Biomimetic vascularized adipose-derived mesenchymal stem cells bone-periosteum graft enhances angiogenesis and osteogenesis in a male rabbit spine fusion model.

Aims: Several artificial bone grafts have been developed but fail to achieve anticipated osteogenesis due to their insufficient neovascularization capacity and periosteum support. This study aimed to develop a vascularized bone-periosteum construct (VBPC) to provide better angiogenesis and osteogenesis for bone regeneration. Methods: A total of 24 male New Zealand white rabbits were divided into four groups according to the experimental materials. Allogenic adipose-derived mesenchymal stem cells (AMSCs) were cultured and seeded evenly in the collagen/chitosan sheet to form cell sheet as periosteum. Simultaneously, allogenic AMSCs were seeded onto alginate beads and were cultured to differentiate to endothelial-like cells to form vascularized bone construct (VBC). The cell sheet was wrapped onto VBC to create a vascularized bone-periosteum construct (VBPC). Four different experimental materials - acellular construct, VBC, non-vascularized bone-periosteum construct, and VBPC - were then implanted in bilateral L4-L5 intertransverse space. At 12 weeks post-surgery, the bone-forming capacities were determined by CT, biomechanical testing, histology, and immunohistochemistry staining analyses. Results: At 12 weeks, the VBPC group significantly increased new bone formation volume compared with the other groups. Biomechanical testing demonstrated higher torque strength in the VBPC group. Notably, the haematoxylin and eosin, Masson's trichrome, and immunohistochemistry-stained histological results revealed that VBPC promoted neovascularization and new bone formation in the spine fusion areas. Conclusion: The tissue-engineered VBPC showed great capability in promoting angiogenesis and osteogenesis in vivo. It may provide a novel approach to create a superior blood supply and nutritional environment to overcome the deficits of current artificial bone graft substitutes.

Cultural Intelligence Deployed in One's Own vs. in a Different Culture: The Same or Different?

Cultural intelligence is one's ability to adapt when confronted with problems arising in interactions with people or artifacts of cultures other than one's own. In this study, we explored two maximum-performance tests of cultural intelligence. One, used in previous research, measured cultural intelligence in the context of an individual conducting a business trip in another culture. The second, new to this research, measured cultural intelligence in the context of meeting someone from another culture while one is in the context of one's own culture. So, the difference between the two tests was whether one was in one's own culture or another and whether the individual who most had to adapt was oneself or someone else. We found that cultural intelligence in the two contexts was essentially the same construct. Cultural intelligence as measured by a typical-performance test is a different construct from cultural intelligence as measured by a maximum-performance test. In this research, general intelligence showed some limited correlation with cultural intelligence as measured by a maximum-performance, but not a typical-performance test. Cultural intelligence as an ability and as a disposition are not the same but rather complement each other.

The oxDNA Coarse-Grained Model as a Tool to Simulate DNA Origami.

This chapter introduces how to run molecular dynamics simulations for DNA origami using the oxDNA coarse-grained model.

The Use of Ultrasonic Bone Scalpel (UBS) in Unilateral Biportal Endoscopic Spine Surgery (UBESS): Technical Notes and Outcomes.

STUDY DESIGN: Case Series and Technical Note, Objective: UBS has been extensively used in open surgery. However, the use of UBS during UBESS has not been reported in the literature. The aim of this study was to describe a new spinal surgical technique using an ultrasonic bone scalpel (UBS) during unilateral biportal endoscopic spine surgery (UBESS) and to report the preliminary results of this technique. METHODS: We enrolled patients diagnosed with lumbar spinal stenosis who underwent single-level UBESS. All patients were followed up for more than 12 months. A unilateral laminotomy was performed after bilateral decompression under endoscopy. We used the UBS system after direct visualization of the target for a bone cut. We evaluated the demographic characteristics, diagnosis, operative time, and estimated blood loss of the patients. Clinical outcomes included the visual analog scale (VAS), the Oswestry Disability Index (ODI), the modified MacNab criteria, and postoperative complications. RESULTS: A total of twenty patients (five males and fifteen females) were enrolled in this study. The mean follow-up period was 13.2 months (range 12-17 months). The VAS score, ODI, and modified MacNab criteria classification improved after the surgery. A minimal mean blood loss of 22.1 mL was noted during the operation. Only one patient experienced neuropraxia, which resolved within 2 weeks. There was no durotomy, iatrogenic pars fracture, or infection. CONCLUSIONS: In conclusion, our study represents the first report of the use of UBS during UBESS. Our findings demonstrate that this technique is safe and efficient, with improved clinical outcomes and minimal complications. These preliminary results warrant further investigation through larger clinical studies with longer follow-up periods to confirm the effectiveness of this technique in the treatment of lumbar spinal stenosis.

Cultural Intelligence: What Is It and How Can It Effectively Be Measured?

We administered both maximum-performance and typical-performance assessments of cultural intelligence to 114 undergraduates in a selective university in the Northeast of the United States. We found that cultural intelligence could be measured by both maximum-performance and typical-performance tests of cultural intelligence. Cultural intelligence as assessed by a maximum-performance measure is largely distinct from the construct as assessed by a typical-performance measure. The maximum-performance test, the Sternberg Test of Cultural Intelligence (SCIT), showed high internal consistency and inter-rater reliability. Sections with problems from two content domains-Business (SCIT-B) and Leisure (SCIT-L) activities-were highly intercorrelated, suggesting they measured largely the same construct. The SCIT showed substantial correlations with another maximum-performance measure of cultural intelligence, Views-on-Culture. It also was correlated, at more modest levels, with fluid intelligence and personal intelligence tests. Factorially, the (a) maximum-performance cultural intelligence tests, (b) typical-performance cultural intelligence test and a test of openness to experience, and (c) fluid intelligence tests formed three separate factors.

Does Direct Surgical Repair Benefit Pars Interarticularis Fracture? A Systematic Review and Meta-analysis.

BACKGROUND: Promising results have been shown in previous studies from direct pars interarticularis repair. These include Scott wiring, Buck repair, pedicle screw repair, and Morscher techniques. In addition, several minimally invasive techniques have been reported to show high union rates, low rates of implant failure and wound complications, shorter length of stay, a lower postoperative pain score with faster recovery, and minimal blood loss. OBJECTIVES: To compare the evidence on techniques for direct pars interarticularis repair. STUDY DESIGN: Systematic review and meta-analysis. SETTING: Review article. METHODS: We conducted a comprehensive search of databases to identify studies assessing outcomes of direct pars interarticularis defect repair. Two authors independently screened electronic search results, performed study selection, and extracted data for meta-analysis. Sensitivity and subgroup analyses were performed to assess risk of bias. RESULTS: Forty studies were included in the final analysis. Union rate was higher in the pedicle screw repair group (effect size [ES] 95%; 95% CI, 86% to 100%), followed by the Buck repair group (ES 93%; 95% CI, 86% to 98%), Scott wiring (ES 85%; 95% CI, 63% to 99%), and Morscher method group (ES 63%; 95% CI, 2% to 100%). Positive functional outcome was higher for the Morscher method (ES 91%; 95% CI, 86% to 96%), followed by the Buck repair group (ES 85%; 95% CI, 68% to 97%), pedicle screw repair (ES 84%; 95% CI, 59% to 99%) and Scott repair group (ES 80%; 95% CI, 60% to 95%). Complication rates were highest among the Scott repair group (ES 12%; 95% CI, 4% to 22%) and Morscher method group (ES 12%; 95% CI, 0% to 34%). LIMITATIONS: Heterogeneity of the included studies were noted. However, we performed sensitivity analyses from the available data to address this issue. CONCLUSION: Our results indicate that pedicle screw repair and Buck repair may be associated with a higher union rate and lower complication rates compared to the Scott repair and Morscher method. Ultimately, the choice of technique should be based on the surgeon's preference and experience.

ECNano: A cost-effective workflow for target enrichment sequencing and accurate variant calling on 4800 clinically significant genes using a single MinION flowcell.

BACKGROUND: The application of long-read sequencing using the Oxford Nanopore Technologies (ONT) MinION sequencer is getting more diverse in the medical field. Having a high sequencing error of ONT and limited throughput from a single MinION flowcell, however, limits its applicability for accurate variant detection. Medical exome sequencing (MES) targets clinically significant exon regions, allowing rapid and comprehensive screening of pathogenic variants. By applying MES with MinION sequencing, the technology can achieve a more uniform capture of the target regions, shorter turnaround time, and lower sequencing cost per sample. METHOD: We introduced a cost-effective optimized workflow, ECNano, comprising a wet-lab protocol and bioinformatics analysis, for accurate variant detection at 4800 clinically important genes and regions using a single MinION flowcell. The ECNano wet-lab protocol was optimized to perform long-read target enrichment and ONT library preparation to stably generate high-quality MES data with adequate coverage. The subsequent variant-calling workflow, Clair-ensemble, adopted a fast RNN-based variant caller, Clair, and was optimized for target enrichment data. To evaluate its performance and practicality, ECNano was tested on both reference DNA samples and patient samples. RESULTS: ECNano achieved deep on-target depth of coverage (DoC) at average > 100× and > 98% uniformity using one MinION flowcell. For accurate ONT variant calling, the generated reads sufficiently covered 98.9% of pathogenic positions listed in ClinVar, with 98.96% having at least 30× DoC. ECNano obtained an average read length of 1000 bp. The long reads of ECNano also covered the adjacent splice sites well, with 98.5% of positions having ≥ 30× DoC. Clair-ensemble achieved > 99% recall and accuracy for SNV calling. The whole workflow from wet-lab protocol to variant detection was completed within three days. CONCLUSION: We presented ECNano, an out-of-the-box workflow comprising (1) a wet-lab protocol for ONT target enrichment sequencing and (2) a downstream variant detection workflow, Clair-ensemble. The workflow is cost-effective, with a short turnaround time for high accuracy variant calling in 4800 clinically significant genes and regions using a single MinION flowcell. The long-read exon captured data has potential for further development, promoting the application of long-read sequencing in personalized disease treatment and risk prediction.

Detecting structural variations with precise breakpoints using low-depth WGS data from a single oxford nanopore MinION flowcell.

Structural variation (SV) is a major cause of genetic disorders. In this paper, we show that low-depth (specifically, 4×) whole-genome sequencing using a single Oxford Nanopore MinION flow cell suffices to support sensitive detection of SV, particularly pathogenic SV for supporting clinical diagnosis. When using 4× ONT WGS data, existing SV calling software often fails to detect pathogenic SV, especially in the form of long deletion, terminal deletion, duplication, and unbalanced translocation. Our new SV calling software SENSV can achieve high sensitivity for all types of SV and a breakpoint precision typically ± 100 bp; both features are important for clinical concerns. The improvement achieved by SENSV stems from several new algorithms. We evaluated SENSV and other software using both real and simulated data. The former was based on 24 patient samples, each diagnosed with a genetic disorder. SENSV found the pathogenic SV in 22 out of 24 cases (all heterozygous, size from hundreds of kbp to a few Mbp), reporting breakpoints within 100 bp of the true answers. On the other hand, no existing software can detect the pathogenic SV in more than 10 out of 24 cases, even when the breakpoint requirement is relaxed to ± 2000 bp.

Characterizing the free-energy landscapes of DNA origamis.

We show how coarse-grained modelling combined with umbrella sampling using distance-based order parameters can be applied to compute the free-energy landscapes associated with mechanical deformations of large DNA nanostructures. We illustrate this approach for the strong bending of DNA nanotubes and the potentially bistable landscape of twisted DNA origami sheets. The homogeneous bending of the DNA nanotubes is well described by the worm-like chain model; for more extreme bending the nanotubes reversibly buckle with the bending deformations localized at one or two "kinks". For a twisted one-layer DNA origami, the twist is coupled to the bending of the sheet giving rise to a free-energy landscape that has two nearly-degenerate minima that have opposite curvatures. By contrast, for a two-layer origami, the increased stiffness with respect to bending leads to a landscape with a single free-energy minimum that has a saddle-like geometry. The ability to compute such landscapes is likely to be particularly useful for DNA mechanotechnology and for understanding stress accumulation during the self-assembly of origamis into higher-order structures.

Minimally Invasive Percutaneous Vertebroplasty for Thoracolumbar Instrumented Vertebral Fracture in Patients With Posterior Instrumentation.

BACKGROUND: The traditional treatment for an instrumented vertebral fracture involves removing the loosened pedicle screws and extending the posterior instrumentation cephaladly or caudally. There has been a recent trend of performing minimally invasive fluoroscopy-guided percutaneous vertebroplasty as a salvage procedure. OBJECTIVE: The aim of this study was to compare the outcomes of surgical interventions for instrumented vertebral fracture. STUDY DESIGN: Retrospective assessment. SETTING: All data came from Chang Gung Memorial Hospital, Taiwan. METHODS: We retrospectively reviewed 35 patients with an instrumented vertebral fracture who underwent fluoroscopy-guided percutaneous vertebroplasty (Group I, n = 16) or extension of the posterior instrumentation (Group II, n = 19). Demographic data were recorded. The operating time, amount of intraoperative blood loss, time to postoperative ambulation, and duration of hospital stay were also evaluated. The visual analog scale (VAS) score, kyphotic angle on radiological images, Kirkaldy-Willis functional score, complications, and revision surgery were evaluated at one week and one, 3, 6, and 12 months postoperatively. RESULTS: Group I had a shorter operating time (P < 0.001), less intraoperative blood loss (P < 0.001), earlier postoperative ambulation (P < 0.001), and a shorter hospital stay (P < 0.001). The mean VAS score improved significantly after surgery in both groups (P = 0.001). The postoperative kyphotic angle was better in Group II (P < 0.05). There was no significant between-group difference in the Kirkaldy-Willis functional score at the last follow-up (P = 0.91). There was no significant between-group difference in the need for revision surgery (Group I, n = 4; Group II, n = 5; P = 0.93). LIMITATION: This study is a retrospective cohort. CONCLUSIONS: Minimally invasive fluoroscopy-guided percutaneous vertebroplasty can be used as an alternative to extension of posterior instrumentation for instrumented vertebral fracture. It has several advantages, including a shorter operating time, earlier postoperative ambulation, less blood loss, and a shorter hospital stay. The clinical outcomes of these 2 treatment approaches were similar.

Understanding and Assessing Cultural Intelligence: Maximum-Performance and Typical-Performance Approaches.

Cultural intelligence is one's ability to adapt when confronted with problems arising in interactions with people or artifacts of diverse cultures. In this study, we conduct an initial construct-validation and assessment of a maximum-performance test of cultural intelligence. We assess the psychometric properties of the test and also correlate the test with other measures with which it might be expected there would be some connection. We found that our test was internally consistent and correlated significantly with maximum-performance tests of abilities but generally less or not at all with typical-performance tests, including cultural intelligence and openness to experience. However, our test appears to be distinct in what it measures from the other tests of cognitive abilities. The results lead us to suggest that cultural intelligence may have both maximum-performance and typical-performance aspects.

How to design an icosahedral quasicrystal through directional bonding.

Icosahedral quasicrystals (IQCs) are materials that exhibit long-range order but lack periodicity in any direction. Although IQCs were the first reported quasicrystals1, they have been experimentally observed only in metallic alloys2, not in other materials. By contrast, quasicrystals with other symmetries (particularly dodecagonal) have now been found in several soft-matter systems3-5. Here we introduce a class of IQCs built from model patchy colloids that could be realized experimentally using DNA origami particles. Our rational design strategy leads to systems that robustly assemble in simulations into a target IQC through directional bonding. This is illustrated for both body-centred and primitive IQCs, with the simplest systems involving just two particle types. The key design feature is the geometry of the interparticle interactions favouring the propagation of an icosahedral network of bonds, despite this leading to many particles not being fully bonded. As well as furnishing model systems in which to explore the fundamental physics of IQCs, our approach provides a potential route towards functional quasicrystalline materials.

Self-Limiting Polymerization of DNA Origami Subunits with Strain Accumulation.

Biology demonstrates how a near infinite array of complex systems and structures at many scales can originate from the self-assembly of component parts on the nanoscale. But to fully exploit the benefits of self-assembly for nanotechnology, a crucial challenge remains: How do we rationally encode well-defined global architectures in subunits that are much smaller than their assemblies? Strain accumulation via geometric frustration is one mechanism that has been used to explain the self-assembly of global architectures in diverse and complex systems a posteriori. Here we take the next step and use strain accumulation as a rational design principle to control the length distributions of self-assembling polymers. We use the DNA origami method to design and synthesize a molecular subunit known as the PolyBrick, which perturbs its shape in response to local interactions via flexible allosteric blocking domains. These perturbations accumulate at the ends of polymers during growth, until the deformation becomes incompatible with further extension. We demonstrate that the key thermodynamic factors for controlling length distributions are the intersubunit binding free energy and the fundamental strain free energy, both which can be rationally encoded in a PolyBrick subunit. While passive polymerization yields geometrical distributions, which have the highest statistical length uncertainty for a given mean, the PolyBrick yields polymers that approach Gaussian length distributions whose variance is entirely determined by the strain free energy. We also show how strain accumulation can in principle yield length distributions that become tighter with increasing subunit affinity and approach distributions with uniform polymer lengths. Finally, coarse-grained molecular dynamics and Monte Carlo simulations delineate and quantify the dominant forces influencing strain accumulation in a molecular system. This study constitutes a fundamental investigation of the use of strain accumulation as a rational design principle in molecular self-assembly.

Cement Augmentation for Single-Level Osteoporotic Vertebral Compression Fracture: Comparison of Vertebroplasty With High-Viscosity Cement and Kyphoplasty.

BACKGROUND: Although the majority of available evidence suggests that vertebroplasty and kyphoplasty (KP) can relieve pain associated with vertebral compression fractures (VCFs) and improve function, evidence of clinical and radiographic outcome in highly viscous cement vertebroplasty (HVC) or KP for the treatment of VCFs is limited. The purpose of this study was to compare the clinical effects between HVC and KP in the treatment of single-level osteoporotic VCFs including radiographic and clinical outcomes. METHODS: From January 2017 to October 2018, 96 patients with single-level osteoporotic vertebral compression fracture who had undergone either KP or HVC surgery at our hospital were reviewed retrospectively, with at least 1 year follow-up. All patients were divided into the HVC group (n = 50) or the KP group (n = 46). Clinical data including clinical and radiologic evaluation results were performed pre- and postoperatively. RESULTS: The operation time of the HVC group (32.24 ± 10.08 minutes) was less than that of the KP group (40.76 ± 9.49 minutes), with significant differences. Compared with preoperative data, the visual analog scale scores, Oswestry disability index scores, vertebral body height, and local kyphotic angle were improved after surgery. There were no significant differences between the 2 groups in local kyphotic angle, vertebral body height, leakage rate of bone cement, and incidence of adjacent-level vertebra fracture. CONCLUSIONS: Restoring the vertebral height and local kyphotic angle corrections of HVC are similar with those of KP. Additionally, KP is not superior in the leakage rate of bone cement and incidence of adjacent-level vertebra fracture compared to HVC.

Surgical Outcomes for Upper Lumbar Disc Herniation: Decompression Alone versus Fusion Surgery.

Upper lumbar herniated intervertebral disc (HIVD), defined as L1-2 and L2-3 levels, presents with a lower incidence and more unfavorable surgical outcomes than lower lumbar levels. There are very few reports onthe appropriate surgical interventions for treating upper lumbar HIVD. This study aimed to evaluate the surgical outcome of decompression alone, when compared with spinal fusion surgery. A retrospective study involving a total of 7592 patients who underwent surgery due to HIVD in our institution was conducted. A total of 49 patients were included in this study: 33 patients who underwent decompression-only surgery and 16 patients who underwent fusion surgery. Demographic data, perioperative information, and functional outcomes were recorded. The visual analog scale (VAS) scores showed improvement in both groups postoperatively. The three-month postoperative Oswestry Disability Index score was significantly better in the fusion group. Additionally, 10 patients (76.9%) in the decompression group and 5 patients (83.3%) in the fusion group reported improvement in preoperative motor weakness. The final "satisfactory" rate was 66.7% in the decompression group and 93.8% in the fusion group (p = 0.034). The overall surgical outcomes of patients with upper lumbar HIVD were satisfactory in this study without any major complications. More reliable satisfactory rates and better functional scores at the three-month postoperative follow-up were reported in the fusion group.

The Relation of Tests of Scientific Reasoning to Each Other and to Tests of General Intelligence.

We conducted two studies to replicate and extend, as well as test, the limits of previous findings regarding an apparent disconnect between scientific-reasoning skills in psychological science, on the one hand, and scores on standardized tests of general intelligence, on the other. In Study 1, we examined whether this disconnect would extend beyond psychological science to additional sciences as well, such as nutrition and agriculture. The results did indeed extend, suggesting that scientific reasoning across various natural sciences is comparable to scientific reasoning in psychological science, but different in kind from the reasoning required on conventional standardized tests. In Study 2, we examined whether these findings were linked to the format of presentation of scientific problems. Whereas real scientific-reasoning problems are open-ended, standardized tests tend to use multiple-choice format. We discovered that using multiple-choice format did indeed result in an apparently closer relation of the scientific-reasoning tests to two of the conventional ability measures (SAT Reading and Number Series) but not to two other tests (Letter Sets and SAT Math). Thus, one can increase the correlations of scientific-reasoning tests with at least some standardized ability tests but at the cost of content validity and ecological validity.

Comparison of Percutaneous Endoscopic Surgery and Traditional Anterior Open Surgery for Treating Lumbar Infectious Spondylitis.

Minimally invasive surgery is becoming popular for treating spinal disorders. The advantages of percutaneous endoscopic debridement and drainage (PEDD) for infectious spondylitis include direct observation of the lesion, direct pus drainage, and earlier pain relief. We retrospectively reviewed 37 patients who underwent PEDD and 31 who underwent traditional anterior open debridement and interbody fusion with bone grafting from 2004 to 2012. The causative organisms were isolated from 30 patients (81.1%) following PEDD, and from 25 patients (80.6%) following open surgery (p = 0.48). Staphylococcus aureus was the most common pathogen (38.2%). In the PEDD group, blood loss (<50 mL versus 585 ± 428 mL, p < 0.001) was significantly lesser and the duration of hospitalization (24.4 ± 12.5 days versus 31.5 ± 14.6 days, p = 0.03) was shorter than that in the open surgery group. Serologically, there were significantly faster C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) normalization rates in the PEDD group (p < 0.001, p = 0.009, respectively). In the two-year follow-up radiographs, 26 out of 30 (86.7%) open surgery patients showed bony fusions of the infected segments. On the contrary, sclerotic change of the destructive endplates was observed and the motion of infected spinal segments was still preserved in the PEDD group. There was no significant difference in the change of sagittal profile, including primary correction gain, correction loss, and actual correction gain/loss. PEDD is an effective alternative option and should be considered prior to traditional extensive spinal surgery-particularly for patients with early-stage spinal infection or serious complicated medical conditions.

Rational design of gelatin/nanohydroxyapatite cryogel scaffolds for bone regeneration by introducing chemical and physical cues to enhance osteogenesis of bone marrow mesenchymal stem cells.

Identification of key components in the chemical and physical milieu for directing osteogenesis is a requirement in the investigation of tissue engineering scaffolds for advancement of bone regeneration. In this study, we engineered different gelatin-based cryogels and studied the effect of nanohydroxyapatite (nHAP) and crosslinking agents on scaffold properties and its osteogenic response towards bone marrow stem cells (BMSCs). The cryogels examined are 5% gelatin and 5% gelatin/2.5% nHAP, crosslinked either with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) or glutaraldehyde (GA). We confirmed that nHAP or the crosslinking agent has no effects on scaffold pore size and porosity. Nonetheless, incorporation of nHAP increased mechanical strength, swelling ratio and degree of crosslinking, but decreased degradation rate. Cryogels crosslinked with EDC showed faster degradation and promoted osteogenic differentiation of BMSCs while those prepared from GA crosslinking promoted proliferation of BMSCs. Furthermore, osteogenic differentiation was always enhanced in the presence of nHAP irrespective of the culture medium (normal or osteogenic) used but osteogenic medium always provide a higher extent of osteogenic differentiation. Employing gelatin/nHAP cryogel crosslinked by EDC in a bioreactor for dynamic culture of BMSCs, cyclic compressive mechanical simulation was found to be beneficial for both cell proliferation and osteogenic differentiation. However, the optimum conditions for osteogenic differentiation and cell proliferation were found at 30% and 60% strain, respectively. We thus demonstrated that osteogenic differentiation of BMSCs could be tuned by taking advantages of chemical cues generated from scaffold chemistry or physical cues generated from dynamic cell culture in vitro. Furthermore, by combining the best cryogel preparation and in vitro cell culture condition for osteogenesis, we successfully employed in vitro cultured cryogel/BMSCs constructs for repair of rabbit critical-sized cranial bone defects.

Engineered periosteum-bone biomimetic bone graft enhances posterolateral spine fusion in a rabbit model.

BACKGROUND CONTEXT: Bone marrow derived mesenchymal stem cells (BMSCs) and periosteum-derived cells (PDCs) have shown great viability in terms of osteogenic potential and have been considered the major cellular source for skeletal tissue engineering. Using a PDCs-impregnated cell sheet to surround a BMSCs-impregnated tricalcium phosphate (TCP) scaffold might create a periosteum-bone biomimetic bone graft substitute to enhance spine fusion. PURPOSE: The purpose of this study was to determine the feasibility of using this newly tissue-engineered biomimetic bone graft for posterolateral spine fusion. STUDY DESIGN/SETTING: This study design was based on an animal model using adult male New Zealand White rabbits. METHODS: New Zealand White rabbits underwent operation and were divided into three groups based on the experimental material implanted in the bilateral L4-L5 intertransverse space. Group 1 was BMSCs-free TCP wrapped in a PDCs-free cell sheet. Group 2 was BMSCs-loaded-TCP wrapped in a PDCs-free cell sheet. Group 3 was BMSCs-loaded-TCP wrapped in a PDCs-loaded cell sheet. After 12 weeks, six rabbits from each group were euthanized for computed tomography scanning, manual palpation, biomechanical testing, and histology. Each group had 12 radiographic fusion areas for analysis because the right and left intertransverse fusion areas were collected separately. RESULTS: Radiographic union of 12 fusion areas for groups 1, 2, and 3 was 0, 3, and 9, respectively. Group 3 had significantly higher fusion success than groups 1 and 2 (p<.001). Solid fusion of six fusion segments in each group by manual palpation was 0, 1, and 5, accordingly. Group 3 had a higher successful solid fusion rate than groups 1 and 2 (p=.005). The average maximal torques at failure were 727±136 N mm, 627±91 N mm, and 882±195 N mm for groups 1, 2, and 3, accordingly. The maximal torque was significantly higher in group 3 than in group 2 (p=.028). Histological evaluation verified that new bone regeneration were greater in the group 3 samples. CONCLUSIONS: The results indicated the potential of using a PDCs-impregnated cell sheet to surround the BMSCs-impregnated TCP scaffold for creating a periosteum-bone biomimetic bone graft substitute to enhance bone regeneration and posterolateral fusion success.

Appropriate duration of post-surgical intravenous antibiotic therapy for pyogenic spondylodiscitis.

BACKGROUND: Most guidelines recommend 6 to 12 weeks of parenteral antibiotic treatment for pyogenic spondylodiscitis. When surgical debridement is adequately performed, further intravenous antibiotic treatment duration can be reduced than that of conservative treatment alone theoretically. However, the appropriate duration of post-surgical parenteral antibiotic treatment is still unknown. This study aimed to identify the risk factors of recurrence and evaluate the appropriate duration after surgical intervention. METHODS: This 3-year retrospective review included 102 consecutive patients who were diagnosed with pyogenic spondylodiscitis and underwent surgical intervention. Recurrence was defined as recurrent signs and symptoms and the need for another unplanned parenteral antibiotic treatment or operation within one year. This study included two major portions. First, independent risk factors for recurrence were identified by multivariable analysis, using the database of demographic information, pre-operative clinical signs and symptoms, underlying illness, radiographic findings, laboratory tests, intraoperative culture results, and treatment. Patients with any one of the risk factors were considered high-risk; those with no risk factors were considered low-risk. Recurrence rates after short-term (≤3 weeks) and long-term (> 3 weeks) parenteral antibiotic treatment were compared between the groups. RESULTS: Positive blood culture and paraspinal abscesses were identified as independent risk factors of recurrence. Accordingly, 59 (57.8%) patients were classified as low-risk and 43 (42.2%) as high-risk. Among the high-risk patients, a significantly higher recurrence rate occurred with short-term than with long-term antibiotic therapy (56.2% vs. 22.2%, p = 0.027). For the low-risk patients, there was no significant difference between short-term and long-term antibiotic therapy (16.0% vs. 20.6%, p = 0.461). CONCLUSIONS: The appropriate duration of parenteral antibiotic treatment in patients with pyogenic spondylodiscitis after surgical intervention could be guided by the risk factors. The duration of postoperative intravenous antibiotic therapy could be reduced to 3 weeks for patients without positive blood culture or abscess formation.