The impact of nonosteogenic factors on the expression of osteoprotegerin and RANKL during human fracture healing

Aging Influences Fracture Healing on the Cellular Level and Alters Systemic RANKL and OPG Concentrations in a Murine Model

Clinical complications frequently follow polytrauma and bleeding fractures, increasing the risk of delayed fracture healing and nonunions, especially in aged patients. Therefore, this study examines age's impact on fracture repair with and without severe bleeding in mice. Young (17-26 weeks) and aged (64-72 weeks) male C57BL/6J mice (n = 72 in total, n = 6 per group) are allocated into 3 groups: the fracture group (Fx) undergoes femur osteotomy stabilized via external fixator, the combined trauma group (THFx) additionally receives pressure-controlled trauma hemorrhage (TH) and Sham animals are implanted with catheter and fixator without blood loss or osteotomy. Femoral bones are evaluated histologically 24 h and 3 weeks post-trauma, while RANKL/OPG and β-CTx are measured systemically via ELISA after 3 weeks. Aging results in less mineralized bone and fewer osteoclasts within the fracture of aged mice in contrast to young groups after three weeks. Systemically, aged animals exhibit increased RANKL and OPG levels after fracture compared to their young counterparts. The RANKL/OPG ratio rises in aged Fx animals compared to young mice, with a similar trend in THFx groups. In conclusion, age has an effect during the later course of fracture healing on the cellular and systemic levels.

Is human immunodeficiency virus a risk factor for the development of nonunion?-a case-control study

OBJECTIVE

Human immunodeficiency virus (HIV) infection has been suggested to be associated with an increased risk of the development of nonunion after a fracture. This prospective matched case-control study in South Africa investigated common risk factors, including HIV status, that influence the development of a nonunion after a femur or tibia fracture.

METHODS

Adult participants (cases) with established nonunions of the femur or tibia shaft were recruited over a 16-month period, between December 2017 and April 2019. They were matched for (1) age; (2) sex; (3) fracture site; and (4) fracture management type, with "control" participants who progressed to fracture union within 6 months of injury. All participants were tested for HIV. Multivariable logistic regression models were constructed to investigate associations between known risk factors for the development of nonunion and impaired fracture healing.

RESULTS

A total of 57 cases were matched with 57 "control" participants (44/57 male, 77.2% vs. 13/57 female, 22.8%, median age 36 years). HIV status was not associated with the development of nonunion after the management of tibia and femur fractures, on both univariate (odds ratio, 0.40; confidence interval, 0.10-1.32; P = 0.151) or multivariable (odds ratio, 0.86; confidence interval, 0.18-3.73; P = 0.831) analysis. No other confounding factors were shown to have any statistically significant impact on the odds of developing nonunion in this study cohort.

CONCLUSION

This study demonstrates that HIV does not seem to increase the risk of the development of nonunion and HIV-positive individuals who sustain a fracture can be managed in the same manner as those who are HIV negative.

The Impact of Angiotensin Converting Enzyme-2 (ACE-2) on Bone Remodeling Marker Osteoprotegerin (OPG) in Post-COVID-19 Iraqi Patients

Introduction As COVID-19 affects human genes in several types of peripheral tissue, numerous disorders occur after recovery. The virus enters host cells via angiotensin-converting enzyme-2 (ACE-2) receptors that affect bone remodeling, leading to osteopenia or osteoporosis, which is characterized by low bone mineral density (BMD). The adult skeleton undergoes about 10% remodeling annually, which is crucial for preventing fatigue damage and preserving calcium homeostasis. An imbalance in the rates of bone production and resorption causes bone loss. Osteoprotegerin (OPG) is one of the regulators involved in the bone remodeling mechanism, it decreases the activity of NF-B receptors that activates the receptor activators of NF-B ligand (RANKL) pathway, which maintains the bone homeostasis balance. This study aims to find out the disruption of bone homeostasis balance in Iraqi post-COVID-19 patients. Materials and methods It is a case-control study that includes 130 Iraqi subjects enrolled. They were divided into two groups - the first group consisted of 80 post-COVID-19 infection patients, while the second group consisted of 50 who were not infected with COVID-19. Also, the levels of ACE-2 and OPG were measured in the serum by the ELISA technique. The BMD was measured by the DEXA scan technique. Results This study found that there is an effect of coronavirus infection on the bone strength measured by the Mean of the OPG level, which was found to be highly significant in the serum of post-COVID-19 patients when compared with non-COVID-19 subjects (P-value = 0.001), but the Mean of ACE-2 level was statistically non-significant between the two groups (P-value = 0.13). Also, the BMD of post-COVID-19 patients that was measured by DEXA scan had a statistically highly significant T-score% between the two groups. Conclusion The current study found that there was an effect of COVID-19 on the bone remodeling mechanism, which may be causing osteopenia or osteoporosis for Iraqi subjects enrolled in the current study. Also, analyzing the OPG level in the serum could be helpful in predicting low BMD.

Effects of physical training on physical and functional fitness, physical activity level, endothelial function, hemodynamic variables, bone metabolism, and quality of life of post-bariatric patients: study protocol for a randomized controlled trial

BACKGROUND

Evidence of the benefits induced from resistance exercise on health markers of post-bariatric patients is limited. The study will investigate the effects of a resistance training (RT) program on muscle mass and strength, bone metabolism biomarkers, bone mineral density (BMD), bone microarchitecture, and endothelial function of patients subjected to Roux-en-Y gastric bypass.

METHODS/DESIGN

This randomized controlled trial will include 60 post-bariatric patients, physically inactive, aging 18 to 50 years, with a post-surgery period ≥ 12 months. They will be randomly assigned into two groups: (i) the non-exercised control group, which will receive the standard clinical follow-up, or (ii) the intervention group which will consist of RT (60 min/session; 3 times/week, for 6 months). The primary outcomes will include muscle mass and strength, bone metabolism biomarkers, BMD, and bone microarchitecture. The secondary outcomes will be anthropometry, hemodynamic measurements, cardiovascular risk factors, health-related quality of life (QoL), and endothelial function. Outcomes will be assessed by blood biomarkers of bone formation and reabsorption, dual X-ray absorptiometry, repetition maximum and handgrip strength tests, high-resolution peripheral quantitative computed tomography, 36-Item Short-Form Health Survey, venous occlusion plethysmography, and nailfold videocapillaroscopy.

DISCUSSION

It is expected that there are greater benefits from the RT program, possibly improving muscle mass and strength, bone metabolism, density and microarchitecture, QoL, and cardiovascular risk.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04193397. Registered on 7 December 2019.

N,N-Dimethylformamide inhibits high glucose-induced osteoporosis via attenuating MAPK and NF-κB signalling

Aims

The role of N,N-dimethylformamide (DMF) in diabetes-induced osteoporosis (DM-OS) progression remains unclear. Here, we aimed to explore the effect of DMF on DM-OS development.

Methods

Diabetic models of mice, RAW 264.7 cells, and bone marrow macrophages (BMMs) were established by streptozotocin stimulation, high glucose treatment, and receptor activator of nuclear factor-κB ligand (RANKL) treatment, respectively. The effects of DMF on DM-OS development in these models were examined by micro-CT analysis, haematoxylin and eosin (H&E) staining, osteoclast differentiation of RAW 264.7 cells and BMMs, H&E and tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assay (ELISA) of TRAP5b and c-terminal telopeptides of type 1 (CTX1) analyses, reactive oxygen species (ROS) analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), Cell Counting Kit-8 (CCK-8) assay, and Western blot.

Results

The established diabetic mice were more sensitive to ovariectomy (OVX)-induced osteoporosis, and DMF treatment inhibited the sensitivity. OVX-treated diabetic mice exhibited higher TRAP5b and c-terminal telopeptides of type 1 (CTX1) levels, and DMF treatment inhibited the enhancement. DMF reduced RAW 264.7 cell viability. Glucose treatment enhanced the levels of TRAP5b, cathepsin K, Atp6v0d2, and H⁺-ATPase, ROS, while DMF reversed this phenotype. The glucose-increased protein levels were inhibited by DMF in cells treated with RANKL. The expression levels of antioxidant enzymes Gclc, Gclm, Ho-1, and Nqo1 were upregulated by DMF. DMF attenuated high glucose-caused osteoclast differentiation by targeting mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signalling in BMMs.

Conclusion

DMF inhibits high glucose-induced osteoporosis by targeting MAPK and NF-κB signalling.

Cite this article: Bone Joint Res 2022;11(4):200–209.

High slew rate pulsed electromagnetic field enhances bone consolidation and shortens daily treatment duration in distraction osteogenesis

Aims

Distraction osteogenesis (DO) is a useful orthopaedic procedure employed to lengthen and reshape bones by stimulating bone formation through controlled slow stretching force. Despite its promising applications, difficulties are still encountered. Our previous study demonstrated that pulsed electromagnetic field (PEMF) treatment significantly enhances bone mineralization and neovascularization, suggesting its potential application. The current study compared a new, high slew rate (HSR) PEMF signal, with different treatment durations, with the standard Food and Drug Administration (FDA)-approved signal, to determine if HSR PEMF is a better alternative for bone formation augmentation.

Methods

The effects of a HSR PEMF signal with three daily treatment durations (0.5, one, and three hours/day) were investigated in an established rat DO model with comparison of an FDA-approved classic signal (three hrs/day). PEMF treatments were applied to the rats daily for 35 days, starting from the distraction phase until termination. Radiography, micro-CT (μCT), biomechanical tests, and histological examinations were employed to evaluate the quality of bone formation.

Results

All rats tolerated the treatment well and no obvious adverse effects were found. By comparison, the HSR signal (three hrs/day) treatment group achieved the best healing outcome, in that endochondral ossification and bone consolidation were enhanced. In addition, HSR signal treatment (one one hr/day) had similar effects to treatment using the classic signal (three three hrs/day), indicating that treatment duration could be significantly shortened with the HSR signal.

Conclusion

HSR signal may significantly enhance bone formation and shorten daily treatment duration in DO, making it a potential candidate for a new clinical protocol for patients undergoing DO treatments.

Cite this article: Bone Joint Res 2021;10(12):767–779.

Osteoblast function in patients with idiopathic osteonecrosis of the femoral head : implications for a possible novel therapy

Aims

To investigate whether idiopathic osteonecrosis of the femoral head (ONFH) is related to impaired osteoblast activities.

Methods

We cultured osteoblasts isolated from trabecular bone explants taken from the femoral head and the intertrochanteric region of patients with idiopathic ONFH, or from the intertrochanteric region of patients with osteoarthritis (OA), and compared their viability, mineralization capacity, and secretion of paracrine factors.

Results

Osteoblasts from the intertrochanteric region of patients with ONFH showed lower alkaline phosphatase (ALP) activity and mineralization capacity than osteoblasts from the same skeletal site in age-matched patients with OA, as well as lower messenger RNA (mRNA) levels of genes encoding osteocalcin and bone sialoprotein and higher osteopontin expression. In addition, osteoblasts from patients with ONFH secreted lower osteoprotegerin (OPG) levels than those from patients with OA, resulting in a higher receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) ligand (RANKL)-to-OPG ratio. In patients with ONFH, osteoblasts from the femoral head showed reduced viability and mineralized nodule formation compared with osteoblasts from the intertrochanteric region. Notably, the secretion of the pro-resorptive factors interleukin-6 and prostaglandin E₂ as well as the RANKL-to-OPG ratio were markedly higher in osteoblast cultures from the femoral head than in those from the intertrochanteric region.

Conclusion

Idiopathic ONFH is associated with a reduced mineralization capacity of osteoblasts and increased secretion of pro-resorptive factors.

Cite this article: Bone Joint Res 2021;10(9):619–628.