffness nor failure load in either strain. The results of this study show strain-, time- and region-(trabecular or cortical) dependent changes in morphometric and densitometric properties. These findings highlight the importance of choosing an appropriate mouse model and time points for research of treatments against accelerated bone resorption.

Both Oleanolic Acid and a Mixture of Oleanolic and Ursolic Acids Mimic the Effects of Fructus ligustri lucidi on Bone Properties and Circulating 1,25-Dihydroxycholecalciferol in Ovariectomized Rats

Background

Oleanolic acid (OA) and ursolic acid (UA) are major chemical constituents found in Fructus ligustri lucidi (FLL), a Chinese herb previously shown to increase bone properties and modulate calcium-vitamin D metabolism in rats. OA and UA have been reported to exert osteoprotective effects in vitro.

Objective

The present study was designed to determine whether OA or OA + UA mimicked the effects of FLL on bone and calcium homeostasis using ovariectomized rats.

Methods

Three-month-old ovariectomized Sprague-Dawley rats were stabilized for 2 mo and randomly assigned to 4 groups offered the same amount (15-17 g/d) of a control diet or experimental diets containing FLL (18.8 g/kg), OA (0.67 g/kg), or OA (0.67 g/kg) + UA (0.22 g/kg) for 6 wk. Serum was obtained for measurement of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and bones were collected for micro-CT analysis. Calcium balance was measured at weeks 1 and 6. A calcium kinetic study using 45Ca was conducted at week 6 and modeled using WinSAAM software.

Results

Compared with the control group, rats fed the FLL-, OA-, and OA + UA-enriched diets had better bone properties and 51%, 31%, and 27% higher serum 1,25(OH)2D3 concentrations at week 6, respectively. These variables did not differ between the treatments. Calcium balance was not affected by diet at either week 1 or week 6. Kinetic modeling predicted that FLL and OA + UA diet-fed rats had 9% and 15% less endogenous excretion of calcium, respectively, compared with the control group. All 3 treatments resulted in a higher calcium mass of compartment 3 because of changes in transfer rate between compartments 2 and 3, and were positively associated with the serum 1,25(OH)2D3 concentration (R2 = 0.28; P < 0.01).

Conclusion

Similar to FLL, OA and OA + UA increase bone properties, serum 1,25(OH)2D3 concentration, and calcium use in ovariectomized rats, suggesting their potential role in management of osteoporosis.

Can repeated in vivo micro-CT irradiation during adolescence alter bone microstructure, histomorphometry and longitudinal growth in a rodent model?

In vivo micro-computed tomography (micro-CT) can monitor longitudinal changes in bone mass and microstructure in small rodents but imposing high doses of radiation can damage the bone tissue. However, the effect of weekly micro-CT scanning during the adolescence on bone growth and architecture is still unknown. The right proximal tibia of male Sprague-Dawley rats randomized into three dose groups of 0.83, 1.65 and 2.47 Gy (n = 11/group) were CT scanned at weekly intervals from 4th to 12th week of age. The left tibia was used as a control and scanned only at the last time point. Bone marrow cells were investigated, bone growth rates and histomorphometric analyses were performed, and bone structural parameters were determined for both left and right tibiae. Radiation doses of 1.65 and 2.47 Gy affected bone marrow cells, heights of the proliferative and hypertrophic zones, and bone growth rates in the irradiated tibiae. For the 1.65 Gy group, irradiated tibiae resulted in lower BMD, Tb.Th, Tb.N and a higher Tb.Sp compared with the control tibiae. A decrease in BMD, BV/TV, Tb.Th, Tb.N and an increase in Tb.Sp were observed between the irradiated and control tibiae for the 2.47 Gy group. For cortical bone parameters, no effects were noticed for 1.65 and 0.83 Gy groups, but a lower Ct.Th was observed for 2.47 Gy group. Tibial bone development was adversely impacted and trabecular bone, together with bone marrow cells, were negatively affected by the 1.65 and 2.47 Gy radiation doses. Cortical bone microstructure was affected for 2.47 Gy group. However, bone development and morphometry were not affected for 0.83 Gy group. These findings can be used as a proof of concept for using the reasonable high-quality image acquisition under 0.83 Gy radiation doses during the adolescent period of rats without interfering with the bone development process.

Discrete tomography in an in vivo small animal bone study

This study aimed at assessing the feasibility of a discrete algebraic reconstruction technique (DART) to be used in in vivo small animal bone studies. The advantage of discrete tomography is the possibility to reduce the amount of X-ray projection images, which makes scans faster and implies also a significant reduction of radiation dose, without compromising the reconstruction results. Bone studies are ideal for being performed with discrete tomography, due to the relatively small number of attenuation coefficients contained in the image [namely three: background (air), soft tissue and bone]. In this paper, a validation is made by comparing trabecular bone morphometric parameters calculated from images obtained by using DART and the commonly used standard filtered back-projection (FBP). Female rats were divided into an ovariectomized (OVX) and a sham-operated group. In vivo micro-CT scanning of the tibia was done at baseline and at 2, 4, 8 and 12 weeks after surgery. The cross-section images were reconstructed using first the full set of projection images and afterwards reducing them in number to a quarter and one-sixth (248, 62, 42 projection images, respectively). For both reconstruction methods, similar changes in morphometric parameters were observed over time: bone loss for OVX and bone growth for sham-operated rats, although for DART the actual values were systematically higher (bone volume fraction) or lower (structure model index) compared to FBP, depending on the morphometric parameter. The DART algorithm was, however, more robust when using fewer projection images, where the standard FBP reconstruction was more prone to noise, showing a significantly bigger deviation from the morphometric parameters obtained using all projection images. This study supports the use of DART as a potential alternative method to FBP in X-ray micro-CT animal studies, in particular, when the number of projections has to be drastically minimized, which directly reduces scanning time and dose.

Proper Positioning and Restraint of a Rat Hind Limb for Focused High Resolution Imaging of Bone Micro-architecture Using In Vivo Micro-computed Tomography

The use of in vivo micro-computed tomography (µCT) is a powerful tool which involves the non-destructive imaging of internal structures at high resolutions in live animal models. This allows for repeated imaging of the same rodent over time. This feature not only reduces the total number of rodents required in an experimental design and thereby reduces the inter-subject variation that can arise, but also allows researchers to assess longitudinal or life-long responses to an intervention. To acquire high quality images that can be processed and analyzed to more accurately quantify outcomes of bone micro-architecture, users of in vivo µCT scanners must properly anesthetize the rat, and position and restrain the hind limb. To do this, it is imperative that the rat be anesthetized to a level of complete relaxation, and that pedal reflexes are lost. These guidelines may be modified for each individual rat, as the rate of isoflurane metabolism can vary depending on strain and body size. Proper technique for in vivo µCT image acquisition enables accurate and consistent measurement of bone micro-architecture within and across studies.

Early bony changes associated with bisphosphonate-related osteonecrosis of the jaws in rats: A longitudinal in vivo study

OBJECTIVE

To evaluate early bony changes in an animal model of Medication-Related Osteonecrosis of the Jaw (MRONJ) at the side of the local trauma and at the contralateral side, comparing with a control group. Bony changes were evaluated by Microcomputed Tomography (MicroCT) at three times points: at baseline (T0), after drug administration (T1) and after dental extraction (T2).

DESIGN

Two groups were compared: the experimental group in which zoledronic acid (ZA) was administered (17 rats) and the control group (13 rats). Dental extractions of the lower left first molars were performed in all animals. The left side was considered as the supposed affected area in the ZA group, and the right side was considered as the unaffected area. In these areas, the following structural microtomographic bone parameters were calculated: Bone Mineral Density (BMD), Trabecular Thickness (Tb.Th), and Bone Volume Proportion (BV/TV). The comparison of quantitative bone parameters among the different sides and experimental phases of both studied groups were performed by ANOVA-factorial.

RESULTS

None of the animals of the control group developed MRONJ. In the ZA group, 76% presented bone exposure. From T0 to T1, Tb.Th and BV/TV increased, and in T2, the mean values were higher in ZA group than in the control group. BMD increased throughout the different phases of both groups.

CONCLUSIONS

Structural bony changes occurred in the ZA group at both mandibular sides before the dental extraction (T1). Tb.Th and BV/TV should be further investigated as potential early bone markers of MRONJ.

Fast and flexible X-ray tomography using the ASTRA toolbox

Object reconstruction from a series of projection images, such as in computed tomography (CT), is a popular tool in many different application fields. Existing commercial software typically provides sufficiently accurate and convenient-to-use reconstruction tools to the end-user. However, in applications where a non-standard acquisition protocol is used, or where advanced reconstruction methods are required, the standard software tools often are incapable of computing accurate reconstruction images. This article introduces the ASTRA Toolbox. Aimed at researchers across multiple tomographic application fields, the ASTRA Toolbox provides a highly efficient and highly flexible open source set of tools for tomographic projection and reconstruction. The main features of the ASTRA Toolbox are discussed and several use cases are presented.

A STUDY ON THE EVALUATION OF THE PLGA-CURCUMIN TREATED RAT MODELS FOR OSTEOPOROSIS IMPROVEMENT USING FINITE ELEMENT ANALYSIS

Osteoporosis induced bone fracture is not limited to simple damage according to its fractured region and the age of the damaged person. Therefore, there has been more necessity to understand and study the biomechanical aspects of osteoporosis, and relevant research has actively been conducted. With the development of medical imaging technology, the reconstruction of CT images into a 3D model has been made possible, and it has been conducted to analyze 3-dimensionally and inhomogeneously distributed bone mineral density according to CT values. The 3D bone strength computational analysis based on 2D bone images utilized for evaluating the new treatment using the mixture of PLGA and curcumin for rat osteoporosis model. After the treatment, bone mineral density recovered by 65% compared to the osteoporosis model, moreover, bone strength improved by 113%. This study suggested that the limitations of conventional bone monitoring method using 2D bone images can be overcome by considering 3D bone computational analysis. It is considered that introducing the newly proposed Deformation Per Volume (DPW) and Stress Per Weight (SPW) can be also used as effective parameters to more accurately predict the change in bone stiffness.

Panax notoginseng saponins mitigate ovariectomy-induced bone loss and inhibit marrow adiposity in rats

OBJECTIVE

Previous data have suggested that Panax notoginseng saponins (PNS) can prevent estrogen deficiency-induced bone loss by dual action: stimulation of new bone formation and inhibition of bone resorption. Marrow adipogenesis has been identified as a negative indicator of skeletal strength and integrity. This study assessed the effects of early PNS supplementation on bone microarchitecture preservation and marrow fat content in an ovariectomized rat model.

METHODS

Forty adult female Sprague-Dawley rats were randomly assigned to four equal groups for 12 weeks of treatment: (1) sham operation (SHAM) + vehicle; (2) ovariectomy (OVX) + vehicle; (3) OVX + 17β-estradiol (25 μg/kg); (4) OVX + PNS (300 mg/kg/d, PO). Marrow fat content of the femur was determined, using fat/water magnetic resonance imaging (MRI), at baseline and 6 and 12 weeks after operation. At the end of the experiment, bone turnover, trabecular microarchitecture, and marrow adipocytes were assessed by serum biomarkers, micro-computed tomography (micro-CT), and histopathology, respectively. The effects of PNS on adipocytic differentiation were reflected by expression levels of the adipogenic genes PPARγ2 and C/EBPα, as determined by reverse transcription-polymerase chain reaction.

RESULTS

Ovariectomized rats experienced remarkable increases in marrow fat content across time points, which were accompanied by elevated rate of bone turnover, global volumetric bone density, and trabecular microarchitecture deterioration. These OVX-induced pathological changes are reversible in that most of them could be mostly corrected upon 17β-estradiol treatment. PNS treatment significantly reduced marrow adipogenesis (adipocyte density, -27.2%; size, -22.7%; adipocyte volume-to-tissue volume ratio, -53.3%; all P < 0.01) and adipocyte marker gene expression, and prevented bone mass loss and microarchitecture deterioration. Moreover, PNS enhanced osteoblast activity but suppressed osteoclast turnover, as evidenced by decreased levels of serum C-terminal telopeptides of type I collagen and elevated levels of alkaline phosphatase.

CONCLUSIONS

PNS mitigates estrogen deficiency-induced deterioration of trabecular microarchitecture and suppresses marrow adipogenesis.

Preparation and in vivo evaluation of an orally available enteric-microencapsulated parathyroid hormone (1-34)-deoxycholic acid nanocomplex

The N-terminal 34-amino-acid peptide fragment of human parathyroid hormone PTH (1-34), is used clinically to treat osteoporosis; however, it is currently administered by a once-daily subcutaneous injection, resulting in poor patient compliance. We have developed enteric microcapsules containing an ionic nanocomplex between PTH (1-34) and lysine-linked deoxycholic acid (LysDOCA) for the oral delivery of PTH (1-34). We measured the particle size of the PTH/LysDOCA complex and assessed its biological activity by determining the cAMP content in MC3T3-E1 cells. We also assessed its permeability across a Caco-2 cell monolayer and the bioavailability of the intrajejunally administered PTH/LysDOCA complex compared with PTH (1-34) in rats. In addition, the antiosteoporotic activity of the PTH/LysDOCA complex, encapsulated in an enteric carrier by coaxial ultrasonic atomization, was evaluated after it was orally administered to ovariectomized (OVX) rats. The formation of an ionic complex between PTH (1-34) and LysDOCA produced nanoparticles of diameter 33.0±3.36 nm, and the bioactivity of the complex was comparable with that of PTH (1-34). The Caco-2 cell permeability and AUClast value of the PTH/LysDOCA (1:10) nanocomplex increased by 2.87- and 16.3-fold, respectively, compared with PTH (1-34) alone. Furthermore, the OVX rats treated with oral PTH/LysDOCA-loaded enteric microcapsules showed an increase in bone mineral density (159%), bone volume fraction (175%), and trabecular number (174%) compared with those in the OVX control group. Therefore, the PTH/LysDOCA nanocomplex oral delivery system is a promising treatment modality for osteoporosis because it improves osteogenesis and trabecular connectivity.

Quantifying shape changes of silicone breast implants in a murine model using in vivo micro-CT

A major complication of silicone breast implants is the formation of a capsule around the implant known as capsular contracture which results in the distortion of the implant. Recently, a mouse model for studying capsular contracture was examined using micro-computed tomography (micro-CT), however, only qualitative changes were reported. The aim of this study was to develop a quantitative method for comparing the shape changes of silicone implants using in vivo micro-CT. Mice were bilaterally implanted with silicone implants and underwent ionizing radiation to induce capsular contracture. On day 28 post-surgery mice were examined in vivo using micro-CT. The reconstructed cross-section images were visually inspected to identify distortion. Measurements were taken in 2D and 3D to quantify the shape of the implants in the normal (n = 11) and distorted (n = 5) groups. The degree of anisotropy was significantly higher in the distorted implants in the transaxial view (0.99 vs. 1.19, p = 0.002) and the y-axis lengths were significantly shorter in the sagittal (9.27 mm vs. 8.55 mm, p = 0.015) and coronal (9.24 mm vs. 8.76 mm, p = 0.031) views, indicating a deviation from the circular cross-section and shortening of the long axis. The 3D analysis revealed a significantly lower average thickness (sphere-fitting method) in distorted implants (6.86 mm vs. 5.49 mm, p = 0.002), whereas the volume and surface area did not show significant changes. Statistically significant differences between normal and distorted implants were found in 2D and 3D using distance measurements performed via micro-CT. This objective analysis method can be useful for a range of studies involving deformable implants using in vivo micro-CT. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1447-1452, 2017.

Oral delivery of zoledronic acid by non-covalent conjugation with lysine-deoxycholic acid: In vitro characterization and in vivo anti-osteoporotic efficacy in ovariectomized rats

We assessed the possibility of changing the route of administration of zoledronic acid to an oral dosage form and its therapeutic efficacy in an estrogen-deficient osteoporosis rat model. To enhance oral bioavailability, we formed an ionic complex by electrostatic conjugation of zoledronic acid with lysine-linked deoxycholic acid (Lys-DOCA, an oral absorption enhancer). After forming the complex, the characteristic crystalline features of pure zoledronic acid disappeared completely in the powder X-ray diffractogram and differential scanning calorimetry thermogram, indicating that zoledronic acid existed in an amorphous form in the complex. In vitro permeabilities of zoledronic acid/Lys-DOCA (1:1) (ZD1) and zoledronic acid/Lys-DOCA (1:2) (ZD2) complex across Caco-2 cell monolayers were 2.47- and 4.74-fold higher than that of zoledronic acid, respectively. Upon intra-jejunal administration to rats, the intestinal absorption of zoledronic acid was increased significantly and the resulting oral bioavailability of the ZD2 complex was determined to be 6.76±2.59% (0.548±0.161% for zoledronic acid). Ovariectomized (OVX) rats showed 122% increased bone mineral density versus the OVX control at 12weeks after treatment with once weekly oral administration of ZD2 complex (16μg/kg of zoledronic acid). Furthermore, rats treated with ZD2 complex orally showed significant improvement in the parameters of trabecular microarchitecture and bone strength: 149% higher bone volume fraction (BV/TV), 115% higher trabecular number (Tb.N), and 56% higher mean maximum load (Fmax) than in the OVX group. The trabecular microstructure and bone mechanical properties in the oral zoledronic acid group were not significantly changed compared with the OVX control. Thus, the oral ZD2 complex inhibited osteoporosis progression effectively by promoting osteogenesis and trabecular connectivity. The oral ZD2 complex would be expected to improve patient compliance by replacing the conventional injectable form and expand the indications, to include prophylaxis for osteoporosis and bone metastases.

The X-Linked Inhibitor of Apoptosis Protein Inhibitor Embelin Suppresses Inflammation and Bone Erosion in Collagen Antibody Induced Arthritis Mice

Objective. To investigate the effect of Embelin, an inhibitor of X-Linked Inhibitor of Apoptosis Protein (XIAP), on inflammation and bone erosion in a collagen antibody induced arthritis (CAIA) in mice. Methods. Four groups of mice (n = 6 per group) were allocated: CAIA untreated mice, CAIA treated with Prednisolone (10 mg/kg/day), CAIA treated with low dose Embelin (30 mg/kg/day), and CAIA treated with high dose Embelin (50 mg/kg/day). Joint inflammation was evaluated using clinical paw score and histological assessments. Bone erosion was assessed using micro-CT, tartrate resistant acid phosphatase (TRAP) staining, and serum carboxy-terminal collagen crosslinks (CTX-1) ELISA. Immunohistochemistry was used to detect XIAP protein. TUNEL was performed to identify apoptotic cells. Results. Low dose, but not high dose Embelin, suppressed inflammation as reflected by lower paw scores (P < 0.05) and lower histological scores for inflammation. Low dose Embelin reduced serum CTX-1 (P < 0.05) and demonstrated lower histological score and TRAP counting, and slightly higher bone volume as compared to CAIA untreated mice. XIAP expression was not reduced but TUNEL positive cells were more abundant in Embelin treated CAIA mice. Conclusion. Low dose Embelin suppressed inflammation and serum CTX-1 in CAIA mice, indicating a potential use for Embelin to treat pathological bone loss.

Caffeic acid phenethyl ester abrogates bone resorption in a murine calvarial model of polyethylene particle-induced osteolysis

Particle-induced bone loss by osteoclasts is a common cause of aseptic loosening around implants. This study investigates whether caffeic acid phenethyl ester (CAPE), a potent and specific inhibitor of nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1 and nuclear factor kappa B, at a low dose reduces bone resorption in a murine calvarial model of polyethylene (PE) particle-induced osteolysis. The effects of particles and CAPE treatment on gastrointestinal tract (GIT) histopathology were also evaluated. Mice were scanned using in vivo animal micro-computed tomography (μCT) as a baseline measurement. PE particles (2.82 × 10(9) particles/mL) were implanted over the calvariae on day 0. CAPE was administered subcutaneously (1 mg/kg/day) at days 0, 4, 7 and 10. Mice were killed at day 14 and serum was analysed for Type-1 carboxyterminal collagen crosslinks (CTX)-1 and osteoclast-associated receptor (OSCAR) levels. Ex vivo μCT scans were conducted to assess bone volume (BV) change and percentage area of calvarial surface resorbed. Calvarial and GIT tissue was processed for histopathology. By day 14, PE particles significantly induced calvarial bone loss compared with control animals as evidenced by resorption areas adjacent to the implanted PE in three-dimensional μCT images, an increase in percentage of resorbed area (p = 0.0022), reduction in BV (p = 0.0012) and increased Tartrate-resistant acid phosphatase positive cells. Serum CTX-1 (p = 0.0495) and OSCAR levels (p = 0.0006) significantly increased in the PE implant group. CAPE significantly inhibited PE particle-induced calvarial osteolysis, as evidenced by a significant reduction in surface bone resorption (p = 0.0012) and volumetric change (p = 0.0154) compared with PE only, but had no effect on systemic CTX-1. Neither particles nor CAPE had an effect on GIT histopathology.

Parthenolide reduces empty lacunae and osteoclastic bone surface resorption induced by polyethylene particles in a murine calvarial model of peri-implant osteolysis

The study aimed to determine the effects of parthenolide (PAR) on bone volume (BV) and bone surface resorption as assessed by live-animal microcomputed tomography (μCT) and possible osteocyte death as indicated by empty lacunae histologically in polyethylene (PE) particle-induced calvarial osteolysis in mice. Baseline μCT scans were conducted 7 days preimplantation of 2 × 10(8) PE particles/mL over the calvariae (day 0). PAR at 1 mg/kg/day was subcutaneously injected on days 0, 4, 7, and 10. At day 14, BV and surface resorption was analyzed with μCT. Calvarial tissue was processed for histomorphometric osteocyte evaluation. Serum was analyzed for type-1 carboxy-terminal collagen crosslinks (CTX-1) and osteoclast associated receptor (OSCAR) levels by ELISA. PE significantly decreased BV (p = 0.0368), increased surface bone resorption area (p = 0.0022), and increased the percentage of empty lacunae (p = 0.0043). Interestingly, PAR significantly reduced the resorption surface area (p = 0.0022) and the percentage of empty osteocyte lacunae (p = 0.0087) in the PE-calvariae, but it did not affect BV, serum CTX-1 or OSCAR levels. The ability of PAR to inhibit PE-induced surface bone erosion may better reflect the in vivo situation, where bone resorption occurs on the surface at the bone-implant interface and may also be related to the role of osteocytes in this pathology.

Quantifying not only bone loss, but also soft tissue swelling, in a murine inflammatory arthritis model using micro-computed tomography

In rodent models of inflammatory arthritis, bone erosion has been non-invasively assessed by micro-computed tomography (micro-CT). However, non-invasive assessments of paw swelling (oedema) are still based on clinical grading by visual evaluation, or measurements by callipers, not always reliable for the tiny mouse paws. The aim of this work was to demonstrate a novel straightforward 3D micro-CT analysis protocol capable of quantifying not only joint bone erosion, but also soft tissue swelling, from the same scans, in a rodent inflammatory arthritis model. Balb/c mice were divided into two groups: collagen antibody-induced arthritis (CAIA) and CAIA treated with prednisolone, the latter reflecting an established treatment in human rheumatoid arthritis. Clinical paw scores were recorded. On day 10, front paws were assessed by micro-CT and histology. Micro-CT measurements included paw volume (bone and soft tissue together) and bone volume at the radiocarpal joint, and bone volume from the radiocarpal to the metacarpophalangeal joint. Micro-CT analysis revealed significantly lower paw volume (−36%, P < 0.01) and higher bone volume (+17%, P < 0.05) in prednisolone-treated CAIA mice compared with untreated CAIA mice. Paw volume and bone volume assessed by micro-CT correlated significantly with clinical and histological scores (|r| > 0.5, P < 0.01). Untreated CAIA mice showed significantly higher clinical scores, higher inflammation levels histologically, cartilage and bone degradation, and pannus formation, compared with treated mice (P < 0.01). The presented novel micro-CT analysis protocol enables 3D-quantification of paw swelling at the micrometre level, along with the typically assessed bone erosion, using the same images/scans, without altering the scanning procedure or using contrast agents.

Longitudinal assessment of oxytocin efficacy on bone and bone marrow fat masses in a rabbit osteoporosis model through 3.0-T magnetic resonance spectroscopy and micro-CT

This study aims to longitudinally assess the effect of oxytocin on bone and bone fat masses using micro-CT, in vivo magnetic resonance spectroscopy (MRS), and histopathological adipocyte quantification. Early in vivo oxytocin (OT) treatment to the osteoporosis (OP) rabbit model may reliably inhibit bone degeneration and reduce bone marrow fat accumulation by decreasing marrow adipocyte size and density.

INTRODUCTION

This study aims to longitudinally assess the effect of early OT treatment on bone and bone fat masses in a rabbit OP model by comparing the results of MRS and micro-CT with histopathological findings.

METHODS

Sixty 20-week-old female rabbits were randomly assigned into three groups. The control and OP groups were subjected to either sham surgery or bilateral ovariectomy (OVX). The OT group was subcutaneously injected with OT daily from the second week after OVX for 8 weeks. The left proximal femurs of the rabbits were evaluated through MRS, micro-CT, and histopathological examination at 0, 4, 8, 10, and 12 weeks after operation. Differences in fat fraction (FF) values, micro-CT parameters, and calculated pathological marrow adipocytes among three groups were analyzed.

RESULTS

The FF values of the OP group significantly increased (p = 0.019), but the tissue mineral density (TMD) decreased (p = 0.037) from eighth week compared with those of the control group. The FF values of the OT group significantly decreased (p = 0.044), but the TMD values increased (p = 0.042) from eighth week compared with those of the OP group. The adypocyte diameter of the OT group significantly decreased (p = 0.041) from eighth week and then adypocyte density did so too from tenth week, compared with those of the OP group at the same time point. No difference in adypocyte calculation was found between the OT and control groups until the 12th week after operation.

CONCLUSION

Early in vivo OT treatment slowed down bone deterioration and reduced bone marrow adiposity accumulation in a rabbit OP model, which is consistent with pathologic findings. OT treatment is a promising preventive OP therapy.

A grape-enriched diet increases bone calcium retention and cortical bone properties in ovariectomized rats

BACKGROUND

Grapes and their associated phytochemicals have been investigated for beneficial effects on cardiovascular health, cancer prevention, and other chronic diseases, but the effect of grape consumption on bone health has not been fully determined. We previously found short-term benefits of grape products on reducing bone turnover in ovariectomized rats.

OBJECTIVE

The objective of this study was to determine the long-term benefits of a grape-enriched diet on bone in ovariectomized rats.

METHODS

Rats were ovariectomized at 3 mo of age and were administered a single dose of (45)Ca to prelabel bones at 4 mo of age. After a 1-mo equilibration period, baseline urinary (45)Ca excretion was determined. Rats (n = 22/group) were then randomly assigned to a modified AIN93M diet containing 25% freeze-dried grape powder or to a control diet for 8 wk. Urinary (45)Ca excretion was monitored throughout the study to determine changes in bone (45)Ca retention. Calcium balance was assessed after 1 and 8 wk of consuming the experimental diets, and a calcium kinetic study was performed at 8 wk. After 8 wk, femurs were collected for micro-computed tomographic imaging, 3-point bending, and reference point indentation.

RESULTS

Rats fed the grape-enriched diet had 44% greater net bone calcium retention than did rats fed the control diet. There were no differences in calcium balance due to diet at either week 1 or week 8, but there was a significant increase in net calcium absorption (10.6%) and retention (5.7%) from week 1 to week 8 in the grape-enriched diet group only. Grape-enriched diet-fed rats had 3% greater cortical thickness and 11% greater breaking strength. There were no differences in femur bone mineral density, trabecular microarchitecture, or reference point indentation variables due to diet.

CONCLUSION

This study of ovariectomized rats indicates that the consumption of grape products may improve calcium utilization and suppress bone turnover, resulting in improvements in bone quality.

Structure Model Index Does Not Measure Rods and Plates in Trabecular Bone

Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI(+)) and negative (SMI(-)) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species' femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabecule and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely <20%, of the trabecular surface is concave (CF 0.155-0.700). SMI is unavoidably influenced by aberrations induced by SMI(-), which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from the close and artifactual relationship between SMI and BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds' more plate-like trabecule. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be treated with suspicion. We propose that EF should be used instead of SMI for measurements of rods and plates in trabecular bone.

Additive effect of PTH (1-34) and zoledronate in the prevention of disuse osteopenia in rats

Immobilization is known to cause a rapid bone loss due to increased osteoclastic bone resorption and decreased osteoblastic bone formation. Zoledronate (Zln) is a potent anti-resorptive pharmaceutical, while intermittent PTH is a potent bone anabolic agent. The aim of the present study was to investigate whether PTH or Zln alone or in combination could prevent immobilization-induced osteopenia. Immobilization was achieved by injecting 4IU Botox (BTX) into the right hind limb musculature. Seventy-two 16-week-old female Wistar rats were randomized into 6 groups; baseline (Base), control (Ctrl), BTX, BTX+PTH, BTX+Zln, and BTX+PTH+Zln. PTH (1-34) (80μg/kg) was given 5days/week and Zln (100μg/kg) was given once at study start. The animals were killed after 4weeks of treatment. The bone properties were evaluated using DEXA, μCT, dynamic bone histomorphometry, and mechanical testing. BTX resulted in lower femoral trabecular bone volume fraction (BV/TV) (-25%, p<0.05), lower tibial trabecular bone formation rate (BFR/BS) (-29%, p<0.05), and lower bone strength (Fmax) at the distal femur (-19%, p<0.001) compared with Ctrl. BTX+PTH resulted in higher femoral BV/TV (+31%, p<0.05), higher tibial trabecular BFR/BS (+297%, p<0.05), and higher Fmax at the distal femur (+11%, p<0.05) compared with BTX. BTX+Zln resulted in higher femoral BV/TV (+36%, p<0.05), lower tibial trabecular BFR/BS (-93%, p<0.05), and higher Fmax at the distal femur (+10%, p<0.05) compared with BTX. BTX+PTH+Zln resulted in higher femoral BV/TV (+70%, p<0.001), higher tibial trabecular BFR/BS (+59%, p<0.05), and higher Fmax at the distal femur (+32%, p<0.001) compared with BTX. In conclusion, BTX-induced immobilization led to lower BV/TV, BFR/BS, and Fmax. In general, PTH or Zln alone prevented the BTX-induced osteopenia, whereas PTH and Zln given in combination not only prevented, but also increased BV/TV and BFR/BS, and maintained Fmax at the distal femoral metaphysis compared with Ctrl.

Modic (endplate) changes in the lumbar spine: bone micro-architecture and remodelling

PURPOSE

In the literature, inter-vertebral MRI signal intensity changes (Modic changes) were associated with corresponding histological observations on endplate biopsies. However, tissue-level studies were limited. No quantitative histomorphometric study on bone biopsies has yet been conducted for Modic changes. The aim of this study was to characterise the bone micro-architectural parameters and bone remodelling indices associated with Modic changes.

METHODS

Forty patients suffering from disabling low back pain, undergoing elective spinal surgery, and exhibiting Modic changes on MRI (Modic 1, n = 9; Modic 2, n = 25; Modic 3, n = 6), had a transpedicular vertebral body biopsy taken of subchondral bone. Biopsies were first examined by micro-CT, for 3D morphometric analysis of bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation, trabecular number, and structure model index. Then, samples underwent histological analysis, for determination of bone remodelling indices: osteoid surface to bone surface ratio (OS/BS), eroded surface to bone surface (ES/BS) and osteoid surface to eroded surface ratio (OS/ES).

RESULTS

Micro-CT analysis revealed significantly higher BV/TV (up to 70% increase, p < 0.01) and Tb.Th (up to +57%, p < 0.01) in Modic 3 biopsies, compared to Modic 1 and 2. Histological analysis showed significantly lower OS/BS in Modic 2 biopsies (more than 28% decrease, p < 0.05) compared to 1 and 3. ES/BS progressively decreased from Modic 1 to 2 to 3, whereas OS/ES progressively increased with significantly higher values in Modic 3 (up to 159% increase, p < 0.05) than in Modic 1 and 2.

CONCLUSIONS

Significant differences were found in bone micro-architectural parameters and remodelling indices among Modic types. Modic 1 biopsies had evidence of highest bone turnover, possibly due to an inflammatory process; Modic 2 biopsies were consistent with a reduced bone formation/remodelling stage; Modic 3 biopsies suggested a more stable sclerotic phase, with significantly increased BV/TV and Tb.Th compared to Modic 1 and 2, linked to increased bone formation and reduced resorption.

Calorie restriction aggravated cortical and trabecular bone architecture in ovariectomy-induced estrogen-deficient rats

We hypothesized that calorie restriction (CR) and estrogen deficiency (ovariectomy [OVX]) would aggravate bone biomarkers and structural parameters in rats. Seven-week-old female Sprague-Dawley rats were randomized to sham-operated groups and fed either an ad libitum diet (SHAM-AL) or a CR diet (SHAM-CR); ovariectomy-operated groups were fed an ad libitum diet (OVX-AL) or a CR diet (OVX-CR). For 8 weeks, the OVX-AL and SHAM-AL groups were fed the same diet, whereas CR groups were fed a diet containing 50% fewer calories. Bone-related biomarkers and structural parameters (OC; deoxypyridinoline [DPD]; N-terminal telopeptide, NTx; architecture and mineralization; and microcomputed tomography images) were analyzed at the end of the experiment. The serum OC levels of calorie-restricted groups (SHAM-CR and OVX-CR) were significantly lower than those of the AL groups (SHAM-AL and OVX-AL) (P < .05). Urinary DPD levels of calorie-restricted and ovariectomized groups were higher than those of their counterparts (P < .05), whereas urinary NTx levels of calorie-restricted groups were higher than those of AL groups (P < .05). In regard to trabecular bone, the calorie-restricted and ovariectomized groups had lower values of bone volume to total volume, trabecular number, and bone mineral density, but higher values of trabecular separation than those of their counterparts (P < .05). Regarding cortical bone, the calorie-restricted groups had reduced values of bone volume, mean polar moment of inertia, and cortical thickness compared to the AL groups (P < .05). In conclusion, severe CR with or without OVX during the growth period in rats is equally detrimental to bone; CR has detrimental effects on trabecular and cortical bone; and estrogen deficiency only had an effect on trabecular bone.

External and internal bone micro-architecture in normal and Kienböck's lunates: a whole-bone micro-computed tomography study

Kienböck's disease is idiopathic osteonecrosis of the lunate, leading to its fracture and collapse. This study compares internal and external bone micro-architecture of normal and fractured lunates (Kienböck's), by using high-resolution three-dimensional (3D) micro-computed tomography (micro-CT) on the whole bone of the two lunate types, and histology. Fractured Kienböck-diseased lunates were obtained from patients undergoing proximal-row-carpectomy, while normal cadaveric lunates served as controls. 3D-micro-CT-imaging of control lunates revealed an encircling cortex surrounding trabecular bone. Trabeculae were arranged in a radial pattern, spanning from the distal to the proximal subchondral plate. Kienböck's lunates exhibited clear fracture lines, with fragmented bone, both proximally and distally, in areas the radially-patterned trabeculae and enveloping cortex were absent, producing height loss. In trabecular bone, Kienböck's lunates revealed increased bone volume fraction, trabecular thickness and number, and decreased trabecular separation and structure model index. Histologically, Kienböck's lunates revealed osteonecrosis, as well as remodeling fronts with osteoblasts and osteoid surrounding bone marrow. Whole-bone high-resolution 3D examination of normal and Kienböck's diseased lunates contributes to a better understanding of micro-architectural changes occurring in the pathology.

Bisphosphonates inhibit bone remodeling in the jaw bones of rats and delay healing following tooth extractions

OBJECTIVE

This study aimed to evaluate the impact of concurrent administration of clinically relevant doses of zoledronic acid (ZA) and dexamethasone (DX) on bone healing after tooth extraction (EXO).

MATERIALS AND METHODS

Forty-four Sprague-Dawley rats (6-8 month old) were randomized into five groups: ZA + DX = weekly injection of ZA with DX for 7 weeks; WD = ZA with DX for 3 weeks then DX alone for 4 weeks; C = control saline for 7 weeks; ZA = ZA alone for 7 weeks and DX = DX alone for 7 weeks. ZA was administered at 0.13 mg/kg/week and DX at 3.8 mg/kg/week and body weights recorded at the time of injection. All rats underwent extraction (EXO) of the mandibular and maxillary first molars at 3 weeks and were euthanized at 7 weeks. The extracted and non-extracted sides of both jaws were harvested for micro-CT analyses.

RESULTS

All rats, particularly those injected with ZA, exhibited weight gain till EXO followed by decline then recovery. ZA + DX group demonstrated highest fractional bone to tissue volume (BV/TV) in the non-extracted side. ZA + DX rats exhibited also highest volume and surface of sequestra. Only sequestra volume was statistically higher in the WD group compared to C group.

CONCLUSION

Combined treatment with ZA and DX over a prolonged period inhibits bone remodeling and increased sequestra formation to a greater extent than either drug alone. Trauma caused by these sequestra cutting through the mucosa could play a key role in the development of BRONJ by potentially facilitating infection. ZA withdrawal may promote bone-remodeling reactivation following EXO.

Super-resolution for computed tomography based on discrete tomography

In computed tomography (CT), partial volume effects impede accurate segmentation of structures that are small with respect to the pixel size. In this paper, it is shown that for objects consisting of a small number of homogeneous materials, the reconstruction resolution can be substantially increased without altering the acquisition process. A super-resolution reconstruction approach is introduced that is based on discrete tomography, in which prior knowledge about the materials in the object is assumed. Discrete tomography has already been used to create reconstructions from a low number of projection angles, but in this paper, it is demonstrated that it can also be applied to increase the reconstruction resolution. Experiments on simulated and real μCT data of bone and foam structures show that the proposed method indeed leads to significantly improved structure segmentation and quantification compared with what can be achieved from conventional reconstructions.

MHC class II transactivator is an in vivo regulator of osteoclast differentiation and bone homeostasis co-opted from adaptive immunity

The molecular networks controlling bone homeostasis are not fully understood. The common evolution of bone and adaptive immunity encourages the investigation of shared regulatory circuits. MHC Class II Transactivator (CIITA) is a master transcriptional co-activator believed to be exclusively dedicated for antigen presentation. CIITA is expressed in osteoclast precursors, and its expression is accentuated in osteoporotic mice. We thus asked whether CIITA plays a role in bone biology. To this aim, we fully characterized the bone phenotype of two mouse models of CIITA overexpression, respectively systemic and restricted to the monocyte-osteoclast lineage. Both CIITA-overexpressing mouse models revealed severe spontaneous osteoporosis, as assessed by micro-computed tomography and histomorphometry, associated with increased osteoclast numbers and enhanced in vivo bone resorption, whereas osteoblast numbers and in vivo bone-forming activity were unaffected. To understand the underlying cellular and molecular bases, we investigated ex vivo the differentiation of mutant bone marrow monocytes into osteoclasts and immune effectors, as well as osteoclastogenic signaling pathways. CIITA-overexpressing monocytes differentiated normally into effector macrophages or dendritic cells but showed enhanced osteoclastogenesis, whereas CIITA ablation suppressed osteoclast differentiation. Increased c-fms and receptor activator of NF-κB (RANK) signaling underlay enhanced osteoclast differentiation from CIITA-overexpressing precursors. Moreover, by extending selected phenotypic and cellular analyses to additional genetic mouse models, namely MHC Class II deficient mice and a transgenic mouse line lacking a specific CIITA promoter and re-expressing CIITA in the thymus, we excluded MHC Class II expression and T cells from contributing to the observed skeletal phenotype. Altogether, our study provides compelling genetic evidence that CIITA, the molecular switch of antigen presentation, plays a novel, unexpected function in skeletal homeostasis, independent of MHC Class II expression and T cells, by exerting a selective and intrinsic control of osteoclast differentiation and bone resorption in vivo.

Comparison of chemical compositions and osteoprotective effects of different sections of velvet antler

ETHNOPHARMACOLOGICAL RELEVANCE

Velvet antlers (VA) have been claimed for centuries to have numerous medical benefits including strengthen bones. To investigate and compare the anti-osteoporotic activities from different sections of VA.

MATERIALS AND METHODS

Fresh VA prepared from farmed sika deers (Cervus nippon) was divided into upper (VAU), middle (VAM), and basal (VAB) sections. The chemical constituents and anti-osteoporotic effect of different sections from VA were evaluated using ovariectomized rats.

RESULTS

Levels of water-soluble extracts, diluted alcoholic extract, amino acids, testosterone, insulin-like growth factor (IGF)-1 and testosterone plus estradiol significantly differed among the different sections. Levels of these constituents were significantly higher in the upper section than in the basal section. Moreover, levels of testosterone and IGF-1 of the VAM were also significantly higher than those of the VAB. Calcium level increased downward from the tip with statistical significance. The strength of vertebrae increased in all VA-treated groups compared to the control, but only treatment with VAU and VAM increased the strength of the femur and the microarchitecure of the trabecular bone. Alkaline phosphatase levels of VAU- and VAM-treated groups significantly decreased, but osteocalcin did not significantly change. Moreover, VAU and VAM dose-dependently increased proliferation and mineralization of MC3T3-E1 cells.

CONCLUSION

Our study provides strong evidence for the regional differences in the effectiveness of velvet antler in treating osteoporosis. However, further studies are needed to elucidate the bioactive chemical constituents associated with the anti-osteoporotic effects of velvet antler.

Long-term in vivo degradation behaviour and biocompatibility of the magnesium alloy ZEK100 for use as a biodegradable bone implant

Magnesium alloys are the focus of research as resorbable materials for osteosynthesis, as they provide sufficient stability and would make surgery to remove implants unnecessary. The new degradable magnesium alloy ZEK100 was developed to improve the stability and corrosion resistance by alloying with zinc, rare earth metals and zirconium. As the implants were degraded to only a limited extent after 6 months implantation in a previous in vivo study the present study was conducted to evaluate the long-term degradation behaviour and biocompatibility in the same animal model over 9 and 12 months. Five rabbits each with intramedullary tibia implants were examined over 9 and 12 months. Three legs were left without an implant to serve as negative controls. Numerous examinations were performed in the follow-up (clinical examinations, serum analysis, and radiographic and in vivo micro-CT investigations) and after death (ex vivo micro-CT, histology, and implant analysis) to assess the in vivo degradation and biocompatibility. It could be shown that favourable in vivo degradation behaviour is not necessarily associated with good biocompatibility. Although ZEK100 provided a very high initial stability and positive biodegradation, it must be excluded from further biomedical testing as it showed pathological effects on the host tissue following complete degradation.

Pre-emptive, early, and delayed alendronate treatment in a rat model of knee osteoarthritis: effect on subchondral trabecular bone microarchitecture and cartilage degradation of the tibia, bone/cartilage turnover, and joint discomfort

OBJECTIVE

Bisphosphonates are considered potential disease modifying osteoarthritis (OA) agents. The present study investigated the efficacy of pre-emptive, early, and delayed alendronate (ALN) treatment initiation on subchondral trabecular bone and cartilage in low-dose monosodium iodoacetate (MIA)-induced knee OA in rats.

METHODS

Male rats received pre-emptive (n = 12, day 0-end of week 2), early (n = 12, end of week 2-end of week 6), or delayed (n = 12, end of week 6-end of week 10) ALN treatment (30 μg/kg/week). Pre-emptive ALN-treated rats were scanned using in vivo micro-computed tomography (micro-CT) after 2 weeks and then sacrificed, early ALN-treated rats were scanned after 2 and 6 weeks and sacrificed, and the delayed ALN-treated rats were scanned after 2, 6, and 10 weeks of OA induction and sacrificed. After sacrifice, bone histomorphometry and histology of the tibia and biomarker analyses were undertaken. Changes in hind limb weight-bearing were assessed from day -1 until day 14.

RESULTS

MIA-induced pathological features similar to progressive human OA in the cartilage and subchondral bone. Pre-emptive ALN treatment preserved subchondral trabecular bone microarchitecture, prevented bone loss, decreased bone turnover and joint discomfort. Pre-emptive ALN treatment had moderate effects on cartilage degradation. Early and delayed ALN treatments prevented loss of trabeculae and decreased bone turnover, but had no significant effect on cartilage degradation.

CONCLUSION

ALN prevented increased bone turnover and preserved the structural integrity of subchondral bone in experimental OA. The time point of treatment initiation is crucial for treating OA. Treating both the subchondral bone and cartilage in OA would be clinically more beneficial.

The effect of bone morphometric changes on orthodontic tooth movement in an osteoporotic animal model

OBJECTIVE

To elucidate the effect of bone morphometric changes on orthodontic tooth movement (OTM) in zoledronic acid-treated ovariectomized rats.

MATERIALS AND METHODS

Twenty-one 10-week-old female Wistar rats were divided into ovariectomy (OVX), OVX with zoledronic acid administration (OVX + ZOL), and sham operation (control) groups. Two weeks after OVX, ZOL administration was initiated. Twelve weeks after OVX, a nickel-titanium closed-coil spring of 25-g force was applied mesially to the maxillary left first molar. In vivo micro-computed tomography (CT) of the left proximal tibia was performed for bone morphometric analysis every 2 weeks after OVX. In addition, OTM was investigated using micro-CT at 0, 12, and 14 weeks after OVX.

RESULTS

There were significant differences in the bone mineral content (BMC), bone volume (BV), BMC to tissue volume ratio (BMC/TV), and BV to TV ratio of trabecular bone between the control and OVX groups and also between the OVX + ZOL and OVX groups. In the OVX + ZOL group, increased BMC and BV in the cortical bone and increased bone mineral density (BMD) in the trabecular bone were observed. Interestingly, OTM in the OVX group was almost two times more than that in the control and OVX + ZOL groups. Moreover, OTM was correlated with BMD, BMC, BV, and BMC/TV in the trabecular bone.

CONCLUSIONS

OVX accelerated OTM, while ZOL suppressed it. OTM demonstrated a significant negative relationship with trabecular bone mass.

Alendronate protects against articular cartilage erosion by inhibiting subchondral bone loss in ovariectomized rats

Osteoporosis (OP) and osteoarthritis (OA) are major health problems in the increasing elderly population, particularly in postmenopausal women, but their relationship remains unclear. The present study investigated whether alendronate (ALN), a potent inhibitor of bone resorption, could protect articular cartilage from degeneration in a combined animal model of OP and OA induced by ovariectomy (OVX). Seventy-eight seven-month-old female Sprague-Dawley rats were assigned into five experimental groups: (1) sham-operated with vehicle treatment, (2) sham-operated with ALN treatment, (3) OVX with vehicle treatment, (4) ALN treatment starting at OVX, and (5) ALN treatment starting at eight weeks after OVX. Histological and micro-CT analyses, together with urine collagen degradation markers, indicated that early ALN treatment completely prevented both subchondral bone loss and cartilage surface erosion induced by OVX. Although late ALN treatment also inhibited subchondral bone loss and significantly reduced cartilage erosion in the OVX rats, these tissues did not completely recover even after 10-weeks of ALN treatment. Quantitative RT-PCR analyses showed that the protective effect of ALN correlated with increased ratio of OPG/RANKL in both subchondral bone and cartilage. Moreover, whereas OVX caused upregulation of expression of matrix metalloproteinases MMP-13 and MMP-9 in the articular cartilage and chondrocytes in the interface between the articular cartilage and subchondral bone, respectively, early ALN treatment blocked whereas late ALN treatment attenuated the upregulation of these catabolic enzymes in the corresponding tissues. Together, these data indicate that the subchondral bone loss plays an important role in OA pathogenesis in the combined OP and OA model and suggest that treatment timing is an important factor for the effectiveness of anti-resorptive drug therapy of combined OP and OA.

Promotion of peri-implant bone healing by systemically administered parathyroid hormone (1-34) and zoledronic acid adsorbed onto the implant surface

The effect of human parathyroid hormone 1-34 (PTH) and zoledronic acid (ZA) alone or in combination on bone healing in osteoporotic settings was tested using implants inserted in tibiae of ovariectomized (OVX) rats. Combination therapy promoted bone healing more than each treatment alone 12 weeks after implant insertion.

INTRODUCTION

PTH and ZA have been demonstrated to be effective on implant fixation. However, reports about the combined use of PTH and ZA for promotion of bone healing around implant in osteoporotic settings are still limited. This study aims to investigate effects of PTH+ZA on implant stabilization in OVX rats.

METHODS

Twelve weeks after bilateral ovariectomy, OVX rats randomly received implants without or with ZA (by immersion in 1 mg/ml ZA solution for 24 h). Subsequently, half of the animals from each group also received subcutaneous injections of PTH (60 μg/kg, three times a week) for 12 weeks. Thus, there were four groups: control, PTH, ZA, and PTH+ZA.

RESULTS

All treatments promoted bone healing around implant compared to control, but PTH+ZA treatment showed significantly stronger effects than PTH or ZA alone in histological, micro-CT, and biomechanical tests.

CONCLUSION

The results indicated the additive effects of PTH and ZA on implant fixation in OVX rats; it was suggested that the anabolic effect of PTH was potent and not blunted by ZA during bone healing around implant when used concurrently.

Marrow adiposity recovery after early zoledronic acid treatment of glucocorticoid-induced bone loss in rabbits assessed by magnetic resonance spectroscopy

BACKGROUND

Although there is an inverse relationship between bone mass and marrow adiposity, the reversal function of zoledronic acid (ZOL) on increased marrow fat has not been studied. The aim of our study is to use the 3T magnetic resonance spectroscopy (MRS) to characterize the dynamical change process of the marrow fat responding to early ZOL treatment in the rabbit model with glucocorticoid-induced bone loss.

METHODS

Fifteen 20-week-old female New Zealand White rabbits were randomized to control group, methylprednisolone (MPS) group, and MPS+ZOL group equally. Bone mineral density (BMD) and marrow fat fraction (FF) at L3-L4 vertebrae and left proximal femur were measured by Dual-energy X-ray absorptiometry and MRS at week 0, 4, 8, and 12. The animals were euthanized at the end of our experiment and their left femurs were dissected out for the histopathological examination.

RESULTS

The MPS group demonstrated a remarkable increase in FF but a reduction in BMD compared with the controls at week 4 and 8, respectively (P<0.05 for all). Early treatment of ZOL can inhibit bone degeneration, although the bone mass would not recover to its original level. FF in MPS group exhibited a dramatic increase over time, with an increased FF variation (+31.6%, P=0.009) at week 4 from baseline and it was maintained until week 12 (+75.2%, P<0.001). In MPS+ZOL group, the FF returned to baseline value after the ZOL treatment. Comparing with the controls, larger marrow adipocyte density, the mean of the adipocyte diameter, and the percentage area of the adipocyte were observed in the MPS group (P<0.05 for all), whereas there were no significant differences in quantitative parameters of marrow adipocytes between the ZOL-treated group and the normal rabbits.

CONCLUSION

An increase of the marrow adiposity is synchronized with the deterioration of the MPS-induced bone mass. A single dose of early ZOL can reverse the marrow adiposity to its original level completely.

Orthodontic tooth movement and root resorption in ovariectomized rats treated by systemic administration of zoledronic acid

INTRODUCTION

The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken.

METHODS

Fifteen 10-week-old female Wistar rats were divided into 3 groups: ovariectomy, ovariectomy + zoledronic acid, and control. Only the ovariectomy and ovariectomy + zoledronic acid groups underwent ovariectomies. Two weeks after the ovariectomy, zoledronic acid was administered only to the ovariectomy + zoledronic acid group. Four weeks after the ovariectomy, 25-g nickel-titanium closed-coil springs were applied to observe tooth movement and orthodontically induced root resorption.

RESULTS

There were significant differences in the amounts of tooth movement and orthodontically induced root resorption between the ovariectomy and the control groups, and also between the ovariectomy and the ovariectomy + zoledronic acid groups. There was no statistically significant difference in tooth movement and orthodontically induced root resorption between the ovariectomy + zoledronic acid and the control groups. Zoledronic acid inhibited significantly more tooth movement and significantly reduced the severity of orthodontically induced root resorption in the ovariectomized rats. The ovariectomy + zoledronic acid group showed almost the same results as did the control group in both tooth movement and orthodontically induced root resorption.

CONCLUSIONS

Zoledronic acid inhibits excessive orthodontic tooth movement and also reduces the risk of severe orthodontically induced root resorption in ovariectomized rats.