Protective effects of Batroxobin on spinal cord injury in rats

Quercetin enhances survival and axonal regeneration of motoneurons after spinal root avulsion and reimplantation: experiments in a rat model of brachial plexus avulsion

BACKGROUND

Brachial plexus avulsion (BPA) physically involves the detachment of spinal nerve roots themselves and the associated spinal cord segment, leading to permanent paralysis of motor function of the upper limb. Root avulsion induces severe pathological changes, including inflammatory reaction, oxidative damage, and finally massive motoneuron apoptosis. Quercetin (QCN), a polyphenolic flavonoid found in abundance in fruit and vegetables, has been reported to possess anti-oxidative, anti-inflammatory, and neuroprotective effects in many experimental models of both central nervous system (CNS) and peripheral nervous system (PNS) disorders. The purpose of this study was to investigate whether QCN could improve motor function recovery after C5-7 ventral root avulsion and C6 reimplantation in a rat model of BPA.

METHODS

The right fifth cervical (C5) to C7 ventral roots were avulsed followed by re-implantation of only C6 to establish the spinal root avulsion plus re-implantation model in rats. After surgery, rats were treated with QCN (25, 50, and 100 mg/kg) by gavage for 2 or 8 consecutive weeks. The effects of QCN were assessed using behavior test (Terzis grooming test, TGT) and histological evaluation. The molecular mechanisms were determined by immunohistochemistry analysis and western blotting.

RESULTS

Our results demonstrated that QCN significantly expedited motor function recovery in the forelimb as shown by the increased Terzis grooming test score, and accelerated motor axon regeneration as evidenced by the ascending number of Fluoro-Ruby-labeled and P75-positive regenerative motoneurons. The raised ChAT-immunopositive and cresyl violet-stained neurons indicated the enhanced survival of motoneurons by QCN administration. Furthermore, QCN treatment markedly alleviated muscle atrophy, restored functional motor endplates in biceps and inhibited the microglial and astroglia activation via modulating Nrf2/HO-1 and neurotrophin/Akt/MAPK signaling pathway.

CONCLUSIONS

Taken together, these findings have for the first time unequivocally indicated that QCN has promising potential for further development into a novel therapeutic in conjunction with reimplantation surgery for the treatment of BPA. .

The BE COOL Treatments (Batroxobin, oxygEn, Conditioning, and cOOLing): Emerging Adjunct Therapies for Ischemic Cerebrovascular Disease

Ischemic cerebrovascular disease (ICD), the most common neurological disease worldwide, can be classified based on the onset time (acute/chronic) and the type of cerebral blood vessel involved (artery or venous sinus). Classifications include acute ischemic stroke (AIS)/transient ischemic attack (TIA), chronic cerebral circulation insufficiency (CCCI), acute cerebral venous sinus thrombosis (CVST), and chronic cerebrospinal venous insufficiency (CCSVI). The pathogenesis of cerebral arterial ischemia may be correlated with cerebral venous ischemia through decreased cerebral perfusion. The core treatment goals for both arterial and venous ICDs include perfusion recovery, reduction of cerebral ischemic injury, and preservation of the neuronal integrity of the involved region as soon as possible; however, therapy based on the current guidelines for either acute ischemic events or chronic cerebral ischemia is not ideal because the recurrence rate of AIS or CVST is still very high. Therefore, this review discusses the neuroprotective effects of four novel potential ICD treatments with high translation rates, known as the BE COOL treatments (Batroxobin, oxygEn, Conditioning, and cOOLing), and subsequently analyzes how BE COOL treatments are used in clinical settings. The combination of batroxobin, oxygen, conditioning, and cooling may be a promising intervention for preserving ischemic tissues.

Mitochondrial Transplantation Promotes Remyelination and Long-Term Locomotion Recovery following Cerebral Ischemia

Cerebral ischemia usually leads to axonal degeneration and demyelination in the adjacent white matter. Promoting remyelination still remains a challenging issue in the field. Considering that ischemia deprives energy supply to neural cells and high metabolic activities are required by oligodendrocyte progenitor cells (OPCs) for myelin formation, we assessed the effects of transplanting exogenous healthy mitochondria on the degenerating process of oligodendrocytes following focal cerebral ischemia in the present study. Our results showed that exogenous mitochondria could efficiently restore the overall mitochondrial function and be effectively internalized by OPCs in the ischemic cortex. In comparison with control cortex, there were significantly less apoptotic and more proliferative OPCs in mitochondria-treated cortex. More importantly, higher levels of myelin basic protein (MBP) and more morphologically normal myelin-wrapped axons were observed in mitochondria-treated cortex at 21 days postinjury, as revealed by light and electron microscope. Behavior assay showed better locomotion recovery in mitochondria-treated mice. Further analysis showed that olig2 and lipid synthesis signaling were significantly increased in mitochondria-treated cortex. In together, our data illustrated an antidegenerating and myelination-promoting effect of exogenous mitochondria, indicating mitochondria transplantation as a potentially valuable treatment for ischemic stroke.

Reducing host aldose reductase activity promotes neuronal differentiation of transplanted neural stem cells at spinal cord injury sites and facilitates locomotion recovery

Neural stem cell (NSC) transplantation is a promising strategy for replacing lost neurons following spinal cord injury. However, the survival and differentiation of transplanted NSCs is limited, possibly owing to the neurotoxic inflammatory microenvironment. Because of the important role of glucose metabolism in M1/M2 polarization of microglia/macrophages, we hypothesized that altering the phenotype of microglia/macrophages by regulating the activity of aldose reductase (AR), a key enzyme in the polyol pathway of glucose metabolism, would provide a more beneficial microenvironment for NSC survival and differentiation. Here, we reveal that inhibition of host AR promoted the polarization of microglia/macrophages toward the M2 phenotype in lesioned spinal cord injuries. M2 macrophages promoted the differentiation of NSCs into neurons in vitro. Transplantation of NSCs into injured spinal cords either deficient in AR or treated with the AR inhibitor sorbinil promoted the survival and neuronal differentiation of NSCs at the injured spinal cord site and contributed to locomotor functional recovery. Our findings suggest that inhibition of host AR activity is beneficial in enhancing the survival and neuronal differentiation of transplanted NSCs and shows potential as a treatment of spinal cord injury.

The Repression of the HMGB1-TLR4-NF-κB Signaling Pathway by Safflower Yellow May Improve Spinal Cord Injury

Spinal cord injury (SCI) often results in abnormal sensory and motor functions. Current interventions for SCI in the clinical setting are not effective partly due to the complexity concerning its pathophysiological mechanism. In the wake of SCI, considerable inflammatory cells assemble around the injured area that induces a series of inflammatory reactions and aggravates tissue lesions, thereby affecting the recovery of the damaged nerve tissue. Therefore, the inhibition of inflammatory responses can improve the repair of the injured spinal cord tissue. Safflower Yellow (SY) is the main active ingredient of Carthamus tinctorius. SY has anti-inflammatory effect, as it can inhibit IκBα phosphorylation to impede the NF-κB signaling pathway and p53 nuclear translocation. Besides, SY can limit the release of pro-inflammatory factors, which in turn may alleviate secondary SCI and prevent further complications. In this report, we analyze the pathophysiological mechanism of SCI, the role of inflammatory responses, and how SY interferes with the HMGB1-TLR-4-NF-κB signaling pathway to attenuate inflammatory responses in SCI.

Use of Batroxobin in Central and Peripheral Ischemic Vascular Diseases: A Systematic Review

Background and Purpose: The mechanism of action of Batroxobin included the decomposition of the fibrinogen to fibrin degradation products (FDPs) and D-dimer and mobilization of endothelial cells to release endogenous nt-PA and to promote thrombolysis. This review aims to summarize current study findings about batroxobin on correcting cerebral arterial, venous, and peripheral vascular diseases, to explore the mechanism of batroxobin on anti-thrombosis process.

Methods: A thorough literature search was conducted utilizing the PubMed Central (PMC) and EMBASE databases to identify studies up to June 2021. Data from clinical studies and animal experiments about batroxobin were extracted, integrated and analyzed based on Cochrane handbook for systematic reviews of interventions approach and the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P), including the condition of subjects, the usage and dosage, research observation index and main findings.

Results: A total of 62 studies were enrolled in this systematic review, including 26 clinical studies and 36 animal experiments. The 26 clinical studies involved 873 patients with arterial ischemic events, 92 cases with cerebral venous thrombosis, 13 cases with cerebral cortical vein thrombosis, and 1,049 cases with peripheral vascular diseases. These patients included 452 males and 392 females aged 65.6 ± 5.53 years. The results revealed that batroxobin had broad effects, including improving clinical prognosis (n = 12), preventing thrombosis (n = 7), promoting thrombolysis (n = 6), and improving vascular cognitive dysfunction (n = 1). The effects of batroxobin on reducing neuronal apoptosis (n = 8),relieving cellular edema (n = 4), improving spatial memory (n = 3), and promoting thrombolysis (n = 13) were concluded in animal experiments. The predominant mechanisms explored in animal experiments involved promoting depolymerization of fibrinogen polymers (n = 6), regulating the expression of related molecules (n = 9); such as intercellular adhesion molecule, heat shock proteins, tumor necrosis factor), reducing oxidative stress (n = 5), and reducing inflammation response (n = 4).

Conclusion: Batroxobin can correct both arterial and venous ischemic diseases by promoting depolymerization of fibrinogen polymers, regulating the expression of related molecules, reducing oxidative stress, and reducing the inflammation response.

Neuroprotective effects of Hemocoagulase Agkistrodon on experimental traumatic brain injury

Traumatic brain injury (TBI) is the major cause of disability and mortality among young people and is associated with neurodegenerative diseases. However, the available clinical options have limited effectiveness. Here, we investigated the neuroprotective effect of Hemocoagulase Agkistrodon (HCA), a thrombin-like enzyme (TLE) isolated and purified from snake venom. Rats subjected to experimental TBI were administered a single dose of HCA or vehicle 10 min after injury. Neurological function was assessed with modified neurological severity score (mNSS). Brain edema were evaluated by measuring brain water content. Levels of hemoglobin and inflammatory cytokines were detected by Enzyme-linked immunosorbent assay (ELISA). In addition, assays including Evans blue extravasation, Western blot analysis and immunofluorescence staining were utilized to determined blood-brain barrier (BBB) integrity. Our results showed that HCA treatment ameliorated neurological deficits (p < 0.01), alleviated brain edema (p < 0.01) and hemorrhage (p < 0.01), decreased the production of the proinflammatory cytokines IL-1β (p < 0.01), TNF-α (p < 0.01) and IL-6 (p < 0.05), and increased the anti-inflammatory cytokine IL-10 at the contusion site (p < 0.01). Moreover, HCA administration reduced BBB disruption by regulating expression of tight junction proteins, including ZO-1, occludin and claudin-5 (ps < 0.01). Together, our results demonstrate that HCA might have therapeutic efficacy in acute TBI, suggesting a potential clinical application for mitigating the neuropathological damage associated with TBI.

LncRNA CASC9 attenuates lactate dehydrogenase-mediated oxidative stress and inflammation in spinal cord injury via sponging miR-383-5p

Long non-coding RNAs (lncRNAs) play important roles in various diseases, but the effect of lncRNA CASC9 on spinal cord injury (SCI) remains unclear. Therefore, the present study was conducted to explore the role of this lncRNA in SCI. SCI model was established by laminectomy in rats in vivo or induced by LPS in PC12 cells in vitro. Methylprednisolone (MP) was used for treatment in vivo. Spinal cord tissues were stained with H&E, and the oxidative stress- and inflammation-related factors were detected using their commercial kits. Cell apoptosis was determined using flow cytometry assay. Relative expression of corresponding genes was measured using qRT-PCR and western blotting. Luciferase reporter assay was used to verify binding site between CASC9 and miR-383-5p, as well as miR-383-5p and LDHA. The results showed that lncRNA CASC9 was downregulated and miR-383-5p was upregulated in SCI rats and LPS-induced PC12 cells. Severe histological injury and increased water content were also found in SCI rats. Increased levels of LDH, MDA, lactic acid, TNF-α, and IL-1β were found in SCI rats and LPS-induced PC12 cells. These changes could be reversed by MP treatment in vivo or overexpression of CASC9 in vitro. Besides, overexpression of CASC9 decreased cell apoptosis and protein expression of LDHA and increased protein expression of Nrf2 and HO-1 in LPS-induced PC12 cells. Furthermore, miR-383-5p was a direct target of CASC9 and was negatively regulated by CASC9. LDHA was a direct target of miR-383-5p and was negatively regulated by CASC9. In conclusion, lncRNA CASC9 exerted a protective role against oxidative stress, inflammation, and cell apoptosis in SCI, providing a novel therapeutic target or prognostic factor for SCI.

Batroxobin inhibits astrocyte activation following nigrostriatal pathway injury

Batroxobin is a thrombin-like serine protease from the venom of the Bothrops atrox and Bothrops moojeni snake species. Sirtuin 1 (Sirt1) has been shown to play an important role in neuroprotection after traumatic brain injury. However, its underlying mechanism of action remains poorly understood. The purpose of this study was to investigate whether the mechanism by which batroxobin participates in the activation of astrocytes is associated with Sirt1. Mouse models of nigrostriatal pathway injury were established. Immediately after modeling, mice were intraperitoneally administered 39 U/kg batroxobin. Batroxobin significantly reduced the expression of cleaved caspase-3 in both the substantia nigra and striatum, inhibited neuronal apoptosis, and promoted the recovery of rat locomotor function. These changes coincided with a remarkable reduction in astrocyte activation. Batroxobin also reduced Sirt1 expression and extracellular signal-regulated kinase activation in brain tissue. Intraperitoneal administration of the Sirt1-specific inhibitor EX527 (5 mg/kg) 30 minutes prior to injury could inhibit the abovementioned effects. In mouse astrocyte cultures, 1 ng/mL batroxobin attenuated interleukin-1β-induced activation of astrocytes and extracellular signal-regulated kinase. EX527 could also inhibit the effects of batroxobin. These findings suggest that batroxobin inhibits astrocyte activation after nigrostriatal pathway injury through the Sirt1 pathway. This study was approved by the Animal Ethics Committee of China Medical University, China (approval No. CMU2020037) on July 19, 2015.

Inhibiting HMGB1-RAGE axis prevents pro-inflammatory macrophages/microglia polarization and affords neuroprotection after spinal cord injury

Background

Spinal cord injury (SCI) favors a persistent pro-inflammatory macrophages/microglia-mediated response with only a transient appearance of anti-inflammatory phenotype of immune cells. However, the mechanisms controlling this special sterile inflammation after SCI are still not fully elucidated. It is known that damage-associated molecular patterns (DAMPs) released from necrotic cells after injury can trigger severe inflammation. High mobility group box 1(HMGB1), a ubiquitously expressed DNA binding protein, is an identified DAMP, and our previous study demonstrated that reactive astrocytes could undergo necroptosis and release HMGB1 after SCI in mice. The present study aimed to explore the effects and the possible mechanism of HMGB1on macrophages/microglia polarization, as well as the neuroprotective effects by HMGB1 inhibition after SCI.

Methods

In this study, the expression and the concentration of HMGB1 was determined by qRT-PCR, ELISA, and immunohistochemistry. Glycyrrhizin was applied to inhibit HMGB1, while FPS-ZM1 to suppress receptor for advanced glycation end products (RAGE). The polarization of macrophages/microglia in vitro and in vivo was detected by qRT-PCR, immunostaining, and western blot. The lesion area was detected by GFAP staining, while neuronal survival was examined by Nissl staining. Luxol fast blue (LFB) staining, DAB staining, and western blot were adopted to evaluate the myelin loss. Basso-Beattie-Bresnahan (BBB) scoring and rump-height Index (RHI) assay was applied to evaluate locomotor functional recovery.

Results

Our data showed that HMGB1 can be elevated and released from necroptotic astrocytes and HMGB1 could induce pro-inflammatory microglia through the RAGE-nuclear factor-kappa B (NF-κB) pathway. We further demonstrated that inhibiting HMGB1 or RAGE effectively decreased the numbers of detrimental pro-inflammatory macrophages/microglia while increased anti-inflammatory cells after SCI. Furthermore, our data showed that inhibiting HMGB1 or RAGE significantly decreased neuronal loss and demyelination, and improved functional recovery after SCI.

Conclusions

The data implicated that HMGB1-RAGE axis contributed to the dominant pro-inflammatory macrophages/microglia-mediated pro-inflammatory response, and inhibiting this pathway afforded neuroprotection for SCI. Thus, therapies designed to modulate immune microenvironment based on this cascade might be a prospective treatment for SCI.

Involvement of Shh/Gli1 signaling in the permeability of blood-spinal cord barrier and locomotion recovery after spinal cord contusion

Shh/Gli1 signaling plays important roles in development of spinal cord. How it is involved in spinal cord injury (SCI) remains unclear. In this study, we explored the roles of Shh/Gli1 signaling in SCI by using Shh signaling reporter Gli1^lz mice and Gli1 mutant Gli1^lz/lz mice. For detecting the Shh/Gli1 signaling after SCI, X-gal staining and double-immunostaining of Shh/PDGFR-β, Shh/GFAP and LacZ/GFAP was conducted at 3 days post injury (dpi) on Gli1^lz mice. To investigate the effects of Gli1 mutation on pathological changes after SCI, astrocytic proliferation and the content of intra-parenchymal Evans Blue were evaluated at 7dpi in wild-type and Gli1^lz/lz mice. Furthermore, locomotor recovery was assessed by BMS scoring at 1, 3, 5 and 7dpi. The results of X-gal staining and immunohistochemistry showed that Shh/Gli1 signaling was mainly activated in reactive astrocytes after SCI. The 5-bromo-2-deoxyuridine (BrdU) incorporation assay showed that mutation of Gli1 did not affect the proliferation of astrocytes. However, the leakage of Evans Blue was significantly increased in the injured cord of Gli1^lz/lz mice compared to wild-type mice. In addition, locomotor recovery was significantly impaired in the Gli1^lz/lz mice. The findings demonstrated that Shh/Gli1 signaling could be induced in reactive astrocytes by SCI, and plays important role in permeability of blood-spinal cord barrier (BSCB) and locomotor recovery after SCI.

Protective effect of rhodioloside and bone marrow mesenchymal stem cells infected with HIF-1-expressing adenovirus on acute spinal cord injury

Rhodioloside has been shown to protect cells from hypoxia injury, and bone marrow mesenchymal stem cells have a good effect on tissue repair. To study the effects of rhodioloside and bone marrow mesenchymal stem cells on spinal cord injury, a rat model of spinal cord injury was established using the Infinite Horizons method. After establishing the model, the rats were randomly divided into five groups. Rats in the control group were intragastrically injected with phosphate buffered saline (PBS) (5 μL). PBS was injected at 6 equidistant points around 5 mm from the injury site and at a depth of 5 mm. Rats in the rhodioloside group were intragastrically injected with rhodioloside (5 g/kg) and intramuscularly injected with PBS. Rats in the mesenchymal stem cell (MSC) group were intramuscularly injected with PBS and intramuscularly with MSCs (8 × 10⁶/mL in a 50-μL cell suspension). Rats in the Ad-HIF-MSC group were intragastrically injected with PBS and intramuscularly injected with HIF-1 adenovirus-infected MSCs. Rats in the rhodioloside + Ad-HIF-MSC group were intramuscularly injected with MSCs infected with the HIF-1 adenovirus and intragastrically injected with rhodioloside. One week after treatment, exercise recovery was evaluated with a modified combined behavioral score scale. Hematoxylin-eosin staining and Pischingert’s methylene blue staining were used to detect any histological or pathological changes in spinal cord tissue. Levels of adenovirus IX and Sry mRNA were detected by real-time quantitative polymerase chain reaction and used to determine the number of adenovirus and mesenchymal stem cells that were transfected into the spinal cord. Immunohistochemical staining was applied to detect HIF-1 protein levels in the spinal cord. The results showed that: (1) compared with the other groups, the rhodioloside + Ad-HIF-MSC group exhibited the highest combined behavioral score (P < 0.05), the most recovered tissue, and the greatest number of neurons, as indicated by Pischingert’s methylene blue staining. (2) Compared with the PBS group, HIF-1 protein expression was greater in the rhodioloside group (P < 0.05). (3) Compared with the Ad-HIF-MSC group, Sry mRNA levels were higher in the rhodioloside + Ad-HIF-MSC group (P < 0.05). These results confirm that rhodioloside combined with bone marrow mesenchymal stem cells can promote the recovery of spinal cord injury and activate the HIF-1 pathway to promote the survival of bone marrow mesenchymal stem cells and repair damaged neurons within spinal cord tissue. This experiment was approved by the Animal Ethics Committee of Gansu University of Traditional Chinese Medicine, China (approval No. 2015KYLL029) in June 2015.

Batroxobin accelerated tissue repair via neutrophil extracellular trap regulation and defibrinogenation in a murine ischemic hindlimb model

Batroxobin, isolated from Bothrops moojeni, is a defibrinogenating agent used as a thrombin-like serine protease against fibrinogen for improving microcirculation. Here, we investigated whether, and if so, how batroxobin restores ischemic tissue injury in terms of anti-inflammatory effects. In an in vitro flow cytometry assay for human neutrophil extracellular traps (NETs), batroxobin (DF-521; Defibrase) inhibited human NETs induced by tumor necrosis factor-α (TNF-α) in the presence of human fibrinogen. Next, the effect of batroxobin was investigated by immunohistochemistry of the anterior tibial muscle (ATM) in an ischemic hindlimb model using C57BL/6J mice intraperitoneally injected with DF-521 versus the saline control. NETs and fibrinogen deposition in the ischemic ATM decreased in DF-521-treated mice on day 2 after ischemia. Meanwhile, reverse transcription-quantitative PCR assay of the ischemic ATM unveiled continuous downregulation in the expression of the genes; Tnf-α and nitric oxide synthase2 (Nos2) with hypoxia-inducible factor-1α (Hif-1α) and vascular endothelial growth factor-a (Vegf-a) from day 3 to day 7, but the upregulation of arginase-1 (Arg-1) and placental growth factor (Plgf) with myogenin (Myog) on day 7. Daily intraperitoneal DF-521 injection for the initial 7 days into mice with ischemic hindlimbs promoted angiogenesis and arteriogenesis on day 14. Moreover, DF-521 injection accelerated myofiber maturation after day 14. Laser doppler imaging analysis revealed that blood perfusion in DF-521-injected mice significantly improved on day 14 versus the saline control. Thus, DF-521 improves microcirculation by protecting NETs with tissue defibrinogenation, thereby protecting against severe ischemic tissue injury and accelerating vascular and skeletal muscular regeneration. To our knowledge, batroxobin might be the first clinically applicable NET inhibitor against ischemic diseases.

Fibrinogen in neurological diseases: mechanisms, imaging and therapeutics

The blood coagulation protein fibrinogen is deposited in the brain in a wide range of neurological diseases and traumatic injuries with blood-brain barrier (BBB) disruption. Recent research has uncovered pleiotropic roles for fibrinogen in the activation of CNS inflammation, induction of scar formation in the brain, promotion of cognitive decline and inhibition of repair. Such diverse roles are possible in part because of the unique structure of fibrinogen, which contains multiple binding sites for cellular receptors and proteins expressed in the nervous system. The cellular and molecular mechanisms underlying the actions of fibrinogen are beginning to be elucidated, providing insight into its involvement in neurological diseases, such as multiple sclerosis, Alzheimer disease and traumatic CNS injury. Selective drug targeting to suppress the damaging functions of fibrinogen in the nervous system without affecting its beneficial effects in haemostasis opens a new fibrinogen therapeutics pipeline for neurological disease.

Pretreatment with AQP4 and NKCC1 Inhibitors Concurrently Attenuated Spinal Cord Edema and Tissue Damage after Spinal Cord Injury in Rats

Spinal cord injury (SCI) affects more than 2.5 million people worldwide. Spinal cord edema plays critical roles in the pathological progression of SCI. This study aimed to delineate the roles of aquaporin 4 (AQP4) and Na⁺-K⁺-Cl⁻ cotransporter 1 (NKCC1) in acute phase edema and tissue destruction after SCI and to explore whether inhibiting both AQP4 and NKCC1 could improve SCI-induced spinal edema and damage. Rat SCI model was established by modified Allen's method. Spinal cord water content, cerebrospinal fluid lactose dehydrogenase (LDH) activity, AQP4 and NKCC1 expression, and spinal cord pathology from 30 min to 7 days after SCI were monitored. Additionally, aforementioned parameters in rats treated with AQP4 and/or NKCC1 inhibitors were assessed 2 days after SCI. Spinal cord water content was significantly increased 1 h after SCI while AQP4 and NKCC1 expression and spinal fluid LDH activity elevated 6 h after SCI. Spinal cord edema and spinal cord destruction peaked around 24 h after SCI and maintained at high levels thereafter. Treating rats with AQP4 inhibitor TGN-020 and NKCC1 antagonist bumetanide significantly reduced spinal cord edema, tissue destruction, and AQP4 and NKCC1 expression after SCI in an additive manner. These results demonstrated the benefits of simultaneously inhibiting both AQP4 and NKCC1 after SCI.

Acute and repeated dose (28 days) toxicity studies in rats and dogs of recombinant batroxobin, a snake venom thrombin-like enzyme expressed from Pichia pastoris

Recombinant batroxobin is a thrombin-like enzyme of Bothrops atrox moojeni venom. To evaluate its toxicological effect, it was highly expressed in Pichia pastorisand successfully purified to homogeneity from culture broth supernatant following Good Manufacturing Practice (GMP). The maximum tolerated dose of the recombinant batroxobin was examined in Sprague-Dawley (SD) rat and Beagle dogs following Good Laboratory Practice (GLP) regulations. The approximate lethal dose of recombinant batroxobin was 10 National Institute of Health (NIH) u/kg in male and female rats. Slight test substance-related effects were clearly in male and female dogs at more than 10 NIH u/kg. The maximum tolerated dose (MTD) was considered to be greater than 30 NIH u/kg in dogs. To investigate the repeated dose toxicity of batroxobin, the test item was intravenously administered to groups of SD rat and Beagle dog every day for 4 weeks. We observed that all animals survived the duration of the study without any effects on their mortality. There were no effects in both rats and dogs regarding their clinical signs, body weight, food consumption, ophthalmological examination, urinalysis, hematology, clinical chemistry, organ weightand gross post mortem examinations. The no adverse effect level (NOAEL) of recombinant batroxobin for both males and females is considered to be greater than 2.5 NIH u/kgin rats and 1 NIH u/kg in dogs, respectively. No toxic effects were noted in target organs. In conclusion, these results show a favorable preclinical profile and may contribute clinical development of recombinant batroxobin.

Slit2/Robo1 promotes synaptogenesis and functional recovery of spinal cord injury

Neuronal network reconstruction is a pivotal determinant for functional recovery after spinal cord injury (SCI), the process of which includes synaptogenesis. Slit2 protein has been identified as a key regulator of axon regeneration and synapse formation in the vertebrate. Meanwhile, RhoA is the converging cascade of inhibitory molecules that interrupt synaptic plasticity in SCI. In the present study, we investigated the interaction among Slit2, Robo1, and RhoA and the potential roles of Slit2 in the pathological process of SCI. We showed that Slit2 was decreased, whereas Robo1 and RhoA were increased in the same surviving neurons in the spinal cord following SCI. We also found that inhibition of Slit2 led to upregulation of the expression of Robo1 and RhoA. However, the severe dysfunctions of the locomotor performance induced by SCI were reversed by treatments of Slit2-N, the active portion of Slit2, knockdown of Robo1 by the RNAi lentivirus, or inhibition of RhoA by the C3 exoenzyme, respectively. Further results suggested that downregulation of Slit2 and therefore upregulation of Robo1 and RhoA inhibited the activity of growth cone and hindered the formation of new synapses of surviving neurons near the injury sites of the spinal cord following SCI. Our study indicated a new mechanism of deficiency of synaptogenesis during the development of SCI and provided a potential strategy for the treatment of SCI.

Beneficial effects of early hemostasis on spinal cord injury in the rat

STUDY DESIGN

Experimental study.

OBJECTIVES

To investigate the effect of early hemostasis on spinal cord injury (SCI).

SETTING

Fourth Military Medical University, Xi'an, China.

METHODS

Sprague Dawley rats were used. Hematoxylin and eosin (HE) staining was performed to observe hemorrhage at different time points (2, 6, 12, 24 and 48 h) after SCI to determine the time window of hemostatic drug administration (n=3 per time point). Three different concentrations of Etamsylate (0.025, 0.05 and 0.1 g kg-1) were administered immediately and 5 and 10 h after SCI to evaluate the effective dosage (n=6 per group). Another 82 rats were then randomly divided into two groups, Etamsylate group (0.1 g kg-1, n=41) and glucose control group (n=41). Nissl staining was performed to observe neurons at 10 days post injury. Immunohistochemistry, western blot and quantitative real-time PCR were performed to detect tissue necrosis at 7 d.p.i., the activation of astrocytes and microglia/macrophages and lesion cavity at 10 d.p.i. Basso-Beattie-Bresnahan scoring and rump height index assay were used to examine locomotion recovery.

RESULTS

Early hemostasis reduced the lesion area and tissue necrosis, enhanced neuronal survival, alleviated the activation of microglia/macrophages and astrocytes and facilitated functional recovery after spinal cord contusion in rats. Early hemostasis decreased hemorrhage area and lesion area after spinal cord transection in rats.

CONCLUSION

The present study demonstrated that early hemostasis has beneficial effects on SCI in the rat. It has the potential to be translated into clinical practice.

Protective effects of batroxobin on a nigrostriatal pathway injury in mice

Traumatic brain injury triggers a series of damaged processes, such as neuronal death and apoptosis, inflammation and scar formation, which contribute to evolution of brain injury. The present study investigated the neuroprotective effects of batroxobin, a drug widely used clinically for ischemia, in a nigrostriatal pathway injury model. Mice subjected to the nigrostriatal pathway injury were injected with batroxobin (30 BU/kg) or vehicle immediately after injury. The behavioral studies showed that batroxobin could improve the motor function in injured mice in long term. Batroxobin also reduced neuronal apoptosis and inflammation at the acute stage. Moreover, administration of batroxobin attenuated the scar formation and reduced the lesion size at 4 and 14days after brain injury. These results suggest that batroxobin has beneficial effects on the nigrostriatal pathway injury, indicating a potential clinical application.

G-1 exerts neuroprotective effects through G protein-coupled estrogen receptor 1 following spinal cord injury in mice

Spinal cord injury (SCI) always occurs accidently and leads to motor dysfunction because of biochemical and pathological events. Estrogen has been shown to be neuroprotective against SCI through estrogen receptors (ERs), but the underlying mechanisms have not been fully elucidated. In the present study, we investigated the role of a newly found membrane ER, G protein-coupled estrogen receptor 1 (GPR30 or GPER1), and discussed the feasibility of a GPR30 agonist as an estrogen replacement. Forty adult female C57BL/6J mice (10-12 weeks old) were divided randomly into vehicle, G-1, E2, G-1 + G-15 and E2 + G-15 groups. All mice were subjected to SCI using a crushing injury approach. The specific GPR30 agonist, G-1, mimicked the effects of E2 treatment by preventing SCI-induced apoptotic cell death and enhancing motor functional recovery after injury. GPR30 activation regulated phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK/extracellular signal-regulated kinase (ERK) signalling pathways, increased GPR30 and anti-apoptosis proteins Bcl-2 and brain derived neurotrophic factor (BDNF), but decreased the pro-apoptosis factor Bax and cleaved caspase-3. However, the neuroprotective effects of G-1 and E2 were blocked by the specific GPR30 antagonist, G-15. Thus, GPR30 rather than classic ERs is required to induce estrogenic neuroprotective effects. Given that estrogen replacement therapy may cause unexpected side effects, especially on the reproductive system, GPR30 agonists may represent a potential therapeutic approach for treating SCI.

Reactive astrocytes undergo M1 microglia/macrohpages-induced necroptosis in spinal cord injury

Background

A unique feature of the pathological change after spinal cord injury (SCI) is the progressive enlargement of lesion area, which usually results in cavity formation and is accompanied by reactive astrogliosis and chronic inflammation. Reactive astrocytes line the spinal cavity, walling off the lesion core from the normal spinal tissue, and are thought to play multiple important roles in SCI. The contribution of cell death, particularly the apoptosis of neurons and oligodendrocytes during the process of cavitation has been extensively studied. However, how reactive astrocytes are eliminated following SCI remains largely unclear.

Results

By immunohistochemistry, in vivo propidium iodide (PI)-labeling and electron microscopic examination, here we reported that in mice, reactive astrocytes died by receptor-interacting protein 3 and mixed lineage kinase domain-like protein (RIP3/MLKL) mediated necroptosis, rather than apoptosis or autophagy. Inhibiting receptor-interacting protein 1 (RIP1) or depleting RIP3 not only significantly attenuated astrocyte death but also rescued the neurotrophic function of astrocytes. The astrocytic expression of necroptotic markers followed the polarization of M1 microglia/macrophages after SCI. Depleting M1 microglia/macrophages or transplantation of M1 macrophages could significantly reduce or increase the necroptosis of astrocytes. Further, the inflammatory responsive genes Toll-like receptor 4 (TLR4) and myeloid differentiation primary response gene 88 (MyD88) are induced in necroptotic astrocytes. In vitro antagonizing MyD88 in astrocytes could significantly alleviate the M1 microglia/macrophages-induced cell death. Finally, our data showed that in human, necroptotic markers and TLR4/MyD88 were co-expressed in astrocytes of injured, but not normal spinal cord.

Conclusion

Taken together, these results reveal that after SCI, reactive astrocytes undergo M1 microglia/macrophages-induced necroptosis, partially through TLR/MyD88 signaling, and suggest that inhibiting astrocytic necroptosis may be beneficial for preventing secondary SCI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-016-0081-8) contains supplementary material, which is available to authorized users.

Hydrogen-rich saline injection into the subarachnoid cavity within 2 weeks promotes recovery after acute spinal cord injury

Hydrogen can relieve tissue-damaging oxidative stress, inflammation and apoptosis. Injection of hydrogen-rich saline is an effective method for transporting molecular hydrogen. We hypothesized that hydrogen-rich saline would promote the repair of spinal cord injury induced by Allen's method in rats. At 0.5, 1, 2, 4, 8, 12 and 24 hours after injury, then once daily for 2 weeks, 0.25 mL/kg hydrogen-rich saline was infused into the subarachnoid space through a catheter. Results at 24 hours, 48 hours, 1 week and 2 weeks after injury showed that hydrogen-rich saline markedly reduced cell death, inflammatory cell infiltration, serum malondialdehyde content, and caspase-3 immunoreactivity, elevated serum superoxide dismutase activity and calcitonin gene-related peptide immunoreactivity, and improved motor function in the hindlimb. The present study confirms that hydrogen-rich saline injected within 2 weeks of injury effectively contributes to the repair of spinal cord injury in the acute stage.

Spinal cord contusion

Spinal cord injury is a major cause of disability with devastating neurological outcomes and limited therapeutic opportunities, even though there are thousands of publications on spinal cord injury annually. There are two major types of spinal cord injury, transaction of the spinal cord and spinal cord contusion. Both can theoretically be treated, but there is no well documented treatment in human being. As for spinal cord contusion, we have developed an operation with fabulous result.