Prophylactic Effects of NFκB Essential Modulator-Binding Domain Peptides on Bone Infection: An Experimental Study in a Rabbit Model.

Introduction: Osteomyelitis is characterized by intensive inflammatory bone disease and remains a clinical challenge in orthopedic surgery, despite the advances made in medical and surgical therapies. Staphylococcus aureusis a major causative agent of osteomyelitis, causing the progressive inflammatory destruction of bone. Prophylaxis of osteomyelitis during orthopedic surgery is necessary. NFκB essential modulator-binding domain (NBD) peptides are cell-permeable peptide inhibitors of the IκB-kinase complex. The prophylactic effect of NBD peptides in relieving inflammation and inhibiting bone defects in osteomyelitis is still under investigation. Our purpose was to determine the preventive effect of NBD peptides in S. aureus infection-induced bone defects in osteomyelitis. Methods: An S. aureus osteomyelitis rabbit model was used in this study. The rabbits were divided into four groups: NBD, cefazolin, control, and PBS. Clinical and laboratory indicators of erythrocyte-sedimentation rate, CRP, and TNFα levels were assessed to monitor systemic reactions. The efficacy of NBD peptides in S. aureus-induced osteomyelitis was evaluated by radiological, histological, and microbiological examinations, immunohistochemistry, immunofluorescence, and micro-CT scans. Results: In general, NBD peptides effectively reduced clinical signs in rabbits when compared with the control group. Radiography indicated that there was more severe osteomyelitis in the bacterium-infection control group. There was no significance between cefazolin- and NBD-group average scores. The histological results of the lesion slices further confirmed different severity among the groups. Additionally, significant pathological differences were found between the cefazolin and NBD groups, and the PBS group showed no obvious pathological changes. Conclusion: Prophylactic administration of NBD peptides to bone-defect areas inhibited bacterial spread and promoted bone regeneration, making NBD peptides a possible treatment option for prophylaxis in bone infections.

Novel Elongator Protein 2 Inhibitors Mitigating Tumor Necrosis Factor-α Induced Osteogenic Differentiation Inhibition.

Tumor necrosis factor-α is a common cytokine that increases in inflammatory processes, slows the differentiation of bone formation, and induces osteodystrophy in the long-term inflammatory microenvironment. Our previous study confirmed that the Elongation protein 2 (ELP2) plays a significant role in osteogenesis and osteogenic differentiation, which is considered a drug discovery target in diseases related to bone formation and differentiation. In this study, we applied an in silico virtual screening method to select molecules that bind to the ELP2 protein from a chemical drug molecule library and obtained 95 candidates. Then, we included 11 candidates by observing the docking patterns and the noncovalent bonds. The binding affinity of the ELP2 protein with the candidate compounds was examined by SPR analysis, and 5 out of 11 compounds performed good binding affinity to the mouse ELP2 protein. After in vitro cell differentiation assay, candidates 2# and 5# were shown to reduce differentiation inhibition after tumor necrosis factor-α stimulation, allowing further optimization and development for potential clinical treatment of inflammation-mediated orthopedic diseases.

Physiochemical properties of copper doped calcium sulfate in vitro and angiogenesis in vivo.

Bone cements were prepared by mixing calcium sulfate and copper sulfate in various proportions. We examined physical and physicochemical properties of the copper doped calcium sulfates and the effects of the cements on angiogenesis in vivo. Rod shaped calcium sulfate crystals were visible by scanning electron microscopy in the cement that contained no copper sulfate, whereas plate-like crystals covered the surface of the cement with high copper content. After immersion of the cements in simulated body fluid (SBF) for 1 day, X-ray diffractometric analysis showed that gypsum precipitates had formed in the copper doped calcium sulfate. The compressive strength of the cements increased from 3.3 MPa for pure calcium sulfate to 6.4 MPa for samples with copper sulfate added. Calcium ion release was greatest from pure calcium sulfate, and the rate of copper ion release was higher for cements containing the most copper. We found that 6 weeks after implantation, more blood vessels had formed around the high copper cement than for the copper-free cement. Copper doped calcium sulfate appears to be useful for application to regenerative medicine including wound healing and bone tissue engineering.

SDF-1/CXCR4 axis coordinates crosstalk between subchondral bone and articular cartilage in osteoarthritis pathogenesis.

Crosstalk between subchondral bone and articular cartilage is considered a central feature of osteoarthritis (OA) initiation and progression, but its underlying molecular mechanism remains elusive. Meanwhile, specific administration of drugs in subchondral bone is also a great challenge during investigation of the process. We here explore the role of stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis in the crosstalk between subchondral bone and articular cartilage in OA pathogenesis, using osmotic infusion pumps implanted in tibial subchondral bone directly to ensure quantitative, continuous and steady drug delivery over the entire experiment. We found that increased SDF-1 in subchondral bone firstly induced subchondral bone deterioration by erroneous Mesenchymal Stem Cells (MSCs) recruitment and excessive bone resorption in anterior cruciate ligament transection (ACLT) mice. Deterioration of subchondral bone then led to the traverse of SDF-1 from subchondral bone to overlying cartilage. Finally, SDF-1 from underlying subchondral bone combined with CXCR4 in chondrocytes to induce articular cartilage degradation by promoting the shift of transforming growth factor-ß receptor type I (TßRI) in chondrocytes from activin receptor-like kinase 5 (ALK5) to activin receptor-like kinase 1 (ALK1). More importantly, specific inhibition of SDF-1/CXCR4 axis in ACLT rats attenuated OA by stabilizing subchondral bone microarchitecture, reducing SDF-1 in cartilage and abrogating the shift of TßRI in chondrocytes. Our data demonstrate that the SDF-1/CXCR4 axis may coordinate the crosstalk between subchondral bone and articular cartilage in OA pathogenesis. Therefore, specific inhibition of SDF-1/CXCR4 axis in subchondral bone or intervention in SDF-1 traverse may be therapeutic targets for OA.

Interleukin-1 Beta Gene Polymorphism rs16944 May Associate with Increased Susceptibility to Extremity Chronic Osteomyelitis in Chinese Han Population.

BACKGROUND: Previous studies had indicated that interleukin-1 beta (IL-1ß) gene single nucleotide polymorphisms (SNPs) associate with different inflammatory diseases. However, potential links between these polymorphisms and susceptibility to extremity chronic osteomyelitis (COM) remain unclear. This study aimed to investigate relationships between IL-1ß gene polymorphisms (rs16944, rs1143627, rs1143634, and rs2853550) and risks of developing extremity COM in Chinese Han population. METHODS: Altogether 233 extremity COM patients and 200 healthy controls were genotyped for the four tag SNPs of the IL-1ß gene using the SNapShot genotyping method. Comparisons were performed regarding genotype distribution, mutant allele frequency, and four genetic models (dominant, recessive, homozygous, and heterozygous models) of the four SNPs between the two groups. RESULTS: Significant associations were identified between rs16944 polymorphism and the risk of developing COM by dominant model (P = 0.026, OR = 1.698, 95% CI 1.065-2.707) and heterozygous model (P = 0.030, OR = 1.733, 95% CI 1.055-2.847). Although no statistical differences were found of rs1143627 polymorphism between the two groups, there existed a trend that rs1143627 may be linked to an elevated risk of developing COM by outcomes of dominant (P = 0.061), homozygous (P = 0.080) and heterozygous (P = 0.095) models. However, no statistical correlations were found between rs1143634 and rs2853550 polymorphisms and susceptibility to COM in Chinese Han population. CONCLUSIONS: To our knowledge, we reported for the first time that IL-1ß gene rs16944 polymorphism may contribute to the increased susceptibility to extremity COM in Chinese Han population, with genotype of AG as a risk factor.

Lateral Subcutaneous Locking Compression Plate and Small Incision Reduction for Distal-third Diaphyseal Humerus Fractures.

OBJECTIVE: Iatrogenic radial nerve injury is a great challenge for orthopaedic surgeons who deal with distal-third diaphyseal humerus fractures. Conventional open reduction and internal fixation (ORIF) remains the gold standard, but complications such as nonunion and iatrogenic radial nerve injury still occur. We fixed the fractures with a lateral locking compression plate (LCP) subcutaneously after small incision reduction to protect the radial nerve. This study reports the clinical and radiographic outcomes of our modified method. METHODS: Thirty-eight patients with distal-third diaphyseal humerus fractures were treated with lateral subcutaneous LCP and small incision reduction at our department between September 2013 and August 2016. There were 33 males and 5 females, with an average age of 30.3 years (range, 17 to 49 years). All the cases were types A or B (AO/OTA classification, type A, 24 cases; type B, 14 cases). Among them, 6 cases were combined with preoperative radial nerve palsy. All patients were diagnosed with closed humeral fractures after X-ray examination, and had typical upper limb pain, swelling, and movement disorders. The operations were performed by a single surgeons' team. Union time, range of motion (ROM), University of California, Los Angeles (UCLA) shoulder rating scale, and Mayo Elbow Performance Index (MEPI) scores were assessed to evaluate the postoperative results. RESULTS: All patients were followed up for an average of 11.4 months (range, 3 to 36 months). The average operation time was 75.5 min (range, 60 to 150 min) and average intraoperative radiation exposure was 10.5 s (range, 8 to 18 s). Bony union was achieved in all cases after an average of 16.2 weeks (range, 12 to 25 weeks). No complications such as infection or screw and plate fracture occurred, and no iatrogenic radial nerve injury was observed. According to the UCLA shoulder rating scale, the average score was 33.7 (range, 31 to 35), with 33 excellent (86.8%) and 5 good cases (13.2%). They were all excellent according to their MEPI scores (ranging, 94 to 100, with an average of 97.4). The average operation time for secondary removal of the plate was 15.2 min (range, 10 to 20 min), and no complications such as infection or secondary radial nerve injury occurred. CONCLUSIONS: Lateral subcutaneous LCP and small incision reduction may reduce the risk of iatrogenic radial nerve injury significantly in the treatment of distal-third diaphyseal humerus fractures. It also leads to solid fixation, good postoperative function, and convenient removal of the plate without injuring the radial nerve.

Serum TNF-α, erythrocyte sedimentation rate and IL-6 are more valuable biomarkers for assisted diagnosis of extremity chronic osteomyelitis.

AIM: This study aimed to investigate the values of preoperative serum levels of white blood cell, erythrocyte sedimentation rate (ESR), C-reactive protein, procalcitonin, IL-6, TNF-α and serum amyloid A for diagnosis of chronic osteomyelitis (COM) in Chinese patients. METHODS: All 586 eligible patients were included for analysis. RESULTS: Outcomes revealed that positive ratios of TNF-α, ESR and IL-6 lied in top three. Taken predicted probability and detection cost into consideration, combination of ESR, IL-6 and TNF-α might be the optimal model due to its high predicted probability for COM (91.02%) with an acceptable cost (CN¥161). CONCLUSION: Combination of preoperative serum TNF-α, ESR and IL-6 can help a reliable predication of COM.

[Preparation and biocompatibility of a novel strontium-containing calcium sulfate].

OBJECTIVE: To prepare a novel strontium-containing calcium sulfate and assess its and biocompatibility. METHODS: A novel strontium-containing α-calcium sulfate hemihydrate (Sr-caS) bone substitute as prepared with hydrothermal reaction and examined for X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric differential scanning calorimetric (TG-DSC) patterns. The biocompatibility of the material was evaluated by in vitro cytotoxicity test in L-929 cells, hemolysis test of blood, and in vivo implantation test in SD rats. RESULTS: The XRD spectra of the prepared Sr-CaS powder highlighted 3 strong characteristic peaks of α-CaSO4 at 14.63°, 25.72° and 29.80° with a strontium-specific peak at 24.78°. The FTIR patterns of Sr-CaS resembled those of CaS. TG-DSC results showed that the material contained a non-evaporable water content of 6.03%. In vitro cytotoxicity test in L-929 cells suggested that the material had a class 1 cytotoxicity, and the hemolysis rate of its aqueous extract was 4.3%. The material implanted in the muscular tissues of SD rats maintained a steady state in the surrounding tissues. CONCLUSION: This strontium-containing calcium sulfate material we prepared shows an excellent biocompatibility for potential use as a novel artificial bone material.

A novel resorbable strontium-containing α-calcium sulfate hemihydrate bone substitute: a preparation and preliminary study.

Distraction osteogenesis after aggrieved bone segment resections is promising in the treatment of bone tumors and osteomyelitis. However, there is ambiguity with regard to the optimal choice of bone substitute, with biodegradability and excellent bone repair performance constituting key requirements. The purpose of this study was to develop a novel resorbable strontium-containing α-calcium sulfate hemihydrate (Sr-CaS) bone substitute to provide an alternative option for surgeons that better meets these requirements. The Sr-CaS was prepared using co-precipitation and hydrothermal methods and analyzed using x-ray diffraction (XRD), Fourier transform infrared (FTIR) scanning and thermogravimetric differential scanning calorimeter (TG-DSC) patterns. Cytotoxicity by tetrazolium bromide (MTT), sub-acute toxicity and hemolysis tests were performed to assess the initial biocompatibility of the new bone substitute. Radiographic analysis, micro-CT measurements and histological observation were used to evaluate the bone repair ability in rat tibia bone defects. The XRD and FTIR patterns of Sr-CaS were both very similar to CaS and the product had comparable characteristics similar to α-CaS as demonstrated by TG-DSC. Cytotoxicity of the substitute was class 1 (no cytotoxicity) and hemolysis was 4.3% (no hemolysis). Sub-acute toxicity was not seen after a 14 day evaluation. The substitute was radio-opaque. The empty group exhibited the lowest levels of both bone mineral densities (BMD) and bone volume/total volume (BV/TV) of the defects when compared to all other groups. The two Sr-CaS groups resulted in significantly greater BMDs and BV/TV of the defect compared to the CaS only group. However, there was no significant difference between the 5% and 10% Sr-CaS groups. The Sr-CaS was resorbable with satisfactory biocompatibility. The doped strontium ions enhanced the bone repair performance of CaS in a rat model and the new substitute demonstrated promising results for clinical use.

Are platelet concentrates an ideal biomaterial for arthroscopic rotator cuff repair? A meta-analysis of randomized controlled trials.

PURPOSE: The present study aims to conduct a meta-analysis of Level I evidence studies to investigate the efficacy of concomitant platelet concentrate (PC) used in arthroscopic rotator cuff repair. METHODS: We systematically searched electronic databases to identify randomized controlled trials (RCTs) evaluating the role of PC augmentation in arthroscopic rotator cuff repairs for patients with full-thickness tears. The search strategy followed the requirements in the Cochrane Library Handbook. The primary outcome was retearing of the rotator cuff. Functional outcomes were analyzed in terms of Constant score, specific Constant pain score, University of California, Los Angeles (UCLA) shoulder score, Simple Shoulder Test (SST) score, and American Shoulder and Elbow Surgeons (ASES) score. RESULTS: Seven studies with a total of 417 patients available at the latest follow-up reporting data about retears were analyzed in this meta-analysis. However, 4 studies with Constant scores (n = 237), 3 studies with UCLA scores (n = 168), 2 studies with Constant pain scores (n = 164), 2 studies with ASES scores (n = 101), and 2 studies with SST scores (n = 121) were analyzed. The retear rates and functional scores showed that there was no significant efficacy of PC application in arthroscopic rotator cuff repairs. CONCLUSIONS: This meta-analysis of high-level evidence suggests that PCs have no benefit regarding retear rate and overall clinical outcomes for the arthroscopic repair of full-thickness rotator cuff tears. LEVEL OF EVIDENCE: Level II, meta-analysis of randomized controlled trials.