Is the expression of Transforming Growth Factor-Beta1 after fracture of long bones solely influenced by the healing process?

A pilot study of circulating levels of TGF-β1 and TGF-β2 as biomarkers of bone healing in patients with non-hypertrophic pseudoarthrosis of long bones

Background

Pseudoarthrosis or non-union is a complication with an incidence of 5-10% of bone fractures, most frequently located in the diaphysis of long bones. The management of this complication is addressed by means of complex surgical procedures and is a concern for orthopaedic and trauma surgeons nowadays. The use of biomarkers for diagnosing patients at risk of non-union would help us to establish special measures for early corrective treatment.

Methods

Prospective exploratory pilot study with a cohort of 20 patients diagnosed of non-hypertrophic pseudoarthrosis of long bones who were treated surgically with either autologous bone graft or a Tissue Engineering Product composed of bone marrow-derived Mesenchymal Stromal Cells. Patients were followed for 12 months and plasma blood samples were obtained to determine circulating levels of Transforming Growth Factor Beta 1 and Beta 2 (TGF-β1 and TGF-β2, respectively) at inclusion, and at 1 week, 2 weeks, and months 1, 2, 3, 6 and 12 after surgery. Radiological bone healing was evaluated by the Tomographic Union Score (TUS).

Results

Basal levels of TGF-β1 and TGF-β2 were determined in the twenty patients (26,702 ± 14,537 pg/mL and 307.8 ± 83.1 pg/mL, respectively). Three of them withdrew from the study, so complete follow-up was conducted on 17 patients (9 successfully healed vs. 8 that did not heal). Statistically significant differences between the bone healing group and the non-union group were found at month 12 for both TGF-β1 (p = 0.005) and TGF-β2 (p = 0.02).

Conclusions

TGF-β1 and TGF-β2 are biomarkers that correlate with clinical evidence of bone regeneration and may be used to monitor patients, although early predictive value after intervention needs to be further studied in combination with other molecules.

The Effect of Tobacco Smoking on Musculoskeletal Health: A Systematic Review

This systematic review explored associations between smoking and health outcomes involving the musculoskeletal system. AMSTAR criteria were followed. A comprehensive search of PubMed, Web of Science, and Science Direct returned 243 articles meeting inclusion criteria. A majority of studies found smoking has negative effects on the musculoskeletal system. In research on bones, smoking was associated with lower BMD, increased fracture risk, periodontitis, alveolar bone loss, and dental implant failure. In research on joints, smoking was associated with increased joint disease activity, poor functional outcomes, and poor therapeutic response. There was also evidence of adverse effects on muscles, tendons, cartilage, and ligaments. There were few studies on the musculoskeletal health outcomes of secondhand smoke, smoking cessation, or other modes of smoking, such as waterpipes or electronic cigarettes. This review found evidence that suggests tobacco smoking has negative effects on the health outcomes of the musculoskeletal system. There is a need for further research to understand mechanisms of action for the effects of smoking on the musculoskeletal system and to increase awareness of healthcare providers and community members of the adverse effects of smoking on the musculoskeletal system.

Delayed Expression of Circulating TGF-β1 and BMP-2 Levels in Human Nonunion Long Bone Fracture Healing

BACKGROUND

The healing process of bone fracture requires a well-controlled multistage and sequential order beginning immediately after the injury. However, complications leading to nonunion exist, creating serious problems and costs for patients. Transforming growth factor-beta 1 (TGF-β1) and bone morphogenic protein 2 (BMP-2) are two major growth factors involved in human bone fracture healing by promoting various stages of bone ossification. In this study, we aimed to determine the role of these factors during the fracture healing of human long bones and assess their impacts on nonunion condition.

MATERIALS AND METHODS

We performed a comprehensive analysis of plasma TGF-β1 and BMP-2 levels in blood samples from 10 patients with proved nonunion and 10 matched patients with normal union following a predetermined time schedule. The concentrations of TGF-β1 and BMP-2 were measured at each time point using a solid-phase ELISA.

RESULTS

TGF-β1 and BMP-2 levels were detectable in all patients. For all patients, a maximal peak for TGF-β1 was found at 3-week. In normal union group, TGF-β1 showed a maximal peak at 2-week while nonunion group had a delayed maximal peak at 3-week. Plasma levels of BMP-2 for all patients and for normal union group reached a maximal peak at 1-week, but nonunion group showed a delayed maximal peak at 2-week. In general, plasma TGF-β1 or BMP-2 level was not significantly different between normal union and nonunion groups.

CONCLUSION

The expression levels of TGF-β1 and BMP-2 appeared to be delayed in nonunion patients which could play an important role in developing an early marker of fracture union condition and facilitate improved patient's management.

Fracture healing: A review of clinical, imaging and laboratory diagnostic options

A fundamental issue in clinical orthopaedics is the determination of when a fracture is united. However, there are no established "gold standards," nor standardized methods for assessing union, which has resulted in significant disagreement among orthopaedic surgeons in both clinical practice and research. A great deal of investigative work has been directed to addressing this problem, with a number of exciting new techniques described. This review provides a brief summary of the burden of nonunion fractures and addresses some of the challenges related to the assessment of fracture healing. The tools currently available to determine union are discussed, including various imaging modalities, biomechanical testing methods, and laboratory and clinical assessments. The evaluation of fracture healing in the setting of both patient care and clinical research is integral to the orthopaedic practice. Weighted integration of several available metrics must be considered to create a composite outcome measure of patient prognosis.

Low bone mineral density in patients with type 1 diabetes: association with reduced expression of IGF1, IGF1R and TGF B 1 in peripheral blood mononuclear cells

BACKGROUND

The negative effects of type 1 diabetes (T1D) on growth factors of bone metabolism lead to a reduction in bone mineral density. This study aimed to evaluate the association between bone mineral density and insulin-like growth factor 1 (IGF1), insulin-like growth factor 1 receptor (IGF1R) and transforming growth factor beta 1 (TGFB1) expressions in children and adolescents with T1D. Moreover, the influences of age at diagnosis, time since diagnosis, glycaemic control and albuminuria on bone mineral density were investigated.

METHODS

Eighty-six T1D children/adolescents (T1D group) and ninety normoglycaemic controls (normoglycaemic group) were included. T1D patients were analysed as a whole and also in subsets of patients with good glycaemic control (glycated hemoglobin concentration ≤7.5%) and with poor glycaemic control (glycated hemoglobin concentration >7.5%). Bone mineral density was assessed by dual energy x-ray absorptiometry. Glycaemic control, renal function and bone markers were also assessed. IGF1, IGF1R and TGFB1 expressions were determined in peripheral blood mononuclear cells by real-time polymerase chain reaction.

RESULTS

Patients with T1D showed low bone mineral density and poor glycaemic control. Serum total calcium and urinary albumin-to-creatinine ratio were higher in patients with poor glycaemic control compared to those with good glycemic control (p = 0.003 and p = 0.035, respectively). There was a reduction of IGF1, IGF1R and TGFB1 expressions in the T1D patients and in the subset with poor glycaemic control compared to normoglycaemic controls (p < 0.05).

CONCLUSIONS

The decreased IGF1, IGF1R and TGFB1 expressions in the T1D patients, who presented with T1D at an early age, had been diagnosed with T1D for a longer time, had poor glycaemic control and albuminuria may contribute to low bone mineral density. Copyright © 2016 John Wiley & Sons, Ltd.

The Difference between Growth Factor Expression after Single and Multiple Fractures: Preliminary Results in Human Fracture Healing

Objectives. Circulating levels of VEGF-A (Vascular Endothelia Growth Factor-A), TGF-β1 (Transforming Growth Factor-beta 1), and M-CSF (Macrophage-Colony Stimulating Factor) were found to be predictors of bone healing and therefore prognostic criteria of delayed bone healing or nonunion. The aim of this study was to evaluate a potential rise of these markers in patients with multiple fractures of long bones compared to patients with single fractured long bone. Methods. 92 patients were included in the study and finally after excluding all female patients 45 male patients were left for final analysis and divided into the single or multiple fracture group. TGF-β1, M-CSF, and VEGF-A serum levels were analysed over a time period of two weeks. Results. MCSF serum concentrations were higher in the group with multiple fractures as also TGF-β1 serum concentrations were at one and two weeks after trauma. No statistically significant difference was observed in the VEGF-A serum concentrations of both groups at either measurement point. Conclusion. We did observe a correlation between the quantity of the M-CSF and TGF-β1 expressions in serum and the number of fractured bones; surprisingly there was no statistically significant difference in the serum levels between patients with single and multiple fractures of long bones.

Exogenous expression of IL-1Ra and TGF-β1 promotes in vivo repair in experimental rabbit osteoarthritis

OBJECTIVES

Potential gene therapy application of single and co-expression of interleukin 1 (IL-1) receptor antagonist (IL-1Ra) and transforming growth factor-β1 (TGF-β1) to alter disease progression was investigated in an in-vivo rabbit model of osteoarthritis (OA).

METHOD

Sixteen young adult rabbits were randomly and equally divided into four groups: blank control group, IL-1Ra transfection group, TGF-β1 transfection group, and IL-1Ra/TGF-β1 double transfection group. Histological examinations were performed to monitor disease progression after haematoxylin and eosin (H&E) staining of articular cartilage. Immunohistochemistry was used to detect IL-1Ra and TGF-β1 in synovial membrane tissues. Exogenous IL-1Ra and TGF-β1 content was assessed in joint lavage fluid using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

ELISA measurements from the joint lavage fluid showed high expressions of IL-1Ra and TGF-β1 in the single and double transfection groups. Remarkably, concomitant reductions in IL-1β and tumour necrosis factor alpha (TNF-α) levels were observed in these single and double transfection groups. Radioimmunoassay (RIA)-based detection showed that IL-1β and TNF-α levels in the gene transfection groups were significantly lower compared to the blank control group, in parallel experiments. Importantly, injection of IL-1Ra and TGF-β1 expressing cartilage cells into joints led to a significant inhibition of cartilage matrix degradation. Finally, IL-1Ra and TGF-β1 expression in tissues correlated with disease reversal in the experimental group, with improved tissue architecture and collagen deposition.

CONCLUSIONS

Our results reveal that both single- and double-gene transfection of IL-1Ra and TGF-β1 promote extensive repair of damaged cartilage, and double transfections showed better recovery than single transfections, suggesting that co-expression of IL-1Ra and TGF-β1 inhibits degeneration and improves repair of articular cartilage in OA.

Transforming growth factor Beta family: insight into the role of growth factors in regulation of fracture healing biology and potential clinical applications

The transforming growth factor beta (TGF-β) family forms a group of three isoforms, TGF-β1, TGF-β2, and TGF-β3, with their structure formed by interrelated dimeric polypeptide chains. Pleiotropic and redundant functions of the TGF-β family concern control of numerous aspects and effects of cell functions, including proliferation, differentiation, and migration, in all tissues of the human body. Amongst many cytokines and growth factors, the TGF-β family is considered a group playing one of numerous key roles in control of physiological phenomena concerning maintenance of metabolic homeostasis in the bone tissue. By breaking the continuity of bone tissue, a spread-over-time and complex bone healing process is initiated, considered a recapitulation of embryonic intracartilaginous ossification. This process is a cascade of local and systemic phenomena spread over time, involving whole cell lineages and various cytokines and growth factors. Numerous in vivo and in vitro studies in various models analysing cytokines and growth factors' involvement have shown that TGF-β has a leading role in the fracture healing process. This paper sums up current knowledge on the basis of available literature concerning the role of the TGF-β family in the fracture healing process.

A single nucleotide polymorphism in the TGF-β1 gene (rs1982073 C>T) may contribute to increased risks of bone fracture, osteoporosis, and osteoarthritis: a meta-analysis

Genetic factors have been shown to be of great importance for the pathogenesis of bone diseases, such as fracture, osteoporosis (OP), and osteoarthritis (OA). However, published studies on the correlations of transforming growth factor-β1 (TGF-β1) gene polymorphisms with bone diseases have been hampered by small sample sizes or inconclusive findings. We hence aimed at examining the relationships between a single nucleotide polymorphism in the TGF-β1 gene (rs1982073 C>T) with bone fracture, OP, and OA risks in this meta-analysis. A systematic electronic search of literature was conducted to identify all published studies in English or Chinese on the association between the TGF-β1 gene and fracture, OP, or OA risks. Data were abstracted independently by two reviewers. To investigate the strength of this relationship, crude odds ratios with 95 % confidence intervals were used. An updated meta-analysis based on nine independent case-control studies were chosen (patients with fracture, OP, or OA = 1569; healthy controls = 1638). Results identified a higher frequency of rs1982073 C>T in patients with fracture, OP, or OA than in healthy controls. Ethnicity and genotyping method-stratified analysis under both models implied that the rs1982073 C>T polymorphism was positively correlated with the risk of fracture, OP, and OA among Asians under detection via the non-PCR-RFLP method. Disease-stratified results yielded that rs1982073 C>T may increase the risk of fracture, OP, and OA under the allele model, but was only significantly related to OP under the dominant model. According to the sample size-stratified analysis, subjects with the rs1982073 C>T polymorphism in the allele model were more likely to develop the three bone diseases in both the small and large sample size groups, and only in the large sample size under the dominant model. Our findings show that TGF-β1 rs1982073 C>T has a modest effect in increasing susceptibility to bone fracture, OP, and OA.

Current Options for Determining Fracture Union

Determining whether a bone fracture is healed is one of the most important and fundamental clinical determinations made in orthopaedics. However, there are currently no standardized methods of assessing fracture union, which in turn has created significant disagreement among orthopaedic surgeons in both clinical and research settings. An extensive amount of research has been dedicated to finding novel and reliable ways of determining healing with some promising results. Recent advancements in imaging techniques and introduction of new radiographic scores have helped decrease the amount of disagreement on this topic among physicians. The knowledge gained from biomechanical studies of bone healing has helped us refine our tools and create more efficient and practical research instruments. Additionally, a deeper understanding of the molecular pathways involved in the bone healing process has led to emergence of serologic markers as possible candidates in assessment of fracture union. In addition to our current physician centered methods, patient-centered approaches assessing quality of life and function are gaining popularity in assessment of fracture union. Despite these advances, assessment of union remains an imperfect practice in the clinical setting. Therefore, clinicians need to draw on multiple modalities that directly and indirectly measure or correlate with bone healing when counseling patients.

Fracture non-union: Can biomarkers predict outcome?

Delayed bone healing and non-union occurs in approximately 10-15% of long bone fractures. Both pathologies may result in prolonged period of pain, disability and repetitive operative interventions. Despite intense investigations and progress done in understanding the pathophysiologic processes governing bone healing, the diagnostic tools have not been altered. The clinical findings and radiographic features remain the two important landmarks of diagnosing non-union and even when the diagnosis is established there is debate on the ideal timing and mode of intervention. Emerging evidence suggest that there are certain molecules and genes that can serve as predictors of potentially unsuccessful fracture union. This article summarises the current evidence on the available 'bio-markers'to predict fracture non-union.

The influence of non-osteogenic factors on the expression of M-CSF and VEGF during fracture healing

INTRODUCTION

Macrophage colony stimulating factor (M-CSF) as well as vascular endothelial growth factor (VEGF) play an important role in bone homeostasis and in the process of fracture healing. To date, limited data regarding the influence of age, gender, diabetes, smoking, and alcohol consumption on the systemic expression of M-CSF and VEGF after long bone fracture exist.

METHODS

From a total of 113 patients with long bone fractures 51 patients met inclusion criteria and were finally enrolled in this study. Patient's serum was collected over a period of 6 months following a standardised time schedule. M-CSF and VEGF serum concentrations were measured. Patient's history with special focus on cigarette smoking, diabetes mellitus, and regular alcohol intake was recorded. All patients were followed up clinically and radiologically for at least 24 weeks after trauma. A total of 22 male and 29 female patients formed the study population.

RESULTS

The present results show significantly elevated mean overall M-CSF serum concentration in women, older patients as well as in non-smoking individuals. The mean overall VEGF serum concentration was significantly higher in women, older patients, and diabetic individuals as well as in non-smokers. Statistically significant differences were not observed at any time point regarding alcohol consumption.

CONCLUSION

These results suggest that age, gender, diabetes mellitus and cigarette smoking significantly influence the expression of M-CSF and VEGF after fracture of long bones in human. Of note, diabetic patients showed significantly elevated overall VEGF levels when compared to non-diabetic patients. Therefore, further studies with larger patient cohorts are needed to better understand the influence of these endogenous and exogenous factors on the expression of the osteogenic during human fracture healing.

Circulating bone morphogenetic protein levels and delayed fracture healing

OBJECTIVE

Despite adequate treatment 5-30% of bone fracture patients experience delayed union. During normal fracture union, bone morphogenetic proteins (BMPs) induce healing through a sequential cascade of events. Improved fracture healing after BMP-2 or -7 supplementation in patients with impaired fracture union suggests a deficiency of one or more of these factors. We postulated that low levels of circulating BMPs may result in delayed bone healing. The aim of this study was to quantify differences in levels of circulating BMP-2, -4, -6, -7, and -9 in patients that have demonstrated normal or delayed fracture healing.

PATIENTS AND METHODS

Blood samples were collected from an unselected cohort of 65 patients that had been treated for a diaphyseal tibia or femur fracture. Patients were divided into a group with fracture healing within nine months after injury and a group with delayed fracture union. BMP plasma concentrations were quantified using ELISAs and compared between these two groups.

RESULTS

Circulating plasma levels of BMP-2, -4, -6, and -7 did not differ between 34 patients with normal fracture healing and 31 patients with delayed fracture healing. Also the median BMP-9 plasma levels were not statistically different between the two groups of patients. However, the distribution in the patients with normal union showed a wider range (72-2496 pg/ml) compared with the delayed union group (120-816 pg/ml).

CONCLUSION

In general, circulating BMP concentrations are not statistically different between patients who demonstrated normal or delayed fracture healing. High circulating BMP-9 levels seem to be associated with faster fracture healing, but are apparently not decisive.