Targeting foamy macrophages by manipulating ABCA1 expression to facilitate lesion healing in the injured spinal cord.

Spinal cord injury (SCI) triggers a complex cascade of events, including myelin loss, neuronal damage, neuroinflammation, and the accumulation of damaged cells and debris at the injury site. Infiltrating bone marrow derived macrophages (BMDMϕ) migrate to the epicenter of the SCI lesion, where they engulf cell debris including abundant myelin debris to become pro-inflammatory foamy macrophages (foamy Mϕ), participate neuroinflammation, and facilitate the progression of SCI. This study aimed to elucidate the cellular and molecular mechanisms underlying the functional changes in foamy Mϕ and their potential implications for SCI. Contusion at T10 level of the spinal cord was induced using a New York University (NYU) impactor (5 g rod from a height of 6.25 mm) in male mice. ABCA1, an ATP-binding cassette transporter expressed by Mϕ, plays a crucial role in lipid efflux from foamy cells. We observed that foamy Mϕ lacking ABCA1 exhibited increased lipid accumulation and a higher presence of lipid-accumulated foamy Mϕ as well as elevated pro-inflammatory response in vitro and in injured spinal cord. We also found that both genetic and pharmacological enhancement of ABCA1 expression accelerated lipid efflux from foamy Mϕ, reduced lipid accumulation and inhibited the pro-inflammatory response of foamy Mϕ, and accelerated clearance of cell debris and necrotic cells, which resulted in functional recovery. Our study highlights the importance of understanding the pathologic role of foamy Mϕ in SCI progression and the potential of ABCA1 as a therapeutic target for modulating the inflammatory response, promoting lipid metabolism, and facilitating functional recovery in SCI.

[Development and in vivo biomechanics of goat mobile artificial lumbar spine complex].

OBJECTIVE: Mobile artificial lumbar complex (MALC) which suitable for reconstruction after subtotal lumbar resection in goats was developed,and to test stability of the complex and postoperative lumbar segmental motor function. METHODS: Eighteen male boer goats aged from 1 to 2 years old (weighted from 35 to 45 kg) were selected and divided into control group,fusion group and non-fusion group,with 6 goats in each group. According to preoperative CT scans and MRI examinations of lumbar,the goat MALC was designed and performed by 3D printed for non-fusion group. Operation was performed on three groups respectively,and only vertebral body and disc were exposed in control group. In fusion group,L4 part of vertebral body and the upper and lower complete disc tissues were removed,and the lumbar spine bone plate fixation was performed with titanium mesh bone grafting. In non-fusion group,vertebral body and disc were removed in the same way,and MALC was implanted. AP and lateral X-rays of lumbar vertebrae in goat were taken at 6 months after surgery,in order to understand whether the plant was dislocated,displaced and fractured. Biomechanical tests were performed on the specimens by mechanical instrument to measure range of motion (ROM) of L2,3,L3,4,L4,5 intervertebral space and the overall ROM of L2-5 lumbar vertebrae. RESULTS: MALC of lumbar vertebra was designed by 3D printing,and its component artificial vertebrae and upper and lower artificial end plates were manufactured. The semi-spherical structure was fabricated by precision lathe using high-crosslinked polyethylene material,and the prosthesis was assembled. Postoperative AP and lateral X-rays of lumbar vertebra at 6 months showed the implant position of implant and MALC were good without displacement and dislocation. In vitro biomechanical test of lumbar vertebrae specimens:(1) There were no statistical significance in ROM of lumbar intervertebral space flexion and extension,lateral flexion and rotation on L3,4 and L4,5,between non-fusion group and control group (P>0.05),while ROM of fusion group was significantly reduced compared with the other two groups (P<0.05). There were no significant difference in ROM of L2,3 intervertebral flexion and extension,lateral flexion and rotation between non-fusion group and control group (P>0.05),while fusion group was significantly increased compared with the other two groups (P<0.001). (2) There was no significant difference in overall lumbar ROM of L2-5 (P> 0.05). CONCLUSION: The individual MALC could restore intervertebral height of lumbar vertebra while maintaining the stability of lumbar vertebra and re-establishing motor function of lumbar space.

Comparing the osteogenesis outcomes of different lumbar interbody fusions (A/O/X/T/PLIF) by evaluating their mechano-driven fusion processes.

BACKGROUND: In lumbar interbody fusion (LIF), achieving proper fusion status requires osteogenesis to occur in the disc space. Current LIF techniques, including anterior, oblique, lateral, transforaminal, and posterior LIF (A/O/X/T/PLIF), may result in varying osteogenesis outcomes due to differences in biomechanical characteristics. METHODS: A mechano-regulation algorithm was developed to predict the fusion processes of A/O/X/T/PLIF based on finite element modeling and iterative evaluations of the mechanobiological activities of mesenchymal stem cells (MSCs) and their differentiated cells (osteoblasts, chondrocytes, and fibroblasts). Fusion occurred in the grafting region, and each differentiated cell type generated the corresponding tissue proportional to its concentration. The corresponding osteogenesis volume was calculated by multiplying the osteoblast concentration by the grafting volume. RESULTS: TLIF and ALIF achieved markedly greater osteogenesis volumes than did PLIF and O/XLIF (5.46, 5.12, 4.26, and 3.15 cm3, respectively). Grafting volume and cage size were the main factors influencing the osteogenesis outcome in patients treated with LIF. A large grafting volume allowed more osteoblasts (bone tissues) to be accommodated in the disc space. A small cage size reduced the cage/endplate ratio and therefore decreased the stiffness of the LIF. This led to a larger osteogenesis region to promote osteoblastic differentiation of MSCs and osteoblast proliferation (bone regeneration), which subsequently increased the bone fraction in the grafting space. CONCLUSION: TLIF and ALIF produced more favorable biomechanical environments for osteogenesis than did PLIF and O/XLIF. A small cage and a large grafting volume improve osteogenesis by facilitating osteogenesis-related cell activities driven by mechanical forces.

Integrated evaluation of biomechanical and biological properties of the biomimetic structural bone scaffold: Biomechanics, simulation analysis, and osteogenesis.

A porous structure is essential for bone implants because it increases the bone ingrowth space and improves mechanical and biological properties. The biomimetically designed porous Voronoi scaffold can reconstruct the structure and function of cancellous bone; however, its comprehensive properties need to be investigated further. In this study, algorithms based on scaling factors were used to design the Voronoi scaffolds. Classic approaches, such as computer-aided design and the implicit surface method, have been used to design Diamond, Gyroid, and I-WP scaffolds as controls. All scaffolds were prepared by selective laser melting of titanium alloys and three-dimensional printing. Mechanical tests, finite element analysis, and in vitro and in vivo experiments were performed to investigate the biomechanical, cytologic, and osteogenic performance of the scaffolds, while computational fluid dynamics simulations were used to explore the underlying mechanisms. Diamond scaffolds have a better loading capacity, and the mechanical behaviors and fluid flow of Voronoi scaffolds are similar to those of the human trabecular bone. Cells showed more proliferation and distribution on the Diamond and Voronoi scaffolds and exhibited evident differentiation on Gyroid and Voronoi scaffolds. Bone formation was apparent on the inner part of the Gyroid, the outer part of the I-WP, and the entire Diamond and Voronoi scaffolds. The hydrodynamic properties and stimulus response of cells influenced by the porous structure account for the varied biological performance of the scaffolds. The Voronoi scaffolds with bionic mechanical behavior and an appropriate hydrodynamic response exhibit evident cell growth and osteogenesis, making them preferable for porous structural bone implants.

Circadian clock regulator Bmal1 gates axon regeneration via Tet3 epigenetics in mouse sensory neurons.

Axon regeneration of dorsal root ganglia (DRG) neurons after peripheral axotomy involves reconfiguration of gene regulatory circuits to establish regenerative gene programs. However, the underlying mechanisms remain unclear. Here, through an unbiased survey, we show that the binding motif of Bmal1, a central transcription factor of the circadian clock, is enriched in differentially hydroxymethylated regions (DhMRs) of mouse DRG after peripheral lesion. By applying conditional deletion of Bmal1 in neurons, in vitro and in vivo neurite outgrowth assays, as well as transcriptomic profiling, we demonstrate that Bmal1 inhibits axon regeneration, in part through a functional link with the epigenetic factor Tet3. Mechanistically, we reveal that Bmal1 acts as a gatekeeper of neuroepigenetic responses to axonal injury by limiting Tet3 expression and restricting 5hmC modifications. Bmal1-regulated genes not only concern axon growth, but also stress responses and energy homeostasis. Furthermore, we uncover an epigenetic rhythm of diurnal oscillation of Tet3 and 5hmC levels in DRG neurons, corresponding to time-of-day effect on axon growth potential. Collectively, our studies demonstrate that targeting Bmal1 enhances axon regeneration.

Nanoenzyme-Reinforced Multifunctional Scaffold Based on Ti3C2Tx MXene Nanosheets for Promoting Structure-Functional Skeletal Muscle Regeneration via Electroactivity and Microenvironment Management.

The completed volumetric muscle loss (VML) regeneration remains a challenge due to the limited myogenic differentiation as well as the oxidative, inflammatory, and hypoxic microenvironment. Herein, a 2D Ti3C2Tx MXene@MnO2 nanocomposite with conductivity and microenvironment remodeling was fabricated and applied in developing a multifunctional hydrogel (FME) scaffold to simultaneously conquer these hurdles. Among them, Ti3C2Tx MXene with electroconductive ability remarkably promotes myogenic differentiation via enhancing the myotube formation and upregulating the relative expression of the myosin heavy chain (MHC) protein and myogenic genes (MyoD and MyoG) in myogenesis. The MnO2 nanoenzyme-reinforced Ti3C2Tx MXene significantly reshapes the hostile microenvironment by eliminating reactive oxygen species (ROS), regulating macrophage polarization from M1 to M2 and continuously supplying O2. Together, the FME hydrogel as a bioactive multifunctional scaffold significantly accelerates structure-functional VML regeneration in vivo and represents a multipronged strategy for the VML regeneration via electroactivity and microenvironment management.

Green polymer hydrogels from a natural monomer with inherent antioxidative capability for efficient wound healing and spinal cord injury treatment.

Development of polymeric hydrogels with multiple functions (adhesiveness, self-healability, anti-oxidation efficiency, etc.) through one-step green polymerization of naturally occurring small molecules in water is critical for various biomedical applications and clinical transformation. In this work, benefiting from the dynamic disulfide bond in α-lipoic acid (LA), we directly obtain an advanced hydrogel (poly(lipoic acid-co-sodium lipoate) (PLAS)) through heat and concentration-induced ring-opening polymerization of LA with the addition of NaHCO3 in an aqueous solution. The presence of COOH, COO- and disulfide bonds endows the resulting hydrogels with comprehensive mechanical properties, facile injectability, fast self-healability and adequate adhesiveness. Moreover, the PLAS hydrogels show promising antioxidative efficiency, inherited from naturally occurring LA, and can efficiently eliminate intracellular reactive oxygen species (ROS). We also verify the advantage of PLAS hydrogels in a rat spinal injury model. Through the regulation of ROS and in situ inflammation, our system can promote the recovery of spinal cord injury. Owing to the natural origin and inherent anti-oxidative capability of LA, and a green preparation method, our hydrogel should be beneficial for clinical transformation and may be a good candidate for various biomedical applications.

miR-145a-5p/Plexin-A2 promotes the migration of OECs and transplantation of miR-145a-5p engineered OECs enhances the functional recovery in rats with SCI.

BACKGROUND: Olfactory ensheathing cells (OECs) serve as a bridge by migrating at the site of spinal cord injury (SCI) to facilitate the repair of the neural structure and neural function. However, OEC migration at the injury site not only faces the complex and disordered internal environment but also is closely associated with the migration ability of OECs. METHODS: We extracted OECs from the olfactory bulb of SD rats aged <7 days old. We verified the micro ribonucleic acid (miR)-145a-5p expression level in the gene chip after SCI and OEC transplantation using quantitative reverse transcription (qRT)-polymerase chain reaction (PCR). The possible target gene Plexin-A2 of miR-145a-5p was screened using bioinformatics and was verified using dual-luciferase reporter assay, Western blot, and qRT-PCR. The effect of miR-145a-5p/plexin-A2 on OEC migration ability was verified by wound healing assay, Transwell cell migration assay, and immunohistochemistry. Nerve repair was observed at the injured site of the spinal cord after OEC transplantation using tissue immunofluorescence and magnetic resonance imaging, diffusion tensor imaging, and the Basso-Beattie-Bresnahan locomotor rating scale were further used for imaging and functional evaluation. RESULTS: miR-145a-5p expression in the injured spinal cord tissue after SCI considerably decreased, while Plexin-A2 expression significantly increased. OEC transplantation can reverse miR-145a-5p and Plexin-A2 expression after SCI. miR-145a-5p overexpression enhanced the intrinsic migration ability of OECs. As a target gene of miR-145a-5p, Plexin-A2 hinders OEC migration. OEC transplantation overexpressing miR-145a-5p after SCI can increase miR-145a-5p levels in the spinal cord, reduce Plexin-A2 expression in the OECs and the spinal cord tissue, and promote OEC migration and distribution at the injured site. OEC transplantation overexpressing miR-145a-5p can promote the repair of neural morphology and neural function. CONCLUSIONS: Our study demonstrated that miR-145a-5p could promote OEC migration by down-regulating the target gene Plexin-A2, and transplantation of miR-145a-5p engineered OECs was beneficial to enhance neural structural and functional recovery in SCI rats.

Roles of irregularity of pore morphology in osteogenesis of Voronoi scaffolds: From the perspectives of MSC adhesion and mechano-regulated osteoblast differentiation.

Bone scaffolds designed based on the Voronoi-tessellation algorithm have been increasingly studied owing to their structural similarity with natural cancellous bone. The irregularity of pore morphology (IPM) influences the osteogenesis efficiency of Voronoi scaffolds since it may alter the static and hydromechanical microenvironments for the initial adhesion and mechano-regulated osteoblast differentiation (MrOD) of mesenchymal stem cells (MSCs). In this work, animal experiments were conducted to explore the relationship between IPM and osteogenesis efficiency in Voronoi scaffolds. A computational fluid dynamics (CFD) analysis based on discrete phase models was performed to predict the efficiency of MSC adhesion in different IPMs. Another combined finite element and CFD analysis based on the mechano-regulation algorithm was performed to predict the influence of IPM on the MrOD of the adhesive MSCs. The results showed that the osteogenesis efficiency of the Voronoi scaffolds increased as the IPM rose from low to moderate and then dropped as the IPM further rose. Same trends were also found in the MSC adhesion and MrOD, which caused by the changes of strain tensors on the strut surface and the tortuosity and fluid velocity of the fluid pathway. Moderate IPM induced the highest osteogenesis efficiency owing to its highest efficiencies of MSC adhesion and MrOD. This work identified the optimal IPM for the osteogenesis of Voronoi scaffolds and clarified its biomechanical mechanisms from the adhesion and mechano-regulated differentiation of MSCs, which is of great importance for guiding Voronoi scaffold design when it is used for bone defect repair.

Biocompatibility and osteointegration capability of ß-TCP manufactured by stereolithography 3D printing: In vitro study.

Beta-tricalcium phosphate (ß-TCP) bioceramics have an inorganic composition similar to the human bone. While conventional methods can only produce ceramic scaffolds with poor controllability, the advancement of 3D-printing, especially stereolithography, made it possible to manufacture controllable, highly precise, micropore ceramic scaffolds. In this study, the stereolithography was applied to produce ß-TCP bioceramics, while ZrO2, Al2O3, Ti6Al4V, and polyetheretherketone (PEEK) were used as controls. Phase analysis, water contact angle tests, and Micro-CT were applied to evaluate the surface properties and scaffold. Hemolytic toxicity, cell proliferation, and morphological assessment were performed to evaluate the biocompatibility. Alkaline phosphatase (ALP) level, mineralization, and qRT-PCR were measured to evaluate the osteointegration. During the manufacturing of ß-TCP, no evident impurity substance and hemolytic toxicity was found. Cells on ß-TCP had good morphologies, and their proliferation capability was similar to Ti6Al4V, which was higher than the other materials. Cells on ß-TCP had higher ALP levels than PEEK. The degree of mineralization was significantly higher on ß-TCP. The expression of osteogenesis-related genes on ß-TCP was similar to Ti6Al4V and higher than the other materials. In this study, the ß-TCP produced by stereolithography had no toxicity, high accuracy, and excellent osteointegration capability, thus resulting as a good choice for bone implants.

Analysis of surgical strategies and efficacy in the treatment of Os odontoideum with atlantoaxial dislocation.

BACKGROUND: There are many classification systems for atlantoaxial dislocation (AAD). Among these systems, the definitions of irreducible AAD remain vague, and its treatments are not unified. OBJECTIVE: To explore the surgical strategies and efficacy for the treatment of os odontoideum (OO) with AAD. METHODS: The clinical data of 56 OO patients with AAD who underwent surgery from January 2017 to June 2021 were retrospectively analyzed. AAD was classified into four types, Type I and type II were treated with posterior fixation and fusion. Type III received posterior fixation and fusion after irreducible dislocations were converted to reducible dislocations by translateral mass release or transoral release. Type IV required transoral release for conversion into reducible dislocations before posterior fixation and fusion. The operation time, blood loss, and complications were recorded. The preoperative and postoperative neurological function changes were assessed using the Japanese Orthopedic Association (JOA) score. Postoperative fusion status was assessed by X-ray. RESULTS: There were 40 cases of type I-II, 14 cases of type III, and two cases of type IV AAD. The operation times of single posterior fixation and fusion, combined translateral mass release and combined transoral release were 130.52 ± 37.12 min, 151.11 ± 16.91 min and 188.57 ± 44.13 min, the blood loss were 162.63 ± 58.27 mL, 235.56 ± 59.94 mL, 414.29 ± 33.91 mL, respectively. One patient with type III died, one with type III underwent revision surgery due to infection, and three patients with type I had further neurological deterioration after operation. fifty-five patients were followed up for 12-24 months. The follow-up results showed that enough decompression was achieved and that fixation and fusion were effective. The JOA score increased from 9.58 ± 1.84 points preoperative to 13.09 ± 2.68 points at 3 months after operation, 14.07 ± 2.83 points at 6 months and 14.25 ± 2.34 at 12 months after operation, all significant differences compared with preoperative results (P < 0.05). CONCLUSION: OO patients with irreducible AAD can be treated by translateral mass release or transoral release combined with posterior fixation and fusion, while some of those with bony fusion can be treated by transoral release combined with posterior fixation and fusion.

Computational comparison of anterior lumbar interbody fusion and oblique lumbar interbody fusion with various supplementary fixation systems: a finite element analysis.

BACKGROUND AND OBJECTIVE: Anterior lumbar interbody fusion (ALIF) and oblique lumbar interbody fusion (OLIF) have shown a great surgical potential, while it has always been controversial which surgical approach and which type of fixation system should be selected. This study investigated the biomechanical response of ALIF and OLIF with various supplementary fixation systems using the finite element method. MATERIALS AND METHODS: Lumbar L4-L5 ALIF and OLIF models stabilized by different supplementary fixation systems (stand-alone cage, integrated stand-alone cage, anterior plate, and bilateral pedicle screw) were developed to assess the segmental range of motion (ROM), endplate stress (EPS), and screw-bone interface stress (SBIS). EXPERIMENTAL RESULTS: ALIF showed lower ROM and EPS than OLIF in all motion planes and less SBIS in the most of motion planes compared with OLIF when the anterior plate or pedicle screw was used. ALIF induced higher ROM, while lower EPS and SBIS than OLIF in the majority of motion planes when integrated stand-alone cage was utilized. Using a stand-alone cage in ALIF and OLIF led to cage migration. Integrated stand-alone cage prevented the cage migration, whereas caused significantly larger ROM, EPS, and SBIS than other fixation systems except for the rotation plane. In the most of motion planes, the pedicle screw had the lowest ROM, EPS, and SBIS. The anterior plate induced a slightly larger ROM, EPS, and SBIS than the pedicle screw, while the differences were not significant. CONCLUSION: ALIF exhibited a better performance in postoperative segmental stability, endplate stress, and screw-bone interface stress than OLIF when the anterior plate or the pedicle screw was used. The pedicle screw could provide the greatest postoperative segmental stability, less cage subsidence incidence, and lower risk of fixation system loosening in ALIF and OLIF. The anterior plate could also contribute to the stability required and fewer complications, while not as effectively as the pedicle screw. Extreme caution should be regarded when the stand-alone cage is used due to the risk of cage migration. The integrated stand-alone cage may be an alternative method; however, further optimization is needed to reduce complications and improve postoperative segmental stability.

MicroRNA-137-mediated lysine demethylase 4A regulates the recovery of spinal cord injury via the SFRP4-Wnt/ß-Catenin axis.

OBJECTIVE: Spinal cord injury (SCI) causes great harm to the normal life of patients. Histone demethylase is involved in many biological processes, including SCI. Hence, this study explored the role and mechanism of histone lysine demethylase 4A (KDM4A) in SCI. METHODS: The acute SCI (ASCI) rat model was established after spinal compression and the SCI neuronal model was induced via treating PC12 cells with lipopolysaccharide (LPS). KDM4A expression during SCI was detected. The microRNA (miRNA) targeting KDM4A was predicted and verified. The miRNA and KDM4A expression patterns were intervened in LPS-stimulated PC12 cells to evaluate their combined effects on neuronal cells in SCI. The downstream pathways of KDM4A were predicted, and SFRP4 and H3K9me3 expressions were determined. After the intervention of SFRP4 in LPS-treated cells, ß-Catenin expression and the effect of SFRP4 on neuronal cells in SCI were detected. Finally, the effectiveness of the miR-137/KDM4A/SFRP4/Wnt/ß-Catenin axis was verified in vivo. RESULTS: KDM4A was abnormally elevated in SCI. miR-137 targeted KDM4A. miR-137 effectively inhibited the apoptosis of LPS-challenged PC12 cells, which could be reversed after overexpressing KDM4A. KDM4A promoted SFRP4 expression through demethylation of H3K9me3. Overexpression of SFRP4 blocked the Wnt/ß-Catenin pathway and promoted apoptosis of LPS-stimulated cells. In vivo, miR-137 overexpression remarkably improved SCI symptoms, accompanied by obviously increased ß-Catenin expression and notably decreased KDM4A and SFRP4 expressions, while overexpressed KDM4A treatment showed the opposite trend in the presence of miR-137. CONCLUSION: We demonstrated that miR-137 targeted KDM4A and then downregulated SFRP4 to ameliorate SCI in a Wnt/ß-Catenin-dependent manner.

ZIM3 activation of CCL25 expression in pulmonary metastatic nodules of osteosarcoma recruits M2 macrophages to promote metastatic growth.

Tumor-associated macrophages (TAMs) play an important role in tumor growth and metastasis. However, the involvement of TAMs infiltration in pulmonary osteosarcoma (OS) metastasis remains poorly understood. Therefore, the effect of OS cells on macrophages migration was investigated by in vivo and in vitro experiments to evaluate the infiltration and mechanism of TAMs in pulmonary OS metastases. The results showed that the zinc finger protein ZIM3 was upregulated in OS cells than in osteoblasts and activated the expression of CCL25, which subsequently promoted the migration of M2 macrophages. CCL25 or ZIM3 silencing in OS cells inhibited the infiltration of M2 macrophages and the formation of pulmonary metastatic nodules in a mouse model of pulmonary OS metastasis and prolonged the survival of the mice. Furthermore, bioinformatics analyses revealed that CCL25 and ZIM3 expressions are negatively correlated with the prognosis of OS patients. In conclusion, this study found that a large number of M2 TAMs were recruited into pulmonary metastatic nodules of OS through the activation of the ZIM3-CCL25 axis in OS cells, thereby facilitating OS metastasis. Therefore, the suppression of ZIM3-CCL25-induced recruitment of M2 TAMs to the metastatic sites might be considered as a therapeutic approach to inhibit the growth of pulmonary OS metastases.

Macrophage Extracellular Traps Exacerbate Secondary Spinal Cord Injury by Modulating Macrophage/Microglia Polarization via LL37/P2X7R/NF-κB Signaling Pathway.

Persistent inflammation in the secondary spinal cord injury (SCI) is an important reason for the failure of nerve repair, which is partly due to the continuous activation of local M1-like macrophage/microglia. It is reported that extracellular trap (ET) has been a new way of cell death, which can be released by macrophages and named macrophage extracellular trap (Met). Furthermore, it exists widely in the pathophysiological process of many diseases, but it has been rarely studied in the field of SCI. In this study, we constructed a spinal cord contusion model and assessed the function outcome of SCI rats. We used immunofluorescence, flow cytometry, and transmission electron microscope (TEM) to demonstrate the existence of Mets. Besides, some related experiments had also been employed to explore the relationship between Mets and M1 polarization of macrophage/microglia. We also performed Co-IP and Western blotting to reveal a new extracellular proinflammatory signal pathway. Finally, we made a linear regression analysis between the concentrations of specific markers of Mets in human serum and ASIA scores. Briefly, our results suggested that macrophages infiltrated in SCI area could induce macrophage/microglia to differentiate into M1-like cells by releasing Mets, which may be achieved partly through LL37-P2X37-NF-κB signal pathway. However, limiting Mets could effectively inhibit M1 polarization and promote function recovery. In addition, the concentrations of Met related proteins in human serum showed high correlation with ASIA scores and could be applied to reflect the severity of SCI. In conclusion, Mets may be a new target for SCI therapy and a promising index for SCI assessment.

[miRNA-181a-5p inhibits proliferation and migration of osteosarcoma cell line HOS by targeting HOXB4].

OBJECTIVE: To study the effects and mechanisms of miR-181a-5p on the proliferation, cycle and migration of HOS osteosarcoma cells. METHODS: Real-time quantitative PCR was used to detect the expression of miR-181a-5p and HOXB4 in osteoblast hFOB1.19 cell line and osteosarcoma cell lines (HOS, U2OS, MG63). miR-181a-5p mimics and miR-181a-5p inhibitors were respectively transfected into HOS cells by Lipofectamine 2000, and miR NC group was set as control group. CCK-8 method was used to detect the change in cell proliferation. Flow cytometry was used to detect the changes in cell cycles. Wound healing experiments and Transwell migration experiments were used to detect the changes in cell migration ability. The target gene of miR-181a-5p was predicted by Targetscan website and validated by Dual-luciferase reporter gene system and Western blot. RESULTS: Compared with osteoblast hFOB1.19, miR-181a-5p was low expressed in osteosarcoma cells HOS, U2OS, and MG63(P<0.05), while HOXB4 was high expressed in osteosarcoma cells HOS, U2OS, and MG63(P<0.05). Compared with the miR NC group, over expression of miR-181a-5p inhibited the proliferation and migration of osteosarcoma HOS cells, and the number of cells in S phase decreased(P<0.05). However, knockdown miR-181a-5p promoted the proliferation and migration of osteosarcoma HOS cells, the cells in S phase increased(P<0.05). Bioinformatics prediction and Dual-luciferase reporter gene system validate HOXB4 as a downstream target gene of miR-181a-5p(P<0.05). Western blot showed that miR-181a-5p over expression or knockdown significantly down-regulated or up-regulated HOXB4 expressions in the HOS cells respectively(P<0.05). CONCLUSION: miR-181a-5p is down expressed in osteosarcoma cells, and over-expression miR-181a-5p inhibits the proliferation, cell cycle and migration ability of osteosarcoma cells by targeting HOXB4.

Biomechanics of a novel artificial cervical vertebra from an in vivo caprine cervical spine non-fusion model.

Objective: Anterior cervical corpectomy and fusion (ACCF) has been widely used in the treatment of cervical spondylotic myelopathy (CSM) but is accompanied by unavoidable motion loss and destruction of vertebra. We aim to evaluate the range of motion (ROM) of caprine cervical spine constructs implanted with cervical artificial disc and vertebra system (ADVS). The purpose of this study was to investigate the biomechanical properties of the ADVS from an in vivo caprine cervical spine non-fusion model. Methods: Twelve goats were randomly divided into ADVS or control group, with 6 animals in each group. The animals in the ADVS group were implanted with ADVS at the C4 level. The cervical spine constructs were harvested 6 months after the operation. The ROM of cervical spine specimens in the ADVS group was recorded. Biomechanical testing of the specimens in the control group were conducted to evaluate the ROM of the cervical spine specimens under intact and fixed condition (C3-C5) by an anterior plate, respectively. Results: The biomechanical outcomes showed that the ROM of the levels (C3-C5) implanted with ADVS was maintained. The ROM in the adjacent level (C2-3) did not increase significantly comparing with intact group. Conclusions: In general, ADVS could preserve the ROM of operative levels and could reconstruct the height of the vertebra. ADVS did not increase the ROM of upper adjacent level. This device provides a non-fusion method for the treatment of patients suffering from CSM. However, improvements on the design of ADVS are still needed. Translational potential statement: This study introduced a novel cervical spinal implant, which was designed to have the ability of motion preservation and vertebra construction. Our study provided a non-fusion procedure in the treatment of CSM after ACCF.

Spinal dural arteriovenous fistula: A rare but treatable disease that should not be missed by orthopedic surgeons.

Objective: Spinal dural arteriovenous fistula (SDAVF) is a rare disease that is often misdiagnosed by orthopedic surgeons. We analyzed the reasons for the misdiagnosis and proposed countermeasures. Methods: Twenty-two SDAVF patients who were initially treated in orthopedics were included. The patients were divided into a correct diagnosis group (A) and a misdiagnosis group (B). The clinical data and prognosis were evaluated. Results: There were 10 patients in group A and 12 patients in group B. The clinical manifestations included limb numbness, weakness, and bladder and bowel dysfunction. Among these patients without spinal degenerative diseases which had typical magnetic resonance imaging (MRI) features in Group A were more than Group B (P < 0.05). More patients had spinal degenerative diseases in group B. In group A, seven patients were primarily diagnosed with a SDAVF after multidisciplinary teamwork (MDT). In group B, five patients were misdiagnosed with lumbar spinal stenosis, four with lumbar disc herniation, two with thoracic spinal stenosis, and one with cervical spinal stenosis and lumbar spinal stenosis and underwent cervical spinal canal and lumbar spinal canal decompression. The length of time for confirming the diagnosis was 7 months longer in group B than in group A. All patients underwent microsurgery treatment. The average follow-up duration was 11 months. The modified Aminoff-Logue Disability Scale scores showed a statistically significant difference in improvement between the two groups (P < 0.05). Conclusion: when patients with dysuria especially, have intermittent spinal nerve dysfunction, the possibility of SDAVF should be considered. Awareness of the specific clinical and spinal cord edema and flow voids on MRI of a SDAVF needs to be promoted for orthopedic surgeons. Timely MDT is an important measure for reducing misdiagnosis, and steroids or inappropriate surgery should be avoided until a SDAVF is completely excluded.

Transplantation of olfactory ensheathing cells decreases local and serological monocyte chemoattractant protein 1 level during the acute phase of rat spinal cord injury.

OBJECTIVES: Monocyte chemoattractant protein 1 (MCP1) is one of the most upregulated cytokines in the spinal cord and serum throughout acute spinal cord injury (SCI). Olfactory ensheathing cells (OECs) transplantation improves SCI through multiple mechanisms, including immunomodulation. Our study aimed to investigate whether OECs ameliorate acute inflammation after SCI by modulating MCP1 expression. METHODS: We established a standardized clinically relevant contusion model using the NYU impactor. OECs were administered to the injured spinal cord via microinjection 30 minutes after injury. Rat locomotor functions were assessed by the Basso-Beattie-Bresnahan scale score. Time-course histopathological (H&E and IHC) analyses were performed to record rapid changes in acute inflammation at lesion epicenters. Serum MCP1 level was detected by ELISA assay. RESULTS: BBB scores showed improved locomotor functional recoveries in the OECs transplantation group after SCI ( P < 0.05). Staining of H&E and CD68 illustrated that OECs transplantation attenuated inflammatory response by reducing lesion areas and infiltrating myeloid cell numbers. We further revealed significantly decreased MCP1 levels in the spinal cord and serum after OECs transplantation ( P < 0.05). Noteworthily, distinct expression levels of MCP1 were found in rats undergoing a mild injury (cord impacted from a 10-mm height) compared to the moderate injury (25-mm) group. CONCLUSION: Our study reports that transplantation of OECs promotes locomotor functional recovery after SCI and alleviates acute inflammation by decreasing local and serological MCP1 levels. We provide preliminary evidence that MCP1 might serve as a potential biomarker to reflect the severity of SCI, which is of great interest in future studies.

The application of biomaterials in osteogenesis: A bibliometric and visualized analysis.

Osteogenesis serves an important role in bone tissue repairing. Novel biomaterials are widely prevalent as materials for orthopedic implants due to their biocompatibility and osteogenetic ability. The purpose of this study was to comprehensively analyze hotspots and future trend of biomaterials research in osteogenesis based on bibliometric and visualized analysis. A total of 1,523 papers about biomaterials research in osteogenesis between 2000 and 2021 were included in this study. During the above 20 years, China's leading position in the global biomaterials research in osteogenesis was obvious, and it was also the country that most frequently participates in international cooperation. Chinese Academy of Sciences was the most productive institution and the leader of research cooperation. Acta Biomaterialia and Biomaterials have published the largest number of articles in the field of biomaterials research in osteogenesis. Meanwhile, Acta Biomaterialia and Biomaterials were also the two journals with the highest total citation frequency. Wu CT, Chang J, Kaplan DL, and Xiao Y all made important contributions in the field of biomaterials research in osteogenesis. At present, there are five research hotspots in the field of biomaterials research in osteogenesis: 1) the immunomodulatory role of biomaterial-related inflammatory; 2) mechanisms of osteogenesis in biomaterials; 3) 3D printing and clinical application of biomaterials; 4) bone tissue engineering for biomaterial osteogenesis; and 5) regenerative medicine for biomaterial osteogenesis. The results of this study showed that mechanisms of osteogenesis in biomaterials, bone tissue engineering for biomaterial osteogenesis, and regenerative medicine for biomaterial osteogenesis will remain research hotspots in the future. International cooperation was also expected to expand and deepen the field of biomaterials research in osteogenesis.