Repair Of Injury Research Articles

OSBP Participates in Neural Damage Repair by Regulating Lysosome Transport Under Oxidative Stress.

Oxidative stress is a major pathological factor in acute brain injury, such as traumatic brain injury (TBI). As highly branched cells, the transport of lysosomes plays a crucial role in neuronal homeostasis. However, the effects and mechanisms of oxidative damage on axonal lysosome transport remain unknown. In this study, we demonstrated that the downregulation of the membrane lipid orchestrator oxysterol-binding protein (OSBP) induced by oxidative stress alters the subcellular distribution of lysosomes in neurons through regulating lysosomal phosphatidylinositol-4-monophosphate (PI(4)P)/phosphatidylinositol-3-monophosphate (PI(3)P) contents, thus disrupting lysosomal transport. The results of the cell experiments confirmed the occurrence of an autophagic pressure burst, disordered anterograde lysosome transport, and an imbalance in the PI(4)P/PI(3)P ratio in neurons after H2O2 treatment. Mechanistically, oxidative damage reduced neuronal OSBP protein levels, thus contributing to lysosomal PI(4)P storage. Furthermore, a protein‒liposome binding assay revealed that compared with liposomes containing PI(4)P, liposomes containing PI(3)P or cholesterol presented decreased coprecipitation of Arl8. The overexpression of OSBP restored the PI(4)P/PI(3)P content, improved the binding ability of Arl8 to bind to lysosomes, increased lysosome localization in neurites, and promoted axonal injury repair. Finally, overexpression of neuronal OSBP through adeno-associated virus intervention in vivo alleviated dendritic damage and improved the neurological function of mice with TBI. Taken together, these findings suggest that disturbance of OSBP induced by oxidative stress results in abnormal lysosomal distribution and contributes to neuronal malfunction in TBI, and OSBP could be a potential target to promote neuronal repair and regeneration by regulating lysosomal lipid composition and axonal localization.

Extracorporeal Membranous Oxygenation Associated With Tracheal Procedures: An Extracorporeal Life Support Organization (ELSO) Registry Analysis.

Extracorporeal membrane oxygenation (ECMO) has been primarily used for respiratory and circulatory failure, but its airway-related use has not been investigated well. Tracheal procedures are a situation when ECMO could be used to support patients during anticipated difficult airway management. The Extracorporeal Life Support Organization registry was queried for adult patients treated with ECMO in 2010-2022 during the same admission with types of tracheal procedures. Tracheal procedures were divided into surgical procedure and bronchoscopic procedure groups, and the survival rate was analyzed for each procedural type. Two-hundred sixty-nine patients met the inclusion criteria (64 surgical procedures and 205 bronchoscopic procedures), and 173 (64.3%) patients survived to discharge. Among the surgical procedures, tracheal resection was most performed (30 patients; 46.9%) and was associated with a high survival rate to discharge (86.7%; p = 0.003) compared with airway reconstruction (57.1%) and airway injury repair (46.2%). In bronchoscopic procedure, tracheal stent had favorable survival (76.1%; p = 0.004), whereas tumor debulking was associated with poor prognosis (48.3%; p = 0.006). Hemorrhagic complications were seen in 70 (26.0%) patients and were associated with a worse survival rate (58.6%; p < 0.001). Among them, surgical site bleeding was seen in 35 (13.0%) patients and was also associated with worse survival (42.9%; p = 0.007).

Freeze-Dried Porous Collagen Scaffolds for the Repair of Volumetric Muscle Loss Injuries.

Volumetric muscle loss (VML) injuries are characterized by the traumatic loss of skeletal muscle, resulting in permanent damage to both tissue architecture and electrical excitability. To address this challenge, we previously developed a three-dimensional (3D) aligned collagen-glycosaminoglycan (CG) scaffold platform that supported in vitro myotube alignment and maturation. In this work, we assessed the ability of CG scaffolds to facilitate functional muscle recovery in a rat tibialis anterior (TA) model of VML. Functional muscle recovery was assessed following implantation of either nonconductive CG or electrically conductive CG-polypyrrole (PPy) scaffolds at 4, 8, and 12 weeks postinjury by in vivo electrical stimulation of the peroneal nerve. After 12 weeks, scaffold-treated muscles produced maximum isometric torque that was significantly greater than nontreated tissues. Histological analysis further supported these reparative outcomes with evidence of regenerating muscle fibers at the material-tissue interface in scaffold-treated tissues that were not observed in nonrepaired muscles. Scaffold-treated muscles possessed higher numbers of M1 and M2 macrophages at the injury, while conductive CG-PPy scaffold-treated muscles showed significantly higher levels of neovascularization as indicated by the presence of pericytes and endothelial cells, suggesting a persistent wound repair response not observed in nontreated tissues. Finally, only tissues treated with nonconductive CG scaffolds displayed neurofilament staining similar to native muscle, further corroborating isometric contraction data. Together, these findings show that both conductive and nonconductive CG scaffolds can facilitate improved skeletal muscle function and endogenous cellular repair, highlighting their potential use as therapeutics for VML injuries.

The LINC complex in blood vessels: from physiology to pathological implications in arterioles.

The LINC (linker of nucleoskeleton and cytoskeleton) complex is a critical component of the cellular architecture that bridges the nucleoskeleton and cytoskeleton and mediates mechanotransduction to and from the nucleus. Though it plays important roles in all blood vessels, it is in arterioles that this complex plays a pivotal role in maintaining endothelial cell integrity, regulating vascular tone, forming new microvessels and modulating responses to mechanical and biochemical stimuli. It is also important in vascular smooth muscle cells and fibroblasts, where it possibly plays a role in the contractile to secretory phenotypic transformation during atherosclerosis and vascular ageing, and in fibroblasts' migration and inflammatory responses in the adventitia. Physiologically, the LINC complex contributes to the stability of arteriolar structure, adaptations to changes in blood flow and injury repair mechanisms. Pathologically, dysregulation or mutations in LINC complex components can lead to compromised endothelial function, vascular remodelling and exacerbation of cardiovascular diseases such as atherosclerosis (arteriolosclerosis). This review summarizes our current understanding of the roles of the LINC complex in cells from arterioles, highlighting its most important physiological functions, exploring its implications for vascular pathology and emphasizing some of its functional characteristics in endothelial cells. By elucidating the LINC complex's role in health and disease, we aim to provide insights that could improve future therapeutic strategies targeting LINC complex-related vascular disorders.

Hypoxia-Mimicking Microenvironment Scaffold for Enhanced Tendon Regeneration.

Tendon, a connective tissue structure, serves the crucial role of transmitting force between muscles and bones. However, tendon injury repair continues to pose a significant challenge in clinical settings. In this study, we utilized single-cell RNA sequencing to delve into the cell populations and signaling pathways that are integral to tendon healing. Our findings suggest that hypoxia plays a pivotal role in activating macrophages, stimulating endothelial cell migration, and fostering fibroblast proliferation. Based on these insights, we have developed a PCL scaffold coated with DFOA, which effectively mimics a hypoxic environment to enhance tendon tissue regeneration. Furthermore, the PCL-DFOA scaffolds exhibit exceptional ability in promoting macrophage polarization and angiogenesis. This research offers a therapeutic strategy that harnesses the regenerative power of hypoxia to accelerate and optimize tendon healing processes.

Aristolochic acid I abnormally activates the Wnt7b/β-catenin signaling pathway and affects the repair of renal tubules.

Aristolochic acid I (AAI), which is one of the main forms of aristolochic acid, can cause aristolochic acid nephropathy. Abnormal activation or inhibition of the Wnt7b/β-catenin signaling pathway may lead to the occurrence and development of kidney disease. This study aimed to investigate the effect of the Wnt7b/β-catenin signaling pathway on the damage and repair processes of renal tubular epithelial cells (RTECs) using mouse and zebrafish models of acute aristolochic acid intoxication. Our data revealed that after mice were exposed to 5 mg/kg/day AAI for 4 days and 6 days the expression of Wnt7b on the villi of RTECs increased, the expression of β-catenin on the cytoplasm decreased, and the expression of β-catenin in the nucleus increased. The protein expression levels of PCNA and Kim-1 increased. After zebrafish at 3 days post fertilization were exposed to 2, 4, and 8 μg/mL AAI for 24 h, the results indicated that treatment with AAI resulted in a decrease in the number of RTECs and the occurrence of apoptosis. Importantly, after knockout of the Wnt7ba gene, damage to RTECs in zebrafish larvae was aggravated, the mRNA expression level of PCNA decreased, and that of Kim-1 increased. In addition, we found that AAI exhibits developmental toxicity in fertilized zebrafish eggs. As a result, AAI leads to abnormal activation of the Wnt7b/β-catenin signaling pathway, which affects the repair of renal tubular injury by activating the downstream protein PCNA. The Wnt7ba gene may serve as a potential therapeutic target to promote repair after renal tubular injury.

Unidirectional and sustainable release of NGF and BDNF from a chitosan gel-mediated multilayer ordered composite membrane in promoting both spinal cord and sciatic nerve injury repair.

To develop a scaffold suitable for simultaneous repair of both spinal cord injury (SCI) and sciatic nerve injury (SNI), we designed a multilayer composite membrane capable of unidirectional and sustained release of two factors: nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). The membrane's morphology, mechanical properties, cytocompatibility, drug release kinetics, swelling, and degradation behavior were thoroughly characterized. Additionally, its ability to promote the differentiation of PC-12 cells was assessed. The findings indicated that the composite membrane featured a tri-layered structure and exhibited robust mechanical strength, enabling it to protect and regulate the release of NGF and BDNF. This regulation ensured the appropriate timing and concentration of the factors necessary for cell differentiation and growth. Moreover, the membrane demonstrated excellent cell compatibility and significantly fostered the differentiation of PC-12 cells into axons. In rat models of SCI and SNI, the composite membrane markedly enhanced axon and neuron regeneration, myelination, neural stem cell proliferation, and nerve fiber clustering, while reducing astrocyte formation. It also improved the integrity of spinal cord tissue and motor function recovery, suggesting that this scaffold holds promise for the repair of both SCI and SNI.

Temporal and spatial expression of Phosphodiesterase-4B after sciatic nerve compression in rats and its mechanism of action on sciatic nerve repair.

Macrophage phenotype transformation is vital in sciatic nerve injury. The study of biomolecule expression and its impact on macrophage phenotype transformation is a current research focus. We created a rat model of sciatic nerve compression injury to examine the expression of PDE4B and the distribution of M1 and M2 macrophages over time and their relationship. We confirmed the effect of inhibiting PDE4B expression on macrophage phenotype changes and its role in sciatic nerve injury repair. The experiments consisted of immunofluorescence, western blotting, HE staining, TEM, and behavioral evaluation. Investigate in vivo experiment results with RAW264.7 cells in vitro. PDE4B knockdown lentivirus was transfected into RAW264.7 cells and stimulated with LPS and IFN-γ. We assessed CD86 and CD206 expression using flow cytometry and western blot. The relationship between PDE4B and the TLR4/NF-κB pathway was studied. PDE4B peaked on day 7 after surgery, alongside the highest M1 macrophages count. PDE4B and M1 macrophages decreased, and M2 macrophages increased. PDE4B inhibition reduced M1 macrophages, increased M2 macrophages, suppressed inflammation, and promoted sciatic nerve repair while alleviating pain. In vitro experiments confirmed that PDE4B regulated macrophage phenotype via the TLR4/NF-κB pathway. Inhibiting PDE4B disrupted this pathway and promoted M2 macrophage transformation. In the sciatic nerve injury, PDE4B expression is linked to the M1 macrophage phenotype. Low PDE4B expression facilitates the M1 to M2 macrophage transformation and supports sciatic nerve repair. The TLR4/NF-κB pathway is involved in this process.

Spinal Cord Injury Repair Based on Drug and Cell Delivery: from Remodeling Microenvironment to Relay Connection Formation

Spinal Cord Injury Repair Based on Drug and Cell Delivery: from Remodeling Microenvironment to Relay Connection Formation

Kaempferol attenuates experimental autoimmune neuritis through TNFR1/JNK/p38 signaling pathway inhibition.

Kaempferol (Kae) is a flavonoid that has antioxidant, anti-inflammatory and neuroprotective effects. In recent years, there have been increasing reports on viral infection-induced Guillain-Barré syndrome (GBS) with high rates of disability and fatality. Therefore, in order to search for effective peripheral nerve injury repair drugs, we used rats with experimental autoimmune neuritis (EAN) as the typical animal model for GBS, and implemented Kae treatment intervention on EAN rats. Real-time quantitative polymerase chain reaction (qPCR), western blotting (WB) and immunofluorescence (IF) were utilized to detect the changes of inflammatory factors and signaling pathway proteins in peripheral nerve of rats. The impact of Kae on peripheral nerve damage in EAN rats was evaluated in multiple dimensions by clinical symptom score and neuroelectrophysiology examination, and the protective impact and mechanism of Kae on peripheral nerve injury were revealed. Our results showed that Kae increased the expression of sciatic myelin basic protein (MBP), decreased the expression of peripheral nerve macrophage infiltration and inflammatory cytokines, including TNF-α, IL-1β and IL-6, and down-regulated the expression levels of TNFR1. Additionally, it suppressed the activation of the JNK and p38 pathways. It can alleviate sciatic nerve symptoms and pathological injury in EAN rats. Therefore, we believe that Kae can be used as an adjunct drug in the treatment of GBS.

Nanosphere hydrogel-mediated delivery of miR-34a-5p improves achilles tendon function in rat model.

Restoring motor function and preventing re-rupture and adhesion during Achilles tendon healing remain significant clinical challenges. Increasing evidence suggests that miRNA plays a crucial role in tendon healing and regeneration. The previously designed nanosphere hydrogel sustained-release system enables targeted, controlled release of drugs. In this study, we developed a version of this system loaded with miR-34a-5p for localized delivery to an acute Achilles tendon injury model. The results of the Achilles functional index and Catwalk behavior analysis in rats indicated that miR-34a-5p mimic promoted early recovery of motor function following Achilles tendon injury. Although gross observation suggested that the miR-34a-5p mimic group had a minimal inhibitory effect on the adhesion of Achilles tendon tissue, tension analysis demonstrated that it effectively increased the maximum tensile strength. Additionally, in vitro experiments showed that miR-34a-5p mimic could increase tendon cells proliferation and improve tendon cells viability. This study confirmed the efficacy of the miR-34a-5p nanosphere hydrogel sustained-release system in tendon injury repair, presenting it as a promising treatment strategy for clinical practice.

Gene expression of psychiatric disorder-related kinesin superfamily proteins (Kifs) is potentiated in alternatively activated primary cultured microglia.

Reactivity of microglia, the resident cells of the brain, underlies innate immune mechanisms (e.g., injury repair), and disruption of microglial reactivity has been shown to facilitate psychiatric disorder dysfunctions. Although cellular analyses based on cultured microglia have been conducted, the molecular mechanism regulating microglial polarization remains elusive. We established a primary microglia culture that enabled manipulation of the substate of cells. This allowed us to investigate the expression levels of psychiatric disorder-related Kifs messenger RNA (mRNA) in each condition. Kifs encode molecular motor proteins that transport cargo along microtubules, which are thought to dynamically reorganize during a substate change. As a candidate for a crucial Kifs gene that is associated with microglia polarization, we selected psychiatric disorder-related Kifs including Kif17. We found that the relative amounts of Kif3a, Kif17, and Kif13a mRNA were potentiated in alternatively activated microglia, whereas there were no significant changes in activated microglia. Furthermore, the microglia derived from a mouse line which possesses a mutation inducing truncated KIF17 indicated disrupted morphological phenotype of alternatively activated microglia. These results suggest that the potentiation of specific molecular motor expression is required to maintain the function of alternatively activated microglia.

Delayed primary flexor tendon repair in zone II injuries: results of using WALANT and controlled true active motion.

Early repair of flexor tendon injuries is ideal, but delays are common. We studied the outcomes of flexor tendon repairs delayed from 5 days to 6 months and carried out under wide-awake local anaesthesia with no tourniquet (WALANT). Twenty-four patients (29 fingers) who underwent primary flexor tendon repair on zone II using a four- to six-strand core suture technique, followed by controlled early active motion therapy. Clinical assessments, including total active motion (TAM) and Disabilities of the Arm, Shoulder and Hand, were made 6, 8 and 12 weeks after operation. All outcomes improved significantly over time. At the final assessment, 93% of fingers showed excellent TAM outcomes. Extension deficit was between 5° and 20° in eight of 26 fingers. The results of this study suggest that delayed primary flexor tendon repair under WALANT can achieve excellent functional outcomes, although longer follow-up is needed for extension deficit recovery.Level of evidence: IV.

A BMP-2 sustained-release scaffold accelerated bone regeneration in rats via the BMP-2 consistent activation maintained by a non-sulfate polysaccharide

Bone morphogenetic protein 2 (BMP-2) and a polysaccharide (SUP) were embedded in the calcium phosphate cement (CPC) scaffold, and the bone repair ability was evaluated. The new scaffolds were characterized using x-ray diffraction, Fourier transform-infrared, scanning electron microscopy, and energy dispersive spectroscopy analyses. CPC-BMP2-SUPH scaffold promoted the BMP-2 release by 1.21 folds of the CPC-BMP2 scaffold on day 3. SUP sustained the release of BMP-2 within 21 d. It enhanced alkaline phosphatase activity by 25.9% in comparison to the CPC scaffold. These results suggest that the SUP consistently activated and sustained BMP-2 releasein vitro. Furthermore, the CPC-BMP2-SUPH scaffold activated the BMP-2/Smads and runt-related transcription factor 2 (Runx-2) pathways in MC3T3-E1 cells to up-regulate the levels of osteogenic relative genes (BMP-2, bone sialoprotein, collagen 1, osteocalcin, osteopontin, and Runx-2). Thein vivoresult showed that the bone defect area in the CPC-BMP2-SUPH scaffold-treated Sprague-Dawley rats lessened significantly compared with the CPC group after 4 weeks. CPC-BNP2-SUPH scaffold also improved collagen regeneration in bone. The bone surface and bone volume in the CPC-BMP2-SUPH group improved by 3.68 and 2.17-fold compared with the CPC group, respectively. In conclusion, the CPC-BMP2-SUPH scaffold represents a novel biomaterial capable of accelerating osteoblast differentiation and promoting bone injury repair.

The Impact of Posterior and Posterior Superior (PPS) Labral Injuries and The Effect of Their Treatment on Glenohumeral Kinematics in the Deceleration and Follow-Through Phase of Throwing: A Biomechanical Study.

Combined posterior and posterior superior (PPS) injuries (6:30-12:00; right shoulder) have a much higher incidence than isolated superior labral anterior to posterior (SLAP) injuries (11:00-1:00; right shoulder). However, it is unclear how PPS injuries affect glenohumeral (GH) biomechanics and how they should be treated. This study evaluated if: (1) PPS injuries alter GH kinematics and joint characteristics; (2) standard repair techniques restore GH kinematics and contact characteristics towards their intact state; (3) there are differences between repair techniques. Ten fresh-frozen male cadaveric shoulders (61.4 ± 5.7 years) without pre-existing shoulder pathology were evaluated using a custom shoulder testing system. After a PPS injury was created, a posterior repair technique reattached the labrum from 6:30 to 10:00, while a subsequent posterior superior repair technique included an additional anchor at 11:00. The shoulder was placed in 90 degrees of abduction and tested in the scapular plane at 10, 20, 30 and 40 degrees of horizontal adduction in the scapular plane at both 30 and 60 degrees of external rotation using a deceleration load and two posteriorly directed unbalanced muscle loading conditions. These positions were chosen as they would occur during the deceleration and follow through phases of pitching. All measurements were performed for the following conditions: intact; PPS injury; posterior repair; and posterior superior repair. Humeral head (HH) position, glenohumeral translation, and glenohumeral contact area and pressure were measured. PPS injuries alter GH kinematics and GH joint contact characteristics. There was significant posterior translation of the HH in multiple positions of horizontal adduction in the scapular plane and GH rotation in both muscle imbalance conditions, significant decreases in joint contact area, and increases in joint contact pressure. Repair of PPS injuries by both repair techniques resulted in HH anterior and superior translation towards the intact state in multiple positions of horizontal adduction and GH rotation, increased joint contact area, and decreased joint contact pressure. Compared to posterior repairs, posterior superior repairs resulted in significantly increased non-physiologic anterior and inferior HH translation in relation to the intact state. The PPS injury produces alterations in GH kinematics with implications for GH joint instability, increased GH joint loading, and potential joint damage. The posterior labral repair restores HH kinematics closer to intact, while the addition of a posterior superior repair induces significantly increased non-physiologic anterior and inferior HH translation at multiple positions of adduction and IR.

Are emerging electroconductive biomaterials for spinal cord injury repair the future?

Are emerging electroconductive biomaterials for spinal cord injury repair the future?

CCN5 suppresses injury-induced vascular restenosis by inhibiting smooth muscle cell proliferation and facilitating endothelial repair via thymosin β4 and Cd9 pathway.

Members of the CCN matricellular protein family are crucial in various biological processes. This study aimed to characterize vascular cell-specific effects of CCN5 on neointimal formation and its role in preventing in-stent restenosis (ISR) after percutaneous coronary intervention (PCI). Stent-implanted porcine coronary artery RNA-seq and mouse injury-induced femoral artery neointima single-cell RNA sequencing were performed. Plasma CCN5 levels were measured by enzyme-linked immunosorbent assay. Endothelial cell (EC)- and vascular smooth muscle cell (VSMC)-specific CCN5 loss-of-function and gain-of-function mice were generated. Mass spectrometry and co-immunoprecipitation were conducted to identify CCN5 interacting proteins. Additionally, CCN5 recombinant protein (CCN5rp)-coated stents were deployed to evaluate its anti-ISR effects in a porcine model. Plasma CCN5 levels were significantly reduced and correlated closely with the degree of restenosis in ISR patients. CCN5 expression was significantly decreased in VSMCs of stent-implanted porcine coronary segments and injured mouse femoral arteries, especially in synthetic VSMCs. In contrast, elevated CCN5 expression was observed in regenerating ECs of injured vessels. Endothelial cell- and VSMC-specific CCN5 deletion mice exhibited exacerbation of injury-induced neointimal hyperplasia, while CCN5 gain-of-function alleviated neointimal formation. Mechanistic studies identified thymosin β4 (Tβ4) as a CCN5 interacting protein in ECs and EC-CCN5 promoted injury repair through Tβ4 cleavage product Ac-SDKP. Also, CCN5rp promoted EC repair to suppress neointimal hyperplasia via interaction with Cd9 extracellular domain. Moreover, implantation with CCN5rp-coated stent significantly increased stent strut coverage with ECs, which suppressed neointimal formation and ultimately alleviated ISR. CCN5 exerts a dual protective effect on ISR by inhibiting VSMC proliferation and facilitating EC repair. CCN5rp-coated stent might be promising in the prevention of ISR after PCI.

C60 fullerene improves the contractile activity of the injured rat muscle gastrocnemius

The powerful antioxidant properties of C60fullerenes have been widely used in biomedical nanotechnology. Owing to the negative effects of free radicals in oxidative stress processes, antioxidants are required to protect injured muscles. Here, the effect of water-soluble C60fullerenes (daily oral dose 1 mg kg-1) on the process of restoration of contractile activity of skeletal muscle of rats (muscle gastrocnemius) 15 d after the initiation of open trauma of different severity was studied for the first time. The structural organization of C60fullerene nanoparticles in aqueous solution was analyzed by dynamic light scattering and atomic force microscopy techniques. Such biomechanical parameters ofmuscle gastrocnemiuscontraction as integrated muscle power, levels of generation of its maximum and minimum force, and time interval until reaching 50% of the level of force response of the muscle were analyzed. Such biochemical indices as concentrations of c-reactive protein, creatinine, and lactate in the rat blood, as well as indices of pro- and antioxidant balance (activities of superoxide dismutase and catalase, the concentration of reduced glutathione) in the blood and muscle tissue of experimental animals, were investigated. It was found that application of water-soluble C60fullerenes statistically significantly improves biomechanical parameters of contraction of injuredmuscle gastrocnemiusat the level of 30-45 ± 3%, which is confirmed by normalization of biochemical indices in the blood and muscle tissue of rats at the level of 35-50 ± 3% and 20-37 ± 3%, correspondingly, relative to the open injury group. These findings open the possibility of using C60fullerenes as potential therapeutic nanoagents capable of correcting pathological states of the muscular system during the physiological repair of open injuries.

Engineered Extracellular Vesicles Modified by Angiopep-2 Peptide Promote Targeted Repair of Spinal Cord Injury and Brain Inflammation.

Engineered extracellular vesicles play an increasingly important role in the treatment of spinal cord injury. In order to prepare more effective engineered extracellular vesicles, we biologically modified M2 microglia. Angiopep-2 (Ang2) is an oligopeptide that can target the blood-brain barrier. Through single-cell sequencing and immunofluorescence experiments, we confirmed that the expression of LRP-1, the targeted receptor of Ang2, was elevated after spinal cord injury. Subsequently, we integrated the Ang2 peptide segment into M2 microglia to obtain Ang2-EVs, which could successfully target the site of spinal cord injury. However, in order to improve the function of Ang2-EVs, we pretreated M2 microglia with melatonin, which has anti-inflammatory effects, to obtain M-Ang2-EVs. The results of single-nucleus sequencing of the mouse spinal cord verified that neurons and OPCs gradually transformed into subtypes related to nerve repair functions after treatment with M-Ang2-EVs. This is consistent with the sequencing and enrichment analysis of miRNAs contained in M-Ang2-EVs. We further verified through experiments that M-Ang2-EVs can promote microglia/macrophages to phagocytose sphingomyelin, promote axon remyelination and axon elongation, and maintain the integrity of the blood-spinal barrier. Since Ang2 can also target the blood-brain barrier, we found that M-Ang2-EVs can also reduce brain inflammation that results from spinal cord injury. Our study applied the Angiopep-2 peptide to spinal cord injury to enhance the targeting of injured cells, and successfully construct engineered extracellular vesicles that can target the spinal cord injury site and the brain.

Temporal and spatial pattern of DNA damage in neurons following spinal cord Injury in mice

BackgroundDeficient DNA repair and excessive DNA damage contribute to neurodegenerative disease. However, the role of DNA damage and repair in spinal cord injury (SCI) is unclear. SCI, a debilitating disruption of the structural and biological network of the spinal cord, is characterized by oxidative stress. Nevertheless, the pathophysiological mechanisms leading to neuronal loss following SCI remain incompletely defined. Methods: Using a contusion model, a severe SCI was induced at the L1 spinal level in C57Bl/6J mice. The temporal and spatial presence of DNA damage was then determined via immunolabeling for the DNA damage marker, γH2AX, from 1 h post-injury (hpi) to 28 days post-injury (dpi). Results: Our analysis revealed that increased DNA damage foci were present from 1 hpi to 3 dpi in SCI mice relative to controls (sham surgery and naive), with the damage signal spreading over time longitudinally from the affected area to more rostral and caudal regions. Co-labeling of γH2AX with NeuN revealed neuronal specificity of DNA damage, with increased early cell death (pan-nuclear γH2AX) peaking at 1 dpi and apoptosis (cleaved Caspase-3) arising later at 3 dpi. Conclusion: Our study indicates a possible role of DNA damage in neuronal loss following SCI and highlights the need for early interventions targeting DNA repair to preserve neuronal tissue.