Hypoxia-treated adipose mesenchymal stem cell-derived exosomes attenuate lumbar facet joint osteoarthritis.

BACKGROUND: Lumbar facet joint osteoarthritis (LFJ OA) is a common disease, and there is still a lack of effective disease-modifying therapies. Our aim was to determine the therapeutic effect of hypoxia-treated adipose mesenchymal stem cell (ADSC)-derived exosomes (Hypo-ADSC-Exos) on the protective effect against LFJ OA. METHODS: The protective effect of Hypo-ADSC-Exos against LFJ OA was examined in lumbar spinal instability (LSI)-induced LFJ OA models. Spinal pain behavioural assessments and CGRP (Calcitonin Gene-Related Peptide positive) immunofluorescence were evaluated. Cartilage degradation and subchondral bone remodelling were assessed by histological methods, immunohistochemistry, synchrotron radiation-Fourier transform infrared spectroscopy (SR-FTIR), and 3D X-ray microscope scanning. RESULTS: Hypoxia enhanced the protective effect of ADSC-Exos on LFJ OA. Specifically, tail vein injection of Hypo-ADSC-Exos protected articular cartilage from degradation, as demonstrated by lower FJ OA scores of articular cartilage and less proteoglycan loss in lumbar facet joint (LFJ) cartilage than in the ADSC-Exo group, and these parameters were significantly improved compared to those in the PBS group. In addition, the levels and distribution of collagen and proteoglycan in LFJ cartilage were increased in the Hypo-ADSC-Exo group compared to the ADSC-Exo or PBS group by SR-FTIR. Furthermore, Hypo-ADSC-Exos normalized uncoupled bone remodelling and aberrant H-type vessel formation in subchondral bone and effectively reduced symptomatic spinal pain caused by LFJ OA in mice compared with those in the ADSC-Exo or PBS group. CONCLUSIONS: Our results show that hypoxia is an effective method to improve the therapeutic effect of ADSC-Exos on ameliorating spinal pain and LFJ OA progression.

3D visualization and morphometric analysis of spinal motion segments and vascular networks: A synchrotron radiation-based micro-CT study in mice.

The structure of spinal motion segments and spinal vasculature is complicated. Visualizing the three-dimensional (3D) structure of the spine may provide guidance for spine surgery. However, conventional imaging techniques fail to simultaneously obtain 3D images of soft and hard tissues, and achieving such coimaging states of the spine and its vascular networks remains a challenge. Synchrotron radiation micro-CT (SRµCT) provides a relatively effective and novel method of acquiring detailed 3D information. In this study, specimens of the thoracic spine were obtained from six mice. SRµCT was employed to acquire 3D images of the structure, and histologic staining was performed for comparisons with the SRµCT images. The whole spinal motion segments and the spinal vascular network were simultaneously explored at high resolution. The mean thickness of the cartilaginous end plates (CEPs) and the volume of the intervertebral discs (IVDs) were calculated. The surface of the CEPs and the facet joint cartilage (FJC) were presented as heat maps, which allowed for direct visualization of the thickness distribution. Regional division revealed heterogeneity among the ventral, central, and dorsal parts of the CEPs and between the superior and inferior parts of the facet processes. Moreover, the connections and spatial morphology of the spinal vascular network were visualized. Our study indicates that SRµCT imaging is an ideal method for high-resolution visualization and 3D morphometric analysis of the whole spinal motion segments and spinal vascular network.

UTX/KDM6A Deletion Promotes Recovery of Spinal Cord Injury by Epigenetically Regulating Vascular Regeneration.

The regeneration of the blood vessel system post spinal cord injury (SCI) is essential for the repair of neurological function. As a significant means to regulate gene expression, epigenetic regulation of angiogenesis in SCI is still largely unknown. Here, we found that Ubiquitously Transcribed tetratricopeptide repeat on chromosome X (UTX), the histone H3K27 demethylase, increased significantly in endothelial cells post SCI. Knockdown of UTX can promote the migration and tube formation of endothelial cells. The specific knockout of UTX in endothelial cells enhanced angiogenesis post SCI accompanied with improved neurological function. In addition, we found regulation of UTX expression can change the level of microRNA 24 (miR-24) in vitro. The physical binding of UTX to the promotor of miR-24 was indicated by chromatin immunoprecipitation (ChIP) assay. Meanwhile, methylation sequencing of endothelial cells demonstrated that UTX could significantly decrease the level of methylation in the miR-24 promotor. Furthermore, miR-24 significantly abolished the promoting effect of UTX deletion on angiogenesis in vitro and in vivo. Finally, we predicted the potential target mRNAs of miR-24 related to angiogenesis. We indicate that UTX deletion can epigenetically promote the vascular regeneration and functional recovery post SCI by forming a regulatory network with miR-24.

Endoscopic L5/S1 discectomy through interlaminar approach for the patient with the high iliac crest and migrated disc herniation. / è„ŠæŸ±å† é•œæ¤Žæ¿é—´å ¥è·¯æ²»ç–—é«˜é«‚åµ´L5/S1è„±åž‚åž‹è °æ¤Žé—´ç›˜çªå‡ºç—‡.

OBJECTIVES: To explore the clinical efficacy of endoscopic L5/S1 discectomy through interlaminar approach for the patient with the high iliac crest and migrated disc herniation. METHODS: A retrospective study of 31 patients with the high iliac crest and migrated disc herniation at the L5/S1 level was conducted in our hospital. All of the consented patients accepted endoscopic L5/S1 discectomy through interlaminar approach from January 2016 to January 2019. Preoperative, postoperative, and follow-up Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were used to assess the pain and waist function of patients. The clinical efficacy was evaluated according to Macnab criteria. RESULTS: All the patients were followed up for 12-48 (29.68±9.64) months. The operation time was (79.16±22.43) min. The times of fluoroscopy were 2.71±0.78. The VAS of low back and leg pain was 7.09±0.94 before the surgery, 1.45±1.23 at 3 months after the surgery, and 1.27±0.92 at the last follow-up. The VAS after the surgery and at the last follow-up was significantly lower than that before the operation (P<0.05). The ODI was 56.03±6.64 before the surgery, 16.45±6.83 at 3 months after the surgery, and 13.03±4.96 at the last follow-up. The ODI was significantly lower after the surgery and at the last follow-up compared with that before the surgery (P<0.05). The Macnab score at the last follow-up was graded as excellent in 26 cases, good in 3 cases, fair in 2 cases, and the percentage of excellent and good were 93.5%. Part of the nucleus pulposus remained in 2 cases after the operation, one case underwent endoscopic revision and one case received conservative treatment; postoperative pain due to nerve root irritation was in one case and relieved by conservative treatment. CONCLUSIONS: The endoscopic L5/S1 discectomy through interlaminar approach is a relatively safe and effective treatment for the patient with the high iliac crest and migrated disc herniation, which can reduce X-ray examinations and complications, and achieve satisfactory clinical outcomes.

Synchrotron radiation micro-tomography for high-resolution neurovascular network morphology investigation.

There has been increasing interest in using high-resolution micro-tomography to investigate the morphology of neurovascular networks in the central nervous system, which remain difficult to characterize due to their microscopic size as well as their delicate and complex 3D structure. Synchrotron radiation X-ray imaging, which has emerged as a cutting-edge imaging technology with a high spatial resolution, provides a novel platform for the non-destructive imaging of microvasculature networks at a sub-micrometre scale. When coupled with computed tomography, this technique allows the characterization of the 3D morphology of vasculature. The current review focuses on recent progress in developing synchrotron radiation methodology and its application in probing neurovascular networks, especially the pathological changes associated with vascular abnormalities in various model systems. Furthermore, this tool represents a powerful imaging modality that improves our understanding of the complex biological interactions between vascular function and neuronal activity in both physiological and pathological states.

Feasibility study for evaluating early lumbar facet joint degeneration using axial T1 ρ, T2 , and T2* mapping in cartilage.

PURPOSE: To assess the feasibility of axial T2 , T2*, and T1 ρ mapping of lumbar facet joint (LFJ) cartilage for evaluation of early degeneration. MATERIALS AND METHODS: We examined a total of 176 LFJs from 21 volunteers using axial T2 , T2*, and T1 ρ mapping with a 3.0T magnetic resonance imaging (MRI) scanner. All LFJs were measured and grouped according to the presence of low back pain (LBP), the Weishaupt grading system, and the Pfirrmann grade of the adjacent intervertebral disk (IVD). T2 , T2*, and T1 ρ values were analyzed and compared among the different groups. RESULTS: Low interobserver agreement was found in the Weishaupt grading of LFJs (κ = 0.161). The T1 ρ values of LFJs were significantly different between adjacent two Pfirrmann grade of disks (grade I 50.15 ± 3.63 msec / grade II 53.27 ± 3.80 msec, P = 0.002; grade II 53.27 ± 3.80 msec / grade III 58.40 ± 4.17 msec, P < 0.01), and in different Weishaupt grades of LFJs (P = 0.000). T2* values were only found significantly different between Pfirrmann grade I and III of disks (P = 0.048). There was no significant difference in T2 values of LFJs whatever in Pfirrmann (P = 0.556) or Weishaupt grades (P = 0.694). No significant difference was found in T2 , T2*, and T1 ρ values between volunteers with LBP and without LBP (PT2 = 0.783, PT2*=0.311, PT1 ρ = 0.259). CONCLUSION: Axial T1 ρ could be an effective and sensitive method to assess for early degenerative changes in LFJ cartilage. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:468-475.

Sacroiliac joint tuberculosis: surgical management by posterior open-window focal debridement and joint fusion.

BACKGROUND: Sacroiliac joint tuberculosis(SJT) is relatively uncommon, but it may cause severe sacroiliac joint destruction and functional disorder. Few studies in the literature have been presented on SJT, reports of surgical treatment for SJT are even fewer. In this study, we retrospectively reviewed surgical management of patients with severe SJT of 3 different types and proposed to reveal the clinical manifestations and features and aim to determine the efficiency and security of such surgical treatment. METHODS: We reviewed 17 patients with severe SJT of 3 different types who underwent posterior open-window focal debridement and bone graft for joint fusion. Among them,five patients with anterior sacral abscess had anterior abscess curettage before debridement. Two patients with lumbar vertebral tuberculosis received one-stage posterior tuberculous debridement, interbody fusion and instrumentation. Follow-up was performed 36 months (26 to 45 months) using the following parameters: erythrocyte sedimentation rate(ESR), status of joint bony fusion on CT scan, visual analogue scale (VAS) and the Oswestry Disability Index (ODI). RESULTS: Buttock pain and low back pain were progressively relieved with time. 6 months later, pain was not obvious, and ESR resumed to normal levels within 3 months. Solid fusion of the sacroiliac joint occurred within 12 months in all cases. No complications or recurrence occurred. At final follow-up, all patients had no pain or only minimal discomfort over the affected joint and almost complete functional recovery. CONCLUSIONS: Posterior open-window focal debridement and joint fusion is an efficient and secure surgical method to treat severe SJT. If there is an abscess in the front of the sacroiliac joint, anterior abscess curettage should be performed as a supplement.

[Early and one-stage posterior-anterior surgery for fresh and severe lower cervical spine fracture and dislocation].

OBJECTIVE: To explore the clinical value of early and one-stage posterior laminectomy decompression, fracture reconstruction and lateral mess screw fixation combined with anterior cervical corpectomy or discectomy for the treatment of fresh and severe lower cervical spine fracture and dislocation.
 METHODS: A total of 156 consecutive cases of severe fracture and dislocation of lower cervical spine were reviewed from January 2008 to January 2015. Skull traction was installed when the patients were enrolled in the hospital, so the operation was performed as early as possible. Firstly, the posterior procedure was applied to the patients prone on a frame. A standard posterior laminectomy, fixation and fusion were performed with lateral mass screws and rods. The cervical spine reconstruction was achieved by laminecomy, partially facetectomy, leverage and distraction. The technique of rotating rod was applied to recover the sequence of the cervical and keep or increase the zygopophysis and lordosis of the cervical on the sagittal plane. After the skull traction removed, a standard anterior approach to the cervical spine was initiated as the second stage of the procedure. Anterior cervical corpectomy or discectomy, spinal cord decompression, antograft and cervical spine auto-locking plate fixation were carried out. The stability, the fusion rate of the injured segments and spinal cord decompression were observed on the regular postoperative X-ray film and CT scan. The function of the spinal cord was evaluated by American Spinal Injury Association (ASIA) classification.
 RESULTS: A total of 137 cases were followed-up, 19 failed to follow-up and 8 of them were due to death. The follow-up time was from 9.0 months to 35.0 months (mean: 13.7 months). All patients got completely reduction of the cervical spine. The injured segments were stable. There was no patient of bone graft no-fusion. The cervical intervertebral height and lordosis were reconstructed and maintained and all grafts were fused at the end of follow-up period. There was no complication related to internal fixation breakage, loosening or displacement. There was also no neurovascular and esophagus complications during the operation. Twelve patients complained neck pain at the final follow-up. There were 12 cases of wound infection and 12 cases of neck inflammatory. They were healed after anti-inflammatory therapy. There were 13 cases of cerebrospinal fluid leakage, and they were healed after the symptomatic treatment. The neuro-function of most patients was improved, and ASIA classification was improved by 1 to 2 grade.
 CONCLUSION: Early and one-stage posterior-anterior decompression and reconstruction for the patients with fresh and severe lower cervical spine fracture and dislocation can achieve good reduction and cervical alignment of cervical spine. The injured segments can gain postoperative immediate stability. It also gives a completely decompression, which is benefit to the patients for nursing, functional exercise, and the functional recovery of the spinal cord.

[Treatment of multi-segmental cervical spondylosis by long or segmented anterior cervical decompression and fixation surgery].

OBJECTIVE: To investigate the clinical efficacy of two different anterior cervical surgeries in treatment of multi-segmental cervical spondylosis. METHODS: A total of 86 patients with multi-segmental cervical spondylosis were treated by anterior cervical surgery procedure. Among them, 62 and 24 cases were involved in three and four gap, respectively. Each patient underwent the surgery of long or segmented anterior cervical decompression and fixation. Preoperative and postoperative cervical curvature change, internal fixation stability, fusion rate and nerve function were evaluated. RESULTS: All patients were successfully completed the operation, segmented surgery showed better cervical lordosis recovery, but there were no significant difference between long and segmented anterior cervical surgery in blood loss and recovery of neurological function (P> 0.05). CONCLUSION: The segmented anterior cervical surgery has advantages in the treatment of multisegmental cervical spondylosis.

Active thoracic and lumbar spinal tuberculosis in children with kyphotic deformity treated by one-stage posterior instrumentation combined anterior debridement: preliminary study.

The aim of this study was to retrospectively evaluate the safety, feasibility and efficacy of one-stage posterior instrumentation combined anterior debridement and interbody fusion for treatment of active thoracic and lumbar spinal tuberculosis (TB) in children with kyphotic deformity. A total of 20 children (12 boys, 8 girls) were enrolled in this study from January 2006 to January 2011. All patients underwent one-stage posterior instrumentation combined anterior debridement and interbody fusion. Clinical and radiographic results were analyzed. Patients were followed up for 28.9 months on average. Improvement was shown in all patients with neurologic dysfunction according to American Spinal Injury Association Impairment Scale. The mean preoperative angle of kyphosis was 35.2° ± 6.8° (range 26°-47°), which reduced to 9.7° ± 1.8° (range 6°-13°) postoperatively. The mean angle of kyphosis at the last follow-up was 12.0° ± 1.9° (range 9°-15°). Erythrocyte sedimentation rate and C-reactive protein returned to normal in all patients within 6 months after surgery. All patients acquired bony fusion, and no major complications were observed through the final follow-up visit. One-stage posterior instrumentation combined anterior debridement and fusion were demonstrated to be a safe and effective method to achieve spinal decompression and kyphosis correction in children with thoracic and lumbar spinal TB.

Local delivery of EGFR+NSCs-derived exosomes promotes neural regeneration post spinal cord injury via miR-34a-5p/HDAC6 pathway.

Spinal cord injury (SCI) causes severe axon damage, usually leading to permanent paraparesis, which still lacks effective regenerative therapy. Recent studies have suggested that exosomes derived from neural stem cells (NSCs) may hold promise as attractive candidates for SCI treatment. Epidermal Growth Factor Receptor positive NSC (EGFR+NSC) is a subpopulation of endogenous NSCs, showing strong regenerative capability in central nervous system disease. In the current study, we isolated exosomes from the EGFR+NSCs (EGFR+NSCs-Exos) and discovered that local delivery of EGFR+NSCs-Exos can effectively promote neurite regrowth in the injury site of spinal cord-injured mice and improve their neurological function recovery. Using the miRNA-seq, we firstly characterized the microRNAs (miRNAs) cargo of EGFR+NSCs-Exos and identified miR-34a-5p which was highly enriched in EGFR+NSCs derived exosomes. We further interpreted that exosomal miR-34a-5p could be transferred to neurons and inhibit the HDAC6 expression by directly binding to its mRNA, contributing to microtubule stabilization and autophagy induction for aiding SCI repair. Overall, our research demonstrated a novel therapeutic approach to improving neurological functional recovery by using exosomes secreted from a subpopulation of endogenous NSCs and providing a precise cell-free treatment strategy for SCI repair.

Kdm6a-CNN1 axis orchestrates epigenetic control of trauma-induced spinal cord microvascular endothelial cell senescence to balance neuroinflammation for improved neurological repair.

Cellular senescence assumes pivotal roles in various diseases through the secretion of proinflammatory factors. Despite extensive investigations into vascular senescence associated with aging and degenerative diseases, the molecular mechanisms governing microvascular endothelial cell senescence induced by traumatic stress, particularly its involvement in senescence-induced inflammation, remain insufficiently elucidated. In this study, we present a comprehensive demonstration and characterization of microvascular endothelial cell senescence induced by spinal cord injury (SCI). Lysine demethylase 6A (Kdm6a), commonly known as UTX, emerges as a crucial regulator of cell senescence in injured spinal cord microvascular endothelial cells (SCMECs). Upregulation of UTX induces senescence in SCMECs, leading to an amplified release of proinflammatory factors, specifically the senescence-associated secretory phenotype (SASP) components, thereby modulating the inflammatory microenvironment. Conversely, the deletion of UTX in endothelial cells shields SCMECs against senescence, mitigates the release of proinflammatory SASP factors, and promotes neurological functional recovery after SCI. UTX forms an epigenetic regulatory axis by binding to calponin 1 (CNN1), orchestrating trauma-induced SCMECs senescence and SASP secretion, thereby influencing neuroinflammation and neurological functional repair. Furthermore, local delivery of a senolytic drug reduces senescent SCMECs and suppresses proinflammatory SASP secretion, reinstating a local regenerative microenvironment and enhancing functional repair after SCI. In conclusion, targeting the UTX-CNN1 epigenetic axis to prevent trauma-induced SCMECs senescence holds the potential to inhibit SASP secretion, alleviate neuroinflammation, and provide a novel treatment strategy for SCI repair.

Intranasal delivery of small extracellular vesicles from specific subpopulation of mesenchymal stem cells mitigates traumatic spinal cord injury.

Vascular injury following spinal cord injury (SCI) can significantly exacerbate secondary SCI and result in neurological dysfunction. Strategies targeting angiogenesis have demonstrated potential in enhancing functional recovery post-SCI. In the context of angiogenesis, the CD146+ and CD271+ subpopulations of mesenchymal stem cells (MSCs) have been recognized for their angiogenic capabilities in tissue repair. Small extracellular vesicles (sEVs) derived from MSCs are nanoscale vesicles containing rich bioactive components that play a crucial role in tissue regeneration. However, the precise role of sEVs derived from CD146+CD271+ UCMSCs (CD146+CD271+ UCMSC-sEVs) in SCI remain unclear. In this study, CD146+CD271+ UCMSC-sEVs were non-invasively administered via intranasal delivery, demonstrating a significant capacity to stimulate angiogenesis and improve functional recovery in mice following SCI. Furthermore, in vitro assessments revealed the effective enhancement of migration and tube formation capabilities of the murine brain microvascular endothelial cell line (bEnd.3) by CD146+CD271+UCMSC-sEVs. MicroRNA array analysis confirmed significant enrichment of multiple microRNAs within CD146+CD271+ UCMSC-sEVs. Subsequent in vivo and in vitro experiments demonstrated that CD146+CD271+ UCMSC-sEVs promote enhanced angiogenesis and improved functional recovery mediated by miR-27a-3p. Further mechanistic studies revealed that miR-27a-3p sourced from CD146+CD271+ UCMSC-sEVs enhances migration and tube formation of bEnd.3 cells in vitro by suppressing the expression of Delta Like Canonical Notch Ligand 4 (DLL4), thereby promoting angiogenesis in vivo. Collectively, our results demonstrate that a crucial role of CD146+CD271+ UCMSC-sEVs in inhibiting DLL4 through the transfer of miR-27a-3p, which leads to the promotion of angiogenesis and improved functional recovery after SCI.

Analysis of Degenerative and Isthmic Lumbar Spondylolisthesis from the Difference of Pelvic Parameters and the Degree of Degeneration through Imaging Data.

BACKGROUND: In previous studies, many imaging analyses have been conducted to explore the changes in the intervertebral disc degeneration (DD), facet joint osteoarthritis (FJOA), L4 inclination angle (L4IA), pelvis-related parameters, lumbar lordosis (LL), and paravertebral muscle (PVM) in the occurrence and development of degenerative spinal diseases via measuring the X-ray, CT, and MRI data of clinical patients. However, few studies have quantitatively investigated the pelvic parameters and the degree of spine degeneration in patients with degenerative lumbar spondylolisthesis (DLS) and isthmic lumbar spondylolisthesis (ILS). This study discusses the changes in the imaging parameters of DLS, ILS, and a control group; explores the correlation between different measurement parameters; and discusses their risk factors. METHODS: We evaluated 164 patients with single L4-L5 grade 1 level degenerative lumbar spondylolisthesis (DLS group), 161 patients with single L4-L5 grade 1 level isthmic lumbar spondylolisthesis (ILS group), and 164 patients with non-specific back pain (control group). The grades of DD and FJOA as well as the percentage of the fat infiltration area (%FIA) of multifidus muscle (MM) at the L4-L5 level were measured via CT and MRI. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), the L4 inclination angle (L4IA), and sacral slope (SS) were measured via X-ray film, and the differences among the DLS group, ILS group, and control group were analyzed. Furthermore, the risk factors related to the incidences of the DLS and ILS groups were discussed. RESULTS: First, the pelvis-related parameters of DLS and ILS patients were 51.91 ± 12.23 and 53.28 ± 11.12, respectively, while those of the control group were 40.13 ± 8.72 (p1 < 0.001, p2 < 0.001). Lumbar lordosis (LL) in DLS patients (39.34 ± 8.57) was significantly lower than in the control group (44.40 ± 11.79, p < 0.001). On the contrary, lumbar lordosis (LL) in the ILS group (55.16 ± 12.31) was significantly higher than in the control group (44.40 ± 11.79, p < 0.001). Secondly, the three groups of patients were characterized by significant variations in the L4 inclination angle (L4IA), disc degeneration (DD), facet joint osteoarthritis (FJOA), pelvis-related parameters, and paravertebral muscle (PVM) (p < 0.05). Finally, logistic regression suggests that the L4IA, FJOA, and PT may be risk factors for the occurrence of DLS, and the occurrence of ILS is correlated with the L4IA, FJOA, DD, PT, and LL. CONCLUSIONS: Compared with the control group, there are changes in pelvic parameters, the L4IA, LL, DD, FJOA, and PVM in DLS and ILS patients, and the degree is different. The parameters within the same group are related to each other, and DLS and ILS have different risk factors. The mechanical stability of the spine is affected by the parameter and angle changes, which may be of great significance for explaining the cause of spondylolisthesis, evaluating the health of the lumbar spine, and guiding the lifestyles of patients.

Cerebrospinal fluid-derived extracellular vesicles after spinal cord injury promote vascular regeneration via PI3K/AKT signaling pathway.

Background: The cerebrospinal fluid (CSF), which surrounds the brain and spinal cord, is predominantly produced by the choroid plexus of the ventricle. Although CSF-derived extracellular vesicles (CSF-EVs) may be utilized as diagnostic and prognostic indicators for illnesses of the central nervous system (CNS), it is uncertain if CSF-EVs may have an impact on neurological function after spinal cord injury (SCI). Methods: Here, we isolated EVs using ultracentrifugation after extracting CSF from Bama miniature pigs. We then combined CSF-EVs with hydrogel and put it on the spinal cord's surface. To determine if CSF-EVs had an impact on mice's neurofunctional recovery, behavioral evaluations were employed. Both in vitro and in vivo, the effect of CSF-EVs on angiogenesis was assessed. We investigated whether CSF-EVs stimulated the PI3K/AKT pathway to alter angiogenesis using the PI3K inhibitor LY294002. Results: CSF-EVs were successfully isolated and identified by transmission electron microscope (TEM), nano-tracking analysis (NTA), and western blot. CSF-EVs could be ingested by vascular endothelial cells as proved by in vivo imaging and immunofluorescence. We demonstrated that CSF-EVs derived from pigs with SCI (SCI-EVs) showed a better effect on promoting vascular regeneration as compared to CSF-EVs isolated from pigs receiving laminectomy (Sham-EVs). Behavioral assessments demonstrated that SCI-EVs could dramatically enhance motor and sensory function in mice with SCI. Western blot analysis suggested that SCI-EVs promote angiogenesis by activating PI3K/AKT signaling pathway, and the pro-angiogenetic effect of SCI-EVs was attenuated by the application of the LY294002 (PI3K inhibitor). Conclusion: Our study revealed that CSF-EVs could enhance vascular regeneration by activating the PI3K/AKT pathway, hence improving motor function recovery after SCI, which may offer potential novel therapeutic options for acute SCI. The translational potential of this article: This study demonstrated the promotion of vascular regeneration and neurological function of CSF-derived exosomes, which may provide a potential therapeutic approach for the treatment of spinal cord injury.

Targeted delivery of CD163+ macrophage-derived small extracellular vesicles via RGD peptides promote vascular regeneration and stabilization after spinal cord injury.

Targeted delivery of small extracellular vesicles (sEVs) with low immunogenicity and fewer undesirable side effects are needed for spinal cord injury (SCI) therapy. Here, we show that RGD (Arg-Gly-Asp) peptide-decorated CD163+ macrophage-derived sEVs can deliver TGF-ß to the neovascular endothelial cells of the injured site and improve neurological function after SCI. CD163+ macrophages are M2 macrophages that express TGF-ß and are reported to promote angiogenesis and vascular stabilization in various diseases. Enriched TGF-ß EVs were crucial in angiogenesis and tissue repair. However, TGF-ß also boosts the formation of fibrous or glial scars, detrimental to neurological recovery. Our results found RGD-modified CD163+ sEVs accumulated in the injured region and were taken up by neovascular endothelial cells. Furthermore, RGD-CD163+ sEVs promoted vascular regeneration and stabilization in vitro and in vivo, resulting in substantial functional recovery post-SCI. These data suggest that RGD-CD163+ sEVs may be a potential strategy for treating SCI.

The lymphatic system: a therapeutic target for central nervous system disorders.

The lymphatic vasculature forms an organized network that covers the whole body and is involved in fluid homeostasis, metabolite clearance, and immune surveillance. The recent identification of functional lymphatic vessels in the meninges of the brain and the spinal cord has provided novel insights into neurophysiology. They emerge as major pathways for fluid exchange. The abundance of immune cells in lymphatic vessels and meninges also suggests that lymphatic vessels are actively involved in neuroimmunity. The lymphatic system, through its role in the clearance of neurotoxic proteins, autoimmune cell infiltration, and the transmission of pro-inflammatory signals, participates in the pathogenesis of a variety of neurological disorders, including neurodegenerative and neuroinflammatory diseases and traumatic injury. Vascular endothelial growth factor C is the master regulator of lymphangiogenesis, a process that is critical for the maintenance of central nervous system homeostasis. In this review, we summarize current knowledge and recent advances relating to the anatomical features and immunological functions of the lymphatic system of the central nervous system and highlight its potential as a therapeutic target for neurological disorders and central nervous system repair.

Comprehensive analysis of m6A methylation modification in chronic spinal cord injury in mice.

Chronic spinal cord injury (CSCI) is a catastrophic disease of the central nervous system (CNS), resulting in partial or complete loss of neurological function. N6-methyladenosine (m6A) is the most common form of reversible posttranslational modification at the RNA level. However, the role of m6A modification in CSCI remains unknown. In this study, we established a CSCI model using a water-absorbable polyurethane polymer, with behavioral assessment, electrophysiological analysis, and histochemical staining for validation. Methylated RNA immunoprecipitation sequencing (meRIP-seq) and messenger RNA sequencing (mRNA-seq) were jointly explored to compare the differences between CSCI spinal tissue and normal spinal tissue. Furthermore, real-time quantitative reverse transcription pcr (qRT-PCR), western blot analysis, and immunofluorescence staining were used to analyze m6A modification-related proteins. We found that water-absorbable polyurethane polymer simulated well chronic spinal cord compression. Basso mouse scale scores and electrophysiological analysis showed continuous neurological function decline after chronic compression of the spinal cord. meRIP-seq identified 642 differentially modified m6A genes, among which 263 genes were downregulated and 379 genes were upregulated. mRNA-seq showed that 1544 genes were upregulated and 290 genes were downregulated after CSCI. Gene Ontology terms and enriched Kyoto Encyclopedia of Genes and Genomes pathways were also identified. qRT-PCR, western blotting, and immunofluorescence staining showed that Mettl14, Ythdf1, and Ythdf3 were significantly upregulated after CSCI. Our study revealed a comprehensive profile of m6A modifications in CSCI which may act as a valuable key for future research on CSCI.

Quantitative biochemical phenotypic heterogeneity of macrophages after myelin debris phagocytosis at a single cell level by synchrotron radiation fourier transform infrared microspectroscopy.

During the immuno-inflammatory pathophysiological process of spinal cord injury, traumatic brain injury, and ischemic stroke, macrophages play an important role in phagocytizing and clearing degenerated myelin debris. After phagocytizing myelin debris, the biochemical phenotypes related to the biological function of macrophages show vast heterogeneity; however, it is not fully understood. Detecting biochemical changes after myelin debris phagocytosis by macrophages at a single-cell level is helpful to characterize phenotypic and functional heterogeneity. In this study, based on the cell model of myelin debris phagocytosis by macrophages in vitro, the biochemical changes in macrophages were investigated using Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy. Infrared spectrum fluctuations, principal component analysis, and cell-to-cell Euclidean distance statistical analysis of specific spectrum regions revealed dynamic and significant changes in proteins and lipids within macrophages after myelin debris phagocytosis. Thus, SR-FTIR microspectroscopy is a powerful identification toolkit for exploring biochemical phenotype heterogeneity transformation that may be of great importance to providing an evaluation strategy for studying cell functions related to cellular substance distribution and metabolism.

Mechanical overloading-induced miR-325-3p reduction promoted chondrocyte senescence and exacerbated facet joint degeneration.

OBJECTIVE: Lumbar facet joint (LFJ) degeneration is one of the main causes of low back pain (LBP). Mechanical stress leads to the exacerbation of LFJ degeneration, but the underlying mechanism remains unknown. This study was intended to investigate the mechanism of LFJ degeneration induced by mechanical stress. METHODS: Here, mice primary chondrocytes were used to screen for key microRNAs induced by mechanical overloading. SA-ß-gal staining, qRT-PCR, western blot, and histochemical staining were applied to detect chondrocyte senescence in vitro and in vivo. We also used a dual-luciferase report assay to examine the targeting relationship of miRNA-325-3p (miR-325-3p) and Trp53. By using NSC-207895, a p53 activator, we investigated whether miR-325-3p down-regulated trp53 expression to reduce chondrocyte senescence. A mice bipedal standing model was performed to induce LFJ osteoarthritis. Adeno-associated virus (AAV) was intraarticularly injected to evaluate the effect of miR-325-3p on facet joint degeneration. RESULTS: We observed chondrocyte senescence both in human LFJ osteoarthritis tissues and mice LFJ after bipedally standing for 10 weeks. Mechanical overloading could promote chondrocyte senescence and senescence-associated secretory phenotype (SASP) expression. MicroRNA-array analysis identified that miR-325-3p was obviously decreased after mechanical overloading, which was further validated by fluorescence in situ hybridization (FISH) in vivo. Dual-luciferase report assay showed that miR-325-3p directly targeted Trp53 to down-regulated its expression. MiR-325-3p rescued chondrocyte senescence in vitro, however, NSC-207895 reduced this effect by activating the p53/p21 pathway. Intraarticular injection of AAV expressing miR-325-3p decreased chondrocyte senescence and alleviated LFJ degeneration in vivo. CONCLUSION: Our findings suggested that mechanical overloading could reduce the expression of miR-325-3p, which in turn activated the p53/p21 pathway to promote chondrocyte senescence and deteriorated LFJ degeneration, which may provide a promising therapeutic strategy for LFJ degeneration.