Deubiquitinase UCHL1 promotes angiogenesis and blood-spinal cord barrier function recovery after spinal cord injury by stabilizing Sox17.

Improving the function of the blood-spinal cord barrier (BSCB) benefits the functional recovery of mice following spinal cord injury (SCI). The death of endothelial cells and disruption of the BSCB at the injury site contribute to secondary damage, and the ubiquitin-proteasome system is involved in regulating protein function. However, little is known about the regulation of deubiquitinated enzymes in endothelial cells and their effect on BSCB function after SCI. We observed that Sox17 is predominantly localized in endothelial cells and is significantly upregulated after SCI and in LPS-treated brain microvascular endothelial cells. In vitro Sox17 knockdown attenuated endothelial cell proliferation, migration, and tube formation, while in vivo Sox17 knockdown inhibited endothelial regeneration and barrier recovery, leading to poor functional recovery after SCI. Conversely, in vivo overexpression of Sox17 promoted angiogenesis and functional recovery after injury. Additionally, immunoprecipitation-mass spectrometry revealed the interaction between the deubiquitinase UCHL1 and Sox17, which stabilized Sox17 and influenced angiogenesis and BSCB repair following injury. By generating UCHL1 conditional knockout mice and conducting rescue experiments, we further validated that the deubiquitinase UCHL1 promotes angiogenesis and restoration of BSCB function after injury by stabilizing Sox17. Collectively, our findings present a novel therapeutic target for treating SCI by revealing a potential mechanism for endothelial cell regeneration and BSCB repair after SCI.

USP1/UAF1-Stabilized METTL3 Promotes Reactive Astrogliosis and Improves Functional Recovery after Spinal Cord Injury through m6A Modification of YAP1 mRNA.

RNA N6-methyladenosine (m6A) modification is involved in diverse biological processes. However, its role in spinal cord injury (SCI) is poorly understood. The m6A level increases in injured spinal cord, and METTL3, which is the core subunit of methyltransferase complex, is upregulated in reactive astrocytes and further stabilized by the USP1/UAF1 complex after SCI. The USP1/UAF1 complex specifically binds to and subsequently removes K48-linked ubiquitination of the METTL3 protein to maintain its stability after SCI. Moreover, conditional knockout of astrocytic METTL3 in both sexes of mice significantly suppressed reactive astrogliosis after SCI, thus resulting in widespread infiltration of inflammatory cells, aggravated neuronal loss, hampered axonal regeneration, and impaired functional recovery. Mechanistically, the YAP1 transcript was identified as a potential target of METTL3 in astrocytes. METTL3 could selectively methylate the 3'-UTR region of the YAP1 transcript, which subsequently maintains its stability in an IGF2BP2-dependent manner. In vivo, YAP1 overexpression by adeno-associated virus injection remarkably contributed to reactive astrogliosis and partly reversed the detrimental effects of METTL3 knockout on functional recovery after SCI. Furthermore, we found that the methyltransferase activity of METTL3 plays an essential role in reactive astrogliosis and motor repair, whereas METTL3 mutant without methyltransferase function failed to promote functional recovery after SCI. Our study reveals the previously unreported role of METTL3-mediated m6A modification in SCI and might provide a potential therapy for SCI.SIGNIFICANCE STATEMENT Spinal cord injury is a devastating trauma of the CNS involving motor and sensory impairments. However, epigenetic modification in spinal cord injury is still unclear. Here, we propose an m6A regulation effect of astrocytic METTL3 following spinal cord injury, and we further characterize its underlying mechanism, which might provide promising strategies for spinal cord injury treatment.

Assessing the utility of MRI-based vertebral bone quality (VBQ) for predicting lumbar pedicle screw loosening.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The purpose of this study is to assess the potential of utilizing the MRI-based vertebral bone quality (VBQ) score as a predictive tool for pedicle screw loosening (PSL) in patients who have undergone pedicle screw fixation and to identify risk factors associated with VBQ scores. METHODS: One hundred and sixteen patients who had undergone pedicle screw fixation between December 2019 and January 2021 and had more than a year of follow-up were divided into two groups of PSL and non-PSL. The radiological and clinical parameters investigated were age, gender, body mass index, the VBQ score, length of fusion and the DXA T-score. RESULTS: Of the 116 patients included in the study, 22 patients developed pedicle screw loosening after surgery (18.97%). VBQ score of PSL group was higher than the non-PSL group (3.61 ± 0.63 vs. 2. 86 ± 0.43, p < 0.001). According to logistic regression, PSL was independently linked with a higher VBQ score (OR = 3.555, 95% confidence interval [1.620-7.802], p < 0.005). The AUC of predicting screw loosening was 0.774 (p < 0.001) for VBQ score, and the best threshold was 3.055 (sensitivity, 81.8%; specificity, 71.3%). High VBQ score was associated with age (r (114) = 0.29, p = 0.002), while it was not negatively correlated with T-scores of each part. CONCLUSION: VBQ score is an independent predictor of pedicle screw loosening, with higher scores indicating a greater risk. Our results showed that older patients and women had higher VBQ scores.

Expression and function of myelin expression factor 2 in hepatocellular carcinoma.

INTRODUCTION: Hepatocellular carcinoma (HCC) is one of the most common malignant tumours in the world and has a high mortality rate. However, the pathogenesis of HCC remains unclear. This study aimed to investigate the potential biomarkers of HCC. METHODS: ONCOMINE, HCCDB and THE HUMAN PROTEIN ATLAS were used to identify myelin expression factor 2 (MYEF2) as a potential biomarker for HCC. The Cancer Genome Atlas database was used to further validate and analyse the value of MYEF2. Kaplan-Meier Plotter was used for the prognostic analysis. The COX regression model and Kaplan-Meier method were used to investigate the clinical value of MYEF2 in the prognosis of HCC by reviewing the survival status of patients. Fluorescent quantitative polymerase chain reaction (qPCR) and immunohistochemistry were used to detect the expressions of the MYEF2 mRNA and protein in HCC tissues and cell lines. qPCR and Western blotting were used to validate the efficiency of MYEF2 knockout and overexpression in HCC cells. The invasion and migration abilities regulated by MYEF2 were detected by performing transwell and wound healing assays. RESULTS: MYEF2 is significantly upregulated in HCC and is mainly located in the nucleus of HCC cells. MYEF2 expression is significantly associated with the tumour stage, histological grade and TNM stage. High MYEF2 expression is an independent prognostic factor for patients with HCC. Functionally, elevated MYEF2 facilitated cell migration and invasion in vitro. In contrast, decreased MYEF2 inhibited cell migration and invasion. CONCLUSIONS: MYEF2 may be a novel biomarker with potential diagnosis and prognosis values and as a potential therapeutic target for HCC.

Radiographic predictors for recurrence of lumbar symptoms after prioritized cervical surgery in patients with tandem spinal stenosis.

OBJECTIVES: The purpose of the current study was to explore radiographic predictors for recurrence of lumbar symptoms after prioritized cervical surgery in patients with tandem spinal stenosis (TSS). METHODS: The current retrospective cohort study included 74 patients with TSS, who underwent prioritized cervical surgery. Based on presence or absence of improvement in lower limb symptoms, patients were grouped into improved and non-improved groups. Medical records and radiological parameters including age, sex, body mass index, cervical and lumbar parameters were analyzed. In improved group, patients were divided into relapsed and non-relapsed groups based on recurrence in lower limb symptoms. RESULTS: Lumbar symptoms improved in 70.1% (n = 52) of patients. Comparison between the improved and non-improved group showed that there were no statistically significant differences in cervical parameters while comparisons between the relapsed and non-relapsed groups showed significant differences in redundant nerve roots (RNRs) (p = 0.029), narrow segment (p = 0.042) and lumbar stenosis index (LSI) (p = 0.003). In multivariate logistic regression analysis, LSI > 10 (p = 0.016) was independently associated with recurrence of lumbar symptoms. CONCLUSIONS: Finding of the current study indicated that LSI > 10 was associated with recurrence of lumbar symptoms in TSS patients following cervical surgery.

Deubiquitinase USP18 regulates reactive astrogliosis by stabilizing SOX9.

Reactive astrogliosis is a pathological feature of spinal cord injury (SCI). The ubiquitin-proteasome system plays a crucial role in maintaining protein homeostasis and has been widely studied in neuroscience. Little, however, is known about the underlying function of deubiquitinating enzymes in reactive astrogliosis following SCI. Here, we found that ubiquitin-specific protease 18 (USP18) was significantly upregulated in astrocytes following scratch injury, and in the injured spinal cord in mice. Knockdown of USP18 in vitro and conditional knockout of USP18 in astrocytes (USP18 CKO) in vivo significantly attenuated reactive astrogliosis. In mice, this led to widespread inflammation and poor functional recovery following SCI. In contrast, overexpression of USP18 in mice injected with adeno-associated virus (AAV)-USP18 had beneficial effects following SCI. We showed that USP18 binds, deubiquitinates, and thus, stabilizes SRY-box transcription factor 9 (SOX9), thereby regulating reactive astrogliosis. We also showed that the Hedgehog (Hh) signaling pathway induces expression of USP18 through Gli2-mediated transcriptional activation after SCI. Administration of the Hh pathway activator SAG significantly increased reactive astrogliosis, reduced lesion area and promoted functional recovery in mice following SCI. Our results demonstrate that USP18 positively regulates reactive astrogliosis by stabilizing SOX9 and identify USP18 as a promising target for the treatment of SCI.

Small extracellular vesicles encapsulating CCL2 from activated astrocytes induce microglial activation and neuronal apoptosis after traumatic spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) is a severe traumatic disease which causes high disability and mortality rates. The molecular pathological features after spinal cord injury mainly involve the inflammatory response, microglial and neuronal apoptosis, abnormal proliferation of astrocytes, and the formation of glial scars. However, the microenvironmental changes after spinal cord injury are complex, and the interactions between glial cells and nerve cells remain unclear. Small extracellular vesicles (sEVs) may play a key role in cell communication by transporting RNA, proteins, and bioactive lipids between cells. Few studies have examined the intercellular communication of astrocytes through sEVs after SCI. The inflammatory signal released from astrocytes is known to initiate microglial activation, but its effects on neurons after SCI remain to be further clarified. METHODS: Electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blotting were applied to characterize sEVs. We examined microglial activation and neuronal apoptosis mediated by astrocyte activation in an experimental model of acute spinal cord injury and in cell culture in vitro. RESULTS: Our results indicated that astrocytes activated after spinal cord injury release CCL2, act on microglia and neuronal cells through the sEV pathway, and promote neuronal apoptosis and microglial activation after binding the CCR2. Subsequently, the activated microglia release IL-1ß, which acts on neuronal cells, thereby further aggravating their apoptosis. CONCLUSION: This study elucidates that astrocytes interact with microglia and neurons through the sEV pathway after SCI, enriching the mechanism of CCL2 in neuroinflammation and spinal neurodegeneration, and providing a new theoretical basis of CCL2 as a therapeutic target for SCI.

Hsa_circ_0013290 Acts as Cancer-Promoting Gene in Hepatocellular Carcinoma.

BACKGROUND: As a new class of non-coding RNAs, circRNAs have been recently reported to be involved in the tumorigenesis and progression of human cancers. In the current study, we attempted to explore the potential function of a novel circRNA (hsa_circ_0013290) in hepatocellular carcinoma (HCC). METHODS: Relative hsa_circ_0013290 expression was analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The subcellular location of hsa_circ_0013290 was performed by RNA subcellular isolation and fluorescence in situ hybridization (FISH) assays. The effect of hsa_circ_0013290 on proliferation was detected by Cell Counting Kit-8 (CCK-8) assays. The effect of hsa_circ_0013290 on cell cycle distribution and apoptosis was detected by flow cytometry. The invasion and migration abilities of hsa_circ_0013290 were detected by transwell assays. RESULTS: Hsa_circ_0013290 is significantly upregulated in HCC cell lines and mainly located in cytoplasm of HCC cells. Hsa_circ_0013290 overexpression promotes cell invasion and migration and inhibits cell apoptosis. In contrast, hsa_circ_0013290 knockdown impedes cell invasion and migration and accelerates cell apoptosis. However, hsa_circ_0013290 did not affect cell proliferation. CONCLUSIONS: Hsa_circ_0013290 is overexpressed in HCC cell lines and is mainly located in the cytoplasm of HCC cells. Hsa_circ_0013290 promotes cell invasion and migration, and inhibits cell apoptosis.

Extracellular vesicles derived from melatonin-preconditioned mesenchymal stem cells containing USP29 repair traumatic spinal cord injury by stabilizing NRF2.

Spinal cord injury (SCI) is a devastating trauma that leads to irreversible motor and sensory dysfunction and is, so far, without effective treatment. Recently, however, nano-sized extracellular vesicles derived from preconditioned mesenchymal stem cells (MSCs) have shown great promise in treating various diseases, including SCI. In this study, we investigated whether extracellular vesicles (MEVs) derived from MSCs pretreated with melatonin (MT), which is well recognized to be useful in treating diseases, including Alzheimer's disease, non-small cell lung cancer, acute ischemia-reperfusion liver injury, chronic kidney disease, and SCI, are better able to promote functional recovery in mice after SCI than extracellular vesicles derived from MSCs without preconditioning (EVs). MEVs were found to facilitate motor behavioral recovery more than EVs and to increase microglia/macrophages polarization from M1-like to M2-like in mice. Experiments in BV2 microglia and RAW264.7 macrophages confirmed that MEVs facilitate M2-like polarization and also showed that they reduce the production of reactive oxygen species (ROS) and regulate mitochondrial function. Proteomics analysis revealed that ubiquitin-specific protease 29 (USP29) was markedly increased in MEVs, and knockdown of USP29 in MEVs (shUSP29-MEVs) abolished MEVs-mediated benefits in vitro and in vivo. We then showed that USP29 interacts with, deubiquitinates and therefore stabilizes nuclear factor-like 2 (NRF2), thereby regulating microglia/macrophages polarization. In NRF2 knockout mice, MEVs failed to promote functional recovery and M2-like microglia/macrophages polarization. We also showed that MT reduced global N6-methyladenosine (m6 A) modification and levels of the m6 A "writer" methyltransferase-like 3 (METTL3). The stability of USP29 mRNA in MSCs was enhanced by treatment with MT, but inhibited by overexpression of METTL3. This study describes a very promising extracellular vesicle-based approach for treating SCI.

Aerodynamic characteristics in upper airways among orthodontic patients and its association with adenoid nasopharyngeal ratios in lateral cephalograms.

BACKGROUND: Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms. The study investigates the aerodynamic characteristics within the upper airway (UA) by means of computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios. METHODS: This retrospective study included thirty-five patients aged 9-15 years having both lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. The cases were divided into two subgroups according to the AN ratios measured on the lateral cephalograms: Group 1 with an AN ratio < 0.6 and Group 2 with an AN ratio ≥ 0.6. Based on the CBCT images, segmented UA models were created and the aerodynamic characteristics at inspiration and expiration were simulated by the CFD method for the two groups. The studied aerodynamic parameters were pressure drop (ΔP), maximum midsagittal velocity (Vms), maximum wall shear stress (Pws), and minimum wall static pressure (Pw). RESULTS: The maximum Vms exhibits nearly 30% increases in Group 2 at both inspiration (p = 0.013) and expiration (p = 0.045) compared to Group 1. For the other aerodynamic parameters such as ΔP, the maximum Pws, and minimum Pw, no significant difference is found between the two groups. CONCLUSIONS: The maximum Vms seems to be the most sensitive aerodynamic parameter for the groups of cases. An AN ratio of more than 0.6 measured on a lateral cephalogram may associate with a noticeably increased maximum Vms, which could assist clinicians in estimating the airflow features in the UA.

Surgical outcome and risk factors for cervical spinal cord injury patients in chronic stage: a 2-year follow-up study.

PURPOSE: This study aims to assess the nerve function deficient recovery in surgically treated patients with cervical trauma with spinal cord injury (SCI) in chronic stage and figure out prognostic predictors of improvement in impairment and function. METHODS: We reviewed the clinical and radiological data of 143 cervical SCI patients in chronic stage and divided into non-operative group (n = 61) and operative group (n = 82). The severity of neurological involvement was assessed using the ASIA motor score (AMS) and Functional Independence Measure Motor Score (FIM MS). The health-related quality of life was measured using the SF-36 questionnaire. Correspondence between the clinical and radiological findings and the neurological outcome was investigated. RESULTS: At 2-year follow-up, surgery resulted in greater improvement in AMS and FIM MS than non-operative group. Regression analysis revealed that lower initial AMS (P = 0.000), longer duration after injury (P = 0.022) and injury above C4 level (P = 0.022) were factors predictive of lower final AMS. Longer duration (P = 0.020) and injury above C4 level (P = 0.010) were associated with a lower FIM MS. SF-36 scores were significantly lower in higher age (P = 0.015), female patients (P = 0.009) and patients with longer duration (P = 0.001). CONCLUSION: It is reasonable to consider surgical decompression in patients with cervical SCI in chronic stage and persistent spinal cord compression and/or gross cervical instability. Initial AMS, longer duration, injury above C4 level, higher age and female patients are the five major relevant factors of functional recovery.

Exosomes derived from GIT1-overexpressing bone marrow mesenchymal stem cells promote traumatic spinal cord injury recovery in a rat model.

OBJECTIVE: This study aims to explore the effects of exosomes derived from G protein-coupled receptor kinase 2 interacting protein 1 (GIT1)-overexpressing bone marrow mesenchymal stem cell (GIT1-BMSC-Exos) on the treatment of traumatic spinal cord injury (SCI) in a rat model. METHODS: All the rats underwent a T10 laminectomy. A weight-drop impact was performed using a 10-g rod from a height of 12.5 mm except the sham group. Rats with SCI were distributed into three groups randomly and then treated with tail vein injection of GIT1-BMSCs-Exos, BMSCs-Exos and PBS, respectively. The effects of GIT1-Exos on glutamate (GLU)-induced apoptosis in vitro were also evaluated by TUNEL staining. RESULTS: The results showed that rats treated with GIT1-BMSCs-Exos had better functional behavioral recovery than those treated with PBS or BMSCs-Exos only. The overexpression of GIT1 in BMSCs-Exos not only restrained glial scar formation and neuroinflammation after SCI, but also attenuated apoptosis and promoted axonal regeneration in the injured lesion area. Neuronal cell death induced by GLU was controlled remarkably in vitro as well. CONCLUSION: In conclusion, our study suggested that the application of GIT1-BMSCs-Exos may provide a novel avenue for traumatic SCI treatment.

Establishment of a nomogram for predicting the surgical difficulty of anterior cervical spine surgery.

BACKGROUND: For a long time, surgical difficulty is mainly evaluated based on subjective perception rather than objective indexes. Moreover, the lack of systematic research regarding the evaluation of surgical difficulty potentially has a negative effect in this field. This study was aimed to evaluate the risk factors for the surgical difficulty of anterior cervical spine surgery (ACSS). METHODS: This was a retrospective cohort study totaling 291 consecutive patients underwent ACSS from 2012.3 to 2017.8. The surgical difficulty of ACSS was defined by operation time longer than 120 min or intraoperative blood loss equal to or greater than 200 ml. Evaluation of risk factors was performed by analyzing the patient's medical records and radiological parameters such as age, sex, BMI, number of operation levels, high signal intensity of spinal cord on T2-weighted images, ossified posterior longitudinal ligament (OPLL), sagittal and coronal cervical circumference, cervical length, spinal canal occupational ratio, coagulation function index and platelet count. RESULTS: Significant differences were reported between low-difficulty and high-difficulty ACSS groups in terms of age (p = 0.017), sex (p = 0.006), number of operation levels (p < 0.001), high signal intensity (p < 0.001), OPLL (p < 0.001) and spinal canal occupational ratio (p < 0.001). Multivariate logistic regression analysis revealed that number of operation levels (OR = 5.224, 95%CI = 2.125-12.843, p < 0.001), high signal intensity of spinal cord (OR = 4.994, 95%CI = 1.636-15.245, p = 0.005), OPLL (OR = 6.358, 95%CI = 1.932-20.931, p = 0.002) and the spinal canal occupational ratio > 0.45 (OR = 3.988, 95%CI = 1.343-11.840, p = 0.013) were independently associated with surgical difficulty in ACSS. A nomogram was established and ROC curve gave a 0.906 C-index. There was a good calibration curve for difficulty estimation. CONCLUSION: This study indicated that the operational level, OPLL, high signal intensity of spinal cord, and spinal canal occupational ratio were independently associated with surgical difficulty and a predictive nomogram can be established using the identified risk factors. Optimal performance was achieved for predicting surgical difficulty of ACSS based on preoperative factors.

The effect of rapid maxillary expansion on the upper airway's aerodynamic characteristics.

BACKGROUND: The effect of rapid maxillary expansion (RME) on the upper airway (UA) has been studied earlier but without a consistent conclusion. This study aims to evaluate the outcome of RME on the UA function in terms of aerodynamic characteristics by applying a computational fluid dynamics (CFD) simulation. METHODS: This retrospective cohort study consists of seventeen cases with two consecutive CBCT scans obtained before (T0) and after (T1) RME. Patients were divided into two groups with respect to patency of the nasopharyngeal airway as expressed in the adenoidal nasopharyngeal ratio (AN): group 1 was comprised of patients with an AN ratio < 0.6 and group 2 encompassing those with an AN ratio ≥ 0.6. CFD simulation at inspiration and expiration were performed based on the three-dimensional (3D) models of the UA segmented from the CBCT images. The aerodynamic characteristics in terms of pressure drop (ΔP), maximum midsagittal velocity (Vms), and maximum wall shear stress (Pws) were compared by paired t-test and Wilcoxon test according to the normality test at T0 and T1. RESULTS: The aerodynamic characteristics in UA revealed no statistically significant difference after RME. The maximum Vms (m/s) decreased from 2.79 to 2.28 at expiration after RME (P = 0.057). CONCLUSION: The aerodynamic characteristics were not significantly changed after RME. Further CFD studies with more cases are warranted.

Protein kinase C-α upregulates sodium channel Nav1.9 in nociceptive dorsal root ganglion neurons in an inflammatory arthritis pain model of rat.

Previous studies have found that increased expression of Nav1.9 and protein kinase C (PKC) contributes to pain hypersensitivity in a couple of inflammatory pain models. Here we want to observe if PKC can regulate the expression of Nav1.9 in dorsal root ganglion (DRG) in rheumatoid arthritis (RA) pain model. A chronic knee joint inflammation model was produced by intra-articular injection of the complete Freund's adjuvant (CFA) in rats. Nociceptive behaviors including mechanical, cold, and heat hyperalgesia were examined. The expression of Nav1.9 and PKCα in DRG was detected by a quantitative polymerase chain reaction, Western blot, and immunofluorescence. The in vitro and in vivo effects of a PKC activator (phorbol 12-myristate 13-acetate [PMA]) and a PKC inhibitor (GF-109203X) on the expression of Nav1.9 were examined. Moreover, the effects of PKC modulators on nociceptive behaviors were studied. Increased mechanical, heat, and cold sensitivity was observed 3 to 14 days after CFA injection. Parallel increases in messenger RNA and protein expression of Nav1.9 and PKCα were found. Immunofluorescence experiments found that Nav1.9 was preferentially colocalized with IB4+DRG neurons in RA rats. In cultured DRG neurons, PMA increased Nav1.9 expression while GF-109203X prevented the effect of PMA. PMA increased Nav1.9 expression in naïve rats while GF-109203X decreased Nav1.9 expression in RA rats. In naïve rats, PMA caused mechanical and cold hyperalgesia. On the other hand, GF-109203X attenuated mechanical and cold hyperalgesia in RA-pain model. Nav1.9 might be upregulated by PKCα in DRG, which contributes to pain hypersensitivity in CFA-induced chronic knee joint inflammation model of RA pain.

Exosome-shuttled miR-216a-5p from hypoxic preconditioned mesenchymal stem cells repair traumatic spinal cord injury by shifting microglial M1/M2 polarization.

BACKGROUND: Spinal cord injury (SCI) can lead to severe motor and sensory dysfunction with high disability and mortality. In recent years, mesenchymal stem cell (MSC)-secreted nano-sized exosomes have shown great potential for promoting functional behavioral recovery following SCI. However, MSCs are usually exposed to normoxia in vitro, which differs greatly from the hypoxic micro-environment in vivo. Thus, the main purpose of this study was to determine whether exosomes derived from MSCs under hypoxia (HExos) exhibit greater effects on functional behavioral recovery than those under normoxia (Exos) following SCI in mice and to seek the underlying mechanism. METHODS: Electron microscope, nanoparticle tracking analysis (NTA), and western blot were applied to characterize differences between Exos and HExos group. A SCI model in vivo and a series of in vitro experiments were performed to compare the therapeutic effects between the two groups. Next, a miRNA microarray analysis was performed and a series of rescue experiments were conducted to verify the role of hypoxic exosomal miRNA in SCI. Western blot, luciferase activity, and RNA-ChIP were used to investigate the underlying mechanisms. RESULTS: Our results indicate that HExos promote functional behavioral recovery by shifting microglial polarization from M1 to M2 phenotype in vivo and in vitro. A miRNA array showed miR-216a-5p to be the most enriched in HExos and potentially involved in HExos-mediated microglial polarization. TLR4 was identified as the target downstream gene of miR-216a-5p and the miR-216a-5p/TLR4 axis was confirmed by a series of gain- and loss-of-function experiments. Finally, we found that TLR4/NF-κB/PI3K/AKT signaling cascades may be involved in the modulation of microglial polarization by hypoxic exosomal miR-216a-5p. CONCLUSION: Hypoxia preconditioning represents a promising and effective approach to optimize the therapeutic actions of MSC-derived exosomes and a combination of MSC-derived exosomes and miRNAs may present a minimally invasive method for treating SCI.

Association of hypertension with the severity and fatality of SARS-CoV-2 infection: A meta-analysis.

Hypertension is a common comorbidity in COVID-19 patients. However, the association of hypertension with the severity and fatality of COVID-19 remain unclear. In the present meta-analysis, relevant studies reported the impacts of hypertension on SARS-CoV-2 infection were identified by searching PubMed, Elsevier Science Direct, Web of Science, Wiley Online Library, Embase and CNKI up to 20 March 2020. As the results shown, 12 publications with 2389 COVID-19 patients (674 severe cases) were included for the analysis of disease severity. The severity rate of COVID-19 in hypertensive patients was much higher than in non-hypertensive cases (37.58% vs 19.73%, pooled OR: 2.27, 95% CI: 1.80-2.86). Moreover, the pooled ORs of COVID-19 severity for hypertension vs. non-hypertension was 2.21 (95% CI: 1.58-3.10) and 2.32 (95% CI: 1.70-3.17) in age <50 years and ⩾50 years patients, respectively. Additionally, six studies with 151 deaths of 2116 COVID-19 cases were included for the analysis of disease fatality. The results showed that hypertensive patients carried a nearly 3.48-fold higher risk of dying from COVID-19 (95% CI: 1.72-7.08). Meanwhile, the pooled ORs of COVID-19 fatality for hypertension vs. non-hypertension was 6.43 (95% CI: 3.40-12.17) and 2.66 (95% CI: 1.27-5.57) in age <50 years and ⩾50 years patients, respectively. Neither considerable heterogeneity nor publication bias was observed in the present analysis. Therefore, our present results provided further evidence that hypertension could significantly increase the risks of severity and fatality of SARS-CoV-2 infection.

Exosomal miRNA-128-3p from mesenchymal stem cells of aged rats regulates osteogenesis and bone fracture healing by targeting Smad5.

Transplantation of mesenchymal stem cells (MSCs) has been considered an effective therapeutic treatment for a variety of diseases including bone fracture. However, there are associated complications along with MSCs transplantation. There is evidence to show that exosomes (Exos) derived from MSCs exert a similar paracrine function. In addition, repair capabilities of MSCs decline with age. Hence, this study aims to confirm whether the Exos protective function on osteogenic differentiation and fracture healing from aged MSCs was attenuated. This information was used in order to investigate the underlying mechanism. MSCs were successfully isolated and identified from young and aged rats, and Exos were then obtained. Aged-Exos exhibited significantly attenuated effects on MSCs osteogenic differentiation in vitro and facture healing in vivo. Using miRNA array analysis, it was shown that miR-128-3p was markedly upregulated in Aged-Exos. In vitro experiments confirmed that Smad5 is a direct downstream target of miR-128-3p, and was inhibited by overexpressed miR-128-3p. A series gain- and loss- function experiment indicated that miR-128-3P serves a suppressor role in the process of fracture healing. Furthermore, effects caused by miR-128-3P mimic/inhibitor were reversed by the application of Smad5/siSmad5. Taken together, these results suggest that the therapeutic effects of MSCs-derived Exos may vary according to differential expression of miRNAs. Exosomal miR-128-3P antagomir may act as a promising therapeutic strategy for bone fracture healing, especially for the elderly.

Neuron-derived exosomes-transmitted miR-124-3p protect traumatically injured spinal cord by suppressing the activation of neurotoxic microglia and astrocytes.

BACKGROUND: Spinal cord injury (SCI) is a catastrophic injury that can cause irreversible motor dysfunction with high disability. Exosomes participate in the transport of miRNAs and play an essential role in intercellular communication via transfer of genetic material. However, the miRNAs in exosomes which derived from neurons, and the underlying mechanisms by which they contribute to SCI remain unknown. METHODS: A contusive in vivo SCI model and a series of in vitro experiments were carried out to explore the therapeutic effects of exosomes. Then, a miRNA microarray analysis and rescue experiments were performed to confirm the role of neuron-derived exosomal miRNA in SCI. Western blot, luciferase activity assay, and RNA-ChIP were used to investigate the underlying mechanisms. RESULTS: The results indicated that neuron-derived exosomes promoted functional behavioral recovery by suppressing the activation of M1 microglia and A1 astrocytes in vivo and in vitro. A miRNA array showed miR-124-3p to be the most enriched in neuron-derived exosomes. MYH9 was identified as the target downstream gene of miR-124-3p. A series of experiments were used to confirm the miR-124-3p/MYH9 axis. Finally, it was found that PI3K/AKT/NF-κB signaling cascades may be involved in the modulation of microglia by exosomal miR-124-3p. CONCLUSION: A combination of miRNAs and neuron-derived exosomes may be a promising, minimally invasive approach for the treatment of SCI.

MicroRNA-421-3p-abundant small extracellular vesicles derived from M2 bone marrow-derived macrophages attenuate apoptosis and promote motor function recovery via inhibition of mTOR in spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) has a very disabling central nervous system impact but currently lacks effective treatment. Bone marrow-derived macrophages (BMDMs) are recruited to the injured area after SCI and participate in the regulation of functional recovery with microglia. Previous studies have shown that M2 microglia-derived small extracellular vesicles (SEVs) have neuroprotective effects, but the effects of M2 BMDM-derived sEVs (M2 BMDM-sEVs) have not been reported in SCI treatment. RESULTS: In this study, we investigated the role of M2 BMDM-sEVs in vivo and in vitro for SCI treatment and its mechanism. Our results indicated that M2 BMDM-sEVs promoted functional recovery after SCI and reduced neuronal apoptosis in mice. In addition, M2 BMDM-sEVs targeted mammalian target of rapamycin (mTOR) to enhance the autophagy level of neurons and reduce apoptosis. MicroRNA-421-3P (miR-421-3p) can bind to the 3' untranslated region (3'UTR) of mTOR. MiR-421-3p mimics significantly reduced the activity of luciferase-mTOR 3'UTR constructs and increased autophagy. At the same time, tail vein injection of inhibitors of SEVs (Inh-sEVs), which were prepared by treatment with an miR-421-3p inhibitor, showed diminished protective autophagy of neuronal cells in vivo. CONCLUSIONS: In conclusion, M2 BMDM-sEVs inhibited the mTOR autophagy pathway by transmitting miR-421-3p, which reduced neuronal apoptosis and promoted functional recovery after SCI, suggesting that M2 BMDM-sEVs may be a potential therapy for SCI.