Trauma-induced inflammation and fracture healing

Does Scheduled Low-Dose Short-Term NSAID (Ketorolac) Modulate Cytokine Levels After Orthopaedic Polytrauma? A Secondary Analysis of a Randomized Clinical Trial

OBJECTIVES

To determine whether scheduled low-dose, short-term ketorolac modulates cytokine concentrations in orthopaedic polytrauma patients.

METHODS

DESIGN

Secondary analysis of a double-blinded, randomized controlled trial.

SETTING

Single Level I trauma center from August 2018 to October 2022.

PATIENT SELECTION CRITERIA

Orthopaedic polytrauma patients between 18 and 75 years with a New Injury Severity Score greater than 9 were enrolled. Participants were randomized to receive 15 mg of intravenous ketorolac every 6 hours for up to 5 inpatient days or 2 mL of intravenous saline similarly.

OUTCOME MEASURES AND COMPARISONS

Daily concentrations of prostaglandin E2 and interleukin (IL)-1a, IL-1b, IL-6, and IL-10. Clinical outcomes included hospital and intensive care unit length of stay, pulmonary complications, and acute kidney injury.

RESULTS

Seventy orthopaedic polytrauma patients were enrolled, with 35 participants randomized to the ketorolac group and 35 to the placebo group. The overall IL-10 trend over time was significantly different in the ketorolac group ( P = 0.043). IL-6 was 65.8% higher at enrollment compared to day 3 ( P < 0.001) when aggregated over both groups. There was no significant treatment effect for prostaglandin E2, IL-1a, or IL-1b ( P > 0.05). There were no significant differences in clinical outcomes between groups ( P > 0.05).

CONCLUSIONS

Scheduled low-dose, short-term, intravenous ketorolac was associated with significantly different mean trends in IL-10 concentration in orthopaedic polytrauma patients with no significant differences in prostaglandin E2, IL-1a, IL-1b, or IL-6 levels between groups. The treatment did not have an impact on clinical outcomes of hospital or intensive care unit length of stay, pulmonary complications, or acute kidney injury.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

The Impact of Defect Size on Bone Healing in Critical-Size Bone Defects Investigated on a Rat Femur Defect Model Comparing Two Treatment Methods

Critical-size bone defects up to 25 cm can be treated successfully using the induced membrane technique established by Masquelet. To shorten this procedure, human acellular dermis (HAD) has had success in replacing this membrane in rat models. The aim of this study was to compare bone healing for smaller and larger defects using an induced membrane and HAD in a rat model. Using our established femoral defect model in rats, the animals were placed into four groups and defects of 5 mm or 10 mm size were set, either filling them with autologous spongiosa and surrounding the defect with HAD or waiting for the induced membrane to form around a cement spacer and filling this cavity in a second operation with a cancellous bone graft. Healing was assessed eight weeks after the operation using µ-CT, histological staining, and an assessment of the progress of bone formation using an established bone healing score. The α-smooth muscle actin used as a signal of blood vessel formation was stained and counted. The 5 mm defects showed significantly better bone union and a higher bone healing score than the 10 mm defects. HAD being used for the smaller defects resulted in a significantly higher bone healing score even than for the induced membrane and significantly higher blood vessel formation, corroborating the good results achieved by using HAD in previous studies. In comparison, same-sized groups showed significant differences in bone healing as well as blood vessel formation, suggesting that 5 mm defects are large enough to show different results in healing depending on treatment; therefore, 5 mm is a viable size for further studies on bone healing.

Levels of 91 circulating inflammatory proteins and risk of lumbar spine and pelvic fractures and peripheral ligament injuries: a two-sample mendelian randomization study

OBJECTIVE

Lumbar spine and pelvic fractures(LPF) are combined with peripheral ligament injuries(PLI), frequently. It has been reported that the site of fracture injury is usually paralleled by the secretion of inflammatory proteins. This study aimed to investigate the causal relationship between 91 circulating inflammatory proteins and LPF and PLI by using a Two-sample Mendelian randomization (MR) analysis.

METHODS

Single nucleotide polymorphisms (SNPs) associated with 91 circulating inflammatory proteins, as exposures were selected from a large genome-wide association study (GWAS). The genetic variant data for LPF and PLI as outcomes from the FinnGen consortium. The inverse-variance-weighted (IVW) method was utilized as the main analysis for exposures and outcomes. In addition, the final results were reinforced by the methods of MR Egger, weighted median, simple mode, and weighted mode. The sensitivity analyses were used to validate the robustness of results and ensure the absence of heterogeneity and horizontal pleiotropy. MR-Steiger was used to assess whether the causal direction was correct to avoid reverse causality.

RESULTS

This study has shown that Beta-nerve growth factor(Beta-NGF) and Interferon gamma(IFN-gamma) are both involved in the occurrence of LPF and PLI, and they are reducing the risk of occurrence(OR:0.800, 95%CI: 0.650-0.983; OR:0.723, 95%CI:0.568-0.920 and OR:0.812, 95%CI:0.703-0.937; OR:0.828, 95%CI:0.700-0.980). Similarly, Axin-1 and Sulfotransferase 1A1 (SULT-1A1) were causally associated with LPF(OR:0.687, 95%CI:0.501-0.942 and OR:1.178,95%CI:1.010-1.373). Furthermore, Interleukin-4(IL-4), Macrophage inflammatory protein 1a(MIP-1a), and STAM binding protein(STAM-BP) were causally associated with PLI(OR:1.236, 95% CI: 1.058-1.443; OR:1.107, 95% CI: 1.008-1.214 and OR:0.759, 95% CI: 0.617-0.933). The influence of heterogeneity and horizontal pleiotropy were further excluded by sensitivity analysis.

CONCLUSION

This study provides new insights into the relationship between circulating inflammatory proteins and LPF and PLI, and may provide new clues for predicting this risk.

Permissive Weight Bearing in Patients With Surgically Treated Periprosthetic Femoral Fractures Around Total Hip Arthroplasty: A Scoping Review

Periprosthetic femoral fractures (PPFF) around total hip arthroplasty (THA) are one of the leading causes of hip revision. High mortality rates are observed after revision in case of PPFF around THA. To modify risk factors, early postoperative mobilization is necessary. Permissive weight bearing (PWB) is designed to optimize clinical recovery in aftercare. This study aimed to perform a scoping review to summarize the current available evidence on postoperative weight bearing in late PPFF around THA and the implementation of PWB in aftercare. A systematic search was performed on the Cochrane Library, Web of Science, Ovid MEDLINE, EMBASE, and CINAHL databases on January 26th, 2023. Articles were screened in two stages by two independent reviewers. Studies describing adult patients with a history of primary THA who were surgically treated for late PPFF and mentioning prescribed postoperative weight-bearing protocols with relevant outcome measures were included. Seven studies were included, reporting data on 22 patients (age range 47-97 years, BMI range 19-32 kg/m2, ASA classification range 2-3). No studies used PWB in aftercare. The non-weight-bearing group showed no complications. The restricted weight-bearing group had one death and one implant failure. The full weight-bearing group experienced one deep infection and one plate removal because of impingement. The main finding was that, after an extensive systematic search, no articles could be included focusing on PWB in patients with a late PPFF after THA. Addressing this gap in the literature is essential to advancing the understanding of postoperative weight-bearing protocols and PWB for late PPFF around THA.

Nondestructive and high-resolution monitoring of inflammation-type skull defects regeneration on adult zebrafish with optical coherence tomography

Optimized animal models and effective imaging techniques are exceedingly important to study cranial defects in bone loss due to chronic inflammation. In this study, the assessment procedure on a zebrafish inflammation-type skull defects model was monitored in vivo with spectral-domain optical coherence tomography (SD-OCT), and the efficacy of etidronate disodium in bone regeneration was assessed. An acute skull defect injury model was established in adult zebrafish using a stereotaxic craniotomy device. SD-OCT imaging was performed immediately following the mechanical injury. Both SD-OCT and immunohistochemistry results demonstrated an increase in inflammation-induced skull destruction within 5 days, which was confirmed by pathological experiments.

Bioinformatic analysis of the molecular mechanisms underlying the progression of bone defects

Background

The pathophysiology of bone defects (BDs) is complex, and the treatment for bone defects, in particular massive bone defects, remains a major clinical challenge. Our study was conducted to explore the molecular events related to the progression of bone defects a common clinical condition.

Methods

First, microarray data of GSE20980 were obtained from the Gene Expression Omnibus (GEO) database, where 33 samples in total were used to analyze the molecular biological processes related to bone defects. Next, the original data were normalized and differentially expressed genes (DEGs) were identified. Additionally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted. Finally, a protein-protein interaction (PPI) network was constructed and the trends of the different genes were confirmed.

Results

Compared with the samples of non-critical size defects (NCSD), the samples of critical size defects (CSD) had 2057, 827, and 1,024 DEGs at 7, 14, and 21 days post injury, respectively. At day 7, the DEGs were significantly enriched in metabolic pathways, at day 14 the DEGs were predominantly enriched in G-protein coupled signaling pathways and the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, and at day 21 the DEGs were mainly enriched in circadian entrainment and synaptic-related functions. The PPI network showed similar results. Quantitative real-time PCR (qRT-PCR) and western blot (WB) were performed to validate the partial results of sequencing.

Conclusion

This study provides some clues about the molecular mechanism behind bone defects, which should contribute to scientific research and clinical treatment of this condition.

Impact of a Femoral Fracture on Outcome after Traumatic Brain Injury-A Matched-Pair Analysis of the TraumaRegister DGU®

Traumatic brain injury (TBI) is the leading cause of death and disability in polytrauma and is often accompanied by concomitant injuries. We conducted a retrospective matched-pair analysis of data from a 10-year period from the multicenter database TraumaRegister DGU^® to analyze the impact of a concomitant femoral fracture on the outcome of TBI patients. A total of 4508 patients with moderate to critical TBI were included and matched by severity of TBI, American Society of Anesthesiologists (ASA) risk classification, initial Glasgow Coma Scale (GCS), age, and sex. Patients who suffered combined TBI and femoral fracture showed increased mortality and worse outcome at the time of discharge, a higher chance of multi-organ failure, and a rate of neurosurgical intervention. Especially those with moderate TBI showed enhanced in-hospital mortality when presenting with a concomitant femoral fracture (p = 0.037). The choice of fracture treatment (damage control orthopedics vs. early total care) did not impact mortality. In summary, patients with combined TBI and femoral fracture have higher mortality, more in-hospital complications, an increased need for neurosurgical intervention, and inferior outcome compared to patients with TBI solely. More investigations are needed to decipher the pathophysiological consequences of a long-bone fracture on the outcome after TBI.

The Putative Role of Neuroinflammation in the Interaction between Traumatic Brain Injuries, Sleep, Pain and Other Neuropsychiatric Outcomes: A State-of-the-Art Review

Sleep disturbances are widely prevalent following a traumatic brain injury (TBI) and have the potential to contribute to numerous post-traumatic physiological, psychological, and cognitive difficulties developing chronically, including chronic pain. An important pathophysiological mechanism involved in the recovery of TBI is neuroinflammation, which leads to many downstream consequences. While neuroinflammation is a process that can be both beneficial and detrimental to individuals' recovery after sustaining a TBI, recent evidence suggests that neuroinflammation may worsen outcomes in traumatically injured patients, as well as exacerbate the deleterious consequences of sleep disturbances. Additionally, a bidirectional relationship between neuroinflammation and sleep has been described, where neuroinflammation plays a role in sleep regulation and, in turn, poor sleep promotes neuroinflammation. Given the complexity of this interplay, this review aims to clarify the role of neuroinflammation in the relationship between sleep and TBI, with an emphasis on long-term outcomes such as pain, mood disorders, cognitive dysfunctions, and elevated risk of Alzheimer's disease and dementia. In addition, some management strategies and novel treatment targeting sleep and neuroinflammation will be discussed in order to establish an effective approach to mitigate long-term outcomes after TBI.

A non-invasive smart scaffold for bone repair and monitoring

Existing strategies for bone defect repair are difficult to monitor. Smart scaffold materials that can quantify the efficiency of new bone formation are important for bone regeneration and monitoring. Carbon nanotubes (CNT) have promising bioactivity and electrical conductivity. In this study, a noninvasive and intelligent monitoring scaffold was prepared for bone regeneration and monitoring by integrating carboxylated CNT into chemically cross-linked carboxymethyl chitosan hydrogel. CNT scaffold (0.5% w/v) demonstrated improved mechanical properties with good biocompatibility and electrochemical responsiveness. Cyclic voltammetry and electrochemical impedance spectroscopy of CNT scaffold responded sensitively to seed cell differentiation degree in both cellular and animal levels. Interestingly, the CNT scaffold could make up the easy deactivation shortfall of bone morphogenetic protein 2 by sustainably enhancing stem cell osteogenic differentiation and new bone tissue formation through CNT roles. This research provides new ideas for the development of noninvasive and electrochemically responsive bioactive scaffolds, marking an important step in the development of intelligent tissue engineering.

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Existing strategies for bone defect repair are difficult to monitor.

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In this study, a noninvasive and intelligent monitoring scaffold was prepared for bone regeneration and monitoring.

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This scaffold was a combination of CNT integrated into a chemically cross-linked carboxymethyl chitosan hydrogel.

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CNT scaffold showed improved mechanical properties with biocompatibility and electrochemical responsiveness.

Mast Cells Drive Systemic Inflammation and Compromised Bone Repair After Trauma

There is evidence that mast cells contribute to inflammation induced by hemorrhagic shock, severe tissue injury or sepsis. Mast cells are highly responsive to alarm signals generated after trauma, and release many inflammatory mediators including interleukin-6, a key mediator of posttraumatic inflammation. An overwhelming posttraumatic inflammation causes compromised bone healing; however, the underlying cellular and molecular mechanisms are poorly understood. Recently, we found that mast cells trigger local and systemic inflammation after isolated fracture leading to uneventful bone repair. Here, we investigated whether mast cells critically contribute to trauma-induced compromised bone healing. Male Mcpt5-Cre⁺ R-DTA mice, which lack connective tissue type mast cells, and their mast cell-competent Cre^- littermates underwent a femur fracture with/without thoracic trauma. Posttraumatic systemic and local inflammation and bone repair were assessed 3 h and 21 d post injury. Both, the systemic and pulmonary inflammation was significantly increased in mast cell-competent mice upon combined trauma compared to isolated fracture. In mast cell-deficient mice, the increase of inflammatory mediators in the circulation induced by the severe trauma was abolished. In the bronchoalveolar lavage fluid, the trauma-induced increase of inflammatory cytokines was not reduced, but the neutrophil invasion into the lungs was significantly diminished in the absence of mast cells. Locally in the fracture hematoma, mast cell-competent mice displayed reduced inflammatory mediator concentrations after combined trauma compared to isolated fracture, which was abolished in mast cell-deficient mice. Notably, while combined trauma resulted in compromised bone repair in mast cell-competent mice, indicated by significantly reduced bone and increased cartilage fracture callus contents, this was abolished in Mcpt5-Cre⁺ R-DTA mice. Therefore, mast cells contribute to trauma-induced compromised bone repair and could be a potential target for new treatment options to improve fracture healing in multiply injured patients.

Macrophage-Osteoclast Associations: Origin, Polarization, and Subgroups

Cellular associations in the bone microenvironment are involved in modulating the balance between bone remodeling and resorption, which is necessary for maintaining a normal bone morphology. Macrophages and osteoclasts are both vital components of the bone marrow. Macrophages can interact with osteoclasts and regulate bone metabolism by secreting a variety of cytokines, which make a significant contribution to the associations. Although, recent studies have fully explored either macrophages or osteoclasts, indicating the significance of these two types of cells. However, it is of high importance to report the latest discoveries on the relationships between these two myeloid-derived cells in the field of osteoimmunology. Therefore, this paper reviews this topic from three novel aspects of the origin, polarization, and subgroups based on the previous work, to provide a reference for future research and treatment of bone-related diseases.

Effects of Collagen- and Arginine-Fortified Osteokine Supplementation on Fracture Healing

Introduction

Delayed union or nonunion is an important clinical challenge for orthopedic surgeons. In addition to the main treatment algorithms, the use of nutritional supplements is increasingly common. In this study, we investigated the effects of nutritional supplements fortified with arginine and collagen on fracture healing.

Materials and methods

Twenty-four rats with femur fractures were divided into experimental and control groups. Intramedullary fixation was performed in both groups. 20 ml/kg nutritional supplement was given to the experimental group. Radiological examination was performed at third and sixth weeks, and histopathological examination was performed at the sixth week.

Results

No statistically significant difference was found between the radiological scores of the groups at the third and sixth weeks. Nutritional supplement affected the histological properties of callus. Histological evidence of bone healing was observed by the sixth week in both groups but the score was higher in nutritional supplement group. A statistically significant difference was found between the histopathological scores of the groups at the sixth week.

Conclusion

Arginine- and type two collagen-augmented traditional nutritional supplements may help to achieve more successful results in fracture healing.

Missed pathological femoral neck fracture undergoes spontaneous healing

Pathologic fractures are common complications of metastatic bone disease in patients with breast cancer. Fractures involving the proximal femur generally cause significant pain that is exacerbated by ambulation. Due to excessive stress on the weight-bearing hip joint, these fractures present a significant burden on the quality of life among patients. Here we describe a case of a 38-year-old female patient who was found to have a pathologic fracture of the proximal femur missed on imaging studies that underwent spontaneous union. Pathologic fractures rarely heal on their own, since a tumor at the fracture site interferes with bone healing and most fractures have to be managed with surgical intervention. Fractures can be missed on imaging studies in the setting of extensive metastatic disease. Physicians should be cognizant of this fact and maintain a high level of suspicion to recognize fractures with unusual presentations where patients may not present with the typical findings of acute onset of pain and inability to ambulate or bear weight.

Platelet-Rich Plasma for Bone Fracture Treatment: A Systematic Review of Current Evidence in Preclinical and Clinical Studies

Background: Recently, there is an increasing interest in the therapeutic potential of platelet-rich plasma (PRP) for bone fracture treatment. Nevertheless, the effect of PRP for bone fracture treatment remains controversial and is still a matter of discussion. Therefore, we performed a systematic review to evaluate the efficacy and safety of PRP injection for treatment of bone fracture. Methods: The main bibliographic databases, including Medline, PubMed, Embase, Web of Science, and the Cochrane library, were comprehensively searched for studies focusing on the application of platelet-rich plasma (PRP) on bone fracture treatment. All relevant articles were screened for eligibility and subdivided into the preclinical and clinical studies. Data were extracted and presented systematically. Results: Finally, twenty-six in vitro preclinical studies (basic studies), nine in vivo preclinical studies (animal studies), and nine clinical studies, met the selection criteria, and were included in the present systematic review. Preclinical studies showed an overall positive effect of PRP on osteoblast-like cells in vitro and bone healing in animal models. The most used treatment for bone fracture in animal and clinical studies is fixation surgery combined with PRP injection. The clinical studies reported PRP shortened bony healing duration, and had no positive effect on improving the healing rate of closed fractures. However, the results of functional outcomes are controversial. Additionally, compared with control group, PRP would not increase the rate of postoperative wound infection. Conclusion: The present systematic review confirmed the continuing interests of PRP as an additional treatment for bone fracture. Preclinical studies highlighted the potential value of PRP as promising therapy for bone fracture. However, the preclinical evidence did not translate into a similar result in the clinical studies. In addition, types of fractures and procedures of PRP preparation are heterogeneous in enrolled studies, which might result in controversial results. Meanwhile, characteristics of PRP, such as platelet concentration, the numbers of leukocytes, still need to be determined and further research is required.

Effect of coenzyme Q10 supplementation on oxidative stress and clinical outcomes in patients with low levels of coenzyme Q10 admitted to the intensive care unit

Today, trauma is known to be the third leading cause of death in most countries. Studies have demonstrated below-normal plasma levels of antioxidants in trauma patients. The present study aimed to assess the efficacy of Coenzyme Q10 (CoQ10) on oxidative stress, clinical outcomes and anthropometrical parameters in traumatic mechanical ventilated patients admitted to the intensive care unit. Patients were randomised to receive sublingual CoQ10 (400 mg/d) or placebo for 7 d. Primary and secondary outcomes were measured at the baseline and end of the study. We enrolled forty patients for this trial: twenty in the CoQ10 group and twenty in the placebo group. There was not any significant difference in the baseline variables (P > 0⋅05). At the end of the study, CoQ10 administration caused a considerable reduction in the Malondialdehyde (MDA) and Interleukin 6 (IL-6) concentrations (P < 0⋅001), Glasgow Coma Score (GCS; P = 0⋅02), ICU and hospital length of stay and mechanical ventilation (MV) duration (P < 0⋅001). We found that CoQ10 administration could increase Fat-Free Mass (P < 0⋅001) (FFM; P = 0⋅04), Skeletal Muscle Mass (SMM; P = 0⋅04) and Body Cell Mass (BCM) percent (P = 0⋅03). There was not any significant difference in other factors between the two groups (P > 0⋅05). CoQ10 administration has beneficial effects on patients with traumatic injury and has no side effects. However, since the possibility of the type II error was high, the outcomes on the duration of MV, ICU stay and hospital stay, and GCS may very well be false positives.

Impact of Orthodontic Forces on Plasma Levels of Markers of Bone Turnover and Inflammation in a Rat Model of Buccal Expansion

Plasma levels of protein analytes might be markers to predict and monitor the kinetics of bone and tissue remodeling, including maximization of orthodontic treatment stability. They could help predict/prevent and/or diagnose possible adverse effects such as bone dehiscences, gingival recession, or root resorption. The objective of this study was to measure plasma levels of markers of bone turnover and inflammation during orthodontic force application in a rat model of orthodontic expansion. Two different orthodontic forces for bilateral buccal expansion of the maxillary arches around second and third molars were applied in 10 rats equally distributed in low-force (LF) or conventional force (CF) groups. Four rats served as the control group. Blood samples were collected at days 0, 1, 2, 3, 6, 13, 21, and 58. Longitudinal concentrations of osteoprotegerin (OPG), soluble receptor activator of nuclear factor kappaB ligand (sRANKL), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor α (TNF), and parathyroid hormone (PTH) were determined in blood samples by a multiplex immunoassay. CF and LF resulted in a significantly maxillary skeletal expansion while the CF group demonstrated significantly higher expansion than the LF group in the long term. Bone turnover demonstrated a two-phase response. During the “early phase” (up to 6 days of force application), LF resulted in more sRANKL expression and increased sRANKL/OPG ratio than the CF and control animals. There was a parallel increase in PTH levels in the early phase in response to LF. During the “late phase” (6–58 days), the markers of bone turnover were stable in both groups. IL-4, IL-6, and IL-10 levels did not significantly change the test groups throughout the study. These results suggest that maxillary expansion in response to different orthodontic forces follows different phases of bone turnover that may be force specific.

The Effect of Diclofenac Sodium-Loaded PLGA Rods on Bone Healing and Inflammation: A Histological and Histomorphometric Study in the Femur of Rats

Implants made of poly(lactide-co-glycolide) (PLGA) are biodegradable and frequently provoke foreign body reactions (FBR) in the host tissue. In order to modulate the inflammatory response of the host tissue, PLGA implants can be loaded with anti-inflammatory drugs. The aim of this study was to analyze the impact of PLGA 80/20 rods loaded with the diclofenac sodium (DS) on local tissue reactions in the femur of rats. Special emphasis was put on bone regeneration and the presence of multinucleated giant cells (MGCs) associated with FBR. PLGA 80/20 alone and PLGA 80/20 combined with DS was extruded into rods. PLGA rods loaded with DS (PLGA+DS) were implanted into the femora of 18 rats. Eighteen control rats received unloaded PLGA rods. The follow-up period was of 3, 6 and 12 weeks. Each group comprised of six rats. Peri-implant tissue reactions were histologically and histomorphometrically evaluated. The implantation of PLGA and PLGA+DS8 rods induced the formation of a layer of newly formed bone islands parallel to the contour of the implants. PLGA+DS rods tended to reduce the presence of multi-nucleated giant cells (MGCs) at the implant surface. Although it is known that the systemic administration of DS is associated with compromised bone healing, the local release of DS via PLGA rods did not have negative effects on bone regeneration in the femora of rats throughout 12 weeks.

Patient-dependent factors for fractures union failure among Riyadh population 2016

Background:

The primary care has an important role to prevent fractures and make sure of complete healing without any complications like a Malunion which arises when a fracture has healed in a non-anatomical position, and a delayed union which defined as a healing time of more than 12 weeks and a non-union which occurs when absence of fracture healing progression on series of radiographs or with no evidence of healing over 10 weeks.

Objectives:

To identify the proportion of fracture healing failure types and identify Patient-dependent Factors.

Methodology:

cross sectional study consecutive sampling till completing sample size (90) patients. Data collection tool was Pretested Pre-Coded self-administered questionnaire it was subjected to a probe to test for validity and reliability. Data analyzed Using SPSS P value of less than 0.05 considered as significant results. Chi-square test was the test of significance.

Results:

From 90 adult male participants, 71% were 35 years of age and above and below 55 years. Our result indicated that the commonest risk factor was smoking in 62.2% of respondents, and 27.8% have Diabetes mellitus. 50% of fractures failure was diagnosed as delayed union while non-union accounts for 40% and malunion for 10%. We've noticed that smokers mostly had delayed union, while diabetic patients had mostly non-union.

Conclusion:

the study found that the most associating Patient-dependent Factors were cigarettes smoking and Diabetes mellitus, also most fractures failure were diagnosed as delayed union, non-union, and malunion respectively and we can help prevent these complications by controlling DM and stop cigarettes smoking.

MicroRNA-186 improves fracture healing through activating the bone morphogenetic protein signalling pathway by inhibiting SMAD6 in a mouse model of femoral fracture: An animal study

Objectives

MicroRNAs (miRNAs) have been reported as key regulators of bone formation, signalling, and repair. Fracture healing is a proliferative physiological process where the body facilitates the repair of a bone fracture. The aim of our study was to explore the effects of microRNA-186 (miR-186) on fracture healing through the bone morphogenetic protein (BMP) signalling pathway by binding to Smad family member 6 (SMAD6) in a mouse model of femoral fracture.

Methods

Microarray analysis was adopted to identify the regulatory miR of SMAD6. 3D micro-CT was performed to assess the bone volume (BV), bone volume fraction (BVF, BV/TV), and bone mineral density (BMD), followed by a biomechanical test for maximum load, maximum radial degrees, elastic radial degrees, and rigidity of the femur. The positive expression of SMAD6 in fracture tissues was measured. Moreover, the miR-186 level, messenger RNA (mRNA) level, and protein levels of SMAD6, BMP-2, and BMP-7 were examined.

Results

MicroRNA-186 was predicted to regulate SMAD6. Furthermore, SMAD6 was verified as a target gene of miR-186. Overexpressed miR-186 and SMAD6 silencing resulted in increased callus formation, BMD and BV/TV, as well as maximum load, maximum radial degrees, elastic radial degrees, and rigidity of the femur. In addition, the mRNA and protein levels of SMAD6 were decreased, while BMP-2 and BMP-7 levels were elevated in response to upregulated miR-186 and SMAD6 silencing.

Conclusion

In conclusion, the study indicated that miR-186 could activate the BMP signalling pathway to promote fracture healing by inhibiting SMAD6 in a mouse model of femoral fracture.

Cite this article: Bone Joint Res 2019;8:550–562.

The clinical utility of repetitive transcranial magnetic stimulation in reducing the risks of transitioning from acute to chronic pain in traumatically injured patients

Pain is a multifaceted condition and a major ongoing challenge for healthcare professionals having to treat patients in whom pain put them at risk of developing other conditions. Significant efforts have been invested in both clinical and research settings in an attempt to demystify the mechanisms at stake and develop optimal treatments as well as to reduce individual and societal costs. It is now universally accepted that neuroinflammation and central sensitization are two key underlying factors causing pain chronification as they result from maladaptive central nervous system plasticity. Recent research has shown that the mechanisms of action of repetitive transcranial magnetic stimulation (rTMS) make it a particularly promising avenue in treating various pain conditions. This review will first discuss the contribution of neuroinflammation and central sensitization in the transition from acute to chronic pain in traumatically injured patients. A detailed discussion on how rTMS may allow the restoration from maladaptive plasticity in addition to breaking down the chain of events leading to pain chronification will follow. Lastly, this review will provide a theoretical framework of what might constitute optimal rTMS modalities in dealing with pain symptoms in traumatically injured patients based on an integrated perspective of the physiopathological mechanisms underlying pain.

Reduced Terminal Complement Complex Formation in Mice Manifests in Low Bone Mass and Impaired Fracture Healing

The terminal complement complex (TCC) is formed on activation of the complement system, a crucial arm of innate immunity. TCC formation on cell membranes results in a transmembrane pore leading to cell lysis. In addition, sublytic TCC concentrations can modulate various cellular functions. TCC-induced effects may play a role in the pathomechanisms of inflammatory disorders of the bone, including rheumatoid arthritis and osteoarthritis. In this study, we investigated the effect of the TCC on bone turnover and repair. Mice deficient for complement component 6 (C6), an essential component for TCC assembly, and mice with a knockout of CD59, which is a negative regulator of TCC formation, were used in this study. The bone phenotype was analyzed in vivo, and bone cell behavior was analyzed ex vivo. In addition, the mice were subjected to a femur osteotomy. Under homeostatic conditions, C6-deficient mice displayed a reduced bone mass, mainly because of increased osteoclast activity. After femur fracture, the inflammatory response was altered and bone formation was disturbed, which negatively affected the healing outcome. By contrast, CD59-knockout mice only displayed minor skeletal alterations and uneventful bone healing, although the early inflammatory reaction to femur fracture was marginally enhanced. These results demonstrate that TCC-mediated effects regulate bone turnover and promote an adequate response to fracture, contributing to an uneventful healing outcome.

Pharmacological inhibition of IL-6 trans-signaling improves compromised fracture healing after severe trauma

Patients with multiple injuries frequently suffer bone fractures and are at high risk to develop fracture healing complications. Because of its key role both in systemic posttraumatic inflammation and fracture healing, the pleiotropic cytokine interleukin-6 (IL-6) may be involved in the pathomechanisms of trauma-induced compromised fracture healing. IL-6 signals are transmitted by two different mechanisms: classic signaling via the membrane-bound receptor (mIL-6R) and trans-signaling via its soluble form (sIL-6R). Herein, we investigated whether IL-6 classic and trans-signaling play different roles in bone regeneration after severe injury. Twelve-week-old C57BL/6J mice underwent combined femur osteotomy and thoracic trauma. To study the function of IL-6, either an anti-IL-6 antibody, which inhibits both IL-6 classic and trans-signaling, or a soluble glycoprotein 130 fusion protein (sgp130Fc), which selectively blocks trans-signaling, were injected 30 min and 48 h after surgery. Bone healing was assessed using cytokine analyses, flow cytometry, histology, micro-computed tomography, and biomechanical testing. Selective inhibition of IL-6 trans-signaling significantly improved the fracture healing outcome after combined injury, as confirmed by accelerated cartilage-to-bone transformation, enhanced bony bridging of the fracture gap and improved mechanical callus properties. In contrast, global IL-6 inhibition did not affect compromised fracture healing. These data suggest that classic signaling may mediate beneficial effects on bone repair after severe injury. Selective inhibition of IL-6 trans-signaling might have therapeutic potential to treat fracture healing complications in patients with concomitant injuries.

Neutrophils in Tissue Trauma of the Skin, Bone, and Lung: Two Sides of the Same Coin

Following severe tissue injury, patients are exposed to various danger- and microbe-associated molecular patterns, which provoke a strong activation of the neutrophil defense system. Neutrophils trigger and modulate the initial posttraumatic inflammatory response and contribute critically to subsequent repair processes. However, severe trauma can affect central neutrophil functions, including circulation half-life, chemokinesis, phagocytosis, cytokine release, and respiratory burst. Alterations in neutrophil biology may contribute to trauma-associated complications, including immune suppression, sepsis, multiorgan dysfunction, and disturbed tissue regeneration. Furthermore, there is evidence that neutrophil actions depend on the quality of the initial stimulus, including trauma localization and severity, the micromilieu in the affected tissue, and the patient's overall inflammatory status. In the present review, we describe the effects of severe trauma on the neutrophil phenotype and dysfunction and the consequences for tissue repair. We particularly concentrate on the role of neutrophils in wound healing, lung injury, and bone fractures, because these are the most frequently affected tissues in severely injured patients.

Epidemiology of distal radius fractures in polytrauma patients and the influence of high traumatic energy transfer

INTRODUCTION

For several extremity fractures differences in morphology, incidence rate and functional outcome were found when polytrauma patients were compared to patients with an isolated injury. This is not proven for distal radius fractures (DRF). Therefore, this study aimed to analyse fracture morphology in relation to energy transfer in both poly- and mono-trauma patients with a DRF.

METHODS

This was a retrospective cohort study. All patients aged 16 years and older with a DRF were included. Patients with an Injury Severity Score of 16 or higher were classified as polytrauma patients. Injuries were defined as high or low energy. All DRFs were classified using the AO/OTA fracture classification system.

RESULTS

A total of 830 patients with a DRF were included, 12% were polytrauma. The incidence rate of DRF in polytrauma patients was 3.5%. Ipsilateral upper extremity injury was found in >30% of polytrauma and high-energy monotrauma patients, compared to 5% in low-energy monotrauma patients. More type C DRF were found in polytrauma and high-energy monotrauma patients versus low-energy monotrauma patients. Operative intervention rates for all types of DRF were similar for polytrauma and high-energy monotrauma patients. Non-union rates were higher in polytrauma patients.

CONCLUSION

Higher energy mechanisms of injury, in polytrauma and high-energy monotrauma patients, were associated with more severe complex articular distal radius fractures and more ipsilateral upper extremity injuries. Polytrauma and high-energy monotrauma patient have a similar fracture morphology. However, polytrauma patients have in addition to more injured body regions also more non-union related interventions than high-energy monotrauma patients.

Effects of freshwater clam extract on fracture induced inflammation at early stage

The inflammatory process after traumatic fracture and soft tissue injury includes release of inflammatory cytokines and activated polymorph nuclear cells (PMN) that can cause subsequent affected limbs delayed healing and vital organ complications. Analgesics have good effect on relief of the symptom but may cause further burden for hepatic and renal metabolism. Freshwater clam extract (FCE) has been demonstrated to suppress the release of the pro-inflammatory cytokine tumor necrosis factor-α production after hemorrhagic shock, and decrease the level of liver injury marker in rats. The aim of the present study was to determine whether FCE is able to affect the inflammation induced by unilateral tibial fracture in a rat model. The rats were randomly divided into control, fracture, FCE and fracture with FCE groups. The fracture group received left tibia and fibula shaft fractures using a consistent three point bending method. For the fracture with FCE group, FCE (40 mg/kg) was administered orally after fracture. Their physiological changes were continuously monitored for 48 h. Blood samples were extracted from the femoral arterial catheter at 1, 3, 6, 9, 12, 18, 24 and 48 h after fracture. In comparison with fracture group, those whom were fed with FCE had more stable heart rate frequency, lower central temperature at the initial h, and lower serum level of the proinflammatory cytokines and muscle damage markers induced by fracture. FCE was also associated with decreased recruitment of inflammatory cells in the adjacent soft tissue. Thus, the present results suggest that FCE could decrease fracture induced inflammation reaction and have beneficial regulatory effect on post inflammatory response.

Participation of GATA-3 in regulation of bone healing through transcriptional upregulation of bcl-xL expression

We have previously demonstrated the expression of GATA-DNA-binding protein (GATA)-3, a transcription factor, in osteoblasts and have verified its function in transducing cell survival signaling. This translational study was further designed to evaluate the roles of GATA-3 in regulating bone healing and to explore its possible mechanisms. A metaphyseal bone defect was created in the left femurs of male ICR mice. Analysis by micro-computed topography showed that the bone volume, trabecular bone number and trabecular thickness were augmented and that the trabecular pattern factor decreased. Interestingly, immunohistological analyses showed specific expression of GATA-3 in the defect area. In addition, colocalized expression of GATA-3 and alkaline phosphatase was observed at the wound site. As the fracture healed, the amounts of phosphorylated and non-phosphorylated GATA-3 concurrently increased. Separately, GATA-3 mRNA was induced during bone healing, and, levels of Runx2 mRNA and protein were also increased. The results of confocal microscopy and co-immunoprecipitation showed an association between nuclear GATA-3 and Runx2 in the area of insult. In parallel with fracture healing, Bcl-XL mRNA was significantly triggered. A bioinformatic search revealed the existence of a GATA-3-specific DNA-binding element in the promoter region of the bcl-xL gene. Analysis by chromatin immunoprecipitation assays further demonstrated transactivation activity by which GATA-3 regulated bcl-xL gene expression. Therefore, this study shows that GATA-3 participates in the healing of bone fractures via regulating bcl-xL gene expression, owing to its association with Runx2. In the clinic, GATA-3 may be used as a biomarker for diagnoses/prognoses or as a therapeutic target for bone diseases, such as bone fractures.

Identification of key genes influenced by fixation stability in early fracture hematoma and elucidation of their roles in fracture healing

The present study aimed to identify the key genes influenced by fixation stability in early fracture hematoma and to elucidate their roles in fracture healing. The GSE53256 gene expression profile, including six fracture hematoma tissues, was downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) in the fracture hematoma tissues from old rats with rigid fixation compared with semi-rigid fixation were identified using the limma package. Furthermore, Gene Ontology (GO) enrichment analysis for DEGs was performed using BiNGO, and a protein-protein interaction (PPI) network was constructed based on the Search Tool for the Retrieval of Interacting Genes database. A total of 265 DEGs (158 upregulated and 107 downregulated) in the fracture hematoma tissues were screened out. Additionally, the overrepresented GO terms were mainly associated with the extracellular region, positive regulation of locomotion and response to external stimulus. Transforming growth factor, β 1 (Tgfβ1), chemokine (C-X-C motif) ligand 12 (Cxcl12), matrix metallopeptidase 9 (mmp9) and serpin peptidase inhibitor, clade E, member 1 (serpine1) had higher degrees and were hub nodes in the PPI network. In conclusion, fixation stability may influence the fracture healing process, and important DEGs, including Cxcl12, mmp9, Tgfβ1 and serpine1, may be important in this process.

Strategic Targeting of Multiple BMP Receptors Prevents Trauma-Induced Heterotopic Ossification

Trauma-induced heterotopic ossification (tHO) is a condition of pathologic wound healing, defined by the progressive formation of ectopic bone in soft tissue following severe burns or trauma. Because previous studies have shown that genetic variants of HO, such as fibrodysplasia ossificans progressiva (FOP), are caused by hyperactivating mutations of the type I bone morphogenetic protein receptor (T1-BMPR) ACVR1/ALK2, studies evaluating therapies for HO have been directed primarily toward drugs for this specific receptor. However, patients with tHO do not carry known T1-BMPR mutations. Here we show that, although BMP signaling is required for tHO, no single T1-BMPR (ACVR1/ALK2, BMPR1a/ALK3, or BMPR1b/ALK6) alone is necessary for this disease, suggesting that these receptors have functional redundancy in the setting of tHO. By utilizing two different classes of BMP signaling inhibitors, we developed a translational approach to treatment, integrating treatment choice with existing diagnostic options. Our treatment paradigm balances either immediate therapy with reduced risk for adverse effects (Alk3-Fc) or delayed therapy with improved patient selection but greater risk for adverse effects (LDN-212854).

A doxycycline inducible, adenoviral bone morphogenetic protein-2 gene delivery system to bone

We report the novel use of a tuneable, non-integrating viral gene delivery system to bone that can be combined with clinically approved biomaterials in an 'off-the-shelf' manner. Specifically, a doxycycline inducible Tet-on adenoviral vector (AdTetBMP-2) in combination with mesenchymal stromal cells (MSCs), fibrin and a biphasic calcium phosphate ceramic (MBCP®) was used to repair large bone defects in nude rats. Bone morphogenetic protein-2 (BMP-2) transgene expression could be effectively tuned by modification of the doxycycline concentration. The effect of adenoviral BMP-2 gene delivery upon bone healing was investigated in vivo in 4 mm critically sized, internally fixated, femoral defects. MSCs were transduced either by direct application of AdTetBMP-2 or by pre-coating MBCP granules with the virus. Radiological assessment scores post-mortem were significantly improved upon delivery of AdTetBMP-2. In AdTetBMP-2 groups, histological analysis revealed significantly more newly formed bone at the defect site compared with controls. Newly formed bone was vascularized and fully integrated with nascent tissue and implanted biomaterial. Improvement in healing outcome was achieved using both methods of vector delivery (direct application vs. pre-coating MCBP). Adenoviral delivery of BMP-2 enhanced bone regeneration achieved by the transplantation of MSCs, fibrin and MBCP in vivo. Importantly, our in vitro and in vivo data suggest that this can be achieved with relatively low (ng/ml) levels of the growth factor. Our model and novel gene delivery system may provide a powerful standardized tool for the optimization of growth factor delivery and release for the healing of large bone defects. Copyright © 2016 John Wiley & Sons, Ltd.

Osteogenesis Is Improved by Low Tumor Necrosis Factor Alpha Concentration through the Modulation of Gs-Coupled Receptor Signals

In the early phase of bone damage, low concentrations of the cytokine tumor necrosis factor alpha (TNF-α) favor osteoblast differentiation. In contrast, chronic high doses of the same cytokine contribute to bone loss, demonstrating opposite effects depending on its concentration and on the time of exposure. In the bone microenvironment, TNF-α modulates the expression/function of different G protein-coupled receptors (GPCRs) and of their regulatory proteins, GPCR-regulated kinases (GRKs), thus dictating their final biological outcome in controlling bone anabolic processes. Here, the effects of TNF-α were investigated on the expression/responsiveness of the A_2B adenosine receptor (A_2BAR), a Gs-coupled receptor that promotes mesenchymal stem cell (MSC) differentiation into osteoblasts. Low TNF-α concentrations exerted a prodifferentiating effect on MSCs, pushing them toward an osteoblast phenotype. By regulating GRK2 turnover and expression, the cytokine impaired A_2BAR desensitization, accelerating receptor-mediated osteoblast differentiation. These data supported the anabolic effect of TNF-α submaximal concentration and demonstrated that the cytokine regulates GPCR responses by interfering with the receptor desensitization machinery, thereby enhancing the anabolic responses evoked by A_2BAR ligands. Overall, these results indicated that GPCR desensitization plays a pivotal role in osteogenesis and that its manipulation is an effective strategy to favor bone remodeling.

High-Purity Magnesium Staples Suppress Inflammatory Response in Rectal Anastomoses

Magnesium-based materials are promising biodegradable implants, although the impact of magnesium on rectal anastomotic inflammation is poorly understood. Thus, we investigated the inflammatory effects of high-purity Mg staples in rectal anastomoses by in vivo luciferase reporter gene expression in transgenic mice, hematoxylin-eosin staining, immunohistochemistry, and Western blotting. As expected, strong IL-1β-mediated inflammation and inflammatory cell infiltration were observed 1 day after rectal anastomoses were stapled with high-purity Mg or Ti. However, inflammation and inflammatory cell infiltration decreased more robustly 4-7 days postoperation in tissues stapled with high-purity Mg. This rapid reduction in inflammation was confirmed by immunohistochemical analysis of IL-6 and TNF-α. Western blot also suggested that the reduced inflammatory response is due to suppressed TLR4/NF-κB signaling. In contrast, MCP-1, uPAR, and VEGF were abundantly expressed, in line with the notion that expression of these proteins is regulated by feedback between the VEGF and NF-κB pathways. In vitro expression of MCP-1, uPAR, and VEGF was also similarly high in primary rectal mucosal epithelial cells exposed to extracts from Mg staples, as measured by antibody array. Collectively, the results suggest that high-purity Mg staples suppress the inflammatory response during rectal anastomoses via TLR4/NF-κB and VEGF signaling.

Latest perspectives on macrophages in bone homeostasis

Knowledge about macrophages residing in the bone, also known as osteal macrophages or osteomacs, is still limited. A hallmark of this peculiar myeloid population is the expression of macrophage markers distinct from the markers found on osteoclast surface. In bone, osteomacs are in contact with osteoblasts, where they are involved in regulating bone homeostasis. However, additional macrophage subtypes already present in the bone marrow or recruited from the blood circulation could have further functions, which could be all important for the maintenance of the bone architecture and its associated functions. Indeed, bone marrow macrophages have been found to eliminate apoptotic cells, particularly apoptotic osteoblasts through a process named efferocytosis. This phagocytic process plays an essential role in bone tissue homeostasis and new bone formation. In addition, bone marrow macrophages can influence the hematopoietic stem cell (HSC) niches. They contribute to the regulation of the HSC progenitor cell maintenance, mobilization, and function. To do so, macrophages secrete cytokines in steady state or during stress conditions. These cytokines influence hematopoiesis either by a direct effect on HSCs or through the control of stromal cells that are essential for the HSC niches. Interestingly, the similarities between the niches for HSCs and the niche for metastatic tumor cells support the possibility that bone-resident macrophages could control the homing of tumor cells and their proliferation within the bone. In general, macrophage role during metastatic processes is well described; however, their direct involvement in bone metastasis is a rising research area. In this review, we will highlight the macrophage functions in the skeleton, in the maintenance of the HCS niches, and their importance in bone metastasis.

Gene markers of fracture healing in early stage and the regulatory mechanism during the process using microarray analysis

BACKGROUND

The aim of this study was to explore crucial markers and uncover the regulatory mechanisms of fracture healing in the early stage.

METHODS

Gene expression profile of GSE45156 was downloaded, in which 3 fractured samples and 3 unfractured samples were used in our present study. Based on the threshold value, differentially expressed genes (DEGs) were selected between two kinds of samples using limma package in R. Enrichment analysis of these DEGs was performed by DAVID software. Furthermore, protein-protein interaction (PPI) network was established integrating information in STRING database, and visualized by Cytoscape software.

RESULTS

We identified a set of 960 DEGs including 509 up-regulated and 451 downregulated genes. Biological processes involving RNA splicing and cell cycle were significantly enriched for the up-regulated genes such as Snrpd2, Eftud2, Plk1 and Bub1b, whereas skeletal system development and bone development processes were predominant for down-regulated genes like Ubc. In the constructed PPI network, all the five genes were the predominant nodes, of which Snrpd2 was linked to Eftud2, while Bub1b was to interact with Plk1.

CONCLUSION

Five candidate genes crucial for indicating the process of fracture in early stage were identified. Eftud2, Snrpd2, Bub1b and Plk1 might function through the involvement of cell-cycle-related BP, while Ubc might influence the protein degradation during bone development. However, more experimental validations are needed to confirm these results.

Ticagrelor regulates osteoblast and osteoclast function and promotes bone formation in vivo via an adenosine-dependent mechanism

As many as 10% of bone fractures heal poorly, and large bone defects resulting from trauma, tumor, or infection may not heal without surgical intervention. Activation of adenosine A2A receptors (A2ARs) stimulates bone formation. Ticagrelor and dipyridamole inhibit platelet function by inhibiting P2Y12 receptors and platelet phosphodiesterase, respectively, but share the capacity to inhibit cellular uptake of adenosine and thereby increase extracellular adenosine levels. Because dipyridamole promotes bone regeneration by an A2AR-mediated mechanism we determined whether ticagrelor could regulate the cells involved in bone homeostasis and regeneration in a murine model and whether inhibition of P2Y12 or indirect A2AR activation via adenosine was involved. Ticagrelor, dipyridamole and the active metabolite of clopidogrel (CAM), an alternative P2Y12 antagonist, inhibited osteoclast differentiation and promoted osteoblast differentiation in vitro. A2AR blockade abrogated the effects of ticagrelor and dipyridamole on osteoclast and osteoblast differentiation whereas A2BR blockade abrogated the effects of CAM. Ticagrelor and CAM, when applied to a 3-dimentional printed resorbable calcium-triphosphate/hydroxyapatite scaffold implanted in a calvarial bone defect, promoted significantly more bone regeneration than the scaffold alone and as much bone regeneration as BMP-2, a growth factor currently used to promote bone regeneration. These results suggest novel approaches to targeting adenosine receptors in the promotion of bone regeneration.-Mediero, A., Wilder, T., Reddy, V. S. R., Cheng, Q., Tovar, N., Coelho, P. G., Witek, L., Whatling, C., Cronstein, B. N. Ticagrelor regulates osteoblast and osteoclast function and promotes bone formation in vivo via an adenosine-dependent mechanism.

The treatment of nonunions with application of BMP-7 increases the expression pattern for angiogenic and inflammable cytokines: a matched pair analysis

The local application of bone morphogenetic protein-7 (BMP-7) in combination with the transplantation of autologous bone graft improves the outcome in nonunion treatment; however, the specific reasons remain unclear. In this study, we sought to determine if the local application of BMP-7 contributes to improved bone regeneration in nonunion therapy by modulation of the angiogenic and inflammable cytokine expression patterns of the early inflammation response. Therefore, we utilized the analysis of serological cytokine expression patterns. As a matched pair analysis, best-fitting patients who were treated with transplantation of autologous bone graft (G1, n=10) were compared with patients who were treated with additional application of BMP-7 (G2, n=10). The changes in the cytokine expression patterns were monitored and correlated to clinical data of bone healing. Significant differences in angiogenesis potential (vascular endothelial growth factor [VEGF] serum levels) could be found in the first days after surgery (P<0.05). Furthermore, the increase and absolute amount of VEGF levels in the BMP-7 group were considerably higher than in the control group during the first 2 weeks after surgery. The expression pattern of inflammable cytokines showed noticeable differences in the time point of significant elevated levels, in particular, inflammable cytokines showed an earlier peak in G2. Furthermore, interleukin-6 was significantly elevated within the first week only, comparing G2 to G1 (P<0.05). Our findings indicate that BMP-7 induces an early and more intense expression of VEGF via a direct and postulated indirect pathway, thereby providing a favorable environment for bone healing. Moreover, application of BMP-7 leads to an earlier expression of known proinflammatory cytokines. The results of this study show that application of BMP-7 leads to costimulatory effect on both angiogenic and inflammable cytokine expression patterns that may serve as a possible stimulus for bone regeneration.

Platelet Rich Plasma: a short overview of certain bioactive components

Platelet rich plasma (PRP) represents a relatively new approach in regenerative medicine. It is obtained from patient’s own blood and contains different growth factors and other biomolecules necessary for wound healing. Since there are various protocols for PRP preparing, it usually results with PRP generation with different amounts of bioactive substances, which finally may modulate the intensity of wound healing. The reference data about potential effect of some PRP compounds on wound healing, in different tissues, are still controversial. This review summarizes recently known facts about physiological role of certain PRP components and guidance for further research. Also, this review discusses different procedure for PRP generation and potential effect of leukocytes on wound healing.

IL-12p40 impairs mesenchymal stem cell-mediated bone regeneration via CD4+ T cells

Severe or prolonged inflammatory response caused by infection or biomaterials leads to delayed healing or bone repair failure. This study investigated the important roles of the proinflammatory cytokines of the interleukin-12 (IL-12) family, namely, IL-12 and IL-23, in the inflammation-mediated inhibition of bone formation in vivo. IL-12p40^-/- mice lacking IL-12 and IL-23 exhibited enhanced bone formation. IL-12 and IL-23 indirectly inhibited bone marrow mesenchymal stem cell (BMMSC) differentiation by stimulating CD4⁺ T cells to increase interferon γ (IFN-γ) and IL-17 levels. Mechanistically, IL-17 synergistically enhanced IFN-γ-induced BMMSC apoptosis. Moreover, INF-γ and IL-17 exerted proapoptotic effects by upregulating the expression levels of Fas and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), as well as by activating the caspase cascade in BMMSCs. IL-12p40 depletion in mice could promote ectopic bone formation. Thus, IL-12p40 is an attractive therapeutic target to overcome the inflammation-mediated inhibition of bone formation in vivo.

Antagonizing midkine accelerates fracture healing in mice by enhanced bone formation in the fracture callus

BACKGROUND AND PURPOSE

Previous findings suggest that the growth and differentiation factor midkine (Mdk) is a negative regulator of osteoblast activity and bone formation, thereby raising the possibility that a specific Mdk antagonist might improve bone formation during fracture healing.

EXPERIMENTAL APPROACH

In the present study, we investigated the effects of a monoclonal anti-Mdk antibody (Mdk-Ab) on bone healing using a standardized femur osteotomy model in mice. Additional in vitro experiments using chondroprogenitor and preosteoblastic cells were conducted to analyse the effects of recombinant Mdk and Mdk-Ab on differentiation markers and potential binding partners in these cells.

KEY RESULTS

We demonstrated that treatment with Mdk-Ab accelerated bone healing in mice based on increased bone formation in the fracture callus. In vitro experiments using preosteoblastic cells showed that Mdk-Ab treatment abolished the Mdk-induced negative effects on the expression of osteogenic markers and Wnt/β-catenin target proteins, whereas the differentiation of chondroprogenitor cells was unaffected. Phosphorylation analyses revealed an important role for the low-density lipoproteinLDL receptor-related protein 6 in Mdk signalling in osteoblasts.

CONCLUSIONS AND IMPLICATIONS

We conclude that Mdk-Ab treatment may be a potential novel therapeutic strategy to enhance fracture healing in patients with orthopaedic complications such as delayed healing or non-union formation.

Impaired bone healing in multitrauma patients is associated with altered leukocyte kinetics after major trauma

Animal studies have shown that the systemic inflammatory response to major injury impairs bone regeneration. It remains unclear whether the systemic immune response contributes to impairment of fracture healing in multitrauma patients. It is well known that systemic inflammatory changes after major trauma affect leukocyte kinetics. We therefore retrospectively compared the cellular composition of peripheral blood during the first 2 weeks after injury between multitrauma patients with normal (n=48) and impaired (n=32) fracture healing of the tibia. The peripheral blood-count curves of leukocytes, neutrophils, monocytes, and thrombocytes differed significantly between patients with normal and impaired fracture healing during the first 2 weeks after trauma (P-values were 0.0122, 0.0083, 0.0204, and <0.0001, respectively). Mean myeloid cell counts were above reference values during the second week after injury. Our data indicate that leukocyte kinetics differ significantly between patients with normal and impaired fracture healing during the first 2 weeks after major injury. This finding suggests that the systemic immune response to major trauma can disturb tissue regeneration.

The effect of concomitant peripheral injury on traumatic brain injury pathobiology and outcome

Background

Traumatic injuries are physical insults to the body that are prevalent worldwide. Many individuals involved in accidents suffer injuries affecting a number of extremities and organs, otherwise known as multitrauma or polytrauma. Traumatic brain injury is one of the most serious forms of the trauma-induced injuries and is a leading cause of death and long-term disability. Despite over dozens of phase III clinical trials, there are currently no specific treatments known to improve traumatic brain injury outcomes. These failures are in part due to our still poor understanding of the heterogeneous and evolving pathophysiology of traumatic brain injury and how factors such as concomitant extracranial injuries can impact these processes.

Main body

Here, we review the available clinical and pre-clinical studies that have investigated the possible impact of concomitant injuries on traumatic brain injury pathobiology and outcomes. We then list the pathophysiological processes that may interact and affect outcomes and discuss promising areas for future research. Taken together, many of the clinical multitrauma/polytrauma studies discussed in this review suggest that concomitant peripheral injuries may increase the risk of mortality and functional deficits following traumatic brain injury, particularly when severe extracranial injuries are combined with mild to moderate brain injury. In addition, recent animal studies have provided strong evidence that concomitant injuries may increase both peripheral and central inflammatory responses and that structural and functional deficits associated with traumatic brain injury may be exacerbated in multiply injured animals.

Conclusions

The findings of this review suggest that concomitant extracranial injuries are capable of modifying the outcomes and pathobiology of traumatic brain injury, in particular neuroinflammation. Though additional studies are needed to further identify the factors and mechanisms involved in central and peripheral injury interactions following multitrauma and polytrauma, concomitant injuries should be recognized and accounted for in future pre-clinical and clinical traumatic brain injury studies.

Monitoring immune responses in a mouse model of fracture fixation with and without Staphylococcus aureus osteomyelitis

Post-traumatic bone fractures are commonly fixed with implanted devices to restore the anatomical position of bone fragments and aid in the healing process. Bacterial infection in this situation is a challenge for clinicians due to the need for aggressive antibiotic therapy, debridement of infected tissues, and the need to maintain fracture stability. The aim of this study was to monitor immune responses that occur during healing and during Staphylococcus aureus infection, in a clinically relevant murine model of fracture fixation. Skeletally mature C57bl/6 mice received a transverse osteotomy of the femur, which was treated with commercially available titanium fracture fixation plates and screws. In the absence of infection, healing of the fracture was complete within 35days and was characterized by elevated Interleukin (IL)-4 and Interferon-gamma secretion from bone-derived cells and expression of these same genes. In contrast, mice inoculated with S. aureus could not heal the fracture within the observation period and were found to develop typical signs of implant-associated bone infection, including biofilm formation on the implant and osteolysis of surrounding bone. The immune response to infection was characterized by a TH17-led bone response, and a pro-inflammatory cytokine-led Tumor necrosis factor (TNF)-α, Interleukin (IL)-1β) soft tissue response, both of which were ineffectual in clearing implant related bone and soft tissue infections respectively. In this murine model, we characterize the kinetics of pro-inflammatory responses to infection, secondary to bone trauma and surgery. A divergent local immune polarization is evident in the infected versus non-infected animals, with the immune response ultimately unable to clear the S. aureus infection.

Macrophages: Their Emerging Roles in Bone

Macrophages are present in nearly all tissues and are critical for development, homeostasis, and regeneration. Resident tissue macrophages of bone, termed osteal macrophages, are recently classified myeloid cells that are distinct from osteoclasts. Osteal macrophages are located immediately adjacent to osteoblasts, regulate bone formation, and play diverse roles in skeletal homeostasis. Genetic or pharmacological modulation of macrophages in vivo results in significant bone phenotypes, and these phenotypes depend on which macrophage subsets are altered. Macrophages are also key mediators of osseous wound healing and fracture repair, with distinct roles at various stages of the repair process. A central function of macrophages is their phagocytic ability. Each day, billions of cells die in the body and efferocytosis (phagocytosis of apoptotic cells) is a critical process in both clearing dead cells and recruitment of replacement progenitor cells to maintain homeostasis. Recent data suggest a role for efferocytosis in bone biology and these new mechanisms are outlined. Finally, although macrophages have an established role in primary tumors, emerging evidence suggests that macrophages in bone support cancers which preferentially metastasize to the skeleton. Collectively, this developing area of osteoimmunology raises new questions and promises to provide novel insights into pathophysiologic conditions as well as therapeutic and regenerative approaches vital for skeletal health.

An In Vitro Investigation of Platelet-Rich Plasma-Gel as a Cell and Growth Factor Delivery Vehicle for Tissue Engineering

Platelet-rich plasma (PRP) has been used for different applications in human and veterinary medicine. Many studies have shown promising therapeutic effects of PRP; however, there are still many controversies regarding its composition, properties, and clinical efficacy. The aim of this study was to evaluate the influence of different platelet concentrations on the rheological properties and growth factor (GF) release profile of PRP-gels. In addition, the viability of incorporated bone marrow-derived human mesenchymal stem cells (MSCs) was investigated. PRP (containing 1000 × 10(3), 2000 × 10(3), and 10,000 × 10(3) platelets/μL) was prepared from human platelet concentrates. Platelet activation and gelification were achieved by addition of human thrombin. Viscoelastic properties of PRP-gels were evaluated by rheological studies. The release of GFs and inflammatory proteins was measured using a membrane-based protein array and enzyme-linked immunosorbent assay. MSC viability and proliferation in PRP-gels were assessed over 7 days by cell viability staining. Cell proliferation was examined using DNA quantification. Regardless of the platelet content, all tested PRP-gels showed effective cross-linking. A positive correlation between protein release and the platelet concentration was observed at all time points. Among the detected proteins, the chemokine CCL5 was the most abundant. The greatest release appeared within the first 4 h after gelification. MSCs could be successfully cultured in PRP-gels over 7 days, with the highest cell viability and DNA content found in PRP-gels with 1000 × 10(3) platelets/μL. The results of this study suggest that PRP-gels represent a suitable carrier for both cell and GF delivery for tissue engineering. Notably, a platelet concentration of 1000 × 10(3) platelets/μL appeared to provide the most favorable environment for MSCs. Thus, the platelet concentration is an important consideration for the clinical application of PRP-gels.

Stem Cells in Teeth and Craniofacial Bones

Stem cells are remarkable, and stem cell-based tissue engineering is an emerging field of biomedical science aiming to restore damaged tissue or organs. In dentistry and reconstructive facial surgery, it is of great interest to restore lost teeth or craniofacial bone defects using stem cell-mediated therapy. In the craniofacial region, various stem cell populations have been identified with regeneration potential. In this review, we provide an overview of the current knowledge concerning the various types of tooth- and craniofacial bone-related stem cells and discuss their in vivo identities and regulating mechanisms.

Exposure to 100% Oxygen Abolishes the Impairment of Fracture Healing after Thoracic Trauma

In polytrauma patients a thoracic trauma is one of the most critical injuries and an important trigger of post-traumatic inflammation. About 50% of patients with thoracic trauma are additionally affected by bone fractures. The risk for fracture malunion is considerably increased in such patients, the pathomechanisms being poorly understood. Thoracic trauma causes regional alveolar hypoxia and, subsequently, hypoxemia, which in turn triggers local and systemic inflammation. Therefore, we aimed to unravel the role of oxygen in impaired bone regeneration after thoracic trauma. We hypothesized that short-term breathing of 100% oxygen in the early post-traumatic phase ameliorates inflammation and improves bone regeneration. Mice underwent a femur osteotomy alone or combined with blunt chest trauma 100% oxygen was administered immediately after trauma for two separate 3 hour intervals. Arterial blood gas tensions, microcirculatory perfusion and oxygenation were assessed at 3, 9 and 24 hours after injury. Inflammatory cytokines and markers of oxidative/nitrosative stress were measured in plasma, lung and fracture hematoma. Bone healing was assessed on day 7, 14 and 21. Thoracic trauma induced pulmonary and systemic inflammation and impaired bone healing. Short-term exposure to 100% oxygen in the acute post-traumatic phase significantly attenuated systemic and local inflammatory responses and improved fracture healing without provoking toxic side effects, suggesting that hyperoxia could induce anti-inflammatory and pro-regenerative effects after severe injury. These results suggest that breathing of 100% oxygen in the acute post-traumatic phase might reduce the risk of poorly healing fractures in severely injured patients.

Direct or indirect stimulation of adenosine A2A receptors enhances bone regeneration as well as bone morphogenetic protein-2

Promoting bone regeneration and repair of bone defects is a need that has not been well met to date. We have previously found that adenosine, acting via A2A receptors (A2AR) promotes wound healing and inhibits inflammatory osteolysis and hypothesized that A2AR might be a novel target to promote bone regeneration. Therefore, we determined whether direct A2AR stimulation or increasing endogenous adenosine concentrations via purine transport blockade with dipyridamole regulates bone formation. We determined whether coverage of a 3 mm trephine defect in a mouse skull with a collagen scaffold soaked in saline, bone morphogenetic protein-2 (BMP-2; 200 ng), 1 μM CGS21680 (A2AR agonist, EC50 = 160 nM), or 1 μM dipyridamole (EC50 = 32 nM) promoted bone regeneration. Microcomputed tomography examination demonstrated that CGS21680 and dipyridamole markedly enhanced bone regeneration as well as BMP-2 8 wk after surgery (60 ± 2%, 79 ± 2%, and 75 ± 1% bone regeneration, respectively, vs. 32 ± 2% in control, P < 0.001). Blockade by a selective A2AR antagonist (ZM241385, 1 μM) or deletion of A2AR abrogated the effect of CGS21680 and dipyridamole on bone regeneration. Both CGS21680 and dipyridamole treatment increased alkaline phosphatase-positive osteoblasts and diminished tartrate resistance acid phosphatase-positive osteoclasts in the defects. In vivo imaging with a fluorescent dye for new bone formation revealed a strong fluorescent signal in treated animals that was equivalent to BMP-2. In conclusion, stimulation of A2AR by specific agonists or by increasing endogenous adenosine levels stimulates new bone formation as well as BMP-2 and represents a novel approach to stimulating bone regeneration.