Therapeutic implications of osteoprotegerin

Remineralization Rate of Lytic Lesions of the Spine in Multiple Myeloma Patients Undergoing Radiation Therapy

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

In general, Multiple Myeloma (MM) patients are treated with systemic therapy including chemotherapy. Radiation therapy can have an important supportive role in the palliative management of MM-related osteolytic lesions. Our study aims to investigate the degree of radiation-induced remineralization in MM patients to gain a better understanding of its potential impact on bone mineral density and, consequently, fracture prevention. Our primary outcome measure was percent change in bone mineral density measured in Hounsfield Units (Δ% HU) between pre- and post-radiation measurements, compared to non-targeted vertebrae.

METHODS

We included 119 patients with MM who underwent radiotherapy of the spine between January 2010 and June 2021 and who had a CT scan of the spine at baseline and between 3-24 months after radiation. A linear mixed effect model tested any differences in remineralization rate per month (βdifference) between targeted and non-targeted vertebrae.

RESULTS

Analyses of CT scans yielded 565 unique vertebrae (366 targeted and 199 non-targeted vertebrae). In both targeted and non-targeted vertebrae, there was an increase in bone density per month (βoverall = .04; P = .002) with the largest effect being between 9-18 months post-radiation. Radiation did not cause a greater increase in bone density per month compared to non-targeted vertebrae (βdifference = .67; P = .118).

CONCLUSION

Our results demonstrate that following radiation, bone density increased over time for both targeted and non-targeted vertebrae. However, no conclusive evidence was found that targeted vertebrae have a higher remineralization rate than non-targeted vertebrae in patients with MM.

New Perspectives of Therapies in Osteogenesis Imperfecta-A Literature Review

(1) Background: Osteogenesis imperfecta (OI) is a rare skeletal dysplasia characterized as a heterogeneous disorder group with well-defined phenotypic and genetic features that share uncommon bone fragility. The current treatment options, medical and orthopedic, are limited and not efficient enough to improve the low bone density, bone fragility, growth, and mobility of the affected individuals, creating the need for alternative therapeutic agents. (2) Methods: We searched the medical database to find papers regarding treatments for OI other than conventional ones. We included 45 publications. (3) Results: In reviewing the literature, eight new potential therapies for OI were identified, proving promising results in cells and animal models or in human practice, but further research is still needed. Bone marrow transplantation is a promising therapy in mice, adults, and children, decreasing the fracture rate with a beneficial effect on structural bone proprieties. Anti-RANKL antibodies generated controversial results related to the therapy schedule, from no change in the fracture rate to improvement in the bone mineral density resorption markers and bone formation, but with adverse effects related to hypercalcemia. Sclerostin inhibitors in murine models demonstrated an increase in the bone formation rate and trabecular cortical bone mass, and a few human studies showed an increase in biomarkers and BMD and the downregulation of resorption markers. Recombinant human parathormone and TGF-β generated good results in human studies by increasing BMD, depending on the type of OI. Gene therapy, 4-phenylbutiric acid, and inhibition of eIF2α phosphatase enzymes have only been studied in cell cultures and animal models, with promising results. (4) Conclusions: This paper focuses on eight potential therapies for OI, but there is not yet enough data for a new, generally accepted treatment. Most of them showed promising results, but further research is needed, especially in the pediatric field.

Effects of Resveratrol, Curcumin and Quercetin Supplementation on Bone Metabolism—A Systematic Review

Phenolic compounds are natural phytochemicals that have recently reported numerous health benefits. Resveratrol, curcumin, and quercetin have recently received the most attention among these molecules due to their documented antioxidant effects. The review aims to investigate the effects of these molecules on bone metabolism and their role in several diseases such as osteopenia and osteoporosis, bone tumours, and periodontitis. The PubMed/Medline, Web of Science, Google Scholar, Scopus, Cochrane Library, and Embase electronic databases were searched for papers in line with the study topic. According to an English language restriction, the screening period was from January 2012 to 3 July 2022, with the following Boolean keywords: (“resveratrol” AND “bone”); (“curcumin” AND “bone”); (“quercetin” AND “bone”). A total of 36 papers were identified as relevant to the purpose of our investigation. The studies reported the positive effects of the investigated phenolic compounds on bone metabolism and their potential application as adjuvant treatments for osteoporosis, bone tumours, and periodontitis. Furthermore, their use on the titanium surfaces of orthopaedic prostheses could represent a possible application to improve the osteogenic processes and osseointegration. According to the study findings, resveratrol, curcumin, and quercetin are reported to have a wide variety of beneficial effects as supplement therapies. The investigated phenolic compounds seem to positively mediate bone metabolism and osteoclast-related pathologies.

"Lessons from Rare Forms of Osteoarthritis"

Osteoarthritis (OA) is one of the most prevalent conditions in the world, particularly in the developed world with a significant increase in cases and their predicted impact as we move through the twenty-first century and this will be exacerbated by the covid pandemic. The degeneration of cartilage and bone as part of this condition is becoming better understood but there are still significant challenges in painting a complete picture to recognise all aspects of the condition and what treatment(s) are most appropriate in individual causes. OA encompasses many different types and this causes some of the challenges in fully understanding the condition. There have been examples through history where much has been learnt about common disease(s) from the study of rare or extreme phenotypes, particularly where Mendelian disorders are involved. The often early onset of symptoms combined with the rapid and aggressive pathogenesis of these diseases and their predictable outcomes give an often-under-explored resource. It is these "rarer forms of disease" that William Harvey referred to that offer novel insights into more common conditions through their more extreme presentations. In the case of OA, GWAS analyses demonstrate the multiple genes that are implicated in OA in the general population. In some of these rarer forms, single defective genes are responsible. The extreme phenotypes seen in conditions such as Camptodactyly Arthropathy-Coxa Vara-pericarditis Syndrome, Chondrodysplasias and Alkaptonuria all present potential opportunities for greater understanding of disease pathogenesis, novel therapeutic interventions and diagnostic imaging. This review examines some of the rarer presenting forms of OA and linked conditions, some of the novel discoveries made whilst studying them, and findings on imaging and treatment strategies.

Resveratrol promotes osteoblastic differentiation in a rat model of postmenopausal osteoporosis by regulating autophagy

OBJECTIVE

Resveratrol is a natural polyphenolic compound that ameliorates postmenopausal osteoporosis by activating the estrogen receptor. Research has shown that resveratrol exhibits some type of estrogen receptor agonist activity, reducing the risk of breast cancer. However, its mechanism of action remains largely unknown. This study aims to investigate the effect of resveratrol on osteoblastic and osteoclastic differentiation and its potential role in the regulation of autophagy.

METHODS

Sprague Dawley (SD) rats underwent ovariectomies (OVX) and were administered resveratrol (at 10, 20 or 40 mg/kg/d) for 8 weeks. The calcium content and the bone mineral density (BMD) were measured in the lumbar vertebrae (L3) and the right distal femur-tibia bone region. The osteoblasts and osteoclasts were isolated from rat lumbar vertebrae by enzyme digestion and bone marrow induction, respectively. The cells were then cultured with resveratrol in combination with bafilomycin or leupeptin to inhibit or activate autophagy, respectively. Western blotting was used to assess the differentiation markers and autophagy-related genes in the osteoblasts and osteoclasts.

RESULTS

Compared to the sham group, the bone calcium content and BMD were significantly decreased in the OVX group (p < 0.05), while resveratrol attenuated these in a dose-dependent manner. In the osteoblasts, vascular endothelial growth factor (VEGF), and alpha-1 type I collagen (COL1A1) were markedly decreased, and in osteoclasts, the receptor activator of nuclear factor-κB ligand (RANKL) was increased in the OVX group, while resveratrol reversed this pattern in a dose-dependent manner. The inhibition of autophagy in osteoblasts and its activation in osteoclasts was observed in the OVX group. However, with resveratrol, this was reversed in a dose-dependent manner.

CONCLUSION

Overall, resveratrol promotes osteoblastic differentiation and suppresses osteoclastic differentiation in a rat model with postmenopausal osteoporosis by regulating autophagy.

Correlations between the Peptide Hormone Ghrelin and Proinflammatory Cytokines in Experimental Periodontitis Models of Female Rats at Different Stages of the Life Cycle

OBJECTIVE

The aim of this study was to examine the correlations between the levels of ghrelin and inflammatory and bone metabolism markers in rats with periodontitis.

DESIGN

Thirty female Wistar rats (6 trial rats and 4 control rats in each group) were divided into pubertal, adult and postmenopausal groups. Periodontitis was induced by ligatures. On the 21 st day, blood was collected and all rats were then sacrificed. The levels of osteocalcin, osteoprotegerin, alkaline phosphatase, tumour necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), acylated ghrelin, total ghrelin and soluble receptor activator of nuclear factor-kB ligands in the blood samples were measured using enzyme-linked immunosorbent assays. The jaws were decalcified in a Tris-EDTA solution and embedded in paraffin and 4-5 μm sections were cut for IL-β, TNF -α and ghrelin staining.

RESULTS

Significantly higher serum alkaline phosphatase levels were detected in the trial rats in the pubertal group than in the control rats (p = 0.033). In the postmenopausal group, ghrelin levels positively correlated with interleukin 1 beta levels (r = 0.708, p < 0.05). Among all trial rats, the postmenopausal group exhibited significantly higher levels of acylated ghrelin than the other groups (p = 0.001). Significantly higher osteoprotegerin levels were observed in the control rats than in the trial rats in the postmenopausal group (p = 0.012). Inflammation scores were significantly higher in adult trial rats than in controls (p = 0.024); significantly higher TNF-α levels were detected in postmenopausal experimental rats than in the adult experimental group (p = 0.025).

CONCLUSIONS

We concluded that total ghrelin levels in serum only correlated with IL-β levels in postmenopausal rats.

Local application of osteoprotegerin-chitosan gel in critical-sized defects in a rabbit model

BACKGROUND

Osteoprotegerin (OPG) is used for the systemic treatment of bone diseases, although it has many side effects. The aim of this study was to investigate a newly formulated OPG-chitosan gel for local application to repair bone defects. Recent studies have reported that immunodetection of osteopontin (OPN) and osteocalcin (OC) can be used to characterise osteogenesis and new bone formation.

METHODS

The osteogenic potential of the OPG-chitosan gel was evaluated in rabbits. Critical-sized defects were created in the calvarial bone, which were either left unfilled (control; group I), or filled with chitosan gel (group II) or OPG-chitosan gel (group III), with rabbits sacrificed at 6 and 12 weeks. Bone samples from the surgical area were decalcified and treated with routine histological and immunohistochemical protocols using OC, OPN, and cathepsin K (osteoclast marker) antibodies. The toxicity of the OPG-chitosan gel was evaluated by biochemical assays (liver and kidney function tests).

RESULTS

The mean bone growth in defects filled with the OPG-chitosan gel was significantly higher than those filled with the chitosan gel or the unfilled group (p < 0.05). At 6 and 12 weeks, the highest levels of OC and OPN markers were found in the OPG-chitosan gel group, followed by the chitosan gel group. The number of osteoclasts in the OPG-chitosan gel group was lower than the other groups. The results of the liver and kidney functional tests indicated no signs of harmful systemic effects of treatment. In conclusion, the OPG-chitosan gel has many characteristics that make it suitable for bone repair and regeneration, highlighting its potential benefits for tissue engineering applications.

Textural entropy as a potential feature for quantitative assessment of jaw bone healing process

INTRODUCTION

The aim of the study was to propose and evaluate textural entropy as a parameter for bone healing assessment.

MATERIAL AND METHODS

One hundred and twenty radiographs with loss of bone architecture were investigated (a bone defect was circumscribed - ROI DEF). A reference region (ROI REF) of the same surface area as the ROI DEF was placed in a field distant from the defect, where a normal, trabecular pattern of bone structure was well visualized. Data of three time points were investigated: T0 - immediately after the surgical procedure, T1 - 3 months post-op, and T2 - 12 months post-op.

RESULTS

Textural entropy as a parameter describing bone structure regeneration was selected based on Fisher coefficient (F) evaluation. F was highest in T0 (3.4) and was decreasing later in T1 (1.7) and T2 (1.0 - means final lack of difference in the structure to reference bone). Textural entropy is a measure of structure disarrangement which in a bone defect region attains minimal value due to structural homogeneity, i.e. low complexity of the texture. The calculated parameter in the investigated material revealed a gradual increase inside the bone defect (p < 0.05), i.e. increase of complexity in a time-dependent manner starting from immediate post-op (T0 = 2.51; T1 = 2.68) up to most complex 1 year post-operational (T2 = 2.73), reaching the reference level of a normal bone.

CONCLUSIONS

Textural entropy may be useful for computer assisted evaluation of bone regeneration process. The complexity of the texture corresponds to mature trabecular bone formation.

Osteoblastic potential of infrapatellar fat pad-derived mesenchymal stem cells from rheumatoid arthritis and osteoarthritis patients

AIM

To evaluate the osteoblastic potential of adipose-derived mesenchymal stem cells (ASCs) from infrapatellar fat pad (IPFP) of rheumatoid arthritis (RA) patients in comparison to osteoarthritis (OA) patients, as well as the influence of tumor necrosis factor alpha (TNFα) on osteoblastic ASC differentiation in vitro.

METHODS

ASCs were isolated from IPFP of RA and OA patients. After expansion, cells were cultured in osteogenic medium with or without TNFα. After 2 weeks, expression of BMP-2, Runx-2, osterix (Osx), collagen 1a1 (Col1a1) and osteopontin (OPN) messenger RNA (mRNA) was assessed by reverse transcription polymerase chain reaction and calcium deposition by alizarin red staining. Dickkopf-1 (DKK-1) and osteoprotegerin (OPG) protein concentrations were measured in culture supernatants using enzyme-linked immunosorbent assay.

RESULTS

Both RA- and OA-ASCs cultured in osteogenic medium showed calcium deposition. The expression of Runx2 and OPN mRNA was increased in RA-ASCs. These cells expressed significantly more Osx and OPN than OA-ASCs. TNFα potentiated calcium deposition, up-regulated Runx2 and BMP-2 but down-regulated Col1a1 and OPN expression. In osteogenic cultures DKK-1 concentration was increased but that of OPG decreased, whereas TNFα elevated secretion of both cytokines.

CONCLUSION

RA-ASCs have comparable or slightly stronger osteogenic potential than OA-ASCs. RA-ASCs seem to be more sensitive to TNFα treatment. TNFα exerts complex effects on ASC osteoblastogenesis, enhances expression of early osteogenic markers and calcium deposition, inhibits expression of mRNA coding for non-mineral bone components and alters ASC secretory activity.

Adenovirus-mediated transfer of VEGF into marrow stromal cells combined with PLGA/TCP scaffold increases vascularization and promotes bone repair in vivo

INTRODUCTION

Large osseous defect remains a serious clinical problem due to the lack of sufficient blood supply and it has been proposed that this situation can be relieved by accelerating the formation of new vessels in the process of bone defect repair. The aim of this study was to develop a new type of artificial bone by transferring the VEGF gene into marrow stromal cells (MSCs) and seeding them into a porous scaffold.

MATERIAL AND METHODS

An adenovirus vector was employed to transfer the VEGF gene into MSCs and expression of the exogenous gene was confirmed by ELISA. Next the transduced cells were seeded into a collagen I modified PLGA/TCP scaffold. The constructed new complex artificial bone was then assessed for biocompatibility in vitro and blood vessel formation and bone formation in vivo.

RESULTS

We found that adenovirus mediated VEGF gene transfer into MSCs sustained VEGF expression in MSCs for 3 weeks. Porous scaffold PLGA/TCP made by rapid prototyping technology exhibited improved biocompatibility resulting from crosslinking with collagen I. Furthermore, the in vivo study showed that large amounts of blood vessels were detected histologically 1 week after artificial bone implantation, and significant bone formation was detected 8 weeks after implantation.

CONCLUSIONS

Our findings suggest that gene transfer of VEGF into MSCs combined with PLGA/TCP scaffold enhances bone repair in vivo by promoting vascularization.

The effects of chronic zoledronate usage on the jaw and long bones evaluated using RANKL and osteoprotegerin levels in an animal model

The discovery of the receptor activator of nuclear factor kappaB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) system (RANK/RANKL/OPG system) has been one of the most important advances in bone biology in the last decade. We investigated how the chronic application of bisphosphonate affects the RANKL and OPG levels in an animal model and whether this effect may be related to bisphosphonate-related osteonecrosis of the jaws (BRONJ). Thirty female Sprague-Dawley rats were used in this study. The rats were randomly divided into three groups (10 in each): Z, the zolendronate group, injected with zolendronate for 10 weeks; S, a control group, injected with saline solution for 10 weeks; and C, a control group, in which no injection was given. RANKL values in the tibia were increased in the Z group when compared with the two controls; however, the RANKL values in the mandible were decreased when compared with the controls. Although the differences did not reach statistical significance, the mandibular OPG values were increased in the Z group when compared with the C and S groups. The mechanism of RANKL negation and absence in osteoclastic activation could be a predisposing factor for the development of BRONJ.

Immediately transcripted genes in various hepatic ischemia models

PURPOSE

To elucidate the characteristic gene transcription profiles among various hepatic ischemia conditions, immediately transcribed genes and the degree of ischemic injury were compared among total ischemia (TI), intermittent clamping (IC), and ischemic preconditioning (IPC).

METHODS

Sprague-Dawley rats were equally divided into control (C, sham-operated), TI (ischemia for 90 minutes), IC (ischemia for 15 minutes and reperfusion for 5 minutes, repeated six times), and IPC (ischemia for 15 minutes, reperfusion for 5 minutes, and ischemia again for 90 minutes) groups. A cDNA microarray analysis was performed using hepatic tissues obtained by partial hepatectomy after occluding hepatic inflow.

RESULTS

THE CDNA MICROARRAY REVEALED THE FOLLOWING: interleukin (IL)-1β expression was 2-fold greater in the TI group than in the C group. In the IC group, IL-1α/β expression increased by 2.5-fold, and Na+/K+ ATPase β1 expression decreased by 2.4-fold. In the IPC group, interferon regulatory factor-1, osteoprotegerin, and retinoblastoma-1 expression increased by approximately 2-fold compared to that in the C group, but the expression of Na+/K+ ATPase β1 decreased 3-fold.

CONCLUSION

The current findings revealed characteristic gene expression profiles under various ischemic conditions. However, additional studies are needed to clarify the mechanism of protection against IPC.

Potential Markers in Cardiac Hypertrophy?

Cardiomyopathies are diagnosed based on medical history of patient (symptoms and family history), physical examination, results of echocardiogram and in some situations additionally ECG or chest-X-ray results. Currently used non-invasive diagnostic methods, could be complemented by biochemical tests. In this review some emerging potential biomarkers such as: osteopontin, ST-2 receptor, osteoprotegerin, neopterin, urocortins, growth differentiation factor 15 and urotensin II are described. In current article human and non human investigations have been reviewed, since rat is most commonly used model in experimental cardiology and gives important foundations to clinical knowledge.

Age-related BMAL1 change affects mouse bone marrow stromal cell proliferation and osteo-differentiation potential

INTRODUCTION

Aging people's bone regeneration potential is always impaired. Bone marrow stromal cells (MSCs) contain progenitors of osteoblasts. Donor age may affect MSCs' proliferation and differentiation potential, but the genomic base is still unknown. Due to recent research's indication that a core circadian component, brain and muscle ARNT-like 1 protein (BMAL1), has a role in premature aging, we investigated the normal aging mechanism in mice with their MSCs and Bmal1 gene/protein level.

MATERIAL AND METHODS

1, 6 and 16 month old C57BL/6 mice were used and the bone marrow stromal cells were gained and cultured at early passage. Bmal1 gene and protein level were detected in these cells. Marrow stromal cells were also induced to differentiate to osteoblasts or adipocytes. Three groups of mice MSCs were compared on proliferation by flow cytometry, on cell senescence by SA-β-gal expression and after osteo-induction on osteogenic potential by the expression of osterix (Osx), alkaline phosphatase (ALP) and osteocalcin (OCN).

RESULTS

Bmal1 gene and protein level as well as S-phase fraction of the cell cycle decreased in MSCs along with the aging process. At the same time, SA-β-gal+ levels increased, especially in the aged mice MSCs. When induced to be osteogenic, Osx gene expression and ALP activity declined in the mid-age and aged mice MSCs, while OCN protein secretion deteriorated in the aged mice MSCs.

CONCLUSIONS

These findings demonstrate that mouse MSCs changed with their proliferation and osteo-differentiation abilities at different aging stages, and that Bmal1 is related to the normal aging process in MSCs.

Infantile haemangioma expresses tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), TRAIL receptors, osteoprotegerin and receptor activator for nuclear factor кB ligand (RANKL)

AIMS

To investigate the expression of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors and decoy receptors, including osteoprotegerin (OPG) in infantile haemangioma (IH).

METHODS AND RESULTS

Immunostaining, Western blotting and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used on IH biopsies and haemangioma explant-derived cells (HaemEDCs). TRAIL and its receptors and decoy receptors, including OPG, are expressed in proliferating IH tissues and in HaemEDCs. Cells forming the endothelium of immature capillaries of proliferating IHs express abundant OPG and show punctate von Willebrand Factor (vWF) staining. As the cells mature and assume the characteristic of endothelial cells they increase expression of vWF, but lose expression of OPG. The endothelium of IH shows minimal expression of receptor activator for nuclear factor кB ligand (RANKL) compared with a small population of RANKL-positive cells located within the interstitium between microvessels. Proliferating HaemEDCs express significantly higher levels of OPG and decoy receptor 2 than the matched tissue samples. Increased OPG expression is detected in the extracellular matrix and in the conditioned medium of HaemEDCs.

CONCLUSIONS

Our data suggest that OPG through the TRAIL pathway, but not the RANKL pathway, plays a role in regulating anti-apoptosis during the development of IH.

Denosumab for the management of bone disease in patients with solid tumors

Many patients with advanced cancer develop bone metastases, which reduces their quality of life. Bone metastases are associated with an increased risk of skeletal-related events, which can lead to increased morbidity and mortality. In patients with bone metastases, tumor cells disrupt the normal process of bone remodeling, leading to increased bone destruction. Denosumab is a fully human monoclonal antibody against receptor activator of NF-κB ligand (RANKL), a key regulatory factor in bone remodeling. By binding to RANKL, denosumab disrupts the cycle of bone destruction. In clinical studies in patients with prostate or breast cancer and bone metastases, denosumab was superior to the current standard of care, zoledronic acid, for delaying skeletal-related events, while in patients with other solid tumors or multiple myeloma, denosumab was noninferior to zoledronic acid. This article examines the pharmacokinetics, efficacy, and safety and tolerability of denosumab for the management of bone events in patients with cancer.

Pathogenesis of Metastatic Calcification and Acute Pancreatitis in Adult T-Cell Leukemia under Hypercalcemic State

Human T-cell leukemia virus type-1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL). Hypercalcemia is common in patients with ATL. These patients rarely develop metastatic calcification and acute pancreatitis. The underlying pathogenesis of this condition is osteoclast hyperactivity with associated overproduction of parathyroid hormone-related protein, which results in hypercalcemia in association with bone demineralization. The discovery of the osteoclast differentiation factor receptor activator of nuclear factor-κB ligand (RANKL), its receptor RANK, and its decoy receptor osteoprotegerin (OPG), enhanced our understanding of the mechanisms of ATL-associated hypercalcemia. Macrophage inflammatory protein-1-α, tumor necrosis factor-α, interleukin-1, and interleukin-6 are important molecules that enhance the migration and differentiation of osteoclasts and the associated enhanced production of RANKL for osteoblast formation. In this paper, we focus on metastatic calcification and acute pancreatitis in ATL, highlighting recent advances in the understanding of the molecular role of the RANKL/RANK/OPG system including its interaction with various cytokines and calciotropic hormones in the regulation of osteoclastogenesis for bone resorption in hypercalcemic ATL patients.

Functional polymorphisms within the TNFRSF11B (osteoprotegerin) gene increase the risk for low bone mineral density

Polymorphisms within the TNFRSF11B gene have been studied and associated with osteoporosis and fracture risk. Osteoprotegerin (OPG), the product of this gene, is a key negative regulator of osteoclastogenesis and is secreted by osteoblasts/stromal cells. A previous study in Maltese postmenopausal women showed positive association of low bone mineral density (BMD) with a polymorphism found within the promoter region of this gene (C950T). In this study, direct DNA sequencing revealed 12 variants with polymorphisms C950T, G1181C and rs4876869 observed to be in strong linkage disequilibrium. The constructed haplotype T-G-T was found to increase the risk for a low BMD, while C-G-T and C-C-C have a protective role; thus, we investigated the functional role of both C950T and rs4876869 in vitro. The promoter region, including the C950T alleles, was amplified by PCR, cloned into pGL3 enhancer vector and transfected into HeLa, COS-7 and RAW264.7 cell lines. After incubation, luciferase activity was measured. The T/C (rs4876869) change was tested for its possible effect on pre-mRNA splicing, using an exon-trapping vector. A statistical significant difference in gene expression was observed between the alleles for T950C, with the T allele showing a lower luciferase expression in all cell lines (P<0.01). For rs4876869, exon skipping was observed for the C allele, while only one transcript harbouring the whole exon was observed for the T allele. Our findings suggest that the T-G-T haplotype might be increasing the risk for osteoporosis due to lower quantities of the full OPG transcript being expressed resulting in a higher bone resorption.

Wallis interspinous implantation to treat degenerative spinal disease: description of the method and case series

The Wallis interspinous implant is most commonly used in the treatment of intervertebral disc herniation and for tears in the outer layer of the disc. The dynamic vertebral fixation concept was first initiated in 1984 with the goal of imitating the physiologic spinal kinetic. A total of 15 years later, a second generation of implant has been developed, termed the 'Wallis interspinous Implant', which aims to preserve the mobility of the operated spinal segment. To underline our own experience, a retrospective review of 15 patients that were treated with 'Wallis implantation' at our institution between January 2006 and March 2008. Our main inclusion criterion for Wallis implantation was low back pain because of degenerative lumbar spinal stenosis associated with segmental instability along with Modic changes 0-1 and with UCLA arthritic grade <II, while the main exclusion criteria were previous lumbar surgery, severe osteoporosis or degeneration UCLA grade >II in the adjacent two segments cephalad to implantation. The outcome was analyzed according to clinical and radiological parameters. One (n = 9), two (n = 4) and three levels (n = 2) were operated on using Wallis implantation, ranging from L2-L3 to L5-S1. We used implants of 8-14 mm in size. There was a reduction in low back pain (73 vs 43%) and gait disturbances (73 vs 14%) at the 3-month follow-up compared with preoperative values. In line with these results, the modified Japan Orthopedic Association Score (mJAOS) was increased from 12 preoperatively to 18 at 3 months and 20 at 12 months postoperatively. A reduction in low back pain could only be demonstrated for implants that were 10 mm in size or greater at 3 months and 12-15 months postoperatively. An improvement was seen in Modic grades after the operations as compared with those observed at preoperative MRI. The outcome in our patients was rated as good or excellent according to Odom's criteria in all cases, independent of the levels that were used. Wallis implantation is therefore a safe procedure with a good to excellent outcome in the short- and mid-term follow-up and can lead to disc rehydration, as confirmed by postoperative MRI. Principal postoperative (clinical) success is based on the correct implant size.

Role of RANK, RANKL, OPG, and CXCR4 tissue markers in predicting bone metastases in breast cancer patients

This is a retrospective study on 40 breast cancer patients, of which 20 have bone metastases, 10 have visceral metastases, and 10 have no evidence of disease, aimed at evaluating the role of CXCR4 and the RANK/RANKL/OPG system to predict bone metastases. CXCR4 expression, alone or in combination with RANK, identified patients destined to relapse to bone.

BACKGROUND

The RANK/RANKL/OPG system is active in primary cancers such as breast, prostate, and also in their bone metastases. CXCR4 chemokine receptor is highly expressed in human breast cancer cells and is believed to facilitate the homing of tumor cells to organs such as bone that express high levels of its ligand SDF1. Our study aimed to investigate whether the analysis of these markers with an inexpensive and simple test can help to predict bone metastases in breast cancer patients.

PATIENTS AND METHODS

Marker expression was evaluated by immunohistochemical staining in paraffin-embedded tissue sections of primary breast cancers from 40 individuals: 20 patients with bone metastases (BM), 10 with visceral metastases (VM; considered together as the relapsed group), and 10 with no evidence of disease (NED).

RESULTS

RANKL was not detected in tumor cells. OPG- and RANK-positive tumors are found with similar frequency in NED (20%) and in relapsed patients (23% and 17%, respectively). However, in the latter subgroup, only RANK positivity was always associated with bone relapse. The frequency of CXCR4-positive tumors was three-fold higher in relapsed (30%) than in NED (10%) patients and positivity was always linked to bone metastases. Considering NED and VM patients together versus BM patients, we observed that CXCR4 expression, alone (P = .008) or in combination with RANK (P < .001), identified patients destined to relapse to bone.

CONCLUSION

Our results provide the first clinical evidence to support a pivotal role of combined CXCR4 and RANK expression in predicting bone relapse.

Receptor Activator for Nuclear Factor kappa B Ligand (RANKL) as an osteoimmune key regulator in bone physiology and pathology

The strength and integrity of the human skeleton depends on a delicate equilibrium between bone resorption and bone formation. Bone resorption is an elementary cellular activity in the modelling of the skeleton during growth and development. Later in life a most important physiological process in the skeleton is bone remodelling, which is locally initiated by resorption. During remodelling bone resorption is coupled to new bone formation that ensures renewal of bone with only minor local and temporary bone loss. Cells responsible for bone resorption and subsequent bone formation are the osteoclasts and osteoblasts, respectively. The osteoclast is derived from the pluripotent hematopoietic stem cell, which gives rise to a myeloid stem cell that can further differentiate into megakaryocytes, granulocytes, monocytes/macrophages and osteoclasts. The respective bone resorbing and forming actions of osteoclasts and osteoblasts are finely coupled, so that bone mass remains remarkably stable in a healthy adult. Imbalance between osteoclast and osteoblast activities can arise from a wide variety of hormonal changes or perturbations of inflammatory and growth factors resulting in postmenopausal osteoporosis, Paget's disease, lytic bone metastases, or rheumatoid arthritis, leading to increased bone resorption and crippling bone damage. In view of the critical role of osteoclasts in diverse pathology, there has been immense effort aimed at understanding the biology of this unique cell. The present review is focused on the current knowledge of the mechanisms that regulate the functional links between bone turnover and the immune system helping us to understand the main factors that lead to bone loss observed in osteoporosis, cancer and in rheumatoid arthritis. The aim of this review paper is to consider the key molecular interactions involved in the formation of osteoclast cells in normal and pathological conditions.

Examining the metastatic niche: targeting the microenvironment

Some of the most common cancer types, including breast cancer, prostate cancer, and lung cancer, show a predilection to metastasize to bone. The molecular basis of this preferential growth of cancer cells in the bone microenvironment has been an area of active investigation. Although the precise molecular mechanisms underlying this process remain to be elucidated, it is now increasingly being recognized that the unique characteristics of the bone niche provide homing signals to cancer cells, and create a microenvironment conducive for the cancer cells to colonize. Concomitantly, cancer cells release several regulatory factors that result in abnormal bone destruction and/or formation. This complex bidirectional interplay between tumor cells and bone microenvironment establishes a "vicious cycle" that leads to a selective growth advantage for the cancer cells. The molecular insights gained on the underpinnings of bone metastasis in recent years have also provided us with avenues to devise innovative approaches for therapeutic intervention. The goal of this review is to describe our current understanding of molecular pathophysiology of cancer metastases to bone, as well as its therapeutic implications.

Endocrine and metabolic emergencies: hypercalcaemia

Hypercalcaemia is commonly seen in the context of parathyroid dysfunction and malignancy and, when severe, can precipitate Life-threatening sequelae. The differential of hypercalcaemia is broad and can be categorized based on parathyroid hormone (PTH) Levels. The acute management of severe hypercalcaemia is discussed along with a brief review of therapeutic advances in the field.

Cytotoxic effect of zoledronic acid-loaded bone cement on giant cell tumor, multiple myeloma, and renal cell carcinoma cell lines

BACKGROUND

Local recurrence with subsequent osteolysis is a problem after intralesional curettage of giant cell tumor of bone, myeloma, and metastatic carcinoma. The bisphosphonate zoledronic acid (zoledronate) has been shown to reduce osteoclast activity, and its local administration is a potentially attractive therapy, especially for the osteoclast-rich giant cell tumor. The aim of this study was to analyze the elution dynamics of zoledronic acid release from acrylic bone cement and its in vitro antitumor efficacy.

METHODS

Various concentrations of zoledronic acid were mixed with bone cement and placed in distilled water. The concentration in the water was measured daily for fourteen days. The cytotoxic effects of the dissolved zoledronic acid on cultures of multiple myeloma, giant cell tumor, and renal cell carcinoma cells were tested with use of the MTT assay (tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] dye) and analyzed according to the zoledronic acid concentration and the elapsed time.

RESULTS

The release of zoledronic acid was greatest during the first twenty-four hours for all concentrations and decreased rapidly during the next forty-eight hours to reach a plateau after four days. The proliferation assay (MTT) showed zoledronic acid to have significant cytotoxicity in cultures of stromal giant cell tumor, multiple myeloma, and renal cell carcinoma cells. In addition, zoledronic acid decreased the number of viable tumor cells in a dose-dependent manner. Renal cell carcinoma from bone (RBM1-IT4) and stromal giant cell tumor of bone were more susceptible to zoledronic acid than was multiple myeloma.

CONCLUSIONS

The method presented in our study is a reproducible technique for evaluating zoledronic acid elution from bone cement and determining its impact on tumor growth. Zoledronic acid is released from bone cement, remains biologically active despite the polymerization of cement, and inhibits the in vitro growth of cell lines from giant cell tumor of bone, myeloma, and renal cell carcinoma.