Denosumab

Denosumab is an anti-receptor activator of nuclear factor (NF)-kappaB (RANK) ligand human monoclonal antibody studied as a treatment for postmenopausal osteoporosis (PMO) and bone destruction due to rheumatoid arthritis (RA) or metastatic cancers. As of February 2009, the candidate was undergoing US Food and Drug Administration review, and might be approved by October 2009. Late phase clinical trials demonstrated that denosumab possesses a similar safety profile to bisphosphonates, and that it can be either equally or more effective than bisphosphonates at preventing bone loss due to PMO, RA, or cancer treatment and metastases.     

Maturation of cytotoxic T cells within sponge matrix allografts

Two parallel events may provide cytotoxic effector cells at the site of allograft challenge: 1) the migration of effector cells to the graft, and 2) the local maturation of effector cells. Various experimental conditions were manipulated to ascertain the relative role of local maturation of precytotoxic cells at the site of alloantigen challenge. A C57BL/6 allogeneic-coated sponge matrix allograft was placed in a BALB/c animal. The entire animal with the sponge was subjected to sublethal irradiation, or alternatively, just the animal was subjected to the same dose of irradiation, and the sponge was shielded. The data demonstrate that by day 5, precytotoxic cells directed against donor alloantigen appears within the sponge matrix allograft. These precytotoxic cells are in themselves x-ray sensitive, but in the absence of irradiation and in the absence of further contributions from the host can develop into mature cytotoxic cells with specificity limited to that of donor alloantigen. The relative role of local maturation vs continued influx of mature cytotoxic cells cannot be determined from these sets of experiments. These data, however, show that there is potential for local development of mature cytotoxic cells in the absence of other host influences.     

Vascularized bone allograft transplantation in a genetically defined rat model

A heterotopic subcutaneous model for experimental vascularized bone allograft transplantation has been presented. This model uses genetically defined rats and allows serial assessment of graft viability. The reliability of this model has been proven by successful isograft transplantation. This model was used to study the effect of matching at the major histocompatibility complex on vascularized bone allograft survival. Whereas grafts transplanted across a minor histocompatibility barrier survived until sacrifice, grafts transplanted across a major histocompatibility barrier were victims of an acute rejection process. This study, therefore, showed genetic disparity to be a critical determinant of vascularized bone allograft survival. It indicates that primary vascularized bone allografts are as susceptible to rejection as heart and kidney allografts. For these reasons, it can be anticipated that genetic matching will be important in clinical vascularized bone allograft transplantation. The model used in this study should be useful for obtaining further fundamental immunologic information concerning vascularized bone allograft transplantation.     

Denosumab

Denosumab is an anti-receptor activator of nuclear factor (NF)-kappaB (RANK) ligand human monoclonal antibody studied as a treatment for postmenopausal osteoporosis (PMO) and bone destruction due to rheumatoid arthritis (RA) or metastatic cancers. As of February 2009, the candidate was undergoing US Food and Drug Administration review, and might be approved by October 2009. Late phase clinical trials demonstrated that denosumab possesses a similar safety profile to bisphosphonates and that it can be either equally or more effective than bisphosphonates at preventing bone loss due to PMO, RA or cancer treatment and metastases.Key Words: monoclonal antibody, RANKL, bone loss, osteoporosis, breast cancer, rheumatoid arthritis     

Age-related changes in porosity and mineralization and in-service damage accumulation

It has been proposed that bone damageability (i.e. bone's susceptibility to formation of damage) increases with the elevation or suppression of bone turnover. Suppression of turnover via bisphosphonates increases local bone mineralization, which theoretically should increase the susceptibility of bone to microcrack formation. Elevation of bone turnover has also been proposed to increase bone microdamage through an increase in bone intracortical porosity and local stresses and strains. The goal of this paper was to investigate the above proposals, i.e., whether or not increases to mineral content and porosity increase bone in-service damageability. To do this, we measured in vivo diffuse damage area (Df.Dm.Ar, %) and microcrack density (Cr.Dn) (cracks/mm(2)) in the same specimen from human cortical bone of the midshaft of the proximal femur obtained from cadavers with an age range of eight decades and examined their relationships with porosity, mineralization and age. Results of this study showed that Cr.Dn and Df.Dm.Ar increased with a decrease in bulk mineralization. This finding does not appear to support the proposal that damage accumulation increases with low bone turnover that results in increases mineralization. It was proposed however that the negative correlation between damage accumulation and mineralization may be attributed to highly mineralized regions of bone existing with under-mineralized regions resulting in an overall decrease in average bone mineralization. It was also found that microdamage accumulates with increasing porosity which does appear to support the proposal that elevated bone turnover that results in increased porosity can accelerate microdamage accumulation. Finally, it was shown that linear microcracks and Df.Dm.Ar accumulate with age differently, but because they correlate with each other, one may be the precursor for the other.     

Utilisation of bone allograft by orthopaedic surgeons in Scotland

The use of bone allograft in orthopaedic surgery has been predicted to increase, particularly in joint revision surgery. This has led to a potential problem with supply. Questionnaires were distributed to all 146 Consultant Orthopaedic surgeons working in Scotland in 2000. They were asked to indicate their current usage of bone and tissue allograft, any problems encountered with supply and if alternatives to allograft, such as processed bone, might be used. The questions asked were very similar to those asked in a previous study in 1995 to enable comparisons to be made. Replies were received from 125 Consultants (87%) of whom 93 reported using bone allograft. Forty-one consultants (46%) predicted an increase in their requirement for bone allograft, and 23 (26%) felt they could currently use more bone if this was available. Sixty percent of surgeons would consider using processed bone as an alternative. In comparison with figures from 1995, an increasing number of surgeons are prepared to use processed bone as an alternative to fresh frozen allograft. This revised version was published online in July 2006 with corrections to the Cover Date.     

Automatic allograft bone selection through band registration and its application to distal femur

Clinical reports suggest that large bone defects could be effectively restored by allograft bone transplantation, where allograft bone selection acts an important role. Besides, there is a huge demand for developing the automatic allograft bone selection methods, as the automatic methods could greatly improve the management efficiency of the large bone banks. Although several automatic methods have been presented to select the most suitable allograft bone from the massive allograft bone bank, these methods still suffer from inaccuracy. In this paper, we propose an effective allograft bone selection method without using the contralateral bones. Firstly, the allograft bone is globally aligned to the recipient bone by surface registration. Then, the global alignment is further refined through band registration. The band, defined as the recipient points within the lifted and lowered cutting planes, could involve more local structure of the defected segment. Therefore, our method could achieve robust alignment and high registration accuracy of the allograft and recipient. Moreover, the existing contour method and surface method could be unified into one framework under our method by adjusting the lift and lower distances of the cutting planes. Finally, our method has been validated on the database of distal femurs. The experimental results indicate that our method outperforms the surface method and contour method.     

A review of the tolerability and safety of levocabastine eye drops and nasal spray. Implications for patient management

Levocabastine is a highly potent and selective H(1)-receptor antagonist specifically developed for topical administration by ocular and nasal routes. The clinical effects of levocabastine occur rapidly and are predominantly due to local antihistaminic effects at the site of application. Clinically, levocabastine is well tolerated with an adverse effect profile comparable with that of sodium cromoglycate and placebo. As might be expected from the route of drug administration, local irritation is the most frequent adverse event seen with levocabastine eye drops and nasal spray with an incidence comparable with that in placebo-treated controls. Intranasal application of levocabastine has been shown to have no adverse effect on ciliary activity both in vitro and in vivo, while ocular administration has not been shown to have any significant or consistent adverse effect in both animal and human studies. At therapeutic doses, levocabastine appears to be devoid of significant systemic activity producing no apparent effects on cardiovascular, psychomotor and cognitive function. Since levocabastine undergoes little hepatic metabolism, and only low plasma levels of the drug are attained following topical administration, drug interactions are unlikely.     

Synthesis of fluorescently tagged isoprenoid bisphosphonates that inhibit protein geranylgeranylation

Geminal bisphosphonates can be used for a variety of purposes in human disease including reduction of bone resorption in osteoporosis, treatment of fractures associated with malignancies of the prostate, breast, and lung, and direct anticancer activity against bone marrow derived malignancies. Previous research led to identification of some novel isoprenoid bisphosphonates that inhibit geranylgeranyl pyrophosphate (GGPP) synthesis and diminish protein geranylgeranylation. Described here is the synthesis of fluorescent anthranilate analogues of the most active isoprenoid bisphosphonates and examine their ability to impact post-translational processing of the small GTPases Ras, Rap1a, and Rab6. Similar to their non-fluorescent counterparts, some of these fluorescent isoprenoid bisphosphonates diminish protein geranylgeranylation. Their biological activity and fluorescent character suggest that they may be useful in studies of bisphosphonate localization both in cultured cells and in whole organisms.     

Route of Administration of the TLR9 Agonist CpG Critically Determines the Efficacy of Cancer Immunotherapy in Mice

Background

The TLR9 agonist CpG is increasingly applied in preclinical and clinical studies as a therapeutic modality to enhance tumor immunity. The clinical application of CpG appears, however, less successful than would be predicted from animal studies. One reason might be the different administration routes applied in most mouse studies and clinical trials. We studied whether the efficacy of CpG as an adjuvant in cancer immunotherapy is dependent on the route of CpG administration, in particular when the tumor is destructed in situ.

Methodology/Principal Findings

In situ tumor destruction techniques are minimally invasive therapeutic alternatives for the treatment of (nonresectable) solid tumors. In contrast to surgical resection, tumor destruction leads to the induction of weak but tumor-specific immunity that can be enhanced by coapplication of CpG. As in situ tumor destruction by cryosurgery creates an instant local release of antigens, we applied this model to study the efficacy of CpG to enhance antitumor immunity when administrated via different routes: peritumoral, intravenous, and subcutaneous but distant from the tumor. We show that peritumoral administration is superior in the activation of dendritic cells, induction of tumor-specific CTL, and long-lasting tumor protection. Although the intravenous and subcutaneous (at distant site) exposures are commonly used in clinical trials, they only provided partial protection or even failed to enhance antitumor responses as induced by cryosurgery alone.

Conclusions/Significance

CpG administration greatly enhances the efficacy of in situ tumor destruction techniques, provided that CpG is administered in close proximity of the released antigens. Hence, this study helps to provide directions to fully benefit from CpG as immune stimulant in a clinical setting.     

Modulation of bone morphogenetic protein antagonists to stimulate clinical osteogenesis

Bone morphogenetic proteins (BMPs) are important for the development and functioning of a wide variety of tissues and organ systems. Their ability to induce bone formation has been harnessed for clinical application. Specifically, local application of BMPs into fractures and fusions has shown some efficacy in inducing bone formation. However, clinical success has not been as robust as might be expected from the results obtained using animal models. This difference may be due to a number of mechanisms regulating BMP activity in vivo. One class of major regulators is the extracellular antagonist (e.g. Noggin, Gremlin, DAN), the dysfunction of which has been shown to result in ectopic bone formation in animal models and human disease. We hypothesize that local application of BMPs at high concentrations induces increased production of BMP antagonists, thereby limiting BMP activity and clinical efficacy. Therapies blocking the function of BMP antagonists should therefore result in enhanced BMP activity and increased bone formation. Furthermore, titrated systemic regulation of BMP antagonist may potentially reverse osteoporosis. Our collective experience with the clinical use of BMP illustrates the importance of understanding mechanisms of endogenous antagonism and regulation in the exogenous application of a protein as a therapeutic.     

Historical perspectives on the clinical development of bisphosphonates in the treatment of bone diseases

Bisphosphonates (formerly termed diphosphonates) were first synthesized in the late 1800s; however, their clinical use has been relatively recent. The bisphosphonates' affinity for hydroxyapatite crystal surface led Procter and Gamble to test these compounds in dental, then medical applications. With key input from university researchers, this led to the medical use of the first bisphosphonate, etidronate disodium in 1968 to treat a young patient with myositis ossificans progressiva. Further clinical research led to widespread medical application for the bisphosphonate class including use as a diagnostic in radionuclide bone imaging agents, treatment of osteoporosis, Paget's disease of bone, hypercalcemia of malignancy and metastatic bone disease. The historical development of bisphosphonates provides an excellent example of how observations and knowledge obtained at the basic science level were applied and successfully tested in the clinic. The end result of these efforts has provided health care professionals with diagnostic and therapeutic tools to improve the lives of patients.     

Status of Bone Allografting in Japan – Nation-Wide Survey of Bone Grafting Performed from 1995 through 1999

We report the status of bone allografting in Japan on the basis of the information obtained through questionnaires performed by the Japanese Orthopaedic Association (JOA). JOA performed a nation-wide survey in 2000, in order to clarify the current status of musculoskeletal tissue grafting in the orthopaedic practices in Japan. Conducted period was for 5 years from 1995 to 1999. As the results of this survey, it had been clarified that 92,984 bone graftings, which included autografts, allografts and synthetic bone substitutes, were performed during conducted 5 years. While the allografts were used only in 3,212 cases (3%), autograftings were performed in 64,193 cases (69%), synthetic bone substitutes were used in 25,576 cases (28%) in this series. The proportion of the number of operations for use bone substitutes increased every year, whereas that autografting decreased. The proportion of the number of allografting remained almost unaltered. Of the 706 institutions which answered to have experiences of tissue grafting, only 193 (27%) performed allograft.Since Kitasato University Hospital Bone Bank was developed in 1971, we have applied to clinical while doing basic research for preserved bone allograft. When extensive bone graft is required, allograft is very useful. In Japan, however, allograft is not performed widely. The foundation of regional bone banks is expected to resolve this problem. Since excision of bone preparations from cadaver donors is not common, bone allografts are not supplied sufficiently at present. It is needed to develop a network connecting bone banks in Japan. The enlightenment activities to the ordinary people and medical institutions will also be required.     

Modulation of tumour-induced bone resorption by bisphosphonates.

Tumour cells produce systemic or local factors which can stimulate osteoclast development and activity leading to increased bone resorption. The clinical consequences are bone pain, fractures and hypercalcaemia. Inhibitors of osteoclast-mediated bone resorption, such as the bisphosphonates, are now the treatment of choice for tumour-induced hypercalcaemia. Recent evidence indicates that these compounds, especially the newer ones, reduce skeletal morbidity in patients with metastatic bone disease and improve their quality of life. Better understanding of the mechanisms underlying tumour-induced bone resorption and development of more potent and less toxic bisphosphonates will lead to improved management of patients with malignant diseases involving the skeleton.     

The expense for one implantation of a banked bone allograft from a cadaveric donor and the issues affecting current advanced medical treatment in the Japanese orthopaedic field

Demand for banked bone allografts is increasing in Japan; however, there are too few bone banks and the bone bank network is not well-established. One reason for this was lack of funding for banks. Bone banks had to bear all material expenses of banked bone allografts themselves because this was not designated a covered expense. In December 2004, the Japanese government started a new “Advanced Medical Treatment” administration system which allowed an approved institution to charge the expense of authorized advanced medical treatments directly to patients. The treatment named “Cryopreserved allogenic bone and ligamentous tissue retrieved from cadaveric donor” was approved as an advanced medical treatment in March 2007. We present the calculation method and the expense per implantation of a banked bone allograft from a cadaveric donor under this treatment and raise issues which affect this advanced medical treatment and remain to be resolved in the Japanese orthopaedic field.     

Zoledronic acid-induced IPP/ApppI production in vivo

Bisphosphonates are currently the most important class of anti-resorptive drugs used for the treatment of diseases involving excess bone resorption. Recently we discovered a new mechanism of action for bisphosphonates. Previously it has been shown that nitrogen-containing bisphosphonates (N-BPs) are not metabolized. However, our studies revealed that N-BPs induce formation of a novel pro-apoptotic ATP analog (ApppI), as a consequence of the inhibition of FPP synthase in the mevalonate pathway, and the subsequent accumulation of isopentenyl pyrophosphate (IPP) in vitro. The primary aim of the current study was to determine whether zoledronic acid (a N-BP) induces IPP/ApppI formation in vivo. Mass spectrometry was used to identify whether in vivo administration of zoledronic acid-induced IPP/ApppI production by mouse peritoneal macrophages or bone marrow cells. IPP/ApppI could be detected in extracts from peritoneal macrophages isolated from zoledronic acid-treated animals. Increasing IPP/ApppI accumulation was determined up to 7 days after drug injection, indicating prolonged FPP synthase inhibition by zoledronic acid. Importantly, this is the first report of in vivo production of ApppI, supporting the biological significance of this molecule.     

骨髓间充质干细胞在大鼠实验中的移植途径及比较

骨髓间充质干细胞是具有自我更新能力和分化潜能的一类成体干细胞,经过局部微环境的诱导,可在体内外进行扩展,到晚期可分化成为多种细胞系。当组织受损伤时,可迅速到达损伤部位,分化为特异的组织细胞,参与组织修复。骨髓间充质干细胞这种惊人的分化及组织修复能力,为治疗退行性疾病和器官损伤性疾病提供广阔前景,故成为科研热点。国内外相关实验研究多以大鼠为动物模型,而骨髓间充质干细胞如何进入大鼠体内并定植,是实验成功的重要前提。因此如何找到最合适、最安全的移植途径将骨髓间充质干细胞有效地移植进入大鼠疾病模型体内的受损区域,是研究者关心的重点。本文就目前骨髓间充质干细胞在大鼠实验中不同移植途径进行综述,并比较各种途径的优缺点,希望能对临床科研工作提供参考,并期待能有更成熟的移植手段来推动骨髓间充质干细胞实验研究的进展。     

Bisphosphonate-Associated Osteomyelitis of the Jaw: Guidelines for Practicing Clinicians

ObjectiveTo evaluate the literature and discuss the risk factors, mechanisms, pathophysiologic aspects, and recommended management of bisphosphonate-associated osteomyelitis of the jaw (BAOMJ).MethodsMore than 350 published articles, case reports mentioning BAOMJ, and independent histology slides from BAOMJ lesions were reviewed critically. The most pertinent publications are cited and discussed.ResultsThe incidence of BAOMJ increases after extraction of teeth, dentoalveolar surgical procedures, or recent oral trauma leading to exposed maxillary or mandibular bone. Contributory factors include poor oral hygiene, oral infections, periodontal disease; recent or ongoing corticosteroid administration or chemotherapy; compromised immune status; diabetes or vascular insufficiency; old age; chronic diseases; and malignancies. On average, 1 of every 100,000 patients treated with bisphosphonates orally for osteoporosis or Paget disease of bone may develop BAOMJ-like lesions. Patients with cancer often receive bisphosphonate doses 10 times or higher, and also more frequently, than those used in patients with osteoporosis or Paget disease of bone. Therefore, greater frequency of administration of bisphosphonates, higher dosages, and prolonged use (that is, for more than 2 years) are likely to be factors triggering BAOMJ.ConclusionThe association of bisphosphonate therapy with BAOMJ is rare in noncancer patients and is likely to be a class effect that may occur with use of any bisphosphonate. Whether patients with cancer require such a high frequency of intravenously administered bisphosphonates needs to be investigated. Following established guidelines can decrease the risks of BAOMJ in vulnerable patients. Rather than necrotic bone, current evidence supports an infectious and perhaps immunologic underlying cause for BAOMJ. The estimated incidence of BAOMJ among noncancer patients receiving bisphosphonates is about 0.001%, whereas among patients with cancer receiving intravenous bisphosphonate therapy the incidence is between 0.5% and 4%, depending on the dose, frequency, and duration of therapy (on average, ~ 2%). Nevertheless, the benefits of bisphosphonates far outweigh the risks. (Endocr Pract. 2008;14:1150-1168)     

Bisphosphonates, specific inhibitors of osteoclast function and a class of drugs for osteoporosis therapy

Osteoporosis is a result of the disruption of bone homeostasis that is carried out by bone-forming osteoblasts and bone-degrading osteoclasts. The most common treatment of osteoporosis is N-containing bisphosphonates, a class of non-hydrolyzable pyrophosphate analogs. They have strong affinity to Ca(2+) of hydroxyapatite with high specificity and can only be liberated from the bone in an acidic environment. These properties bestow them unique pharmacokinetic features including specific and strong retention at bone resorption surface, uptaken specifically by osteoclasts, quick excretion of non-retained free bisphosphonates, long half-life, and recyclability. Such properties underlie the drugs' high efficacy, minor side effects, and intermittent dosing regimens. Further studies show that bisphosphonates inhibit farnesyl pyrophosphate synthase, a critical enzyme required for synthesis of isoprenyl and geranylgeranyl, and inhibit prenylation and geranylgeranylation of small G-proteins such as Rac and Rho. This leads to defective actin ring formation at the sealed zone, a subcellular structure essential for bone resorption, and a decrease in bone resorption. Bisphosphonates are also used to treat Paget's disease of bone, osteolytic bone metastases, and hypercalcemia. Moreover, these properties also make N-BPs a good candidate as a bone-seeking agent. Here we update our understanding of this remarkable class of anti-resorption drugs.     

Synergistic targeting with bone marrow-derived cells and PDGF improves diabetic vascular function

Diabetes mellitus is associated with an increased risk of vascular disease, with significant alterations in systemic endothelial progenitor cells (EPCs) and peripheral vascular function. To identify the contribution of the different vascular compartments in the diabetic impairment of vascularization, we employed streptozotocin- and control-treated 3-mo-old C57Bl/6 mice in an isogeneic pinnal cardiac allograft model, revealing a significant delay in vascularization of wild-type cardiac tissue transplanted into diabetic mice. To investigate the basis of this impairment, the function of diabetic bone marrow cells was tested by transplantation of bone marrow cells isolated from diabetic and control mice into intact, unirradiated 18-mo-old C57Bl/6 mice, which have impaired function of both EPCs and peripheral endothelial cells. Importantly, cells derived from control, but not diabetic, bone marrow integrated into transplanted cardiac allografts. To assess the contribution of diabetic changes in the local vasculature, diabetic mice were treated with pinnal injections of platelet-derived growth factor (PDGF)-AB, which promotes cardiac angiogenesis in wild-type mice. However, whereas PDGF-AB enhanced allograft function in control mice, the activity of the cardiac transplants in the PDGF-AB-treated diabetic mice was significantly decreased. To decipher the potential interactions between systemic bone marrow-derived cells and local vascular pathways, diabetic mice were transplanted with wild-type bone marrow cells with or without PDGF-AB pinnal pretreatment, resulting in improved allograft function and donor cell recruitment only in the combination treatment arm. Overall, these studies show that the diabetic impairment in cardiac angiogenesis can be reversed by targeting the synergism between local trophic pathways and systemic cell function.