Parathyroid hormone and teriparatide for the treatment of osteoporosis: a review of the evidence and suggested guidelines for its use

Extraction and characterization of matrix protein from pacific oyster (Crassostrea gigs) shell and its anti-osteoporosis properties in vitro and in vivo

Matrix protein is a kind of secretory protein that regulates the biomineralization of the bivalve shell. In this study, a water-soluble matrix protein (WSMP) from Pacific oysters (Crassostrea gigs) shell was isolated, and its structure was analyzed in detail, in addition to its anti-osteoporosis activity in vitro and in vivo. Results showed that WSMP was an acidic protein with an apparent molecular mass of 47 and 79 kDa and contained a glycoprotein structure. In vitro, the reduction of Tartrate-resistant acid phosphatase (TRAP) and deoxypyridinoline (DPD) indicated that osteoclast activity was inhibited compared with the model group. Moreover, the increased osteocalcin (OCN) and BMD levels suggested that the high osteoblast activity and bone mineralization was improved. SEM analysis of the femur showed that there were fewer bone pits in experimental groups, which was consistent with the above results. In vivo, WSMP promoted the expression of alkaline phosphatase (ALP) and osteogenic differentiation factor BMP-2 in osteoblasts. In addition, the activity of osteoclasts was inhibited by regulating the process of osteoclast differentiation induced by RANKL. Both in vitro and in vivo studies showed that WSMP could promote osteogenesis and inhibit osteoclast absorption, thus demonstrating their potential applications in osteoporosis.

Exogenous parathyroid hormone attenuates ovariectomy-induced skeletal muscle weakness in vivo

Osteoporosis commonly affects the elderly and is associated with significant morbidity and mortality. Loss of bone mineral density induces muscle atrophy and increases fracture risk. However, muscle lipid content and droplet size are increased by aging and mobility impairments, inversely correlated with muscle function, and a cause of reduced motor function. Teriparatide, the synthetic form of human parathyroid hormone (PTH) 1-34, has been widely used to treat osteoporosis. Although PTH positively affects muscle differentiation in vitro, the precise function and mechanisms of muscle mass and power preservation are still poorly understood, especially in vivo. In this study, we investigated the effect of PTH on skeletal muscle atrophy and dysfunction using an ovariectomized murine model. Eight-week-old female C57BL/6J mice were ovariectomized or sham-operated. Within each surgical group, the mice were divided into PTH injection or control subgroups. Motor function was evaluated based on grip strength, treadmill running, and lactic acid concentration. PTH receptor was expressed in skeletal muscle cells and myoblasts. PTH inhibited ovariectomy-induced bone loss but not uterine atrophy or increased body weight; PTH not only abolished ovariectomy-induced reduction in grip strength and maximum running speed, but also significantly reduced the ovariectomy-induced increase in lactic acid concentration (compared with that observed in the vehicle control). PTH also abrogated the ovariectomy-induced reduction in the oxidative capacity of muscle fibers, their cross-sectional area, and intramyocellular lipid content, and induced cell proliferation, cell migration, and muscle differentiation, while reducing lipid secretion by C2C12 myoblasts via the Wnt/β-catenin pathway. PTH significantly ameliorated muscle weakness and attenuated exercise-induced lactate levels in ovariectomized mice. Our in vitro study demonstrated that PTH/Wnt signaling regulated the proliferation, migration, and differentiation of myoblasts and also reduced lipid secretion in myoblasts. Thus, PTH could regulate several aspects of muscle function and physiology, and may represent a novel therapeutic strategy for patients with osteoporosis.

Once-weekly parathyroid hormone combined with ongoing long-term alendronate treatment promotes osteoporotic fracture healing in ovariectomized rats

This study examined the effect of once-weekly parathyroid hormone (PTH) combined with alendronate upon osteoporotic fracture healing after long-term alendronate anti-osteoporosis therapy. Seventy-six 12-week-old female Sprague-Dawley rats were either sham operated or bilaterally ovariectomized (OVX). Following confirmation of osteoporosis 3 months after OVX, the remaining 64 animals received alendronate therapy. After 3 months of alendronate treatment, all rats underwent unilateral transverse tibial osteotomy. Animals were immediately randomly assigned to one of four groups: (1) alendronate followed by vehicle (ALN-VEH), (2) continuation of alendronate (ALN-ALN), (3) alendronate followed by once-weekly PTH alone (ALN-PTH), (4) continuation of alendronate combined with once-weekly PTH (ALN-ALN + PTH) until collection at 4 or 8 weeks after osteotomy. The fractured tibia was assessed using x-ray, dual-energy x-ray absorptiometry, microcomputed tomography, biomechanical testing, histology, and sequential fluorescence labeling. The ALN-ALN + PTH treatment significantly increased total callus volume, mineralized callus volume, mineralized callus volume/total callus volume, and biomechanical strength of the callus relative to ALN-VEH and ALN-PTH treatments at both 4 and 8 weeks and produced more mature trabecular bone compared with ALN-ALN treatment at 8 weeks. RANKL/osteoprotegerin (OPG) are osteoclastogenesis markers, while cluster of differentiation 31 (CD31) is an important marker of angiogenesis. Qualitative immunohistochemical analysis revealed that CD31 and OPG expression was was strong after ALN-ALN + PTH compared with ALN-ALN treatment, whereas RANKL expression was weak after ALN-ALN + PTH versus ALN-PTH treatment. Our study showed that once-weekly PTH combined with alendronate was beneficial in promoting the healing of fractures acquired after long-term alendronate therapy in OVX-induced osteoporotic rats.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

The Human Gut Microbiota: A Key Mediator of Osteoporosis and Osteogenesis

An expanding body of research asserts that the gut microbiota has a role in bone metabolism and the pathogenesis of osteoporosis. This review considers the human gut microbiota composition and its role in osteoclastogenesis and the bone healing process, specifically in the case of osteoporosis. Although the natural physiologic processes of bone healing and the pathogenesis of osteoporosis and bone disease are now relatively well known, recent literature suggests that a healthy microbiome is tied to bone homeostasis. Nevertheless, the mechanism underlying this connection is still somewhat enigmatic. Based on the literature, a relationship between the microbiome, osteoblasts, osteoclasts, and receptor activator of nuclear factor-kappa-Β ligand (RANKL) is contemplated and explored in this review. Studies have proposed various mechanisms of gut microbiome interaction with osteoclastogenesis and bone health, including micro-RNA, insulin-like growth factor 1, and immune system mediation. However, alterations to the gut microbiome secondary to pharmaceutical and surgical interventions cannot be discounted and are discussed in the context of clinical therapeutic consideration. The literature on probiotics and their mechanisms of action is examined in the context of bone healing. The known and hypothesized interactions of common osteoporosis drugs and the human gut microbiome are examined. Since dysbiosis in the gut microbiota can function as a biomarker of bone metabolic activity, it may also be a pharmacological and nutraceutical (i.e., pre- and probiotics) therapeutic target to promote bone homeostasis.

Dual actions of osteoclastic-inhibition and osteogenic-stimulation through strontium-releasing bioactive nanoscale cement imply biomaterial-enabled osteoporosis therapy

Repair of defective hard-tissues in osteoporotic patients faces significantly challenges with limited therapeutic options. Although biomedical cements are considered promising materials for healthy bone repair, their uses for healing osteoporotic fracture are clinically limited. Herein, strontium-releasing-nanoscale cement was introduced to provide dual therapeutic-actions (pro-osteogenesis and anti-osteoclastogenesis), eventually for the regeneration of osteoporotic bone defect. The Sr-nanocement hardened from the Sr-doped nanoscale-glass particles was shown to release multiple ions including silicate, calcium and strontium at doses therapeutically relevant over time. When the Sr-nanocement was treated to pre-osteoblastic cells, the osteogenic mRNA level (Runx2, Opn, Bsp, Ocn), alkaline phosphatase activity, calcium deposition, and target luciferase reporter were stimulated with respect to the case with Sr-free-nanocement. When treated to pre-osteoclastic cells, the Sr-nanocement substantially reduced the osteoclastogenesis, such as osteoclastic mRNA level (Casr, Nfatc1, c-fos, Acp, Ctsk, Mmp-9), tartrate-resistant acid trap activity, and bone resorption capacity. In particular, the osteoclastic inhibition resulted in part from the interactive effect of osteoblasts which were activated by the Sr-nanocement, i.e., blockage of RANKL (receptor activator of nuclear factor-κB ligand) binding by enhanced osteoprotegerin and the deactivated Nfatc1. The Sr-nanocement, administered to an ovariectomized tibia defect (osteoporotic model) in rats, exhibited profound bone regenerative potential in cortical and surrounding trabecular area, including increased bone volume and density, enhanced production of osteopromotive proteins, and more populated osteoblasts, together with reduced signs of osteoclastic bone resorption. These results demonstrate that Sr-nanocement, with its dual effects of osteoclastic inhibition and osteogenic-stimulation, can be considered an effective nanotherapeutic implantable biomaterial platform for the treatment of osteoporotic bone defects.

Osteoporosis and Spine Surgery: A Critical Analysis Review

Despite being part of the aging process, early and adequate management of osteoporosis mitigates adverse outcomes associated with low bone mineral density. Although the health-care burden of osteoporosis is on the rise, screening and management of osteoporosis are not yet an integral part of preoperative patient evaluation in spine surgery. Patients with osteoporosis should undergo multidisciplinary evaluation and management, including lifestyle modifications and initiation of multiple therapeutic modalities. Integrating osteoporosis in preoperative optimization and surgical planning for patients undergoing spine surgery has the potential to mitigate osteoporosis-related postoperative complications.

T-Cell Mediated Inflammation in Postmenopausal Osteoporosis

Osteoporosis is the most prevalent metabolic bone disease that affects half the women in the sixth and seventh decade of life. Osteoporosis is characterized by uncoupled bone resorption that leads to low bone mass, compromised microarchitecture and structural deterioration that increases the likelihood of fracture with minimal trauma, known as fragility fractures. Several factors contribute to osteoporosis in men and women. In women, menopause - the cessation of ovarian function, is one of the leading causes of primary osteoporosis. Over the past three decades there has been growing appreciation that the adaptive immune system plays a fundamental role in the development of postmenopausal osteoporosis, both in humans and in mouse models. In this review, we highlight recent data on the interactions between T cells and the skeletal system in the context of postmenopausal osteoporosis. Finally, we review recent studies on the interventions to ameliorate osteoporosis.

Austalide K from the Fungus Penicillium rudallense Prevents LPS-Induced Bone Loss in Mice by Inhibiting Osteoclast Differentiation and Promoting Osteoblast Differentiation

Osteoporosis is a chronic disease that has become a serious public health problem due to the associated reduction in quality of life and its increasing financial burden. It is known that inhibiting osteoclast differentiation and promoting osteoblast formation prevents osteoporosis. As there is no drug with this dual activity without clinical side effects, new alternatives are needed. Here, we demonstrate that austalide K, isolated from the marine fungus Penicillium rudallenes, has dual activities in bone remodeling. Austalide K inhibits the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and improves bone morphogenetic protein (BMP)-2-mediated osteoblast differentiation in vitro without cytotoxicity. The nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK) osteoclast-formation-related genes were reduced and alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and osteopontin (OPN) (osteoblast activation-related genes) were simultaneously upregulated by treatment with austalide K. Furthermore, austalide K showed good efficacy in an LPS-induced bone loss in vivo model. Bone volume, trabecular separation, trabecular thickness, and bone mineral density were recovered by austalide K. On the basis of these results, austalide K may lead to new drug treatments for bone diseases such as osteoporosis.

Recent development of drugs for osteoporosis and anti-cancer agents: a patent analysis

Osteoporosis and cancer are becoming a major public health problem. Some studies have shown that osteoporosis drugs may have anti-cancer effects. To better understand the relationship between drugs for osteoporosis and antineoplastic agents, and to better demonstrate recent developments for patents concerning drugs for osteoporosis, we conducted an analysis of US patents. The results indicated that there was a good correlation between agents for osteoporosis and antineoplastic agents, which indicated that numerous anti-osteoporosis agents displayed antineoplastic activities. Our study was the first one to provide new evidence, through comprehensive analysis, for a correlation between anti-osteoporosis agents and anticancer agents. The present study may open new avenues for developing anticancer drugs and expanding the application role of anti-osteoporosis agents.

Role of bone-forming agents in the management of osteoporosis

Recent evidence confirms the superiority of osteoanabolic therapy compared to anti-remodeling drugs for rapid improvement in bone density and fracture risk reduction, providing strong justification for the use of these anabolic agents as the initial therapy in high-risk patients, to be followed by anti-remodeling therapy. This review will highlight the results of recent studies and define the current status of osteoanabolic therapy for osteoporosis.

Osteogenic effect of low-intensity pulsed ultrasound and whole-body vibration on peri-implant bone. An experimental in vivo study

OBJECTIVES

The aims of this study were (i) to compare the osteogenic impact of low-intensity pulsed ultrasound (LIPUS) and low-magnitude high-frequency (LMHF) loading achieved with whole-body vibration (WBV) on peri-implant bone healing and implant osseointegration in rat tibiae, and (ii) to examine their combined effect on these processes.

MATERIAL AND METHODS

Titanium implants were inserted in the bilateral tibiae of 28 Wistar rats. Rats were randomly divided into four groups: LIPUS + WBV, LIPUS, WBV, and control. LIPUS was applied to the implant placement site for 20 min/day on 5 days/week (1.5 MHz and 30 mW/cm² ). WBV was applied for 15 min/day on 5 days/week (50 Hz and 0.5 g). In the LIPUS + WBV group, both stimuli were applied under the same stimulation conditions as in the LIPUS and WBV groups. After 4 weeks of treatment, peri-implant bone healing and implant osseointegration were assessed using removal torque (RT) tests, micro-CT analyses of relative gray (RG) value, and histomorphometrical analyses of bone-to-implant contact (BIC) and peri-implant bone formation (BV/TV).

RESULTS

The LIPUS + WBV group had significantly greater BIC than the WBV and control groups. Although there were no significant intergroup differences in RT, RG value, and BV/TV, these variables tended to be greater in the LIPUS + WBV group than the other groups.

CONCLUSIONS

The combination of LIPUS and LMHF loading may promote osteogenic activity around the implant. However, further study of the stimulation conditions of LIPUS and LMHF loading is necessary to better understand the osteogenic effects and the relationship between the two stimuli.

The awareness and practice of dentists regarding medication-related osteonecrosis of the jaw and its prevention: a cross-sectional survey

Background

Accurate documentation of a patient’s prior medication use and awareness of side effects associated with anti-osteoporotic agents can assist dentists to prevent medication-related osteonecrosis of the jaw. I aimed to determine the awareness of Korean dentists regarding medication-related osteonecrosis of the jaw and the duration of drug holidays they prescribe to patients who need to undergo various dental procedures.

Methods

An online, questionnaire-based survey was conducted among 1000 dentists registered in an online community in Korea. The following were determined: general characteristics; type of practice; recordkeeping regarding patients’ use of bone-modifying agents; requirement of a doctor’s referral letter; advice given regarding drug holidays of bone-modifying agents before dental surgery procedures; and experience with medication-related osteonecrosis of the jaw. Differences between dentists with and without experience in treating patients with medication-related osteonecrosis of the jaw were evaluated using the χ² test.

Results

Although a relatively high proportion (293/1000, 29.3%) of dentists had experienced cases of medication-related osteonecrosis of the jaw, only 650/1000 (65.0%) routinely documented the type of bone-modifying agent used by patients and the duration of its use. Moreover, only 591/1000 (59.1%) dentists routinely requested referral letters from doctors before performing dental surgery on patients. Although the recommended period for a drug holiday differs for each drug, 533/1000 (53.3%) dentists did not make such a distinction. There was a statistically significant difference in the level of detail documented in terms of anti-osteoporotic drug use between dentists who had no experience in medication-related osteonecrosis of the jaw (707/1000) and those who had such experience (P = 0.007). There was a statistically significant difference in the length of drug holidays prescribed between dentists with and without prior experience with the condition (P = 0.001).

Conclusions

These results suggest that dentists do not respond consistently to patients' drug history prior to performing dental procedures. This implies the need for increased cooperation between dentists and physicians, as well as the development of targeted educational interventions for the dental profession, to reduce the risk of medication-related osteonecrosis of the jaw.

Trial registration

Not applicable.

Supplementary information

The online version contains supplementary material available at 10.1186/s12903-021-01475-6.

Present and future scope of recombinant parathyroid hormone therapy in orthopaedics

Parathyroid Hormone (PTH) has a significant role in calcium metabolism. Its intermittent administration has an anabolic effect on bone mineralization. Teriparatide (PTH 1-34), a recombinant form of parathyroid hormone, is useful in the treatment of osteoporosis, fracture healing, non-union, stress fracture, augmentation of implant fixation with bone, and chondroprotection in osteoarthritis. The present review article will elaborate on the potential approved uses of recombinant PTH in orthopedics and its evolving role in the management of fracture osteosynthesis and other common challenging bone pathologies.

Combination Therapy of PTH and Antiresorptive Drugs on Osteoporosis: A Review of Treatment Alternatives

Antiresorptive drugs have been widely used for osteoporosis. Intermittent parathyroid hormone (PTH), an anabolic agent, increases osteoblast production rate and inhibits apoptosis of osteoblasts, thus increasing skeletal mass besides improving bone microarchitecture and strength. Combination therapy for osteoporosis produced great interests and controversies. Therefore, we performed a systematic literature search from PubMed, EMBASE, Scopus, Web of Science, CINDHL, and the Cochrane Database of Systematic Reviews using the search terms PTH or teriparatide combined with bisphosphonate, alendronate, ibandronate, risedronate, raloxifene, denosumab, and zoledronic acid with the limit osteoporosis. At last, 36 related articles were included for further analysis. Findings from previous studies revealed that combination therapy in different conditions of naive or previous bisphosphonate treatment might have different outcomes. The use of combination therapy, however, may be an alternative option among osteoporotic patients with a history of bisphosphonate use. Combined teriparatide with denosumab appear to show the most substantial and clinically relevant skeletal benefits to osteoporotic patients. Additional research is necessary to define optimal methods of developing sequential and/or cyclical combinations of PTH and antiresorptive agents.

Purinergic Signaling Mediates PTH and Fluid Flow-Induced Osteoblast Proliferation

Both parathyroid hormone (PTH) and mechanical signals are able to regulate bone growth and regeneration. They also can work synergistically to regulate osteoblast proliferation, but little is known about the mechanisms how PTH and mechanical signals interact with each other during this process. In this study, we investigated responses of MC3T3-E1 osteoblasts to PTH and oscillatory fluid flow. We found that osteoblasts are more sensitive to mechanical signals in the presence of PTH according to ERK1/2 phosphorylation, ATP release, CREB phosphorylation, and cell proliferation. PTH may also reduce the osteoblast refractory period after desensitization due to mechanical signals. We further found that the synergistic responses of osteoblasts to fluid flow or ATP with PTH had similar patterns, suggesting that synergy between fluid flow and PTH may be through the ATP pathway. After we inhibited ATP effects using apyrase in osteoblasts, their synergistic responses to mechanical stimulation and PTH were also inhibited. Additionally, knocking down P2Y2 purinergic receptors can significantly attenuate osteoblast synergistic responses to mechanical stimulation and PTH in terms of ERK1/2 phosphorylation, CREB phosphorylation, and cell proliferation. Thus, our results suggest that PTH enhances mechanosensitivity of osteoblasts via a mechanism involving ATP and P2Y2 purinergic receptors.

Osteoporosis increases the likelihood of revision surgery following a long spinal fusion for adult spinal deformity

BACKGROUND

Adult spinal deformity (ASD) can be a debilitating condition that requires surgical intervention. ASD patients often present with osteoporosis, predisposing them to increased rates of instrumentation failure and postoperative fractures, frequent reasons for revision surgery. We hypothesized that the rate and timing of revision surgery are different in osteoporotic and nonosteoporotic patients undergoing long fusions for ASD. To our knowledge, the timing of revision surgeries, in particular, have not previously been explored.

PURPOSE

To determine the rate and timing of revision surgery in osteoporotic and nonosteoporotic patients following a long fusion for ASD.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

ASD patients who underwent a long spinal fusion surgery at two large academic medical centers from 2010 to 2019.

OUTCOME MEASURES

Occurrence of revision surgery.

METHODS

Inclusion criteria were patient age of least 40 years and spinal fusion spanning at least seven levels for ASD. Patient records were reviewed for a diagnosis of osteoporosis as per ICD codes and revision surgery within 2 years of the index procedure. Revision surgery was defined as an unplanned procedure related to the index surgery for the treatment of a spine-related complication. Chi-squared tests comparing demographic data, revision rates, and multiple revisions were conducted. The incidence and prevalence of revision surgeries as a function of time and osteoporotic status were evaluated for significant differences via the Mann-Whitney U and Mantel-Haenszel log rank tests. Finally, a logistic regression analysis was utilized to determine the predictive value of osteoporosis, age, and gender on the likelihood for complications.

RESULTS

Three hundred ninety-nine patients matched the study criteria. In the osteoporotic group, 40.5% of patients underwent a revision surgery compared to 28.0% in the nonosteoporotic group (p=.01). The occurrence of multiple revision surgeries following the index procedure was similar in both groups: 8.4% in osteoporotic patients and 8.6% in nonosteoporotic patients. Age and gender were not statistically correlated with the incidence of revision surgery.

CONCLUSIONS

ASD patients with osteoporosis have an increased risk of undergoing revision for a surgery-related complication within 2 years of the index procedure. These complications included failure of hardware, pseudoarthrosis, proximal junction failure, and infection, among other issues that required surgical intervention. As others have also highlighted the importance of poor bone density on construct failure, our data further underscore the importance of preoperative osteoporosis surveillance. Though intuitive, further study is needed to demonstrate that improving patients' bone density can decrease the incidence of related complications and the need or revision surgery.

Molecular Signaling Pathways and Essential Metabolic Elements in Bone Remodeling: An Implication of Therapeutic Targets for Bone Diseases

Bone is one of the dynamic tissues in the human body that undergoes continuous remodelling through subsequent actions of bone cells, osteoclasts, and osteoblasts. Several signal transduction pathways are involved in the transition of mesenchymal stem cells into osteoblasts. These primarily include Runx2, ATF4, Wnt signaling and sympathetic signalling. The differentiation of osteoclasts is controlled by M-CSF, RANKL, and costimulatory signalling. It is well known that bone remodelling is regulated through receptor activator of nuclear factor-kappa B ligand followed by binding to RANK, which eventually induces the differentiation of osteoclasts. The resorbing osteoclasts secrete TRAP, cathepsin K, MMP-9 and gelatinase to digest the proteinaceous matrix of type I collagen and form a saucer-shaped lacuna along with resorption tunnels in the trabecular bone. Osteoblasts secrete a soluble decoy receptor, osteoprotegerin that prevents the binding of RANK/RANKL and thus moderating osteoclastogenesis. Moreover, bone homeostasis is also regulated by several growth factors like, cytokines, calciotropic hormones, parathyroid hormone and sex steroids. The current review presents a correlation of the probable molecular targets underlying the regulation of bone mass and the role of essential metabolic elements in bone remodelling. Targeting these signaling pathways may help to design newer therapies for treating bone diseases.

Deep Learning With Electronic Health Records for Short-Term Fracture Risk Identification: Crystal Bone Algorithm Development and Validation

Background

Fractures as a result of osteoporosis and low bone mass are common and give rise to significant clinical, personal, and economic burden. Even after a fracture occurs, high fracture risk remains widely underdiagnosed and undertreated. Common fracture risk assessment tools utilize a subset of clinical risk factors for prediction, and often require manual data entry. Furthermore, these tools predict risk over the long term and do not explicitly provide short-term risk estimates necessary to identify patients likely to experience a fracture in the next 1-2 years.

Objective

The goal of this study was to develop and evaluate an algorithm for the identification of patients at risk of fracture in a subsequent 1- to 2-year period. In order to address the aforementioned limitations of current prediction tools, this approach focused on a short-term timeframe, automated data entry, and the use of longitudinal data to inform the predictions.

Methods

Using retrospective electronic health record data from over 1,000,000 patients, we developed Crystal Bone, an algorithm that applies machine learning techniques from natural language processing to the temporal nature of patient histories to generate short-term fracture risk predictions. Similar to how language models predict the next word in a given sentence or the topic of a document, Crystal Bone predicts whether a patient’s future trajectory might contain a fracture event, or whether the signature of the patient’s journey is similar to that of a typical future fracture patient. A holdout set with 192,590 patients was used to validate accuracy. Experimental baseline models and human-level performance were used for comparison.

Results

The model accurately predicted 1- to 2-year fracture risk for patients aged over 50 years (area under the receiver operating characteristics curve [AUROC] 0.81). These algorithms outperformed the experimental baselines (AUROC 0.67) and showed meaningful improvements when compared to retrospective approximation of human-level performance by correctly identifying 9649 of 13,765 (70%) at-risk patients who did not receive any preventative bone-health-related medical interventions from their physicians.

Conclusions

These findings indicate that it is possible to use a patient’s unique medical history as it changes over time to predict the risk of short-term fracture. Validating and applying such a tool within the health care system could enable automated and widespread prediction of this risk and may help with identification of patients at very high risk of fracture.

Osteoporosis in Patients with Chronic Kidney Diseases: A Systemic Review

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. Among CKD patients, adynamic bone disease or low bone turnover is the most common type of renal osteodystrophy. The consequences of CKD-MBD include increased fracture risk, greater morbidity, and mortality. Thus, the goal is to prevent the occurrences of fractures by means of alleviating CKD-induced MBD and treating subsequent osteoporosis. Changes in mineral and humoral metabolism as well as bone structure develop early in the course of CKD. CKD-MBD includes abnormalities of calcium, phosphorus, PTH, and/or vitamin D; abnormalities in bone turnover, mineralization, volume, linear growth, or strength; and/or vascular or other soft tissue calcification. In patients with CKD-MBD, using either DXA or FRAX to screen fracture risk should be considered. Biomarkers such as bALP and iPTH may assist to assess bone turnover. Before initiating an antiresorptive or anabolic agent to treat osteoporosis in CKD patients, lifestyle modifications, such as exercise, calcium, and vitamin D supplementation, smoking cessation, and avoidance of excessive alcohol intake are important. Managing hyperphosphatemia and SHPT are also crucial. Understanding the complex pathogenesis of CKD-MBD is crucial in improving one's short- and long-term outcomes. Treatment strategies for CKD-associated osteoporosis should be patient-centered to determine the type of renal osteodystrophy. This review focuses on the mechanism, evaluation and management of patients with CKD-MBD. However, further studies are needed to explore more details regarding the underlying pathophysiology and to assess the safety and efficacy of agents for treating CKD-MBD.

The impact of thiazide diuretics on bone mineral density and the trabecular bone score: the Rotterdam Study

The decreased risk of osteoporotic fractures in thiazide diuretics (TD) users is possibly not only caused by an increase in bone mineral density (BMD), but by an increase in other determinants of bone strength as well, such as the trabecular bone score (TBS). To test this hypothesis, we studied the association between TD use and both lumbar spine BMD (LS-BMD) and lumbar spine TBS (LS-TBS) cross-sectionally in 6096 participants from the Rotterdam Study, as well as the association between TD use and bone turnover estimated by serum osteocalcin levels. We found that past and current use of TD were associated with an increase of LS-BMD (β = 0.021 g/cm² (95% CI: 0.006;0.036) and β = 0.016 g/cm² (95% CI: 0.002;0.031), respectively). Use of ≥1 defined daily dose (DDD) (β = 0.028, 95% CI: 0.010;0.046; p for trend within DDD of use <0.001) and use of >365 days (β = 0.033, 95% CI: 0.014;0.052; p for trend within duration of use <0.001) were positively associated with LS-BMD. No significant association between TD use and LS-TBS was observed. Mean serum osteocalcin levels were significantly different between users and non-users of TD (20.2 ng/ml (SD 8.3) and 22.5 ng/ml (SD 17.0), respectively, p < 0.001). Furthermore, linear regression analysis showed that the use of TD was associated with a 3.2 ng/l (95% CI: -4.4.; -2.0) lower serum osteocalcin level compared to non-use of TD, when adjusted for Rotterdam Study cohort, age, and sex. Our results may implicate that the decreased fracture risk in TD users is explained by increased bone mass rather than by improved bone microarchitecture. Alternatively, changes in bone microarchitecture might not be detected through TBS and more sophisticated techniques are possibly needed to study a potential effect of TD on bone microarchitecture.

Optimising the management of osteoporosis

With increasing longevity of the population globally, the prevalence of osteoporosis will rise, associated with significant morbidity, disability and increased mortality. Adequate intake of calcium, vitamin D, increasing physical activity, a strategy of avoiding falls, cessation of smoking and avoiding excessive alcohol intake are pivotal in maintaining healthy bones in all age groups. Oral bisphosphonates remain the most cost-effective first line of treatment. Better methods of identifying patients with high fracture risk is needed as there is adequate effective treatment for osteoporosis.

Effects of teriparatide and bisphosphonate on spinal fusion procedure: A systematic review and network meta-analysis

Background

Giving patients anti-osteoporotic agents peri-operatively is a well-accepted strategy to increase fusion rate and prevent complications. The purpose of this study was to investigate effectiveness of teriparatide and bisphosphonate on fusion surgery of thoracic and lumbar spine.

Methods

We searched EMBASE and PubMed for randomized clinical trials (RCTs) and prospective comparative studies using teriparatide or bisphosphonate in peri-operative spinal fusion surgery. Our synthesized data of fusion rate, Oswestry disability index (ODI), and adverse event in contrast-based network meta-analysis. Pooled results were presented in risk ratio (RR) or mean difference (MD) with 95% confidence interval (CI).

Results

Our search hit eight RCTs and three prospective studies with 676 patients receiving spinal surgery. Pooled result showed that teriparatide+Denosumab leads to significantly higher fusion rate than placebo (RR, 2.84; 95% CI: 1.22 to 6.60) and bisphosphonate (RR, 2.59; 95% CI: 1.13 to 5.96). We did not observe significant finding among placebo, teriparatide, and bisphosphonate in the two network models.

Conclusion

This is the first network meta-analysis providing an overview of the use of teriparatide and bisphosphonate for spinal fusion surgery. Teriparatide treatments are worth to be consider for spinal fusion surgery.

Bisphosphonates and parathyroid hormone analogs for improving bone quality in spinal fusion: State of evidence

Spinal fusion is among the most commonly performed surgical procedures for elderly patients with spinal disorders - including degenerative disc disease with spondylolisthesis, deformities, and trauma. With the large increase in the aging population and the prevalence of osteoporosis, the number of elderly osteoporotic patients needing spinal fusion has risen dramatically. Due to reduced bone quality, postoperative complications such as implant failures, fractures, post-junctional kyphosis, and pseudarthrosis are more commonly seen after spinal fusion in osteoporotic patients. Therefore, pharmacologic treatment strategies to improve bone quality are commonly pursued in osteoporotic cases before conducting spinal fusions. The two most commonly used pharmacotherapeutics are bisphosphonates and parathyroid hormone (PTH) analogs. Evidence indicates that using bisphosphonates and PTH analogs, alone or in combination, in osteoporotic patients undergoing spinal fusion, decreases complication rates and improves clinical outcomes. Further studies are needed to develop guidelines for the administration of bisphosphonates and PTH analogs in osteoporotic spinal fusion patients in terms of treatment duration, potential benefits of sequential use, and the selection of either therapeutic agents based on patient characteristics.

Teriparatide (recombinant parathyroid hormone 1-34) enhances bone allograft integration in a clinically relevant pig model of segmental mandibulectomy

Massive craniofacial bone loss poses a clinical challenge to maxillofacial surgeons. Structural bone allografts are readily available at tissue banks but are rarely used due to a high failure rate. Previous studies showed that intermittent administration of recombinant parathyroid hormone (rPTH) enhanced integration of allografts in a murine model of calvarial bone defect. To evaluate its translational potential, the hypothesis that rPTH would enhance healing of a mandibular allograft in a clinically relevant large animal model of mandibulectomy was tested. Porcine bone allografts were implanted into a 5-cm-long continuous mandible bone defect in six adult Yucatan minipigs, which were randomized to daily intramuscular injections of rPTH (1.75 μg/kg) and placebo (n = 3). Blood tests were performed on Day 56 preoperation, Day 0 and on Day 56 postoperation. Eight weeks after the surgery, bone healing was analyzed using high-resolution X-ray imaging (Faxitron and micro computed tomography [CT]) and three-point bending biomechanical testing. The results showed a significant 2.6-fold rPTH-induced increase in bone formation (p = 0.02). Biomechanically, the yield failure properties of the healed mandibles were significantly higher in the rPTH group (yield load: p < 0.05; energy to yield: p < 0.01), and the post-yield displacement and energy were higher in the placebo group (p < 0.05), suggesting increased mineralized integration of the allograft in the rPTH group. In contrast to similar rPTH therapy studies in dogs, no signs of hypercalcemia, hyperphosphatemia, or inflammation were detected. Taken together, we provide initial evidence that rPTH treatment enhances mandibular allograft healing in a clinically relevant large animal model.

Disruption of the aldehyde dehydrogenase 2 gene increases the bone anabolic response to intermittent PTH treatment in an ovariectomized mouse model

Aldehyde dehydrogenase 2 (ALDH2) is the enzyme that oxidizes the acetaldehyde produced by alcohol metabolism. This variant not only affects the response to alcohol but is also associated with several diseases, such as esophageal cancer, myocardial infarction, and particularly osteoporosis. In our previous study, we reported that compared to wild-type (WT) mice, Aldh2 knockout (KO) mice naturally have a strong bone formation ability, and high expression of parathyroid hormone receptor (PTHR1) in osteocytes. The effect of the Aldh2 gene on bone metabolism in response to intermittent PTH treatment is unknown. The purpose of this study was to clarify the effect of the Aldh2 gene on the bone anabolic response to intermittent PTH treatment in ovariectomized mice. Female KO and WT mice were ovariectomized at 8 weeks of age. At 14 weeks of age, the KO and WT mice were divided into vehicle-treated (Veh) and PTH-treated (PTH) groups (i.e., the WT-Veh, WT-PTH, KO-Veh and KO-PTH groups). PTH (1-34) and vehicle were subcutaneously administered to each group at a dose of 40 μg/kg body weight (BW) five times per week for 4 weeks. Micro-CT showed that the bone volume (BV), trabecular number (Tb.N), connectivity density (Conn.D), and cortical thickness (Ct.Th) values in the KO-PTH mice were significantly higher than those in the KO-Veh mice. Histomorphometric analysis showed that the BV, Tb.N, and mineral apposition rate (MAR) values in the KO-PTH group were significantly higher than those in the KO-Veh group. The mRNA expression level of PTHR1 in the KO-PTH group was significantly increased and that of p21 in the KO-PTH group was significantly decreased compared with the levels in the KO-Veh group. The expression of PTHR in osteocytes from the KO-PTH group was also significantly increased compared with that in osteocytes from the KO-Veh group. Furthermore, cell cultures revealed that the ALP⁺CFU-f/total CFU-f percentage was significantly higher in the KO-PTH group than in the KO-Veh group. We concluded that in ovariectomized Aldh2 KO mice, the bone anabolic response to intermittent PTH treatment was significantly enhanced compared to that in WT mice, which may be mediated by the high expression level of PTHR1.

Pharmacologic considerations in patients with osteoporosis undergoing lumbar interbody fusion: A systematic review

OBJECTIVE

As the ageing population continues to grow, the incidence of osteoporosis continues to rise. Patients with osteoporosis are often managed pharmacologically. It is unclear the impact of these medications on osteoporotic patients requiring lumbar interbody fusion, and whether differences exist with respect to patient outcomes among the different medication classes that are often employed. In this systematic review, the authors examine studies evaluating the impact of pharmacologic therapy on osteoporotic patients undergoing lumbar interbody fusion.

METHODS

Using PubMed and MEDLINE databases, the authors conducted a systematic literature review for studies published between 1986 and 2020 following PRISMA guidelines.

RESULTS

A total of 12 articles were ultimately selected. Studies assessing bisphosphonate usage, parathyroid hormone analogues, vitamin D, or combination therapies and their impact on lumbar interbody fusion were included.

CONCLUSIONS

The evidence regarding bisphosphonate therapy and improved fusion rates with reduced incidence of complications is inconsistent. While some studies suggest bisphosphonates to confer added benefit, other studies suggest no such improvements despite reduction in bone turnover biomarkers. Teriparatide, on the other hand, consistently demonstrated improved fusion rates and may reduce screw loosening events. In comparison studies against bisphosphonates, teriparatide demonstrates greater potential. A single study reported vitamin D3 to increase fusion rates, although more studies are needed to validate this finding. It is important to note that these benefits are only demonstrated in single-level fusion, with multi-level fusions not being significantly enhanced by teriparatide therapy. Combination therapy with denosumab further augment fusion rates. Further prospective randomized controlled trials are necessary before standardized recommendations regarding pharmacological intervention in patients undergoing LIF can be made.

Systemic Parathyroid Hormone Enhances Fracture Healing in Multiple Murine Models of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a multisystemic disease that afflicts more than 415 million people globally-the incidence and prevalence of T2DM continues to rise. It is well-known that T2DM has detrimental effects on bone quality that increase skeletal fragility, which predisposes subjects to an increased risk of fracture and fracture healing that results in non- or malunion. Diabetics have been found to have perturbations in metabolism, hormone production, and calcium homeostasis-particularly PTH expression-that contribute to the increased risk of fracture and decreased fracture healing. Given the perturbations in PTH expression and the establishment of hPTH (1-34) for use in age-related osteoporosis, it was determined logical to attempt to ameliorate the bone phenotype found in T2DM using hPTH (1-34). Therefore, the present study had two aims: (i) to establish a suitable murine model of the skeletal fragility present in T2DM because no current consensus model exists; and (ii) to determine the effects of hPTH (1-34) on bone fractures in T2DM. The results of the present study suggest that the polygenic mouse of T2DM, TALLYHO/JngJ, most accurately recapitulates the diabetic osteoporotic phenotype seen in humans and that the intermittent systemic administration of hPTH (1-34) increases fracture healing in T2DM murine models by increasing the proliferation of mesenchymal stem cells. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Standardized Histomorphometric Evaluation of Osteoarthritis in a Surgical Mouse Model

One of the most prevalent joint disorders in the United States, osteoarthritis (OA) is characterized by progressive degeneration of articular cartilage, primarily in the hip and knee joints, which results in significant impacts on patient mobility and quality of life. To date, there are no existing curative therapies for OA able to slow down or inhibit cartilage degeneration. Presently, there is an extensive body of ongoing research to understand OA pathology and discover novel therapeutic approaches or agents that can efficiently slow down, stop, or even reverse OA. Thus, it is crucial to have a quantitative and reproducible approach to accurately evaluate OA-associated pathological changes in the joint cartilage, synovium, and subchondral bone. Currently, OA severity and progression are primarily assessed using the Osteoarthritis Research Society International (OARSI) or Mankin scoring systems. In spite of the importance of these scoring systems, they are semiquantitative and can be influenced by user subjectivity. More importantly, they fail to accurately evaluate subtle, yet important, changes in the cartilage during the early disease states or early treatment phases. The protocol we describe here uses a computerized and semiautomated histomorphometric software system to establish a standardized, rigorous, and reproducible quantitative methodology for the evaluation of joint changes in OA. This protocol presents a powerful addition to the existing systems and allows for more efficient detection of pathological changes in the joint.

Synthesis and biological activities of drugs for the treatment of osteoporosis

Osteoporosis is an asymptomatic progressive disease. With the improvement of people's living standard and the aging of population, osteoporosis and its fracture have become one of the main diseases threatening the aging society. The serious medical and social burden caused by this has aroused wide public concern. Osteoporosis is listed as one of the three major diseases of the elderly. At present, the drugs for osteoporosis include bone resorption inhibitors and bone formation promoters. The purpose of these anti-osteoporosis drugs is to balance osteoblast bone formation and osteoclast bone resorption. With the development of anti-osteoporosis drugs, new anti osteoporosis drugs have been designed and synthesized. There are many kinds of new compounds with anti osteoporosis activity, but most of them are concentrated on the original drugs with anti osteoporosis activity, or the natural products with anti-osteoporosis activity are extracted from the natural products for structural modification to obtain the corresponding derivatives or analogues. These target compounds showed good ALP activity in vitro and in vivo, promoted osteoblast differentiation and mineralization, or had anti TRAP activity, inhibited osteoclast absorption. This work attempts to systematically review the studies on the synthesis and bioactivity of anti-osteoporosis drugs in the past 10 years. The structure-activity relationship was discussed, which provided a reasonable idea for the design and development of new anti-osteoporosis drugs.

Sweroside promotes osteoblastic differentiation and mineralization via interaction of membrane estrogen receptor-α and GPR30 mediated p38 signalling pathway on MC3T3-E1 cells

BACKGROUND

Dipsaci Radix has been clinically used for thousands of years in China for strengthening muscles and bones. Sweroside is the major active iridoid glycoside isolated from Dipsaci Radix. It has been reported that sweroside can promote alkaline phosphatase (ALP) activity in both the human osteosarcoma cell line MG-63 and rat osteoblasts. However, the underlying mechanism involved in these osteoblastic processes is poorly understood.

PURPOSE

This study aimed to characterize the bone protective effects of sweroside and to investigate the signaling pathway that is involved in its actions in MC3T3-E1 cells.

METHODS

Cell proliferation, differentiation and mineralization were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, ALP test and Alizarin Red S staining, respectively. The concentration of sweroside in intracellular and extracellular fluids was determined by ultra-performance liquid chromatography coupled to triple quadrupole xevo-mass spectrometry (UPLC/TQ-XS-MS). Proteins associated with the osteoblastic signaling pathway were analysed by western blot and immunofluorescence methods.

RESULTS

Sweroside did not obviously affect the proliferation but significantly promoted the ALP activity and mineralization of MC3T3-E1 cells. The maximal absorption amount 0.465 ng/ml (1.3 × 10^-9 M) of sweroside was extremely lower than the tested concentration of 358.340 ng/ml (10^-6 M), indicating an extremely low absorption rate by MC3T3-E1 cells. Moreover, the ALP activity, the protein expression of ER-α and G protein-coupled receptor 30 (GPR30) induced by sweroside were markedly blocked by both the ER antagonist ICI 182780 and the GPR30 antagonist G15. In addition, sweroside also activated the phosphorylation of p38 kinase (p-p38), while the phosphorylation effects together with ALP and mineralization activities were completely blocked by a p38 antagonist, SB203580. Additionally, the phosphorylation of p38 induced by sweroside were markedly blocked by both the ER antagonist ICI 182780 and the GPR30 antagonist G15.

CONCLUSIONS

The present study indicated that sweroside, as a potential agent in treatment of osteoporosis, might exert beneficial effects on MC3T3-E1 cells by interaction with the membrane estrogen receptor-α and GPR30 that then activates the p38 signaling pathway. This is the first study to report the specific mechanism of the effects of sweroside on osteoblastic differentiation and mineralization of MC3T3-E1 cells.

Osteoporosis and the Potential of Cell-Based Therapeutic Strategies

Osteoporosis, the most common chronic metabolic bone disease, is characterized by low bone mass and increased bone fragility. Nowadays more than 200 million individuals are suffering from osteoporosis and still the number of affected people is dramatically increasing due to an aging population and longer life, representing a major public health problem. Current osteoporosis treatments are mainly designed to decrease bone resorption, presenting serious adverse effects that limit their safety for long-term use. Numerous studies with mesenchymal stem cells (MSCs) have helped to increase the knowledge regarding the mechanisms that underlie the progression of osteoporosis. Emerging clinical and molecular evidence suggests that inflammation exerts a significant influence on bone turnover, thereby on osteoporosis. In this regard, MSCs have proven to possess broad immunoregulatory capabilities, modulating both adaptive and innate immunity. Here, we will discuss the role that MSCs play in the etiopathology of osteoporosis and their potential use for the treatment of this disease.

Teriparatide may accelerate the growth of a pre-existing malignant tumor in an elderly patient with osteoporosis: A case report

The present report describes a case in which teriparatide, which is widely used to treat osteoporosis, may have accelerated the growth of an undiagnosed pre-existing bone tumor of the femur. A 76-year-old woman visited hospital with pain in the right thigh after falling from a ladder. A non-pathological femoral shaft fracture was diagnosed by plain radiography. There were no findings of pathological fracture on the examination. In addition, the patient underwent intramedullary femoral nail fixation and started teriparatide treatment for osteoporosis. The teriparatide was discontinued after 2 months due to nausea. A total of 6 months after surgery, the woman visited Hirosaki University Hospital with abnormal swelling of the right thigh. Following a diagnosis of high-grade malignant mesenchymal bone tumor by needle biopsy, the patient underwent right hip disarticulation. Pathological examination provided a definitive diagnosis of osteoblastic osteosarcoma. The present case is a reminder that teriparatide may accelerate the growth of a pre-existing malignant tumor and that fractures, particularly in elderly patients, should be screened for pathological fracture prior to administering teriparatide.

Effects of teriparatide compared with risedronate in the treatment of osteoporosis: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis was conducted to compare the effects and safety of teriparatide with risedronate in the treatment of osteoporosis.

MATERIAL AND METHODS

PubMed, Embase, Web of Science and Cochrane library database were systematically reviewed for studies published up to February 24, 2019. Eligible studies that compared the effects of teriparatide with risedronate in osteoporosis were included in this meta-analysis. The outcomes included percentage change in bone mineral density (BMD) of lumbar spine, femoral neck, and total hip, the incidence of clinical fractures, serum bone markers, and adverse events. A random-effects or fixed-effects model was used to pool the estimate, according to the heterogeneity among the included studies.

RESULTS

Seven studies were included in this meta-analysis. Compared with risedronate, teriparatide was associated with a significant increase in lumbar spine BMD [weight mean difference (WMD)=4.24, 95%CI: 3.11, 5.36; P < .001], femoral neck BMD (WMD=2.28, 95%CI: 1.39, 3.18; P < .001), and total hip BMD (WMD = 1.19, 95%CI: 0.47, 1.91; P = .001). Moreover, patients in teriparatide group had significantly lower incidences of clinical fracture (risk ratio [RR] = 0.48, 95%CI: 0.32, 0.72; P < .001), new vertebral fracture (RR = 0.45, 95%CI: 0.32, 0.63; P < .001), and non-vertebral fracture (RR = 0.63, 95%CI: 0.40, 0.98; P = .042) than those in risedronate group. There were significant differences between the 2 groups in serum change, including P1NP (WMD = 122.34, 95%CI: 68.89, 175.99; P < .001), CTx (WMD = 0.62, 95%CI: 0.29, 0.96; P < .001), and iPTH (WMD = -13.18, 95%CI: -15.04, -11.33; P < .001). The incidence of adverse events was similar between the 2 groups (RR = 0.93, 95%CI: 0.69, 1.25; P = .610).

CONCLUSION

This study suggested that teriparatide was more effective than risedronate for increasing the BMD in lumbar spine, femoral neck, and total hip, as well as reducing the incidences of clinical fracture, new vertebral fracture and non-vertebral fracture. There was no significant difference in incidence of adverse events between the 2 drugs. Considering the potential limitations in the present study, further large-scale, well-performed randomized trials are needed to verify our findings.

Foxf1 knockdown promotes BMSC osteogenesis in part by activating the Wnt/β-catenin signalling pathway and prevents ovariectomy-induced bone loss

BACKGROUND

Forkhead box protein f1 (Foxf1) is associated with cell differentiation, and may be a key player in bone homoeostasis. However, the effect of Foxf1 on osteogenesis of bone marrow-derived mesenchymal stem cells (BMSCs) and ovariectomy-induced bone loss, as well as its clinical implications, is unknown.

METHODS

By quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blotting, we assayed Foxf1 expression in bone tissue, BMSCs, and bone marrow-derived macrophages (BMMs), derived from ovariectomised (OVX) mice, and during osteogenic differentiation and osteoclast differentiation. Using a loss-of-function approach (small interfering RNA [siRNA]-mediated knockdown) in vitro, we examined whether Foxf1 regulates osteoblast differentiation of BMSCs via the Wnt/β-catenin signalling pathway. Furthermore, we assessed the anabolic effect of Foxf1 knockdown (siFoxf1) in OVX mice in vivo. We also assayed the expression of Foxf1 in bone tissue derived from postmenopausal osteoporosis (PMOP) patients and its link with bone mineral density (BMD). Finally, we examined the effect of Foxf1 knockdown on the osteoblastic differentiation of human BMSCs.

FINDINGS

Foxf1 expression was significantly increased in bone extract and BMSCs from OVX mice and gradually decreased during osteoblastic differentiation of BMSCs but did not differ significantly in OVX mouse-derived BMMs or during osteoclast differentiation. In vitro, Foxf1 knockdown markedly increased the expression of osteoblast specific genes, alkaline phosphatase (ALP) activity, and mineralisation. Moreover, siFoxf1 activated the Wnt/β-catenin signalling pathway. The siFoxf1-induced increase in osteogenic differentiation was partly rescued by inhibitor of Wnt signalling (DKK1). In OVX mice, Foxf1 siRNA significantly reduced bone loss by enhancing bone formation. Foxf1 expression levels negatively correlated with reduced bone mass and bone formation in bone tissue from PMOP patients. Finally, Foxf1 knockdown significantly promoted osteogenesis by human BMSCs.

INTERPRETATION

Our findings indicate that Foxf1 knockdown promotes BMSC osteogenesis and prevents OVX-induced bone loss. Therefore, Foxf1 has potential as a biomarker of osteogenesis and may be a therapeutic target for PMOP.

Peptide hormone sensors using human hormone receptor-carrying nanovesicles and graphene FETs

Hormones within very low levels regulate and control the activity of specific cells and organs of the human body. Hormone imbalance can cause many diseases. Therefore, hormone detection tools have been developed, particularly over the last decade. Peptide hormones have a short half-life, so it is important to detect them within a short time. In this study, we report two types of peptide hormone sensors using human hormone receptor-carrying nanovesicles and graphene field-effect transistors (FETs). Parathyroid hormone (PTH) and glucagon (GCG) are peptide hormones present in human blood that act as ligands to G protein-coupled receptors (GPCRs). In this paper, the parathyroid hormone receptor (PTHR) and the glucagon receptor (GCGR) were expressed in human embryonic kidney-293 (HEK-293) cells, and were constructed as nanovesicles carrying the respective receptors. They were then immobilized onto graphene-based FETs. The two hormone sensors developed were able to detect each target hormone with high sensitivity (ca. 100 fM of PTH and 1 pM of GCG). Also, the sensors accurately recognized target hormones among different types of peptide hormones. In the development of hormone detection tools, this approach, using human hormone receptor-carrying nanovesicles and graphene FETs, offers the possibility of detecting very low concentrations of hormones in real-time.

Is a Local Administration of Parathyroid Hormone Effective to Tendon-to-Bone Healing in a Rat Rotator Cuff Repair Model?

To evaluate the effect of local parathyroid hormone (PTH) administration on rotator cuff tendon-to-bone healing in a rat model compared with systemic PTH injection and untreated controls. PTH-alginate scaffold was prepared and sustained release of PTH was confirmed. Bilateral supraspinatus tendon repairs were performed in 39 rats (group 1, supraspinatus repair only; group 2, supraspinatus repair with systemic PTH injection; group 3, supraspinatus repair with local PTH administration via an absorbable scaffold; n = 13 each). Biomechanical (cross-sectional area, mode of failure, load to failure, and ultimate stress: right side) and histological analyses (hematoxylin and eosin stain, Masson's Trichrome stain Picrosirius red stain, Immunohistochemistry for BMP2, PTH1R, ColI, and ColIII: Left side) were performed to evaluate tendon-to-bone healing quality at 8 weeks after repair, and blood test (osteocalcin and procollagen type I N-terminal pro-peptide [PINP] levels) was performed in all rats. There was no intergroup difference in the healing failure rate (p = 0.910) or failure mode (p = 0.585). Biomechanically, subjects in groups 2 and 3 exhibited significantly larger cross-sectional areas and higher ultimate failure loads and ultimate stress than those in group 1 (all p < 0.05); however, no differences were noted between groups 2 and 3 (all p > 0.05). Histologically, groups 2 and 3 exhibited more organized tendon-to-bone interface structures with higher density, parallel orientation, and collagen fiber continuity than group 1 (all p < 0.05 except collagen fiber continuity in group 1 vs. 2); however, no differences in histological parameters between groups 2 and 3 (all p > 0.05). The protein levels of bone morphogenic protein 2, PTH 1 receptor, and collagen I and III and the serum level of PINP were increased in groups 2 and 3 versus group 1 (all p < 0.05) without showing differences between groups 2 and 3 (all p > 0.05). Local PTH administration using an absorbable scaffold improved the biomechanical and histological outcomes of rotator cuff tendon-to-bone healing comparable with systemic PTH injection at 8 weeks after repair in a rat model. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:82-91, 2020.

Advances in oral peptide therapeutics

Protein and peptide therapeutics require parenteral administration, which can be a deterrent to medication adherence. For this reason, there have been extensive efforts to develop alternative delivery strategies, particularly for peptides such as insulin that are used to treat endocrine disorders. Oral delivery is especially desirable, but it faces substantial barriers related to the structural organization and physiological function of the gastrointestinal tract. This article highlights strategies designed to overcome these barriers, including permeation enhancers, inhibitors of gut enzymes, and mucus-penetrating and cell-penetrating peptides. It then focuses on the experience with oral peptides that have reached clinical trials, including insulin, calcitonin, parathyroid hormone and vasopressin, with an emphasis on the advances that have recently led to the landmark approval of an oral formulation of the glucagon-like peptide 1 receptor agonist semaglutide for the treatment of type 2 diabetes.

Effects of teriparatide on bone in autochthonous transgenic model mice for diabetes mellitus (Akita mice)

OBJECTIVES

The purpose of this study is to evaluate the effects of teriparatide (TPTD) on bone mineral density (BMD), bone strength, and bone quality in Akita mouse models of diabetes mellitus.

METHODS

Twelve-week-old female Akita mice and control mice (C57/BL/6NCrSlc) were divided into 4 groups: control mice treated with vehicle (n = 7) or TPTD (n = 6); and Akita mice treated with vehicle (n = 6) or TPTD (n = 7). TPTD or vehicle was administered subcutaneously 3 times a week for 8 weeks. Blood glucose, serum sclerostin, total tibial BMD, femoral shaft bone strength, and bone quality using Fourier-transform infrared spectroscopy imaging were evaluated.

RESULTS

No significant differences in serum sclerostin levels were evident among these groups after 8 weeks of treatment. TPTD significantly increased BMD in control mice (+12.7%, P = 0.02) and Akita mice (+29.2%, P = 0.001) compared with vehicle. Maximum load and stiffness were significantly higher in Akita mice treated with TPTD than in Akita mice treated with vehicle (+56.6%, P = 0.03 and + 90.5%, P = 0.02, respectively). On Fourier-transform infrared spectroscopy imaging, the mineral/matrix ratio was significantly lower in Akita mice treated with vehicle than in control mice (-12.2%, P = 0.02), and TPTD treatment significantly increased the mineral/matrix ratio (P = 0.003).

CONCLUSIONS

TPTD thus improved BMD and bone strength in both control mice and Akita mice, with improvements in the mineral/matrix ratio among Akita mice.

Cyclic adenosine monophosphate-dependent activation of transient receptor potential vanilloid 4 (TRPV4) channels in osteoblast-like MG-63 cells

Parathyroid hormone (PTH) directly interacts with bone remodeling osteoblasts and osteocytes expressing the G-protein coupled receptor PTH receptor 1 (PTH1R), and its osteoanabolic effects mostly involve the cAMP/PKA signaling cascade. Considering that PTH-dependent calcium entry in rat enterocytes is reproduced by the adenylate cyclase agonist forskolin or by cAMP analogues, possible involvement of calcium as a second messenger in PTH-dependent cAMP signaling was investigated in MG-63 cells. First, Ca²⁺ influx was confirmed in Fluo3-loaded MG-63 cells treated with a cell-permeable cAMP analog. Second, PTH (1-34) and forskolin promoted calcium influxes that were completely abrogated by the PKA inhibitor H-89. Ca²⁺ entry was not reproduced when PTH (1-34) was combined with the PKC-activating competitor PTH (3-34). Vanilloid transient potential (TRPV) channel inhibitor Ruthenium Red, but not a voltage-dependent calcium channel (VDCC) inhibitor nifedipine, efficiently stunted Ca²⁺ entry, and comparable abrogation was reproduced in cells treated with TRPV4-selective inhibitor RN-1734 or transfected with TRPV4-specific siRNA. Interestingly, PTH-driven Ca²⁺ through TRPV4 significantly inhibited MG63 cell migration through a mechanism requiring extracellular Ca²⁺. In contrast, the inhibitory effects of forskolin on migration were refractory to TRPV4 silencing or to RN-1734. Altogether, our results indicate that single treatment with PTH (1-34) promotes extracellular calcium entry through TRPV4 channels in MG-63 cells through a cAMP/PKA-dependent mechanism, and that this influx affects cell migration.

Update on the safety and efficacy of teriparatide in the treatment of osteoporosis

Following the completion of the Fracture Prevention Trial, teriparatide was approved by the United States Food and Drug Administration and the European Medicine Agency as the first therapeutic anabolic agent for the treatment of postmenopausal women with severe osteoporosis. It subsequently received additional approval for the treatment of osteoporosis in men, and for the treatment of osteoporosis associated with glucocorticoid therapy in men and women at risk of fracture. In this review, we summarize the most important data concerning PTH 1-34 therapy before 2016 in the treatment of osteoporosis, and report some outstanding results published in the last 2 years. New data on safety will also discussed, together with the state of art of nonclassical utilization. Finally, in view of the recent approval of biosimilars, possible future landscapes are discussed.

Osteoblast-specific expression of Panx3 is dispensable for postnatal bone remodeling

Since cost-effective osteoanabolic treatment options remain to be established, it is relevant to identify specific molecules physiologically regulating osteoblast differentiation and/or activity that are principally accessible as drug targets. Specific or predominant gene expression in a given cell type often predicts a relevant function in the respective tissue. Thus, we aimed to identify genes encoding membrane-associated proteins with selective expression in differentiated osteoblasts. We therefore applied an unbiased approach, i.e. Affymetrix Gene Chip hybridization, to compare global gene expression in primary murine osteoblasts at two stages of differentiation. For the most strongly induced genes we analyzed their expression pattern in different tissues, which led us to identify known and unknown osteoblast differentiation markers with predominant expression in bone. One of these genes was Panx3, encoding a transmembrane hemichannel with ill-defined function in skeletal remodeling. To decipher the role of Panx3 in osteoblasts we first generated Panx3-fl/fl mice carrying a Runx2-Cre transgene. Using undecalcified histology followed by bone-specific histomorphometry we did not observe any significant difference between 24 weeks old Cre-negative and Cre-positive littermates. We additionally generated and analyzed mice with ubiquitous Panx3 deletion, where a delay of endochondral ossification did not translate into a detectable skeletal phenotype after weaning, possibly explained by compensatory induction of Panx1. Of note, newborn Panx3-deficient mice displayed significantly reduced serum glucose levels, which was not the case in older animals. Our findings demonstrate that Panx3 expression in osteoblasts is not required for postnatal bone remodeling, which essentially rules out its suitability as a target protein for osteoanabolic medication.

Teriparatide (recombinant human parathyroid hormone [1-34]) increases foot bone remodeling in diabetic chronic Charcot neuroarthropathy: a randomized double-blind placebo-controlled study

BACKGROUND

Currently, there is no consensus regarding the medical treatment of chronic Charcot neuroarthropathy (CN) of foot, except for effective off-loading. Because tarsal bones are predominantly trabecular, teriparatide may improve the macroarchitecture of foot bones in chronic CN.

METHODS

People with diabetes and chronic CN were randomized to receive either 20 μg teriparatide or placebo subcutaneous daily for 12 months. Thirty-eight patients were screened and data were analyzed for 20. The maximum standardized uptake (SUV_max ) value of ¹⁸ F-FDG PET/CT the region of interest, bone turnover markers and foot bone mineral density BMD were determined. The primary outcome measure was change in SUV_max g/ml.

RESULTS

Mid-foot was the most common region involved. After 12 months, SUV_max increased from 30.6 ± 14.7 to 37.7 ± 18.0 (P = 0.044) in the teriparatide group, but decreased from 27.6 ± 12.2 to 22.9 ± 10.4 with placebo (P = 0.148). The estimated treatment difference (ETD) was 11.9 ± 4.3 (95% CI 2.9, 20.8; P = 0.012). Similarly, P1NP increased with teriparatide (19.8 ± 5.5; P = 0.006) but decreased with placebo (-5.1 ± 3.8 ng/mL; P = 0.219); ETD was 24.8 ± 6.6 (95% CI 10.8, 38.8; P < 0.001) and CTX increased in both the teriparatide and placebo groups. Foot BMD increased by 0.06 ± 0.04 g/cm² (P = 0.192) with teriparatide, but decreased by -0.06 ± 0.08 g/cm² with placebo (P = 0.488; intergroup comparison, P = 0.096).

CONCLUSION

Teriparatide increases foot bone remodeling by an osteoanabolic action in people with CN.

A computational study of the dual effect of intermittent and continuous administration of parathyroid hormone on bone remodeling

Bone remodeling is a process known to be governed by constant interactions between osteoblast and osteoclast through complex pathway networks mediated by signaling factors. Experimental studies show that intermittent and continuous administration of PTH/PTHrP led to opposite outcomes in terms of bone mass. To investigate this dual effect of PTH/PTHrP, we develop a computational model based on a simplified signaling pathway network which includes relevant molecular effectors and cells. Multiple ordinary differential equations linking all considered components in the signaling pathway network through reaction kinetics are solved with dose values and patterns of injection from experiments as input. Modeling results show good agreement with experimental observations in that continuous injection of PTH/PTHrP generates catabolic effect on bone mass while intermittent injection yields anabolic effect. The signaling factors governing the interaction between osteoblast and osteoclast indeed play a key role in the dual effect of PTH/PTHrP. Furthermore, there appears to be an optimal interval for intermittent injection of PTH/PTHrP for yielding the most bone regeneration, and a synergistic outcome could be achieved by combining intermittent injection of PTH/PTHrP with application of a treatment (to mimic the filling of bone defects with polymeric scaffolds). This modeling work sheds valuable insights into the influence of temporal control of PTH/PTHrP on bone mass and presents a possible path toward bridging bioengineering approaches with clinical treatment strategies. STATEMENT OF SIGNIFICANCE: A computational model considering simplified signaling pathways containing crucial components of PTH, PTHrP, osteoblast precursor, osteoblast, osteoclast precursor, osteoclast, RANKL and IL-6 family cytokoines has been developed to study the dual effect of PTH/PTHrP on bone metabolism. The model takes the dose values and patterns of injection from experiments as input and yields predictions that convincingly match experimental measurements. This work highlights the importance of providing an optimal hormone treatment strategy for maintaining healthy bone metabolism. Moreover, the integrative approach of relying on experimental observations to find reasonable values for relevant modeling parameters has been proven to be powerful in advancing our understanding of biological interactions among cells and signaling factors.

How To Build a Bone: PHOSPHO1, Biomineralization, and Beyond

Since its characterization two decades ago, the phosphatase PHOSPHO1 has been the subject of an increasing focus of research. This work has elucidated PHOSPHO1's central role in the biomineralization of bone and other hard tissues, but has also implicated the enzyme in other biological processes in health and disease. During mineralization PHOSPHO1 liberates inorganic phosphate (P_i) to be incorporated into the mineral phase through hydrolysis of its substrates phosphocholine (PCho) and phosphoethanolamine (PEA). Localization of PHOSPHO1 within matrix vesicles allows accumulation of P_i within a protected environment where mineral crystals may nucleate and subsequently invade the organic collagenous scaffold. Here, we examine the evidence for this process, first discussing the discovery and characterization of PHOSPHO1, before considering experimental evidence for its canonical role in matrix vesicle–mediated biomineralization. We also contemplate roles for PHOSPHO1 in disorders of dysregulated mineralization such as vascular calcification, along with emerging evidence of its activity in other systems including choline synthesis and homeostasis, and energy metabolism. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Variable osteogenic performance of MC3T3-E1 subclones impacts their utility as models of osteoblast biology

The spontaneously immortalized murine calvarial cell line MC3T3-E1 and its derivative subclones are widely used models of osteoblast biology. Many investigators have reported conflicting data under seemingly similar experimental conditions, though the specific subclone studied is often not specified. The purpose of this study was to directly compare the commercially available MC3T3-E1 subclones 4, 14, and 24 in terms of responsiveness to osteogenic induction media and/or stimulation with rhPTH[1–34]. We assayed osteogenic gene expression, capacity to deposit and mineralize a collagenous matrix, and the expression and signaling function of PTH1R. Our data demonstrate that each subclone bears little functional resemblance to the others, or to primary calvarial osteoblasts. Specifically, whereas subclone 4 is responsive to PTH stimulation and capable of matrix mineralization, subclones 14 and 24 do not faithfully replicate these key aspects of osteoblast biology. Furthermore, little overlap was observed between the gene expression profile of subclone 4 and primary calvarial osteoblasts. Our experience working with these cell lines demonstrates that the MC3T3-E1 derived cell lines are imperfect models of osteoblast biology, and reinforce the importance of clearly articulating selection and reporting of research materials.

Bone mineral density response rates are greater in patients treated with abaloparatide compared with those treated with placebo or teriparatide: Results from the ACTIVE phase 3 trial

BACKGROUND

Abaloparatide is a 34-amino acid peptide that selectively binds to the RG conformation of the parathyroid hormone receptor type 1. It was developed for the treatment of women with postmenopausal osteoporosis at high risk of fracture. In ACTIVE, an 18-month phase 3 study (NCT01343004), abaloparatide increased bone mineral density (BMD), decreased the risk of vertebral and nonvertebral fractures compared with placebo, and decreased the risk of major osteoporotic fractures compared with placebo and teriparatide. Here, we report a prospective, exploratory BMD responder analysis from ACTIVE.

METHODS

Proportions of patients experiencing BMD gains from baseline of >0%, >3%, and >6% at the total hip, femoral neck, and lumbar spine at 6, 12, and 18 months of treatment were compared among the placebo, abaloparatide, and teriparatide groups in ACTIVE. Responders were defined prospectively as patients experiencing BMD gains at all 3 anatomic sites.

RESULTS

At months 6, 12, and 18, there were significantly more >3% BMD responders in the abaloparatide group compared with placebo and teriparatide: month 6, 19.1% vs 0.9% for placebo and 6.5% for teriparatide; month 12, 33.2% vs 1.5% and 19.8%; month 18, 44.5% vs 1.9% and 32.0% (P < 0.001 for all comparisons of abaloparatide to placebo and to teriparatide). Findings were similar for the >0% and >6% responder thresholds.

CONCLUSIONS

In postmenopausal women with osteoporosis, a significantly greater proportion of patients treated with abaloparatide experienced increases in BMD than did those treated with placebo or teriparatide.