Aspirin effect on bone remodeling and skeletal regeneration: Review article

Aspirin/amoxicillin loaded chitosan microparticles and polydopamine modified titanium implants to combat infections and promote osteogenesis

It is known that titanium (Ti) implant surfaces exhibit poor antibacterial properties and osteogenesis. In this study, chitosan particles loaded with aspirin, amoxicillin or aspirin + amoxicillin were synthesized and coated onto implant surfaces. In addition to analysing the surface characteristics of the modified Ti surfaces, the effects of the modified Ti surfaces on the adhesion and viability of rat bone marrow-derived stem cells (rBMSCs) were evaluated. The metabolic activities of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) biofilms on the modified Ti surfaces were also measured in vitro. Moreover, S. aureus was tested for its antibacterial effect by coating it in vivo. Using water as the droplet medium, the contact angles of the modified Ti surfaces increased from 44.12 ± 1.75° to 58.37 ± 4.15°. In comparison to those of the other groups tested, significant increases in rBMSC adhesion and proliferation were observed in the presence of aspirin + amoxicillin-loaded microspheres, whereas a significant reduction in the metabolic level of biofilms was observed in the presence of aspirin + amoxicillin-loaded microspheres both in vitro and in vivo. Aspirin and amoxicillin could be used in combination to coat implant surfaces to mitigate bacterial activities and promote osteogenesis.

The effect of low-frequency high-intensity ultrasound combined with aspirin on tooth movement in rats

BACKGROUND

Given the difficulties or incapacity of teeth movement in orthodontic treatment, the ways to speed tooth movement must be investigated. Besides, nonsteroidal anti-inflammatory drugs (NSAIDs) were utilized to treat pain caused by tooth movement during orthodontic treatment. The purpose of this study is to examine the impact of aspirin and low-frequency high-intensity ultrasound (LFHIU) on rat orthodontic tooth movement in rats.

METHODS

Thirty-six male Sprague-Dawley rats were divided into three groups: orthodontic (O), ultrasound-treated orthodontic (OU), and ultrasound-treated orthodontic with aspirin gavage (OUA) group. In the OU and OUA group, LFHIU (44 W/cm2, 28 kHz) was applied to the buccal side of the maxillary first molar alveolar bone for 10 s every day. In the OUA group, aspirin was given by gavage every day. The rats were sacrificed on days 1, 3, 7, and 14.

RESULTS

After ultrasonic treatment, the speed of tooth movement was increased by about 1.5 times. And the number of osteoclasts considerably increased by about 2 times. However, they decreased slightly after aspirin gavage. By Applying ultrasound therapy, Receptor Activator for Nuclear Factor-κ B Ligand (RANKL) levels in periodontal tissue were elevated. Aspirin was able to reduce these increases. Results from Micro Computed Tomography (Micro-CT) revealed that bone mineral density decreased by about 1/5 after ultrasound treatment on the compression side. The rate of bone mineral apposition indicated that bone was forming under tension, and that of the OU group increased by about 1.3 times that O group.

CONCLUSIONS

Although aspirin slowed this trend, LFHIU still enhanced overall tooth mobility in orthodontic treatment.

Osteogenic and anti-inflammatory effect of the multifunctional bionic hydrogel scaffold loaded with aspirin and nano-hydroxyapatite

Although tissue engineering offered new approaches to repair bone defects, it remains a great challenge to create a bone-friendly microenvironment and rebuild bone tissue rapidly by a scaffold with a bionic structure. In this study, a multifunctional structurally optimized hydrogel scaffold was designed by integrating polyvinyl alcohol (PVA), gelatin (Gel), and sodium alginate (SA) with aspirin (ASA) and nano-hydroxyapatite (nHAP). The fabrication procedure is through a dual-crosslinking process. The chemical constitution, crystal structure, microstructure, porosity, mechanical strength, swelling and degradation property, and drug-release behavior of the hydrogel scaffold were analyzed. Multi-hydrogen bonds, electrostatic interactions, and strong "egg-shell" structure contributed to the multi-network microstructure, bone tissue-matched properties, and desirable drug-release function of the hydrogel scaffold. The excellent performance in improving cell viability, promoting cell osteogenic differentiation, and regulating the inflammatory microenvironment of the prepared hydrogel scaffold was verified using mouse pre-osteoblasts (MC3T3-E1) cells. And the synergistic osteogenic and anti-inflammatory functions of aspirin and nano-hydroxyapatite were also verified. This study provided valuable insights into the design, fabrication, and biological potential of multifunctional bone tissue engineering materials with the premise of constructing a bone-friendly microenvironment.

Daily Low-Dose Aspirin and Risk of Serious Falls and Fractures in Healthy Older People: A Substudy of the ASPREE Randomized Clinical Trial

Importance

Falls and fractures are frequent and deleterious to the health of older people. Aspirin has been reported to reduce bone fragility and slow bone loss.

Objective

To determine if daily low-dose aspirin (100 mg) reduces the risk of fractures or serious falls (fall-related hospital presentations) in healthy older men and women.

Design, Setting, and Participants

This substudy of a double-blind, randomized, placebo-controlled trial studied older adult men and women in 16 major sites across southeastern Australia. The ASPREE-FRACTURE substudy was conducted as part of the Australian component of the ASPREE trial. Between 2010 and 2014 healthy (free of cardiovascular disease, dementia or physical disability), community-dwelling volunteers aged 70 years or older were recruited to participate in the ASPREE trial. Potentially eligible participants were identified by medical practitioners and trial personnel and were then sent a letter of invitation to participate. Interested participants were screened for suitability. Eligible participants with medical practitioner authorization and adherent to a 4-week run-in medication trial were randomized. Data were analyzed from October 17, 2019, to August 31, 2022.

Interventions

Participants in the intervention group received a daily dose of oral 100 mg enteric-coated (low-dose) aspirin. The control group received a daily identical enteric-coated placebo tablet.

Main Outcomes and Measures

The primary outcome of ASPREE-FRACTURE was the occurrence of any fracture. The secondary outcome was serious fall resulting in hospital presentation.

Results

In total, 16 703 people with a median (IQR) age of 74 (72-78) years were recruited, and 9179 (55.0%) were women. There were 8322 intervention participants and 8381 control participants included in the primary and secondary outcome analysis of 2865 fractures and 1688 serious falls over the median follow-up of 4.6 years. While there was no difference in the risk of first fracture between the intervention and control participants (hazard ratio, 0.97; 95% CI, 0.87-1.06; P = .50), aspirin was associated with a higher risk of serious falls (total falls 884 vs 804; incidence rate ratio, 1.17; 95% CI, 1.03-1.33; P = .01). Results remained unchanged in analyses that adjusted for covariates known to influence fracture and fall risk.

Conclusions and Relevance

In this substudy of a randomized clinical trial, the failure of low-dose aspirin to reduce the risk of fractures while increasing the risk of serious falls adds to evidence that this agent provides little favorable benefit in a healthy, White older adult population.

Trial Registration

This substudy is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12615000347561).

A Biomimetic Smart Nanoplatform as “Inflammation Scavenger” for Regenerative Therapy of Periodontal Tissue

Introduction

The functional reconstruction of periodontal tissue defects remains a clinical challenge due to excessive and prolonged host response to various endogenous and exogenous pro-inflammatory stimuli. Thus, a biomimetic nanoplatform with the capability of modulating inflammatory response in a microenvironment-responsive manner is attractive for regenerative therapy of periodontal tissue.

Methods

Herein, a facile and green design of engineered bone graft materials was developed by integrating a biomimetic apatite nanocomposite with a smart-release coating, which could realize inflammatory modulation by “on-demand” delivery of the anti-inflammatory agent through a pH-sensing mechanism.

Results

In vitro and in vivo experiments demonstrated that this biocompatible nanoplatform could facilitate the clearance of reactive oxygen species in human periodontal ligament stem cells under inflammatory conditions via inhibiting the production of endogenous proinflammatory mediators, in turn contributing to the enhanced healing efficacy of periodontal tissue. Moreover, this system exhibited effective antimicrobial activity against common pathogenic bacteria in the oral cavity, which is beneficial for the elimination of exogenous pro-inflammatory factors from bacterial infection during healing of periodontal tissue.

Conclusion

The proposed strategy provides a versatile apatite nanocomposite as a promising “inflammation scavenger” and propels the development of intelligent bone graft materials for periodontal and orthopedic applications.

Anti-Inflammatory and Mineralization Effects of an ASP/PLGA-ASP/ACP/PLLA-PLGA Composite Membrane as a Dental Pulp Capping Agent

Dental pulp is essential for the development and long-term preservation of teeth. Dental trauma and caries often lead to pulp inflammation. Vital pulp therapy using dental pulp-capping materials is an approach to preserving the vitality of injured dental pulp. Most pulp-capping materials used in clinics have good biocompatibility to promote mineralization, but their anti-inflammatory effect is weak. Therefore, the failure rate will increase when dental pulp inflammation is severe. The present study developed an amorphous calcium phosphate/poly (L-lactic acid)-poly (lactic-co-glycolic acid) membrane compounded with aspirin (hereafter known as ASP/PLGA-ASP/ACP/PLLA-PLGA). The composite membrane, used as a pulp-capping material, effectively achieved the rapid release of high concentrations of the anti-inflammatory drug aspirin during the early stages as well as the long-term release of low concentrations of aspirin and calcium/phosphorus ions during the later stages, which could repair inflamed dental pulp and promote mineralization. Meanwhile, the composite membrane promoted the proliferation of inflamed dental pulp stem cells, downregulated the expression of inflammatory markers, upregulated the expression of mineralization-related markers, and induced the formation of stronger reparative dentin in the rat pulpitis model. These findings indicate that this material may be suitable for use as a pulp-capping material in clinical applications.