Use of the oral platelet inhibitors dipyridamole and acetylsalicylic acid is associated with increased risk of fracture

Differential effects of clopidogrel and/or aspirin on the healing of tooth extraction wound bone tissue

Introduction

A multitude of variables influence the healing of tooth extraction wounds, and delayed or non-healing extraction wounds might complicate later prosthodontic therapy. In this research, we analyzed the effects of systemic clopidogrel and aspirin alone or in combination on the healing of tooth extraction wounds in mice in order to provide experimental evidence for the healing of extraction wounds in patients who are clinically treated with the two medicines.

Methods

7-week-old ICR mice were randomly divided into four groups: control group (CON), clopidogrel group (CLOP), aspirin group (ASP), and clopidogrel combined with aspirin group (CLOP + ASP); left upper first molar was extracted, after which mice in 1 week of adaptive feeding, CLOP/ASP/CLOP + ASP groups were respectively administered with clopidogrel (10 mg/kg/d), aspirin (15 mg/kg/d), clopidogrel (10 mg/kg/d)+aspirin (15 mg/kg/d), and the control group was given an equal amount of 0.9% saline by gavage. Mice in each group were euthanized at 14 and 28 days postoperatively, and the maxilla was extracted. The tissues in the extraction sockets were examined using MicroCT and sectioned for HE staining, Masson staining, and TRAP staining, and immunohistochemistry staining (for TRAP, RANKL and osteoprotegerin).

Results

MicroCT analysis showed that at day 14, BS/BV was significantly lower in CLOP and CLOP + ASP groups compared to control and ASP groups, while BV/TV, Tb.Th was significantly higher. At day 28, BV/TV was significantly higher in the CLOP + ASP group compared to the CLOP group, with p < 0.05 for all results. HE staining and Masson trichrome staining findings revealed that at day 28, the mesenchyme in the bone was further decreased compared to that at day 14, accompanied with tightly arranged and interconnected bone trabeculae. In the quantitative analysis of Masson, the fraction of newly formed collagen was significantly higher in the CLOP group in comparison with that in the CON group (p < 0.05). At day 14, the ASP group had substantially more TRAP-positive cells than the CLOP and CLOP + ASP groups (p < 0.05). In immunohistochemical staining, RANKL expression was found to be significantly higher in the ASP group than those in the other three groups at day 28 (p < 0.05); OPG expression was significantly higher in the CLOP group and the CLOP + ASP group compared with that at day 14, and was higher than that in the ASP group at day 14 and day 28. OPG/RANKL was significantly higher in the CLOP and the CLOP + ASP groups than in the ASP group (p < 0.05).

Conclusion

Clopidogrel alone promotes osteogenesis in the extraction wound, whereas aspirin alone inhibits alveolar bone healing. When the two drugs were combined, the healing effect of the extraction wound was more similar to that of the clopidogrel alone group. These results indicated that clopidogrel could promote the healing of the tooth extraction wound, and neutralize the adverse effect of ASP on osteogenesis when the two drugs were used in combination.

Ticagrelor was associated with lower fracture risk than clopidogrel in the dual anti-platelet regimen among patients with acute coronary syndrome treated with percutaneous coronary intervention

PURPOSE

Patients with coronary artery disease have increased fracture risks. P2Y12 inhibitors may impact fracture risks. We compared the fracture risks associated with ticagrelor and clopidogrel in dual anti-platelet therapy (DAPT).

METHODS

We identified all adults who underwent first-ever percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) between 2010 and 2017 from a territory-wide PCI registry in Hong Kong. Following 1:1 propensity-score matching for baseline characteristics, patients were followed up till event occurrence, death, or 30 June 2022. Outcomes of interest were major osteoporotic fractures (MOF) identified by validated ICD-9-CM codes. Cox proportional hazards regression was used to compute the hazard ratio (HR) for MOF associated with ticagrelor versus clopidogrel use.

RESULTS

3018 ticagrelor users and 3018 clopidogrel users were identified after propensity-score matching (mean age: 61.4 years; 84.1% men). Upon median follow-up of 6.5 years, 59 ticagrelor users and 119 clopidogrel users sustained MOF (annualized fracture risks: 0.34% and 0.56%, respectively). Ticagrelor use was associated with lower risks of MOF (HR 0.60, 95%CI 0.44-0.83; p = 0.002). Consistent HRs were observed for fractures over vertebrae, hip and upper limbs. Subgroup analyses showed no interaction according to age, sex, presence of diabetes, presence of chronic kidney disease and prior fracture history.

CONCLUSION

Among adults who underwent first-ever PCI for ACS, ticagrelor use in the DAPT was associated with a lower risk of MOF compared with clopidogrel. Our results support the use of ticagrelor in the DAPT from the perspective of bone health.

Aspirin prevents estrogen deficiency-induced bone loss by inhibiting osteoclastogenesis and promoting osteogenesis

BACKGROUND

Aspirin is a commonly used antipyretic, analgesic, and anti-inflammatory drug. Numerous researches have demonstrated that aspirin exerts multiple biological effects on bone metabolism. However, its spatiotemporal roles remain controversial according to the specific therapeutic doses used for different clinical conditions, and the detailed mechanisms have not been fully elucidated. Hence, in the present study, we aimed to identify the dual effects of different aspirin dosages on osteoclastic activity and osteoblastic bone formation in vitro and in vivo.

METHODS

The effects of varying doses of aspirin on osteoclast and osteoblast differentiation were evaluated in vitro. The underlying molecular mechanisms were detected using quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence techniques. An ovariectomized rat osteoporosis model was used to assess the bone-protective effects of aspirin in vivo.

RESULTS

Aspirin dose-dependently suppressed RANKL-induced osteoclasts differentiation and bone resorption in vitro and reduced the expression of osteoclastic marker genes, including TRAP, cathepsin K, and CTR. Further molecular analysis revealed that aspirin impaired the RANKL-induced NF-κB and MAPK signaling pathways and prevented the nuclear translocation of the NF-κB p65 subunit. Low-dose aspirin promoted osteogenic differentiation, whereas these effects were attenuated when high-dose aspirin was administered. Both low and high doses of aspirin prevented bone loss in an ovariectomized rat osteoporosis model in vivo.

CONCLUSION

Aspirin inhibits RANKL-induced osteoclastogenesis and promotes osteogenesis in a dual regulatory manner, thus preventing bone loss in vivo. These data indicate that aspirin has potential applications in the prevention and treatment of osteopenia.

NHANES cross sectional study of aspirin and fractures in the elderly

Bone fractures are a global public health concern, yet no thorough investigation of low-dose aspirin usage to prevent fractures in the elderly has been conducted. Many interventional human and animal studies have tried to detect the correct role of low-dose aspirin on fractures in elderly persons. The literature doesn't consist of a retrospective observational study that includes a large number of older individuals and evaluates the accurate effect of aspirin on the fractures post falling from low heights. This cross-sectional includes 7132 elderly persons and aimed to detect if there was a link between taking low-dose aspirin to prevent fractures in the elderly. Data was extracted from the National Health and Nutrition Examination Survey (NHANES) database for 2017-2020 and 2013-2014. Demographic and examination data were collected during in-home interviews and study visits to a mobile examination center. Standardized questionnaires were used to collect information such as age, gender, race, educational level, and family income-to-poverty ratio. Body mass index (BMI), weight, standing height, upper leg length, upper arm length, arm circumference, and wrist circumference were all measured during the examination. The study examined 8127 patients, with 7132 elderly patients suitable for data analysis. The odds ratio of fractures due to a fall from standing height or less was 0.963 (95 percent confidence interval 0.08-1.149) in low-dose aspirin users, while having parents with osteoporosis had a related risk of 1.23. (95 percent confidence interval 0.81-1.8). The total number of fractures was 1295; with hip fractures constituting up to 13.82%, wrist fractures of 66.56%, and spine fractures of 19.61%. There was no significant difference in femur and spine bone mineral density (BMD) in the two groups (use low dose aspirin and don't use). Females had a 5.6 times greater fracture risk related to a fall from standing height or less (1 time or more) than males (P-value < 0.001). Furthermore, taking aspirin had no effect on the occurrence of fractures from standing height or less in older people (P-value = 0.468). In addition, the logistic regression after performing the propensity matching score confirmed that there was no impact of taking aspirin on the occurrence of fractures (P-value > 0.05). This cross-sectional study reveals that taking low-dose aspirin to prevent fractures in the elderly is statistically insignificant. However, fractures are more common in older persons, especially in older women; thus, more widespread injury prevention initiatives and access to osteoporosis prevention and diagnosis for older people should improve to minimize the overall burden.

Protective Effects of Higher Exposure to Aspirin and/or Clopidogrel on the Occurrence of Hip Fracture among Diabetic Patients: A Retrospective Cohort Study

Aspirin and clopidogrel are commonly prescribed alone or together among the type 2 diabetes mellitus (T2DM) patients, and both agents could affect bone metabolism. This study aimed at demonstrating the effects of the dosage and the duration of aspirin and/or clopidogrel alone or together on the occurrence of hip fracture among T2DM patients. We chose the patients newly diagnosed with T2DM and divided them into four subgroups which are under aspirin monotherapy (78,522 patients), clopidogrel monotherapy (12,752 patients), dual therapy (7209 patients), and patients not taking antiplatelet drugs (401,686 patients). We found that only higher dosage (>360 cumulative daily defined dose (cDDD)) and longer duration (≥3 years) of antiplatelet agents could be associated with lower fracture risk. Compared with the subjects taking <1-year dual agents, the risk of hip fracture was 0.38-fold for the patients taking ≥3-year dual agents. Lower dosage (28−179 cDDD) and shorter duration (1~2 years) could even be associated with higher fracture risk. Overall, the best regimen to fend off the hip fracture was the use of aspirin and clopidogrel for ≥3 years.

A Novel Antibody Targeting the Second Extracellular Loop of the Serotonin 5-HT2A Receptor Inhibits Platelet Function

Serotonin (5-hydroxytriptamine or 5-HT) is known to be a weak platelet agonist, and is involved in thrombus formation. While 5-HT cannot induce platelet aggregation on its own, when secreted from the alpha granules, it binds to its G-protein Coupled Receptor (GPCR; i.e., 5HT_2AR), thereby acting to amplify platelet functional responses (e.g., aggregation). Thus, 5HT_2AR-mediated responses are more involved in the secondary amplification of platelet aggregation in the growing thrombus. Therefore, even though 5-HT can be seen as a weak inducer of platelet activation, it is an important amplifier of aggregation triggered by agonists such as ADP, collagen, and epinephrine, thereby enhancing thrombogenesis. The 5HT_2AR/5HT_2A signaling pathway is of clinical interest to the scientific and medical communities as it has been implicated in the genesis of several forms of cardiovascular disorders. However, efforts to develop antagonists for 5HT_2AR as therapeutic agents in cardiovascular diseases have thus far failed due to these reagents having deleterious side-effects, and/or to lack of selectivity, amongst other reasons. In light of research efforts that identified that the 5HT_2AR ligand binding domain resides in the second extracellular loop (EL2; amino acids P²⁰⁹-N²³³), we developed an antibody, i.e., referred to as 5HT_2ARAb, against the EL2 region, and characterized its pharmacological activity in the context of platelets. Thus, we utilized platelets from healthy human donors, as well as C57BL/6J mice (10-12 weeks old) to analyze the inhibitory effects of the 5HT_2ARAb on platelet activation in vitro, ex vivo, and on thrombogenesis in vivo as well as on 5HT_2AR ligand binding. Our results indicate that the 5HT_2ARAb inhibits 5-HT-enhanced platelet activation in vitro and ex vivo, but has no apparent effects on that which is agonist-induced. The 5HT_2ARAb was also found to prolong the thrombus occlusion time, and it did so without modulating the tail bleeding time, in mice unlike the P2Y12 antagonist clopidogrel and the 5HT_2AR antagonist ketanserin. Moreover, it was found that the 5HT_2ARAb does so by directly antagonizing the platelet 5HT_2AR. Our findings document that the custom-made 5HT_2ARAb exhibits platelet function blocking activity and protects against thrombogenesis without impairing normal hemostasis.

Pleiotropic Effects of Acetylsalicylic Acid after Coronary Artery Bypass Grafting-Beyond Platelet Inhibition

Acetylsalicylic acid (ASA) is one of the most frequently used medications worldwide. Yet, the main indications for ASA are the atherosclerosis-based cardiovascular diseases, including coronary artery disease (CAD). Despite the increasing number of percutaneous procedures to treat CAD, coronary artery bypass grafting (CABG) remains the treatment of choice in patients with multivessel CAD and intermediate or high anatomical lesion complexity. Taking into account that CABG is a potent activator of inflammation, ASA is an important part in the postoperative therapy, not only due to ASA antiplatelet action, but also as an anti-inflammatory agent. Additional benefits of ASA after CABG include anticancerogenic, hypotensive, antiproliferative, anti-osteoporotic, and neuroprotective effects, which are especially important in patients after CABG, prone to hypertension, graft occlusion, atherosclerosis progression, and cognitive impairment. Here, we discuss the pleiotropic effects of ASA after CABG and provide insights into the mechanisms underlying the benefits of treatment with ASA, beyond platelet inhibition. Since some of ASA pleiotropic effects seem to increase the risk of bleeding, it could be considered a starting point to investigate whether the increase of the intensity of the treatment with ASA after CABG is beneficial for the CABG group of patients.

Effects of low-dose aspirin on the osseointegration process in rats

BACKGROUND

Several drugs are capable of promoting changes in bone metabolism. The aim of this study was to evaluate the effect of long-term low-dose aspirin (LDA) therapy on implant osseointegration.

METHODS

Male Wistar rats were divided into 4 groups (n = 8/group) according to oral gavage solution received prior (42 days) to the implant surgery on the tibia. The control group was treated with saline solution for 7 (CG-7) and 28 (CG-28) days. The use of low-dose aspirin was performed in AG groups (6.75 mg/kg of aspirin) for 7 (AG-7) and 28 (AG-28) days. After experimental periods, histomorphometric evaluation of bone-to-implant contact (BIC) and the bone area between threads (BABT) was performed.

RESULTS

Reduced BIC values were detected in AG-7 (62.8% ± 17.1) group compared to AG-28 (91.9% ± 5.4), CG-7 (82.7% ± 15.2), and CG-28 (89.9% ± 9.7). BABT evaluation revealed lower values in AG-7 (70.9% ± 15.2) compared to AG-28 (95.4% ± 3.7) and CG-28 (87.1% ± 10.2) groups.

CONCLUSIONS

The treatment with low doses of aspirin promoted a discrete inhibitory effect in the early stages (7 days) of repair after implant placement, specifically in the bone deposition. However, these effects were not detected in the late stages (28 days), considering BIC and BABT parameters.

Aspirin and fracture risk: a systematic review and exploratory meta-analysis of observational studies

OBJECTIVES

This review provides insights into the potential for aspirin to preserve bone mineral density (BMD) and reduce fracture risk, building knowledge of the risk-benefit profile of aspirin.

METHODS

We conducted a systematic review and exploratory meta-analysis of observational studies. Electronic searches of MEDLINE and Embase, and a manual search of bibliographies was undertaken for studies published to 28 March 2018. Studies were included if: participants were men or women aged ≥18 years; the exposure of interest was aspirin; and relative risks, ORs and 95% CIs for the risk of fracture or difference (percentage or absolute) in BMD (measured by dual energy X-ray absorptiometry) between aspirin users and non-users were presented. Risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklists for observational studies. Pooled ORs for any fracture and standardised mean differences (SMDs) for BMD outcomes were calculated using random-effects models.

RESULTS

Twelve studies met the inclusion criteria and were included in the meta-analysis. Aspirin use was associated with a 17% lower odds for any fracture (OR 0.83, 95% CI 0.70 to 0.99; I²=71%; six studies; n=511 390). Aspirin was associated with a higher total hip BMD for women (SMD 0.03, 95% CI -0.02 to 0.07; I²=0%; three studies; n=9686) and men (SMD 0.06, 95% CI -0.02 to 0.13, I²=0%; two studies; n=4137) although these associations were not significant. Similar results were observed for lumbar spine BMD in women (SMD 0.03, 95% CI -0.03 to 0.09; I²=34%; four studies; n=11 330) and men (SMD 0.08; 95% CI -0.01 to 0.18; one study; n=432).

CONCLUSIONS

While the benefits of reduced fracture risk and higher BMD from aspirin use may be modest for individuals, if confirmed in prospective controlled trials, they may confer a large population benefit given the common use of aspirin in older people.

Proton pump inhibitors and fracture risk. The HUNT study, Norway

Proton pump inhibitors (PPIs) have been linked to increased risk of fracture; the data have, however, been diverging. We did not find any increased risk of fractures among users of PPIs in a Norwegian population of 15,017 women and 13,241 men aged 50-85 years with detailed information about lifestyle and comorbidity.

INTRODUCTION

Proton pump inhibitors (PPIs) are widely prescribed and have been linked to increased risk of fracture.

METHODS

We used data from the Nord-Trøndelag Health Study (HUNT3), The Fracture registry in Nord-Trøndelag, and the Norwegian Prescription Database, including 15,017 women and 13,241 men aged 50-85 years. The study population was followed from the date of participating in HUNT3 (2006-2008) until the date of first fracture (forearm or hip), death, or end of study (31 December 2012). The Cox proportional hazards model with time-dependent exposure to PPIs was applied, and each individual was considered as unexposed until the first prescriptions was filled. To be included, the prescription of PPIs should minimum be equivalent to 90 defined daily doses (DDD) in the period. Individuals were defined as exposed until 6 months after end of drug supply.

RESULTS

The proportion of women and men using PPIs was 17.9% and 15.5%, respectively. During a median of 5.2 years follow-up, 266 women and 134 men had a first hip fracture and 662 women and 127 men, a first forearm fracture. The combined rate/1000 patient-years for forearm and hip fractures in women was 49.2 for users of PPIs compared with 64.1 among non-users; for men 18.6 and 19.8, respectively. The hazard ratios with 95% confidence interval for the first forearm or hip fracture among users of PPIs in the age-adjusted analysis were 0.82 (0.67-1.01) for women and 1.05 (0.72-1.52) for men. Adjusting for age, use of anti-osteoporotic drugs, and FRAX, the HR declined to 0.80 (0.65-0.98) in women and 1.00 (0.69-1.45) in men.

CONCLUSIONS

Use of PPIs was not associated with an increased risk of fractures.

Dose-dependent roles of aspirin and other non-steroidal anti-inflammatory drugs in abnormal bone remodeling and skeletal regeneration

The failure of remodeling process that constantly regenerates effete, aged bone is highly associated with bone nonunion and degenerative bone diseases. Numerous studies have demonstrated that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) activate cytokines and mediators on osteoclasts, osteoblasts and their constituent progenitor cells located around the remodeling area. These cells contribute to a complex metabolic scenario, resulting in degradative or synthetic functions for bone mineral tissues. The spatiotemporal effects of aspirin and NSAIDs in the bone remodeling are controversial according the specific therapeutic doses used for different clinical conditions. Herein, we review in vitro, in vivo, and clinical studies on the dose-dependent roles of aspirin and NSAIDs in bone remodeling. Our results show that low-dose aspirin (< 100 μg/mL), which is widely recommended for prevention of thrombosis, is very likely to be benefit for maintaining bone mass and qualities by activation of osteoblastic bone formation and inhibition of osteoclast activities via cyclooxygenase-independent manner. While, the roles of high-dose aspirin (150-300 μg/mL) and other NSAIDs in bone self-regeneration and fracture-healing process are difficult to elucidate owing to their dual effects on osteoclast activity and bone formation of osteoblast. In conclusion, this study highlighted the potential clinical applications of low-dose aspirin in abnormal bone remodeling as well as the risks of high-dose aspirin and other NSAIDs for relieving pain and anti-inflammation in fractures and orthopedic operations.

Effects of NSAIDs and environmental oxygen pressure on bone regeneration

Objective: To evaluate the effects of administering diclofenac and ketoprofen, as well as the effects of environmental oxygen pressure variation on mandibular bone regeneration. Methods: Thirty-six guinea pigs were distributed into two equal groups. Mandibular bone defects were performed on both groups. Group A was monitored under oxygen pressure at altitude (3320msl, 107mm Hg). Group B was monitored at sea level oxygen pressure (150msl, 157mm Hg). Each group was subdivided into 3 equal groups (A1, A2, A3 and B1, B2, B3). Subgroups A1 and B1 were given diclofenac; subgroups A2 and B2 ketoprofen; subgroups A3 and B3 NaCl. Bone regeneration was evaluated histologically on days 15 and 30. Results: After 15 days in the group controlled at sea level, the level of osteoblasts presented by the control subgroup was significantly higher (28.00±2.65) compared to the diclofenac subgroup (16.00±6.25) and to the ketoprofen subgroup (18.00±4.36); (p=0.041). After 15 days in the group controlled at altitude, the level of osteoblasts was significantly higher in the control subgroup (38.00±5.29) compared to the diclofenac subgroup (21.67±6.35) and to the ketoprofen subgroup (19.33±2.52); p=0.007. After 30 days in the group at sea level there was no difference found in the cell counting; p>0.05. After 30 days in the group controlled at altitude, the level of osteoblast was significantly higher in the control subgroup (58.00±4.58) compared to the diclofenac subgroup (34.33±4.73) and the ketoprofen subgroup (34.00±11.14); (p=0.003). Conclusion: The administration of diclofenac and ketoprofen produced lower mandibular bone regeneration, the effect being significantly more negative at sea level.

Anti-atherogenic properties of vitamin E, aspirin, and their combination

The present study was designed to assess the extent to which vitamin E and aspirin individually or in combination prevent and/or reverse bone loss and atherosclerotic lesion formation in orchidectomized aged rats. Forty-nine 12-month old male Sprague-Dawley rats were either sham-operated (Sham, one group) or orchidectomized (Orx, four groups) and fed a control diet for 120 days to establish bone loss and atherosclerotic lesions. Thereafter, rats were assigned to the various treatment groups (n = 9 to 10 per group): 1) Sham and 2) Orx groups received AIN93M, containing 75 IU vitamin E and served as control, and the other three Orx groups received either 3) 500 IU vitamin E, 4) 500 mg aspirin, or 5) 500 IU vitamin E + 500 mg aspirin per kg diet for 90 days. After 90 days of treatment, rats were sacrificed, necropsied, and tissues were collected for analyses. Results show that 500 IU vitamin E was able to reduce the development of atherosclerosis lesion formation and aortic streak area compared to Orx control. More importantly, 500 mg aspirin completely reversed the fatty streak area and made the atherosclerotic lesions disappear. Vitamin E and aspirin were not able to reverse bone loss as shown by whole body, lumbar and femoral bone mineral content and bone mineral density due to gonadal hormone deficiency. Instead, 500 mg aspirin somewhat increased the trabecular separation while decreased trabecular thickness compared to Orx control. Our findings suggest that both, vitamin E and aspirin exert anti-atherogenic effects and aspirin is more effective than vitamin E in preventing atherosclerosis lesions in Orx rats.

Dipyridamole enhances osteogenesis of three-dimensionally printed bioactive ceramic scaffolds in calvarial defects

PURPOSE

The objective of this study was to test the osteogenic capacity of dipyridamole-loaded, three-dimensionally printed, bioactive ceramic (3DPBC) scaffolds using a translational, skeletally mature, large-animal calvarial defect model.

MATERIALS AND METHODS

Custom 3DPBC scaffolds designed to present lattice-based porosity only towards the dural surface were either coated with collagen (control) or coated with collagen and immersed in a 100 μM concentration dipyridamole (DIPY) solution. Sheep (n = 5) were subjected to 2 ipsilateral trephine-induced (11-mm diameter) calvarial defects. Either a control or a DIPY scaffold was placed in each defect, and the surgery was repeated on the contralateral side 3 weeks later. Following sacrifice, defects were evaluated through microcomputed tomography and histologic analysis for bone, scaffold, and soft tissue quantification throughout the defect. Parametric and non-parametric methods were used to determine statistical significance based on data distribution.

RESULTS

No exuberant or ectopic bone formation was observed, and no histologic evidence of inflammation was noted within the defects. Osteogenesis was higher in DIPY-coated scaffolds compared to controls at 3 weeks (p = 0.013) and 6 weeks (p = 0.046) in vivo. When bone formation was evaluated as a function of defect radius, average bone formation was higher for DIPY relative to control scaffolds at both time points (significant at defect central regions at 3 weeks and at margins at 6 weeks, p = 0.046 and p = 0.031, respectively).

CONCLUSION

Dipyridamole significantly improves the calvarial bone regeneration capacity of 3DPBC scaffolds. The most significant difference in bone regeneration was observed centrally within the interface between the 3DPBC scaffold and the dura mater.

P2Y12 Receptor Antagonist, Clopidogrel, Does Not Contribute to Risk of Osteoporotic Fractures in Stroke Patients

Background: Stroke is a leading cause of mortality and morbidity. It is associated with excessive bone loss and risk of fracture in stroke patients is high. The P2Y12R antagonist and platelet inhibitor, clopidogrel, is widely used for secondary prevention after a stroke. However, recent studies have shown that clopidogrel has negative effects on bone and that long-term clopidogrel use is associated with increased fracture risk. The purpose of the current study was therefore to investigate the association of clopidogrel treatment with risk of fractures in stroke and TIA patients.

Methods: The study was a cohort study including all subjects who were prescribed clopidogrel between 1996 and 2008 in Denmark (n = 77,503). Age- and gender matched controls (n = 232,510) were randomly selected from the background population. The study end-points were occurrence of stroke or TIA and occurrence of fracture. Clopidogrel use was primary exposure.

Results: Ischemic stroke increased risk of fracture by 50% while haemorrhagic stroke and TIA increased the risk by 30%. However, after adjusting for multiple confounders only patients with ischemic stroke and haemorrhagic stroke had increased fracture risk. Clopidogrel use was not associated with increased fracture risk in subjects with ischaemic stroke or TIA. In contrast, after adjusting for multiple confounders clopidogrel treatment was associated with a 10–35% reduced risk of fracture.

Conclusion: Patients with stroke have increased risk of osteoporotic fractures, but clopidogrel treatment does not increase fracture risk. In contrast, patients less adherent to the treatment have lower risk of fractures than non-users and patients with high adherence. However, based on the increased risk in stroke patients, clinicians should consider evaluation of bone status of these patients.

The Role of Monocyte Percentage in Osteoporosis in Male Rheumatic Diseases

Osteoporosis is easily overlooked in male patients, especially in the field of rheumatic diseases mostly prevalent with female patients, and its link to pathogenesis is still lacking. Attenuated monocyte apoptosis from a transcriptome-wide expression study illustrates the role of monocytes in osteoporosis. This study tested the hypothesis that the monocyte percentage among leukocytes could be a biomarker of osteoporosis in rheumatic diseases. Eighty-seven males with rheumatic diseases were evaluated in rheumatology outpatient clinics for bone mineral density (BMD) and surrogate markers, such as routine peripheral blood parameters and autoantibodies. From the total number of 87 patients included in this study, only 15 met the criteria for diagnosis of osteoporosis. Both age and monocyte percentage remained independently associated with the presence of osteoporosis. Steroid dose (equivalent prednisolone dose) was negatively associated with BMD of the hip area and platelet counts were negatively associated with BMD and T score of the spine area. Besides age, monocyte percentage meets the major requirements for osteoporosis in male rheumatic diseases. A higher monocyte percentage in male rheumatic disease patients, aged over 50 years in this study, and BMD study should be considered in order to reduce the risk of osteoporosis-related fractures.

Chronic use of low-dose aspirin is not associated with lower bone mineral density in the general population

BACKGROUND

Low-dose aspirin is the cornerstone of secondary prevention of cardiovascular disease. Previous studies suggested that the use of aspirin is associated with an increased fracture risk. However, there is uncertainty whether this is due to an effect of aspirin on bone mineral density (BMD).

METHODS

Between 2008 and 2012, information on medication use and dual X-ray absorptiometry measured vertebral and femoral BMD of 916 participants was collected in the Netherland Epidemiology of Obesity study. The cross-sectional association between chronic low-dose aspirin use and BMD was estimated using linear regression, controlling for demography, body composition, comorbidity and other medication use which could affect BMD. A subgroup analysis in postmenopausal women (n=329) was conducted.

RESULTS

After full adjustment, there was no difference between aspirin users and non-users for vertebral BMD (adjusted mean difference: 0.036 (95% CI -0.027 to 0.100) g/cm²) and femoral BMD (adjusted mean difference: 0.001 (-0.067 to 0.069) g/cm²). Also in the subgroup of postmenopausal women, aspirin use was not associated with lower vertebral (adjusted mean difference: 0.069 (-0.046 to 0.184) g/cm²) or femoral BMD (adjusted mean difference: -0.055 (-0.139;0.029) g/cm²).

CONCLUSION

Chronic use of low-dose aspirin is not associated with lower BMD in the general population. The increased risk of fractures observed in aspirin users in previous studies is therefore more likely to be the result of common causes of aspirin use and fractures, but not of direct effects of aspirin on BMD.

A Review on the Relationship between Aspirin and Bone Health

Aspirin is a cyclooxygenase inhibitor commonly used in primary prevention of cardiovascular diseases and cancers. Its users are elderly population susceptible to osteoporosis. It also inhibits the synthesis of prostaglandin E₂ essential in bone remodeling. This prompts the question whether it can influence bone health among users. This review aimed to summarize the current literature on the use of aspirin on bone health. A literature search on experimental and clinical evidence on the effects of aspirin on bone health was performed using major scientific databases. In vitro studies showed that aspirin could enhance the survival of bone marrow mesenchymal stem cells, the progenitors of osteoblasts, and stimulate the differentiation of preosteoblasts. Aspirin also inhibited the nuclear factor kappa-B (NFκB) pathway and decreased the expression of receptor activator of NFκB ligand, thus suppressing the formation of osteoclast. Aspirin could prevent bone loss in animal models of osteoporosis. Despite a positive effect on bone mineral density, the limited human epidemiological studies revealed that aspirin could not reduce fracture risk. A study even suggested that the use of aspirin increased fracture risk. As a conclusion, aspirin may increase bone mineral density but its effect on fracture prevention is inconclusive. More data are needed to determine the effects of aspirin and bone health in human.

A randomised controlled trial of low-dose aspirin for the prevention of fractures in healthy older people: protocol for the ASPREE-Fracture substudy

BACKGROUND

Disability, mortality and healthcare burden from fractures in older people is a growing problem worldwide. Observational studies suggest that aspirin may reduce fracture risk. While these studies provide room for optimism, randomised controlled trials are needed. This paper describes the rationale and design of the ASPirin in Reducing Events in the Elderly (ASPREE)-Fracture substudy, which aims to determine whether daily low-dose aspirin decreases fracture risk in healthy older people.

METHODS

ASPREE is a double-blind, randomised, placebo-controlled primary prevention trial designed to assess whether daily active treatment using low-dose aspirin extends the duration of disability-free and dementia-free life in 19 000 healthy older people recruited from Australian and US community settings. This substudy extends the ASPREE trial data collection to determine the effect of daily low-dose aspirin on fracture and fall-related hospital presentation risk in the 16 500 ASPREE participants aged ≥70 years recruited in Australia. The intervention is a once daily dose of enteric-coated aspirin (100 mg) versus a matching placebo, randomised on a 1:1 basis. The primary outcome for this substudy is the occurrence of any fracture-vertebral, hip and non-vert-non-hip-occurring post randomisation. Fall-related hospital presentations are a secondary outcome.

DISCUSSION

This substudy will determine whether a widely available, simple and inexpensive health intervention-aspirin-reduces the risk of fractures in older Australians. If it is demonstrated to safely reduce the risk of fractures and serious falls, it is possible that aspirin might provide a means of fracture prevention.

TRIAL REGISTRATION NUMBER

The protocol for this substudy is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12615000347561).

Mean platelet volume and platelet distribution width can be related to bone mineralization

Platelets functions are related to bone resorption and formation. The present study aimed at studying the association between platelet function and bone mineralization. We showed that mean platelet volume (MPV) and platelet distribution width (PDW) levels in osteoporosis patients increased. The study also showed that PDW and age independently associated with bone mineralization.

INTRODUCTION

MPV and PDW are widely used for assessing platelet function. Recently, authors argued that platelet function has an important role in bone mineralization. However, only one study has investigated the relationship between MPV and osteoporosis. We aimed to study the levels of MPV and PDW in postmenopausal osteoporosis.

METHODS

We investigated 320 bone mineral density (BMD) measurements between the years 2012 and 2013 retrospectively in our clinic. Eighty patients whom chronic diseases are absent and all laboratory findings are complete enrolled in this study. Patients were divided in three groups as an osteoporosis, osteopenia, and normal BMD group. MPV and PDW levels were investigated in these groups. We performed correlation test and linear regression analysis to determine whether there is a relationship between platelet function markers and BMD measurements.

RESULTS

Eighty patients were divided as an osteoporosis, osteopenia, and normal BMD group. MPV levels and PDW levels in the osteoporosis group were lower than the normal BMD group. PDW was positively correlated with femur total T (FTT) score and lumbar 1-4T (L1-4T) scores. Linear regression analysis showed that age and PDW were independently related to FTT and LTT scores.

CONCLUSION

Platelet functions are related to the bone mineralization. PDW and MPV have a significant role in the development of postmenopausal osteoporosis.

Purinergic signalling in bone

Purinergic signaling in bone was first proposed in the early 1990s with the observation that extracellular ATP could modulate events crucial to the normal functioning of bone cells. Since then the expression of nearly all the P2Y and P2X receptors by osteoblasts and osteoclasts has been reported, mediating multiple processes including cell proliferation, differentiation, function, and death. This review will highlight the most recent developments in the field of purinergic signaling in bone, with a special emphasis on recent work resulting from the European Framework 7 funded collaboration ATPBone, as well as Arthritis Research UK and Bone Research Society supported projects.

The ADP receptor P2RY12 regulates osteoclast function and pathologic bone remodeling

The adenosine diphosphate (ADP) receptor P2RY12 (purinergic receptor P2Y, G protein coupled, 12) plays a critical role in platelet aggregation, and P2RY12 inhibitors are used clinically to prevent cardiac and cerebral thrombotic events. Extracellular ADP has also been shown to increase osteoclast (OC) activity, but the role of P2RY12 in OC biology is unknown. Here, we examined the role of mouse P2RY12 in OC function. Mice lacking P2ry12 had decreased OC activity and were partially protected from age-associated bone loss. P2ry12-/- OCs exhibited intact differentiation markers, but diminished resorptive function. Extracellular ADP enhanced OC adhesion and resorptive activity of WT, but not P2ry12-/-, OCs. In platelets, ADP stimulation of P2RY12 resulted in GTPase Ras-related protein (RAP1) activation and subsequent αIIbβ3 integrin activation. Likewise, we found that ADP stimulation induced RAP1 activation in WT and integrin β3 gene knockout (Itgb3-/-) OCs, but its effects were substantially blunted in P2ry12-/- OCs. In vivo, P2ry12-/- mice were partially protected from pathologic bone loss associated with serum transfer arthritis, tumor growth in bone, and ovariectomy-induced osteoporosis: all conditions associated with increased extracellular ADP. Finally, mice treated with the clinical inhibitor of P2RY12, clopidogrel, were protected from pathologic osteolysis. These results demonstrate that P2RY12 is the primary ADP receptor in OCs and suggest that P2RY12 inhibition is a potential therapeutic target for pathologic bone loss.