Mechanism Of Fracture Healing Research Articles

Fracture-healing effects of Rhizoma Musae ethanolic extract: An integrated study using UHPLC-Q-Exactive-MS/MS, network pharmacology, and molecular docking.

Fracture disrupts the integrity and continuity of the bone, leading to symptoms such as pain, tenderness, swelling, and bruising. Rhizoma Musae is a medicinal material frequently utilized in the Miao ethnic region of Guizhou Province, China. However, its specific mechanism of action in treating fractures remains unknown. This study aimed to elucidate the chemical constituents of the ethanol extract of Rhizoma Musae (EERM) and investigate its fracture-healing mechanism using network pharmacology. The chemical profile of EERM was characterized via UHPLC-Q-Exactive-MS/MS. Subsequently, a comprehensive network of compounds, targets, and pathways was constructed using network pharmacology approaches. The interactions between the active compounds of EERM and their targets were validated through molecular docking, molecular dynamics simulation and in vitro cell experiments. EERM contained 522 identified compounds. Topological analysis of the protein-protein interaction (PPI) network identified 59 core targets, including key proteins like AKT1, IL-6, and EGFR, known for their anti-inflammatory properties and ability to enhance bone cell proliferation and differentiation. Gene Ontology analysis indicated the involvement of EERM in biological processes such as peptidyl-serine phosphorylation, response to xenobiotic stimulus, and nutrient level regulation. KEGG analysis suggested that EERM's mechanism may involve signaling pathways such as PI3K-Akt, lipid and atherosclerosis, EGFR tyrosine kinase inhibitor resistance, and MAPK pathways. Molecular docking and molecular dynamics simulations results demonstrated a strong binding affinity between the main compounds of EERM and key targets. In vitro cell experiments demonstrate that EERM enhances cell proliferation by upregulating the expression levels of EGFR and STAT3, while simultaneously downregulating AKT1 and CASP3. This study investigates the potential active compounds of EERM and its key targets in regulating multiple pathways of fracture, leading to promoting bone cell proliferation. These results offer valuable insights for the future development and clinical application of Rhizoma Musae.

Radiologic and histopathologic effects of favipiravir and hydroxychloroquine on fracture healing in rats

Fracture healing is a process in which many factors interact. In addition to many treatments, physical and biological therapy methods that affect different steps of this process, there are many biological and chemical agents that cause fracture union delay. Although the number of studies on fracture healing is increasing day by day, the mechanism of fracture healing, which is not fully understood, still attracts the attention of all researchers. In this study, we aimed to investigate the effects of favipiravir and hydroxychloroquine used in the treatment of COVID-19. In this study, 48 male Wistar rats weighing 300 ± 50 g were used. Each group was divided into eight subgroups of six rats each to be sacrificed at the 2nd and 4th weeks and evaluated radiologically and histologically. Favipiravir (group 1), hydroxychloroquine (group 2), favipiravir + hydroxychloroquine (group 3), and random control (group 4) were used. A statistically significant difference was observed between the 15th day histological scoring averages of the groups (p < 0.05). Although there was no statistically significant difference between the 15th day radiological score distributions of the groups (p > 0.05), we obtained different results in terms of complete bone union distributions and radiological images of the fracture line. Although favipiravir has a negative effect on fracture union in the early period, favipiravir may have a positive effect on fracture union in the late period. We did not find any effect of hydroxychloroquine on fracture union.

Fracture haematoma proteomics.

The aim of this study was to determine the fracture haematoma (fxH) proteome after multiple trauma using label-free proteomics, comparing two different fracture treatment strategies. A porcine multiple trauma model was used in which two fracture treatment strategies were compared: early total care (ETC) and damage control orthopaedics (DCO). fxH was harvested and analyzed using liquid chromatography-tandem mass spectrometry. Per group, discriminating proteins were identified and protein interaction analyses were performed to further elucidate key biomolecular pathways in the early fracture healing phase. The early fxH proteome was characterized by immunomodulatory and osteogenic proteins, and proteins involved in the coagulation cascade. Treatment-specific proteome alterations were observed. The fxH proteome of the ETC group showed increased expression of pro-inflammatory proteins related to, among others, activation of the complement system, neutrophil functioning, and macrophage activation, while showing decreased expression of proteins related to osteogenesis and tissue remodelling. Conversely, the fxH proteome of the DCO group contained various upregulated or exclusively detected proteins related to tissue regeneration and remodelling, and proteins related to anti-inflammatory and osteogenic processes. The early fxH proteome of the ETC group was characterized by the expression of immunomodulatory, mainly pro-inflammatory, proteins, whereas the early fxH proteome of the DCO group was more regenerative and osteogenic in nature. These findings match clinical observations, in which enhanced surgical trauma after multiple trauma causes dysbalanced inflammation, potentially leading to reduced tissue regeneration, and gained insights into regulatory mechanisms of fracture healing after severe trauma.

Towards a self-healing aluminum metal matrix composite: Design, fabrication, and demonstration

This paper presents a novel approach to designing and synthesizing a self-healing aluminum-based metal matrix composite (MMC) at the macro-scale. The composite comprises an Al 5083 matrix embedded with low melting point particles (LMPPs) that act as healing agents. A two-step electroless micro-encapsulation process is developed to create LMMPs with a diffusion and thermal barrier designed to protect the Zn-8Al core with a Co-P shell. The MMC is fabricated using spark plasma sintering. Following controlled total fracture under tension, external compressive force is applied during heat treatment to heal the fracture effectively. The evolution of phases and interfaces is characterized using electron microscopy, and transient liquid phase bonding (TLPB) is identified as the fracture-healing mechanism, facilitated in areas with sufficiently high Zn concentration to fill the crack. The design can be expanded to incorporate other matrix and LMMP materials, mechanical crack volume reduction by integrating shape memory alloy (SMA) reinforcement during MMC synthesis, and processing of the self-healing MMC using Directed Energy Deposition additive manufacturing.

Computational models of bone fracture healing and applications: a review.

Fracture healing is a very complex physiological process involving multiple events at different temporal and spatial scales, such as cell migration and tissue differentiation, in which mechanical stimuli and biochemical factors assume key roles. With the continuous improvement of computer technology in recent years, computer models have provided excellent solutions for studying the complex process of bone healing. These models not only provide profound insights into the mechanisms of fracture healing, but also have important implications for clinical treatment strategies. In this review, we first provide an overview of research in the field of computational models of fracture healing based on CiteSpace software, followed by a summary of recent advances, and a discussion of the limitations of these models and future directions for improvement. Finally, we provide a systematic summary of the application of computational models of fracture healing in three areas: bone tissue engineering, fixator optimization and clinical treatment strategies. The application of computational models of bone healing in clinical treatment is immature, but an inevitable trend, and as these models become more refined, their role in guiding clinical treatment will become more prominent.

The effects and underlying mechanism of extracorporeal shockwave therapy on fracture healing.

The clinical efficacy of ESWT in treating bone non union has been widely recognized, but the biological mechanism of ESWT promoting bone non union healing is still unclear. ESWT can make old callus micro fracture through mechanical conduction, form subperiosteal hematoma, promote the release of bioactive factors, reactivate the fracture healing mechanism, rebalance the activities of osteoblasts and osteoclast, promote the angiogenesis of fracture site, and accelerate the healing of bone nonunion.Over recent years, great efforts have been made by both scientists and clinicians to explore the underlying mechanism behind the healing effect of ESWT on bone fractures. In this review, we introduced the growth factors during osteogenesis induced by ESWT hoping to provide new insights in the clinical use of ESWT.

The optimal design of 3D-printed lattice bone plate by considering fracture healing mechanism.

The biomechanical stimulus is the most important factor for fracture healing and mainly determined by the structural stiffness of bone plate. Currently, the materials commonly used in bone plates are stainless steel and titanium, which often lead to stress shielding effects because of their higher elastic modulus compared with the bone. This article suggests an optimal design method of lattice bone plate based on fracture healing theory. First, the mechanical regulation model with deviatoric strain is established to simulate the tissue differentiation process during fracture healing process. The ratio of the average elastic modulus of callus at the 120th day to the elastic modulus of mature bone is used to characterize the fracture healing rate. Second, the optimal elastic modulus of the design domain is obtained by the optimization mathematical model with the maximum fracture healing rate. Then, the design domain is filled with microstructures, the porosity of which is adjusted to make it possible that the equivalent elastic modulus is equal to the optimized value. And the finite element analysis of the bone plate with microstructure is executed. Finally, the designed lattice bone plates are manufactured through 3D printing, and the mechanical test is carried out. The simulation results indicate that the fracture healing rate is maximum when the elastic modulus of material in design domain is 38 GPa under the constraints of fixation stability. And both the finite element analysis and experiment results show that the designed lattice bone plate meet the strength requirements of fracture internal fixation implants.

Age-related decrease in periostin expression may be associated with attenuated fracture healing in old mice.

Older adults suffer more bone fractures with higher rates of healing complications and increased risk of morbidity and mortality. An improved understanding of the cellular and molecular mechanism of fracture healing and how such processes are perturbed with increasing age may allow for better treatment options to manage fractures in older adults. Macrophages are attractive therapeutics due to their role in several phases of fracture healing. After injury, bone marrow-derived macrophages are recruited to the injury and propagate the inflammatory response, contribute to resolution of inflammation, and promote bone regeneration. A tissue resident population of macrophages named osteal macrophages are present in the periosteum and are directly associated with osteoblasts and these cells contribute to bone formation. Here, we utilized bulk RNA sequencing to analyze the transcriptional activity of osteal macrophages from old and young mice present in primary calvarial cultures. Macrophages demonstrated a diverse transcriptional profile, expressing genes involved in immune function as well as wound healing and regeneration. Periostin was significantly downregulated in macrophages from old mice compared to young. Periostin is an extracellular matrix protein with important functions that promote osteoblast activity during bone regeneration. An age-related decrease of periostin expression was verified in the fracture callus of old mice compared to young. Young periostin knockout mice demonstrated attenuated fracture healing outcomes that reflected what is observed in old mice. This study supports an important role of periostin in fracture healing, and therapeutically targeting the age-related decrease in periostin may improve healing outcomes in older populations.

Comparison of two non-union models with damaged periosteum in mice: Segmental defect and pin-clip fixation versus transverse fracture and K-wire stabilization.

Despite growing knowledge about the mechanisms of fracture healing, non-union formation still represents a major complication in trauma and orthopedic surgery. Non-union models in mice gain increasing interest, because they allow investigating the molecular and cellular mechanisms of failed fracture healing. These models often use segmental defects to achieve non-union formation. Alternatively, failed fracture healing can be induced by transverse fractures with additional periosteal injury. The present study systematically compared the reliability of these two approaches to serve as non-union model. A 0.6mm K-wire was inserted into the femora of CD-1 mice in a retrograde fashion and a closed transverse femoral fracture was created. Subsequently, the fracture site was exposed and the periosteum was cauterized. This approach was compared with a well-established non-union model involving the pin-clip fixation of a 1.8mm segmental defect. The callus tissue was analyzed by means of radiography, biomechanics, histology and Western blotting. At 10weeks after surgery 10 out of 12 femora (83.3%) of the K-wire group showed a non-union formation. The pin-clip model resulted in 100% non-union formation. The K-wire group showed increased bone formation, osteoclast activity and bending stiffness when compared to the group with pin-clip fixation. This was associated with a higher expression of bone formation markers. However, the number of CD31-positive microvessels was reduced in the K-wire group, indicating an impaired angiogenic capacity after periosteal cauterization. These findings suggest that the pin-clip model is more reliable for the study of non-union formation in mice. The K-wire model including periosteal injury by cauterization however, may be particularly applied in preclinical studies which explore the effects of damaged periosteum and reduced angiogenic capacity to trauma-induced fractures.

Effects of exogenous nerve growth factor on the expression of BMP-9 and VEGF in the healing of rabbit mandible fracture with local nerve injury

BackgroundMandibular fracture healing is a complex process involving nerves and growth factors. Nerve growth factor (NGF) not only facilitates the maintenance of sympathetic neurite growth but also stimulates other growth factors that can promote the essential osteogenesis and angiogenesis for fracture healing. Therefore, it is necessary to analyze the combined effects of NGF, bone morphogenic protein-9 (BMP-9), and vascular endothelial growth factor (VEGF) to accelerate the healing of mandible fractures.MethodsThe models of mandible fracture with local nerve injury established in 48 rabbits were randomly divided into nerve growth factor group (NGF group), gelatin sponge group (GS group), blank group, and intact group. The recovery of nerve reflex was assessed by observing the number of rabbits with lower lip responses to acupuncture. The fracture healing was observed with visual and CBCT, and then callus tissues from the mandibular fracture area were collected for hematoxylin and eosin (HE) staining observation, and the expression of BMP-9 and VEGF in callus at different stages was detected by quantitative real-time PCR (qRT-PCR).ResultsNeedling reaction in the lower lip showed the number of animals with nerve reflex recovery was significantly higher in the NGF group than that in the GS and blank groups at the 2nd and 4th weeks after the operation. The combined results of macroscopic observation, CBCT examination, and histological analysis showed that a large number of osteoblasts and some vascular endothelial cells were found around the trabecular bone in the NGF group and the amount of callus formation and reconstruction was better than that in the GS group at the 2nd week after the operation. The qRT-PCR results indicated that the expression levels of BMP-9 and VEGF in the four groups reached the highest values at the 2nd week, while the expression levels of both in the NGF group were significantly higher than that in the GS group.ConclusionThe exogenous NGF could accelerate the healing of mandible fractures. This work will provide a new foundation and theoretical basis for clarifying the mechanism of fracture healing, thereby promoting fracture healing and reducing the disability rate of patients.

Numerical simulation of fracture healing

Fracture is a common physical injury. Its healing process involves complex biological activities at tissue, cellular and molecular levels and is affected by mechanical and biological factors. Over recent years, numerical simulation methods have been widely used to explore the mechanisms of fracture healing, design fixators and develop novel treatment strategies, etc. This paper mainly recommend the numerical methods used for simulating fracture healing and their latest research progress, which helps people better understand the mechanism of fracture healing, and also provides direction and guidance for the numerical simulation research of fracture healing in the future. First, the fracture healing process and its relationship with mechanical stimulation and biological factors are described. Then, the numerical models used for simulating fracture healing (including mechano-regulatory model, biological regulatory model and mechano-biological regulatory model) and corresponding modeling techniques (mainly including agent-based techniques and fuzzy logic controlling method) were summarized in particular. Finally, the future research directions in numerical simulation of fracture healing were preliminarily prospected.

Lysophosphatidic acid induces interleukin-6 and CXCL15 secretion from MLO-Y4 cells through activation of the LPA1 receptor and PKCθ signaling pathway

Lysophosphatidic acid (LPA) is a multifunctional phospholipid. Osteocytes are the most abundant cells in bone and can orchestrate bone formation and resorption, in part by producing cytokines that regulate osteoblast and osteoclast differentiation and activity. Interleukin (IL)-6 and IL-8 are two important cytokines that have potent effects on bone fracture healing. Previous studies suggest that platelet-derived LPA may influence fracture healing by inducing osteocyte dendrite outgrowth. However, the biological mechanism through which LPA induces cytokine production in osteocytes is poorly understood. In this study, we report that LPA markedly enhanced IL-6 and CXCL15 (mouse homologue of human IL-8) production in MLO-Y4 cells and that this enhancement was suppressed by the LPA1/3-selective antagonist Ki16425, the Gi/o protein inhibitor PTX or the protein kinase C (PKC) inhibitor sotrastaurin. We also observed that of all the PKC isoform targets of sotrastaurin, only PKCθ was activated by LPA in MLO-Y4 cells and that this activation was blocked by sotrastaurin, Ki16425 or PTX. Taken together, the results of the present study demonstrate that LPA may be a potent inducer of IL-6 and CXCL15 production in MLO-Y4 cells and that this induction is associated with the activation of LPA1, Gi/o protein and the PKCθ pathway. These findings may help us better understand the mechanism of fracture healing and contribute to the treatment of bone damage.

MiR-148a regulates bone marrow mesenchymal stem cells-mediated fracture healing by targeting insulin-like growth factor 1.

The purpose of this study was to investigate the underlying molecular mechanisms of fracture healing mediated by bone marrow mesenchymal stem cells. Differentially expressed microRNAs in acutely injured subjects and healthy volunteers were screened by microarray analysis. The dual luciferase reporter system was used to verify whether insulin-like growth factor 1 (IGF1) was the direct target gene regulated by miR-148a. The expression level of miR-148a and IGF1 after osteogenic differentiation was detected by quantitative real-time polymerase chain reaction. Western blot was used to determine the protein expression of bone markers, including IGF1, runt-related transcription factor 2 (Runx2), osteocalcin, and osteopontin inrat bone marrow-derived mesenchymal stem cells. Alkaline phosphatase and alizarin redstaining was used to detect alkaline phosphatase activity and calcium deposition. An animal fracture model was used for in vivo experiments. MiR-148a was highly expressed in acutely injured subjects compared with healthy volunteers, and IGF1 was a target of miR-148a. Moreover, compared with the negative control group, IGF1 messenger RNA expression was significantly increased in the miR-148a antagomir group. Duringosteogenic differentiation, the expression of IGF1, Runx2, osteocalcin, and osteopontin was higher in the miR-148a antagomir group than other groups. In vivo experiments further confirmed that upregulation of IGF1 enhanced fracture healing efficiently by decreasing callus width and area and improving bone mineral density, maximum load, stiffness, and energy absorption. It was proved that IGF1 was the direct target gene of miR-148a, and the use of rat bone marrow-derived mesenchymal stem cells with low expression of miR-148a could improve fracture healing by upregulating IGF1.

Radiological changes during fracture and repair in neural and haemal spines of Atlantic cod (Gadus morhua).

Although spinal injuries in fish have been associated with electric stimuli applied during electrofishing and electrotrawling, bone fracture and repair in the axial skeleton have yet not been studied. To study this, we radiographed a group (n=64) of individually tagged farmed cod twice, with a 1-year interval (∼36cm at first and ∼ 50cm at second inspection). The study focus was on the neural and haemal spines. These structures are un-paired and are not covered by other bones laterally, making them useful for radiological studies on axial skeletal fracture in live fish. At the first examination, four animals showed radiological changes in their neural and haemal spines. Two animals had fractures, and two had callus formations. One year later, at the second radiological examination, the fractures had developed into calluses or into normal morphology, and calluses either remained as calluses or had developed into normal morphology. A further 14 animals that were all normal at the first inspection had developed changes in their neural and haemal spines, both fractures and callus formations. This is the first record of spontaneous bone fracture in fish; the fractures observed occurred under normal farming conditions and were not induced. The results show that cod have a functional fracture healing mechanism in their neural and haemal spines. The findings are discussed in relation to fish hyperostosis.

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions.

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

Mechanical and biological characterization of alkaline substituted orthophosphate bone substitutes containing meta- and diphosphates

Despite the growing knowledge on the mechanisms of fracture healing, bone defects often do not heal in a timely manner. Clinically, tricalcium phosphate (TCP) bone substitutes are used to fill bone defects and promote bone healing. However, the degradation rate of these implants is often too slow for sufficient bone replacement. The use of calcium phosphate material with the crystalline phase Ca10[K/Na](PO4)7 containing different amounts of di- and metaphosphates may overcome this problem, because these materials show an accelerated degradation. Therefore, we generated alkaline substituted Ca–P scaffolds with different amounts of ortho-, di- and metaphosphates. The degradation of these materials was analyzed in TRIS–HCl buffer solution in vitro. Moreover, we measured the compressive strength and porosity of the scaffolds by micro-CT analysis. The biocompatibility of the scaffolds was evaluated in vivo in the mouse dorsal skinfold chamber by means of intravital fluorescence microscopy and histology. We found that higher amounts of incorporated di- and metaphosphates increase the degradation rate and compressive strength of the scaffolds without inducing a stronger leukocytic inflammatory host tissue reaction after implantation. Histological analyses confirmed the good biocompatibility of the scaffolds containing di- and metaphosphates. In summary, this study demonstrates that the compressive strength and degradation rate of Ca–P scaffolds can be improved by incorporation of di- and metaphosphates without affecting their good biocompatibility. Hence, this material modification may be particularly beneficial for the treatment of metaphyseal bone defects in weight bearing locations.

Effect of anisotropy on stress-induced electrical potentials in bovine bone using ultrasound irradiation

The bone fracture healing mechanism of the low-intensity pulsed ultrasound technique is not yet clearly understood. In our previous study, the electrical potentials induced in bone were successfully measured by focusing on piezoelectricity in the MHz range. Bone is composed of collagen and hydroxyapatite and has strong anisotropy. The purpose of this study is to investigate the effects of bone anisotropy on the electrical potentials induced by ultrasound irradiation. For this study, ultrasound bone transducers were fabricated using cortical bovine bone plates as piezoelectric devices. An ultrasound of 7.4 kPapeak-peak (i.e., the peak-to-peak pressure value) was used to irradiate the side surface of each bone plate. Electrical potentials induced in the bone plate were then measured by varying the wave propagation direction in the plate. The peak-to-peak values of these ultrasonically induced electrical potentials were found to vary with changes in the ultrasound propagation direction in the bone sample. The potential was maximized at an inclination of approximately 45° to the bone axis but was minimized around the three orthogonal directions. These maxima and minima ranged from 28 to 33 μVpeak-peak and from 5 to 12 μVpeak-peak, respectively. Additionally, our ultrasound results indicated a change in polarity due to bone anisotropy in the MHz range.

Circulation in Rapid Hip and Knee Bone Destruction

In the hip and knee, the term subchondral insufficiency fracture has been used to describe a focal bone response associated with sudden onset of joint pain, older age, focal osteoporosis, and progression to joint replacement in some cases. Rapidly developing osteoarthritis of the hip is also associated with sudden onset of severe pain, and it usually progresses to larger areas of bone resorption with progression to joint replacement. The literature relative to these three conditions was reviewed focusing on patient demographics, imaging, osteoporosis, associated comorbidities, cytokine changes, similar vascular disorders in other joints, and attempts at nonsurgical treatment. These conditions predominate in, but are not restricted to, individuals who are older than 50, have physical joint abnormalities, are not systemically osteoporotic, and have had no apparent trauma. The biochemical and genetic mechanisms for hip and knee insufficiency fractures is not clear. Although there are reports of hip subchondral insufficiency fractures associated with rapidly developing osteoarthritis of the hip, it is not clear whether all cases are preceded with insufficiency fractures. There is insufficient information on the fracture healing mechanism of insufficiency fractures, and the relationship to vascularity and biochemical imbalance is poorly understood. It is concluded that there are large gaps in the knowledge of biochemical and other mechanisms that might link these conditions. This knowledge may influence nonsurgical treatment strategies.

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

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