Establishment and Validation of a Model for Fetal Neural Ischemia Using Necrotic Core-Free Human Spinal Cord Organoids

Fetal spinal cord ischemia is a serious medical condition that can result in significant neurological damage and adverse outcomes for the fetus. However, the lack of an appropriate experimental model has hindered the understanding of the pathology and the development of effective treatments. In our study, we established a system for screening drugs that affect fetal spinal cord ischemia using spinal cord organoids. Importantly, we produced necrotic core-free human spinal cord organoids (nf-hSCOs) by reducing the organoid size to avoid potential complications of spontaneous necrosis in large organoids. Exposing nf-hSCOs to CoCl2 as a hypoxia mimetic and hypoglycemic conditions resulted in significant neuronal damage, as assessed by multiple assay batteries. By utilizing this model, we tested chemicals that have been reported to exhibit beneficial effects in brain organoid-based ischemia models. Surprisingly, these chemicals did not provide sufficient benefit, and we discovered that rapamycin is a mild neuroprotective reagent for both axon degeneration and neuronal survival. We propose that nf-hSCO is suitable for large-scale screening of fetal neural ischemia due to its scalability, ease of ischemic induction, implementation of quantifiable assay batteries, and the absence of spontaneous necrosis.

Mouse Model of Spinal Cord Hypoperfusion with Immediate Paralysis Caused by Endovascular Repair of Thoracic Aortic Aneurysm

BACKGROUND

A clinically relevant mouse model of thoracic endovascular aortic repair-induced ischemic spinal cord injury has been lacking since the procedure was first employed in 1991. The hypothesis was that ligation of mouse intercostal arteries would simulate thoracic endovascular aortic repair-induced ischemic spinal cord injury and behavioral deficit. The aim was to create a mouse model of thoracic endovascular aortic repair-induced spinal cord hypoperfusion by ligating five pairs of mouse intercostal vessels.

METHODS

Mice were divided into sham (n = 53) and ligation (n = 60) groups. The procedures called for double ligation of three pairs and single ligation of two pairs of thoracic intercostal arteries in adult C57BL/6 mice. A laser Doppler probe was used in vivo on the spinal cords and intercostal arteries to document the extent of arterial ligation and spinal cord hypoperfusion. The Basso Mouse Scale for Locomotion, histological studies, and electron microscopy demonstrated postligation locomotive and histopathological changes.

RESULTS

Ligation induced a significant and instantaneous drop in blood flow in the intercostal arteries (% change; mean = -63.81; 95% CI, -72.28 to -55.34) and the thoracic spinal cord (% change; mean = -68.55; 95% CI, -80.23 to -56.87). Paralysis onset was immediate and of varying degree, with behavioral deficit stratified into three groups: 9.4% exhibited severe paralysis, 37.5% moderate paralysis, and 53.1% mild paralysis at day 1 (n = 32; P < 0.001). Mild and moderate paralysis was transient, gradually improving over time. Severe paralysis showed no improvement and exhibited a higher mortality rate (83%; n = 15 of 18) compared to moderately (33%; n = 6 of 18) and mildly (24%; n = 6 of 25) paralyzed mice (P < 0.001). The overall ligation group survival rate (84%; n = 46 of 55) was significantly lower than the sham group (100%; n = 48 of 48) with P = 0.003.

CONCLUSIONS

The mouse model generates reproducible spinal cord hypoperfusion and accompanying histopathological ischemic spinal cord damage. The resulting anatomical changes and variable behavioral deficits mimic the variability in radiological and clinical findings in human patients.

EDITOR’S PERSPECTIVE

Cerebrolysin Amelioration of Spinal Cord Ischemia/ Reperfusion Injury in Rabbit Model

AIM

To investigate the effects of cerebrolysin on inflammation, oxidative stress, apoptosis, and neurologic recovery in the setting of an experimental rabbit model of spinal cord ischemia/reperfusion injury (SCIRI).

MATERIAL AND METHODS

Rabbits were randomly divided into five groups: control, ischemia, vehicle, methylprednisolone (30 mg/kg), and cerebrolysin (5 ml/kg) group. The rabbits in the control group underwent only laparotomy; the other groups underwent spinal cord ischemia and reperfusion injury for 20 minutes. Neurologic examination after 24 hours was based on the Modified Tarlov scale. Myeloperoxidase activities, catalase and malondialdehyde levels, and caspase-3 concentrations were determined in serum and tissue samples. Serum xanthine oxidase levels were studied and histopathological and ultrastructural changes were examined.

RESULTS

After SCIRI, serum and tissue myeloperoxidase activities, malondialdehyde levels, caspase-3 concentrations, and serum xanthine oxidase activities were increased (p < 0.01?0.001). Catalase levels were significantly diminished (p < 0.001). Cerebrolysin treatment correlated with reduced myeloperoxidase and xanthine oxidase activities, malondialdehyde levels and caspase-3 concentrations; and with increased catalase levels (p < 0.001, for all). The cerebrolysin group showed improved histopathological, ultrastructural, and neurological outcomes.

CONCLUSION

For the first time in the literature, the current study reports anti-inflammatory, antioxidant, antiapoptotic, and neuroprotective effects of cerebrolysin in a SCIRI rabbit model.

Neuroprotective Effects of Dexpanthenol on Rabbit Spinal Cord Ischemia/Reperfusion Injury Model

OBJECTIVE

Dexpanthenol (DXP) reportedly protects tissues against oxidative damage in various inflammation models. This study aimed to evaluate its effects on oxidative stress, inflammation, apoptosis, and neurological recovery in an experimental rabbit spinal cord ischemia/reperfusion injury (SCIRI) model.

METHODS

Rabbits were randomized into 5 groups of 8 animals each: group 1 (control), group 2 (ischemia), group 3 (vehicle), group 4 (methylprednisolone, 30 mg/kg), and group 5 (DXP, 500 mg/kg). The control group underwent laparotomy only, whereas other groups were subjected to spinal cord ischemia by aortic occlusion (just caudal to the 2 renal arteries) for 20 min. After 24 h, a modified Tarlov scale was employed to record neurological examination results. Malondialdehyde and caspase-3 levels and catalase and myeloperoxidase activities were analyzed in tissue and serum samples. Xanthine oxidase activity was measured in the serum. Histopathological and ultrastructural evaluations were also performed in the spinal cord.

RESULTS

After SCIRI, serum and tissue malondialdehyde and caspase-3 levels and myeloperoxidase and serum xanthine oxidase activities were increased (P < 0.05-0.001). However, serum and tissue catalase activity decreased significantly (P < 0.001). DXP treatment was associated with lower malondialdehyde and caspase-3 levels and reduced myeloperoxidase and xanthine oxidase activities but increased catalase activity (P < 0.05-0.001). Furthermore, DXP was associated with better histopathological, ultrastructural, and neurological outcome scores.

CONCLUSIONS

This study was the first to evaluate antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects of DXP on SCIRI. Further experimental and clinical investigations are warranted to confirm that DXP can be administered to treat SCIRI.

Priming protects the spinal cord in an experimental aortic occlusion model

OBJECTIVES

Paraplegia is a devastating complication in aortic aneurysm surgery. Modifying the spinal cord vasculature is a promising method in spinal cord protection. The aim of this study was to assess whether the spinal cord can be primed by occluding thoracic segmental arteries before simulated aneurysm repair in a porcine model.

METHODS

Twelve piglets were randomly assigned to the priming group (6) and the control group (6). Eight uppermost thoracic segmental arteries were occluded at 5-minute intervals in the priming group before a 25-minute aortic crossclamp. In the control group, the aorta was crossclamped for 25 minutes. During the first 5 minutes, 8 segmental arteries were occluded. After the aortic crossclamping, piglets were observed under anesthesia for 5 hours and followed up 5 days postoperatively. Near-infrared spectroscopy, motor-evoked potentials, blood samples, neurology with the modified Tarlov score, and histopathology of the spinal cord were assessed.

RESULTS

The median Tarlov score during the first postoperative day was higher in the priming group than in the control group (P = .001). At the end, 50% of the control animals had paraplegia compared with 0% of paraplegia in the priming group. The mean regional histopathologic score differed between the priming group and the control group (P = .02). The priming group had higher motor-evoked potentials during the operation at separate time points. The lactate levels were lower in the priming group compared with the control group (Pg = .001, Pg×t = .18).

CONCLUSIONS

Acute priming protects the spinal cord from ischemic injury in an experimental aortic crossclamp model.

Stress-induced phosphoprotein 1 restrains spinal cord ischaemia-reperfusion injury by modulating NF-κB signalling

Spinal cord injury (SCI), a major cause of disability, causes high global disease and economic burdens. Stress-induced phosphoprotein 1 (STIP1) has been identified to be involved in spinal cord ischaemia-reperfusion injury (SCII); however, the effect of STIP1 on SCII remains unclear until now. This study aimed to examine the role of STIP1 in SCII and unravel the possible mechanisms. Western blotting and immunohistochemical staining showed that STIP1 expression rapidly increased and then decreased in rat spinal cord following SCII treatment. Neurological function scoring, HE staining, immunohistochemical staining and Western blotting revealed that STIP1 overexpression alleviated SCII-induced motor dysfunction of hind limbs, neuronal loss and inflammation in spinal cord, and inhibited activity of nuclear factor kappa B (NF-κB) signalling in rats. Immunoprecipitation identified that STIP1 was co-located with Iba-1. In addition, STIP1 was found to ameliorate oxygen and glucose deprivation (OGD)-induced inflammation and activation of NF-κB signalling in mouse microglia BV2 cells, and STIP1 resulted in decrease of heat shock protein family A member 8 (HSPA8), increase of IκBβ expression and reduced binding of IκBβ to HSPA8 in BV2 cells. The results of the present study demonstrate that STIP1 alleviates ischaemia/reperfusion-induced neuronal injury and inflammation in rat spinal cord and mouse microglial cells by deactivating NF-κB signalling. These findings may provide novel insights for the clinical diagnosis and treatment of SCI.

Spinal cord ischemia following open surgery of a ruptured isolated internal iliac artery aneurysm: A case report

INTRODUCTION

Isolated internal iliac artery (IIA) aneurysms (IIIAAs) rarely occur. However, they may enlarge asymptomatically and rupture, causing fatality. Even after successful surgery of ruptured IIIAAs, there might be a potential risk of postoperative spinal cord ischemia (SCI)-related paraplegia, which is extremely rare. However, this paraplegia significantly impacts patients' activities of daily living.

PATIENT CONCERNS

A 71-year-old man who had no remarkable medical history was referred to our hospital with sudden lower abdominal pain.

DIAGNOSIS

Computed tomography (CT) revealed right IIIAA with small volumes of contrast medium extravasation and hematoma. He presented with cyanosis in the bilateral lower limbs. Moreover, blood gas analysis showed lactic acidosis. Therefore, he was diagnosed with ruptured IIIAA complicated by peripheral circulatory failure.

INTERVENTIONS

Considering his pre-shock status, an emergency operation comprising ligation of the proximal neck and suture closure of the distal IIA orifice was successfully performed.

OUTCOMES

Immediately after surgery, motor and sensory dysfunction in the bilateral lower limbs occurred. Magnetic resonance imaging confirmed the presence of SCI. The patient could not stand independently and had neurogenic bladder and rectal disorder.

CONCLUSION

Postoperative SCI is a serious complication with no definitive predictors, preventive methods, or highly efficacious treatments. Therefore, vascular surgeons should preempt its occurrence and focus on preventing hemodynamic instability and maintain collateral extra-segmental arterial blood flow, especially in ruptured cases.

Hyperacute extensive spinal cord infarction and negative spine magnetic resonance imaging: a case report and review of the literature

RATIONALE

Spinal cord infarction (SCI) accounts for only 1% to 2% of all ischemic strokes and 5% to 8% of acute myelopathies. Magnetic resonance imaging (MRI) holds a role in ruling out non-ischemic etiologies, but the diagnostic accuracy of this procedure may be low in confirming the diagnosis, even when extensive cord lesions are present. Indeed, T2 changes on MRI can develop over hours to days, thus accounting for the low sensitivity in the hyperacute setting (ie, within 6 hours from symptom onset). For these reasons, SCI remains a clinical diagnosis. Despite extensive diagnostic work-up, up to 20% to 40% of SCI cases are classified as cryptogenic. Here, we describe a case of cryptogenic longitudinally extensive transverse myelopathy due to SCI, with negative MRI and diffusion-weighted imaging at 9 hours after symptom onset.

PATIENT CONCERNS

A 51-year-old woman presented to our Emergency Department with acute severe abdominal pain, nausea, vomiting, sudden-onset of bilateral leg weakness with diffuse sensory loss, and paresthesias on the trunk and legs.

DIAGNOSES

On neurological examination, she showed severe paraparesis and a D6 sensory level. A 3T spinal cord MRI with gadolinium performed at 9 hours after symptom onset did not detect spinal cord alterations. Due to the persistence of a clinical picture suggestive of an acute myelopathy, a 3T MRI of the spine was repeated after 72 hours showing a hyperintense "pencil-like" signal mainly involving the grey matter from T1 to T6 on T2 sequence, mildly hypointense on T1 and with restricted diffusion.

INTERVENTIONS

The patient was given salicylic acid (100 mg/d), prophylactic low-molecular-weight heparin, and began neuromotor rehabilitation.

OUTCOMES

Two months later, a follow-up neurological examination revealed a severe spastic paraparesis, no evident sensory level, and poor sphincteric control with distended bladder.

LESSONS

Regardless of its relatively low frequency in the general population, SCI should be suspected in every patient presenting with acute and progressive myelopathic symptoms, even in the absence of vascular risk factors. Thus, a clinical presentation consistent with a potential vascular syndrome involving the spinal cord overrides an initially negative MRI and should not delay timely and appropriate management.

Therapeutic effects of syringaldehyde on spinal cord ischemia in rabbits

OBJECTIVES

To investigate the effects of syringaldehyde (SA) on the antioxidant and oxidant system in spinal cord ischemia (SCI).

METHODS

These study and experiments were conducted at Medical Research Center, Çanakkale Onsekiz Mart University, Çanakkale, Turkey, between 2014-2018. Eighteen New Zealand White adult male rabbits were randomly divided into 3 groups (n=6). Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), myeloperoxidase (MPO) activities, and malondialdehyde (MDA) levels were measured in the spinal cord tissues. Degenerated neurons, hemorrhage and in ammatory cell migration in the spinal cord were investigated histopathologically. Expressions of neuronal nitric oxide synthase (nNOS), caspase-3, and nuclear factor-κB (NF-κB) were evaluated immunohistochemically. Clinically, it was evaluated with modified Tarlov score.

RESULTS

Biochemically, there was an expected decrease in SOD, CAT, and GPx enzyme activities in ischemia groups, there was also an increase in MPO activity at the same time. When the enzyme activities spinal cord ischemia/ reperfusion (SCI/R)+SA, control and SCI/R groups were compared, the difference was found to be statistically significant (p less than 0.05). Glutathione peroxidase enzyme activity levels were very low in ischemia group compared to the significant increase in the SA group (p less than 0.05). Histopathologically, when SCI/R and SCI/R+SA groups were compared, there were statistically significant differences in the number of degenerative neurons and amount of hemorrhage; this comparison shows the significance of treatment in terms of inflammatory cell migration (p less than 0.05). The expressions of nNOS, caspase-3, and NF-κB were found significantly increased in SCI/R group compared to the control group (p less than 0.05). Syringaldehyde treatment decreased nNOS, caspase-3, and NF-κB expressions immunohistochemically. Clinical evaluation showed improvement in the SA-treated group.

CONCLUSION

Syringaldehyde therapy administered for protective purposes may reduce oxidative stress, degenerative changes and in ammatory cell migration in the ischemic spinal cord.Saudi Med J 2020; Vol. 41 (4): 341-350doi: 10.15537/smj.2020.4.24993 How to cite this article:Malçok UA,  Aras AB, Şehitoğlu MH, Akman T, Yüksel Y. Therapeutic effects of syringaldehyde on spinal cord ischemia in rabbits. Saudi Med J 2020; Vol. 41: 341-350. doi: 10.15537/smj.2020.4.24993.

Breathing hydrogen sulfide prevents delayed paraplegia in mice

Delayed paraplegia complicates the recovery from spinal cord ischemia or traumatic spinal cord injury. While delayed motor neuron apoptosis is implicated in the pathogenesis, no effective treatment or preventive measures is available for delayed paraplegia. Hydrogen sulfide exerts anti-apoptotic effects. Here, we examined effects of hydrogen sulfide breathing on the recovery from transient spinal cord ischemia. Breathing hydrogen sulfide starting 23 h after reperfusion for 5 h prevented delayed paraplegia after 5 min of spinal cord ischemia. Beneficial effects of hydrogen sulfide were mediated by upregulation of anti-apoptotic Bcl-XL and abolished by nitric oxide synthase 2 deficiency. S-nitrosylation of NFkB p65 subunit, which is induced by nitric oxide derived from nitric oxide synthase 2, facilitated subsequent sulfide-induced persulfidation of p65 and transcription of anti-apoptotic genes. These results uncover the molecular mechanism of the anti-apoptotic effects of sulfide based on the interaction between nitric oxide and sulfide. Exploitation of the anti-apoptotic effects of delayed hydrogen sulfide breathing may provide a new therapeutic approach for delayed paraplegia.

Anti-Inflammatory Effect of Lycopene on Experimental Spinal Cord Ischemia Injury via Cyclooxygenase-2 Suppression

OBJECTIVE

Spinal cord ischemia/reperfusion injury (SCII) is a devastating complication following thoracoabdominal aortic surgeries, often leading to severe neurological deficits. We sought to examine the effects of lycopene, a naturally existing carotenoid with anti-inflammatory properties, in the treatment against SCII.

METHODS

Rats were assigned into four treatment groups: Sham (sham operation), SCII (SCII-induction), LY25, and LY50 (lycopene treatment at 25 or 50 mg/kg following SCII induction, respectively).

RESULTS

Lycopene treatment improved the recovery of neurological functions following SCII and suppressed the neuronal cell death and neuroinflammation at 14 days after SCII. Furthermore, Western blot assay revealed that lycopene treatment attenuated the SCII-induced increase in the protein levels of cyclooxygenase-2 (COX-2), nuclear factor-κB, and activate protein-1, as well as the reduction of heme oxygenase-1.

CONCLUSION

Lycopene exerted neuroprotective functions in SCII and inhibited SCII-elicited neuroinflammation via COX-2 suppression.

Atypical spinal cord infarction: A case report

INTRODUCTION

The abrupt onset of sensorimotor deficits is a neurologic emergency that requires immediate management. Acute spontaneous spinal cord infarction (SCI) is rare, but can cause the sudden onset of quadriplegia or quadriparesis. Magnetic resonance imaging (MRI) is an essential imaging modality to diagnose SCI.

CASE PRESENTATION

A 75-year-old man with a history of diabetes mellitus type 2, hypertension, and dyslipidemia was transferred to our facility for further workup of the sudden onset of quadriplegia. Diffusion-weighted contrast MRI (DWI) on hospital day 8 revealed hyperintense signals predominantly at the grey matter, and a contrast T2 signal abnormality with a decreased apparent diffusion coefficient (ADC). Steroid pulse therapy was initiated because myelitis could not be completely ruled out, but this did not improve the neurological deficits. Spontaneous SCI was finally diagnosed as an exclusion diagnosis. Symptoms were gradually recovered with rehabilitation, and he was transferred to a rehabilitation facility on hospital day 40.

CONCLUSION

MRI with DWI of the spine should be considered for an early diagnosis of SCI. A combination of DWI with ADC maps is recommended to distinguish SCI from other differential disorders.

The Neuroprotective Effect of Coumaric Acid on Spinal Cord Ischemia/Reperfusion Injury in Rats

The main causes of spinal cord ischemia are a variety of vascular pathologies causing acute arterial occlusions. We investigated neuroprotective effects of coumaric acid on spinal cord ischemia injury in rats. Rats were divided randomly into four groups of eight animals as follows: control, ischemia, ischemia + coumaric acid, and ischemia + methylprednisolone. In the control group, only a laparotomy was performed. In all other groups, the spinal cord ischemia was performed by the infrarenal aorta cross-clamping model. Levels of malondialdehyde and nuclear respiratory factor 1 were analyzed, as were the activity of superoxide dismutase. Histopathological and immunohistochemical evaluations were performed. Neurological evaluation was performed with the Tarlov scoring system. The ischemia + coumaric acid group was compared with the ischemia group, and a significant decrease in malondialdehyde and levels was observed. Nuclear respiratory factor 1 level and superoxide dismutase activity of the ischemia + coumaric acid group were significantly higher than in the ischemia group. In histopathological samples, the ischemia + coumaric acid group is compared with the ischemia group, and there was a significant increase in numbers of normal neurons. In immunohistochemical staining, hypoxia-inducible factor-1α and NF-kappa B immunopositive neurons were significantly decreased in the ischemia + coumaric acid group compared with that in the ischemia group. The neurological deficit scores of the ischemia + coumaric acid group were significantly higher than the ischemia group at 24 h. Our results revealed for the first time that coumaric acid exhibits meaningful neuroprotective activity following ischemia-reperfusion injury of the spinal cord.

Neuroprotective effect of atorvastatin in spinal cord ischemia-reperfusion injury

OBJECTIVES

Prevention of the development of paraplegia during the repair of the damage caused by descending thoracic and thoracoabdominal aneurysms remains an important issue. Therefore, we investigated the protective effect of atorvastatin on ischemia-induced spinal cord injury in a rabbit model.

METHOD

Thirty-two rabbits were divided into the following four equally sized groups: group I (control), group II (ischemia-reperfusion), group III (atorvastatin treatment) and group IV (atorvastatin withdrawal). Spinal cord ischemia was induced by clamping the aorta both below the left renal artery and above the iliac bifurcation. Seventy-two hours postoperatively, the motor function of the lower limbs of each animal was evaluated according to the Tarlov score. Spinal cord and blood samples were obtained for histopathological and biochemical analyses.

RESULTS

All of the rabbits in group II exhibited severe neurological deficits. Atorvastatin treatment (groups III and IV) significantly reduced the level of motor dysfunction. No significant differences were observed between the motor function scores of groups III and IV at the evaluated time points. Light microscopic examination of spinal cord tissue samples obtained at the 72nd hour of reperfusion indicated greater tissue preservation in groups III and IV than in group II.

CONCLUSION

This study demonstrates the considerable neuroprotective effect of atorvastatin on the neurological, biochemical and histopathological status of rabbits with ischemia-induced spinal cord injury. Moreover, the acute withdrawal of atorvastatin therapy following the induction of spinal cord ischemia did not increase the neuronal damage in this rabbit model.

Supplement zinc as an effective treatment for spinal cord ischemia/reperfusion injury in rats

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a key role in the pathophysiology process and therapy of spinal cord injury (SCI). Accordingly, zinc regulates the expression of BDNF and its receptor in the central nervous system, the mechanism of which is still unknown. The present study investigates whether supplement zinc could reduce neurological damage in a rat model, with spinal cord ischemia-reperfusion (I/R) injury and how the effect of zinc transporter 1(ZnT-1) was involved.

METHODS

100 Sprague-Dawley male rats were randomly and evenly divided into four groups. They were subjected to spinal cord ischemia by clamping the abdominal aorta for 45 min. Rats in the zinc-deficient dietary model group (ZD), zinc-adequate dietary model group (ZA), and zinc-high dietary model group (ZH) were given free access to purified diet, containing 5, 30, or 180 mg Zn/kg. Sham operation rats were subjected to laparotomy without clamping of the aorta and were fed by ZA diet (30 mg Zn/kg). Neurological function was scored by Tarlov's score. The spinal cord segments (L5) were harvested for histological examination, auto-metallographic (AMG) analysis, myeloperoxidase (MPO) activity analysis, expression of ZnT-1 and BDNF.

RESULTS

The rats in the ZH group have shown the higher neurological scores, slighter histological changes and the attenuated MPO activity, compared with those in the ZD and ZA groups at the four observation time points (p<0.05). The AMG staining density in the ZH group was significantly higher than that of ZD group in 14 days later after the operation. Compared with other groups, ZH group's expression of Zn-T1 and BDNF were significantly increased, and was positively correlated with the same time points after surgery (Spearman rho=0.403, p=0.0152.)

CONCLUSION

These findings suggest that zinc supplement can significantly reduce the spinal cord I/R injury in rats. The mechanism may be related with restraining the MPO activity and increasing of ZnT-1, which promoted the synthesis and release of BDNF.

Optical monitoring and detection of spinal cord ischemia

Spinal cord ischemia can lead to paralysis or paraparesis, but if detected early it may be amenable to treatment. Current methods use evoked potentials for detection of spinal cord ischemia, a decades old technology whose warning signs are indirect and significantly delayed from the onset of ischemia. Here we introduce and demonstrate a prototype fiber optic device that directly measures spinal cord blood flow and oxygenation. This technical advance in neurological monitoring promises a new standard of care for detection of spinal cord ischemia and the opportunity for early intervention. We demonstrate the probe in an adult Dorset sheep model. Both open and percutaneous approaches were evaluated during pharmacologic, physiological, and mechanical interventions designed to induce variations in spinal cord blood flow and oxygenation. The induced variations were rapidly and reproducibly detected, demonstrating direct measurement of spinal cord ischemia in real-time. In the future, this form of hemodynamic spinal cord diagnosis could significantly improve monitoring and management in a broad range of patients, including those undergoing thoracic and abdominal aortic revascularization, spine stabilization procedures for scoliosis and trauma, spinal cord tumor resection, and those requiring management of spinal cord injury in intensive care settings.

Transient ischemia-induced changes of excitatory amino acid carrier 1 in the ventral horn of the lumbar spinal cord in rabbits

OBJECTIVES

To examine temporal changes of EAAC1 immunoreactivity and its protein level in the spinal ventral horn after transient ischemia in the rabbit to investigate the correlation between neuronal cell death and EAAC1 in the ventral horn of spinal cord.

METHODS

White rabbits weighing 2.5-3.0 kg were anesthetized with a mixture of 2.5% isoflurane in 30% oxygen and 70% nitrous oxide, and the abdominal aortic artery below the left renal artery was occluded for 15 minutes. At designated times after reperfusion, the immunohistochemical and Western blot analysis for EAAC1 was conducted using tissues of the seventh lumbar spinal segment.

RESULTS

EAAC1 immunoreactivity was detected in the neurons of the normal spinal cord. EAAC1 immunoreactivity and protein level reduced significantly 30 minutes after ischemia/reperfusion, but EAAC1 immunoreactivity and protein level again increased by 80% versus sham 3 hours after ischemia. At this time point, neurological defect in hindlimb was also detected. Thereafter, EAAC1 immunoreactivity and protein levels remained to be attenuated in the ventral horn of spinal cord until 48 hours after ischemia.

CONCLUSION

The significant change in EAAC1 expression and motor defects at early time after transient spinal cord ischemia relates to the acute events following ischemia/reperfusion. These results indicate that EAAC1 has an important role in the modulation of glutamate homeostasis in ischemic neurons in the spinal ventral horn.

Effect of heparin on neuroprotection against spinal cord ischemia and reperfusion in rats

BACKGROUND

Paraplegia due to ischemia/reperfusion (I/R) injury of the spinal cord is a devastating and undesired complication of thoraco-abdominal aortic surgery. Unidentified clots cause a variety of thromboembolic events and deteriorate the severity of ischemia. We investigated the effect of the degree of anticoagulation on spinal cord I/R injury and whether heparin is protective against I/R injury beside its anticoagulant properties.

MATERIALS AND METHODS

Twenty-eight rats were randomly assigned to four groups (n=7 per group) as G1 (no aortic occlusion and heparin administration), G2 (45 min aortic occlusion; no heparin administration), G3 (45 min aortic occlusion; 400 IU/kg heparin to keep activated clotting time (ACT) level around 200 sec), and G4 (45 min aortic occlusion; 800 IU/kg heparin to keep ACT level around 600 sec). After neurologic evaluation at the 48th hour of reperfusion, lumbar spinal cords were removed for histopathologic evaluation and immunohistochemical staining for HSP70 (heat shock protein 70), interleukin-6 and myeloperoxidase (MPO).

RESULTS

The Motor Deficit Index (MDI) scores were lowest in G1 group (p < 0.05) and the MDI scores of G3 and G4 were significantly lower than G2 group (p < 0.05). The neuronal degeneration in G3 was significantly lower than the other groups, respectively (p = 0.03). Histopathological evaluation showed no significant intergroup differences in terms of the degree of edema and inflammatory response. There was no statistically significant difference found among the groups in terms of HSP70 staining, IL-6 staining or the degree of MPO staining.

CONCLUSIONS

Protection of spinal cord from I/R injury requires a multimodal management. We should not miss out the importance of adequate anticoagulation in thoraco-abdominal surgical procedures. Furthermore, the recently discovered anti-inflammatory property of glycosaminoglycans, including heparin, deserves to be investigated.

Effects of xenon on ischemic spinal cord injury in rabbits: a comparison with propofol

BACKGROUND

Xenon has been shown to reduce cellular injury after cerebral ischemia. However, the neuroprotective effects of xenon on ischemic spinal cord are unknown. The authors compared the effects of xenon and propofol on spinal cord injury following spinal cord ischemia in rabbits.

METHODS

Thirty-two male New Zealand white rabbits were randomly assigned to one of three groups. In the xenon and propofol group, 70% of xenon and 0.8 mg/kg/min of propofol were administered 30 min before an aortic occlusion and maintained until the end of the procedure. The aortic occlusion was performed for 15 min. In the sham group, the aorta was not occluded. After an assessment of the hind limb motor function using the Tarlov score (0=paraplegia, 4=normal) at 48 h after reperfusion, gray and white matter injuries were evaluated based on the number of normal neurons in the anterior spinal cord and the percentage areas of vacuolation in the white matter, respectively.

RESULTS

In the xenon and propofol groups, the Tarlov score and the number of normal neurons were significantly lower than those in the sham group, whereas the percentage areas of vacuolation were similar among the three groups. There were no significant differences in Tarlov scores and the number of normal neurons between the xenon and the propofol groups.

CONCLUSION

The results indicated that 70% of xenon has no additional neuroprotective effects on ischemic spinal cord injury in rabbits compared with propofol.

A medical-legal review regarding the standard of care for epidural injections, with particular reference to a closed case

Interventional pain management is an evolving field, with a primary focus on the safety of the patient. One major source of risk to patients is intraarterial or intraneural injections. Interventional pain physicians have considerable interest in identifying techniques which avoid these complications. A recent article has reviewed complications associated with interventional procedures and concluded that the complications were due to deviation from a specific prescribed protocol. One of the cases reviewed went to jury trial and the record of that case is in the public domain. Two of the authors of the recent review were expert witnesses in the trial. They provided conflicting testimony as to alleged violations of the standard of care. Their criticisms also differed from a third criticism contained in the article as well as the protocol being advocated in the article, thus contravening the claim that there is one prescribed protocol which must be followed. The definition of standard of care varies amongst jurisdictions, but is generally defined as either that care which a reasonably well-trained physician in that specialty would provide under similar circumstances or as what would constitute reasonable medical care under the circumstances presented. Analysis of the case which went to trial indicates that there is not one prescribed protocol which must be followed; the definition of standard of care is broader than that. Interventional pain management is an evolving field and the standard of care is broadly defined.

Transcriptional activation of endothelial cells by TGFβ coincides with acute microvascular plasticity following focal spinal cord ischaemia/reperfusion injury

Microvascular dysfunction, loss of vascular support, ischaemia and sub-acute vascular instability in surviving blood vessels contribute to secondary injury following SCI (spinal cord injury). Neither the precise temporal profile of the cellular dynamics of spinal microvasculature nor the potential molecular effectors regulating this plasticity are well understood. TGFβ (transforming growth factor β) isoforms have been shown to be rapidly increased in response to SCI and CNS (central nervous system) ischaemia, but no data exist regarding their contribution to microvascular dysfunction following SCI. To examine these issues, in the present study we used a model of focal spinal cord ischaemia/reperfusion SCI to examine the cellular response(s) of affected microvessels from 30 min to 14 days post-ischaemia. Spinal endothelial cells were isolated from affected tissue and subjected to focused microarray analysis of TGFβ-responsive/related mRNAs 6 and 24 h post-SCI. Immunohistochemical analyses of histopathology show neuronal disruption/loss and astroglial regression from spinal microvessels by 3 h post-ischaemia, with complete dissolution of functional endfeet (loss of aquaporin-4) by 12 h post-ischaemia. Coincident with this microvascular plasticity, results from microarray analyses show 9 out of 22 TGFβ-responsive mRNAs significantly up-regulated by 6 h post-ischaemia. Of these, serpine 1/PAI-1 (plasminogen-activator inhibitor 1) demonstrated the greatest increase (>40-fold). Furthermore, uPA (urokinase-type plasminogen activator), another member of the PAS (plasminogen activator system), was also significantly increased (>7.5-fold). These results, along with other select up-regulated mRNAs, were confirmed biochemically or immunohistochemically. Taken together, these results implicate TGFβ as a potential molecular effector of the anatomical and functional plasticity of microvessels following SCI.

Neuroprotective Effect of KR-31378, a Novel Potassium Channel Activator, on Spinal Cord Ischemic Injury in Rabbits

Neurologic deficits after the surgical repair of thoracic and thoracoabdominal aortic disease are devastating complications. Recently, pharmacologic preconditioning with potassium channel openers was reported to protect the spinal cord against neurologic injury in a model of spinal cord ischemia. A novel benzopyran derivative with an N-cyanoguanidine group, KR-31378, has been synthesized as a new therapeutic agent against ischemic injury. In the present study, we evaluated the protective effects of KR-31378 on spinal cord ischemic injury and compared its neuroprotective activities and hemodynamic stabilities with those of diazoxide. Thirty-four New Zealand white rabbits were randomly divided into four groups: ischemia group (n = 10, 25 min of aortic cross-clamping without any intervention), diazoxide group (n = 8, diazoxide [5 mg/kg] intravenously 15 min before the 25-min cross-clamping), KR20 group (n = 8, KR-31378 [20 mg/kg] intravenously 30 min before the 25-min cross-clamping), and the KR50 group (n = 8, KR-31378 [50 mg/kg] intravenously 30 min before the 25-min cross-clamping). Neurologic functions were evaluated for 72 h postoperatively using modified Tarlov's scores. All rabbits were sacrificed for histopathologic observations after finally scoring neurologic function. All rabbits but three survived. The rest were completely evaluated 72 h postoperatively. Unlike diazoxide-treated rabbits, KR-31378-treated rabbits showed relatively stable hemodynamics. Tarlov's score outcomes showed a marked improvement in the diazoxide group, in the KR20 group, and in the KR50 group compared to the ischemia group (p = .005, .002, and .001, respectively). However, Tarlov's scores in the KR50 group were not significantly different from those of the diazoxide group. Histopathologic data were not significantly different between the groups, but the degree of degenerative change in motor neurons showed a significant correlation with Tarlov's scores 3 days postoperatively (gamma = -.378, p = .036). Thus, the administration of KR-31378 before the aortic cross-clamping resulted in a significant improvement in neurologic outcome with stable hemodynamics in this rabbit model.

[Protective effect of hypothermic propofol on ischemic spinal cords]

OBJECTIVE

To evaluate the protective effect of hypothermic propofol infused via the aorta against ischemia/reperfusion injury of spinal cords in rabbits.

METHODS

Sixty New Zealand white rabbits were randomly divided into six groups (n=10 in each group). The infrarenal circum-aortic clamping model was used in this study. During the 30-clamping time, 5 mL/kg of normal saline, 10% intralipid, propofol, 4 degrees C saline, 4 degrees C intralipid and 4 degrees C propofol were infused into the left femoral arteries of the rabbits in group SN, IPN, PN, SH, PH and IPH, respectively, at a rate 10 mL/(kg x h). The heart rates, blood pressures, respiratory rates and SPO2 were measured during the ischemic-reperfusion processes. The neurological status (Tarlov Scale system) were assessed 6 h, 24 h, and 48 h after the reperfusions. The spinal cords were harvested 48 h after the reperfusions for histological analysis. The concentrations of excitatory amino (EAA, aspartate and glutamate), malondialdehyde (MDA) and superoxide dismutas (SOD) in the harvested spinal cords were determined.

RESULTS

Group PN, SH, PH and IPH had better neurological outcomes and less severe pathological changes than group SN and IPN (P<0.05). There were no significant differences between group SN and IPN (P>0.05). Group PN, SH, PH and IPH had lower concentrations of EAA in spinal cords than group SN and IPN (P<0.05). Group PH had the best neurological outcome, the least histopathological changes of spinal cords, and the lowest concentrations of EAA (P<0.05). Groups PN and PH had lower concentrations of malondialdehyde than group SN, IPN, SH and IPH. Groups PN and PH had higher concentrations of superoxide dismutas than group SN, IPN, SH and IPH (P<0.05).

CONCLUSION

Both propofol and hypothermic liquids can protect spinal cords against ischemia/reperfusion injuries. Combined use of propofol and hypothermia results in significant recovery of spinal cord functions.

Efficacy of remote ischaemic preconditioning for spinal cord protection against ischaemic injury: association with heat shock protein expression

INTRODUCTION

We aimed to determine the efficacy of remote ischaemic preconditioning in the hind limb of rats for ischaemic damage of the spinal cord through neurological and histological investigation and examination of heat shock proteins (HSP).

MATERIAL AND METHODS

Thirty male Sprague-Dawley rats were divided into three groups as Group 1 (control group, n=10), Group 2 (ischaemia control group, n=10), and Group 3 (remote ischaemia preconditioning group, n=10). The right lower limb of the rats in the study group was compressed with a tourniquet for three cycles of ten-minute ischaemia followed by ten-minute reperfusion. After a period of 8 hours, the peritoneal cavity was accessed through a midline vertical incision. The abdominal aorta was clamped between the origin of the renal arteries and the iliac arteries for 45 minutes and spinal cord ischaemia was induced. The same procedure of abdominal aorta clamping was performed in the control group without creating leg ischaemia. The rats were evaluated for neurological parameters at 24 and 48 hours. At the end of this time period, all rats were sacrificed and the spinal cords were stained for determination of HSP and histopathological classification. For immunohistochemical evaluation, the samples were analyzed according to the degree of staining with HSP70 rabbit antibody.

RESULTS

After completing the neurological examinations and histological evaluations, we determined the spinal cords of the animals in the sham group to be completely normal. The post-operative neurological examination scores of Group 3 at 24 and 48 hours were significantly higher than scores measured in the other two groups. There were seven rats with HSP expression and this was detected in animals pretreated with remote ischaemic preconditioning. There were also two rats in Group 2 with HSP expression.

CONCLUSION

Our results show that production of transient remote ischaemia preconditioning in the lower extremities reduces damage in the spinal cord secondary to ischaemia probably by the increase of HSP.

[Morpho-functional changes in the spinal cord of rats after focal photothrombosis]

The aim of this study was to determine the pathomorphological and functional changes after the induced focal photothrombosis of blood vessels in the thoracic region of rat spinal cord. Neuronal damage, characteristic of ischemia, both in the focus of an experimental photothrombosis and in transitional zone, were detected together with the symptoms of motor function and pelvic organ failure. The investigated method of focal photothrombosis induction may be used for modeling of spinal cord ischemia in the development of methods for pharmacological correction and partial restoration of damaged sensomotor functions.

Moderate hypothermia prevents neural cell apoptosis following spinal cord ischemia in rabbits

Paraplegia is a disastrous complication after operations of descending and thoracoabdominal aortic aneurysm. Regional hypothermia protects against spinal cord ischemia although the protective mechanism is not well know. The objective of this study is to examine whether hypothermia protects the spinal cord by preventing apoptosis of nerve cell and also investigate a possible mechanism involved in hypothermia neuroprotection. Cell apoptosis with necrosis was evident in the spinal cord 24 h after 30 min of ischemia. Moderate hypothermia decreased the incidence of apoptotic nerve cells. Both cell apoptosis and necrosis were attenuated by hypothermia. p53 expression increased and bcl-2 expression declined after ischemia, while hypothermia mitigated these changes. This study suggests that apoptosis contributes to cell death after spinal cord ischemia, and that moderate hypothermia can prevent nerve cell apoptosis by a mechanism associated with bcl-2 and p53 genes.

Intravenous Infusion of Dexmedetomidine Can Prevent the Degeneration of Spinal Ventral Neurons Induced by Intrathecal Morphine After a Noninjurious Interval of Spinal Cord Ischemia in Rats

BACKGROUND

In recent studies, we demonstrated that neuraxial morphine after noninjurious spinal cord ischemia in the rat could induce spastic paraplegia and degeneration of selective spinal ventral neurons. Our objective was to investigate the impact of dexmedetomidine infusion on the degeneration of spinal ventral neurons induced by intrathecal (IT) morphine after spinal cord ischemia.

METHODS

Male Sprague-Dawley rats were given repetitive doses of IT morphine (40 microg x 2) at 1 and 5 h after a noninjurious interval (6 min) of spinal cord ischemia. The animals were assigned to one of the following four groups after the first IT injection (n = 8/group): Group S, IV infusion of saline (mL/h); Group Dex 0.1, dexmedetomidine (0.1 microg . kg(-1) x h(-1)); Group Dex 1, dexmedetomidine (1 microg x kg(-1) x h(-1)); Group Dex 3, dexmedetomidine (3 microg x kg(-1) x h(-1)). Follow-up evaluation included a sedation scale, the Motor Deficit Index to determine neurological dysfunction and histopathology of the spinal cord at 72 h of reperfusion.

RESULTS

IV dexmedetomidine produced a dose-dependent increase in the sedation index. Repetitive IT morphine injection induced paraplegia and degeneration of the spinal ventral neurons. IV dexmedetomidine at a sedative dose in comparison with saline significantly attenuated neurological dysfunction and histopathological consequences.

CONCLUSION

These data show that repetitive administration of IT morphine can induce paraplegia with degeneration of spinal ventral neurons, which can be attenuated by IV dexmedetomidine at a sedative dose. The use of dexmedetomidine may provide beneficial effects on neurological outcome after IT morphine after spinal cord ischemia in rats.

Intrathecal injection of bone marrow stromal cells attenuates neurologic injury after spinal cord ischemia

BACKGROUND

It has been shown that transplantation of bone marrow stromal cells (MSCs) into the ischemic brain improves functional outcome. We sought to investigate whether intrathecal injection of MSCs can attenuate neurologic injury of spinal cord ischemia.

METHODS

Rabbit MSCs were expanded in vitro and were pre-labeled with bromodeoxyuridine. Spinal cord ischemia was induced in rabbits by infrarenal aortic occlusion. Group A and control A were subjected to a 20-minute ischemia and the ischemic duration was extended to 30 minutes in group B and control B. Two days before spinal cord ischemia, 1 x 10(8) MSCs were intrathecally injected into groups A and B, whereas vehicle alone was injected into the control groups. Hind-limb motor function was assessed during a 14-day recovery period with Tarlov criteria, and then histologic examination was performed.

RESULTS

Marrow stromal cells survived and engrafted into the spinal cord 2 days after transplantation, and more MSCs were found in the lumbar spinal cord (ischemic segment) than in the thoracic spinal cord (nonischemic segment) at 14 days. Compared with their respective control groups, Tarlov scores were significantly higher in both groups A and B (p < 0.05, group A vs control A, at 2, 7, and 14 days; p < 0.05, group B vs control B, at 1, 2, 7, and 14 days, respectively). The number of intact motor neurons was much higher in the two experimental groups (p < 0.01 vs the corresponding control groups, respectively).

CONCLUSIONS

Intrathecal injection of MSCs attenuates ischemic injury of spinal cord.

Serial magnetic resonance imaging correlates with neurological outcome in an experimental model of spinal cord ischemia

BACKGROUND

Paraplegia complicating surgical thoracoabdominal aneurysm (TAA) repair remains an unpredictable and poorly understood phenomenon. The ability to identify patients at increased risk of delayed paraplegia before the process becomes irreversible could allow early interventions to attenuate this risk.

METHODS

In a rabbit model of infra-renal spinal cord ischemia, serial T2 weighted (T2W) magnetic resonance (MR) imaging was performed 2- and 8 h after the ischemic insult with changes correlated with clinical outcome. Using the axial T2W images, signal intensity measurements of the lateral horns of the spinal cord were acquired, both above (that is, thoracolumbar cord) and below (that is, lumbar cord) the renal arteries. This ratio (lumbar/thoracolumbar cord signal intensity) was evaluated and compared between groups.

RESULTS

No changes were seen in the signal intensity of rabbits that remained neurologically intact. Rabbits with delayed paralysis showed a significant (P<0.01) decrease in signal intensity ratio at 2 h (1.13+/-0.03), while a significant (P<0.01) increase was noted in those rabbits with immediate persistent paralysis (1.43+/-0.04). There was a significant (P<0.01) increase in the signal intensity ratios at 2 h in the delayed paralysis group (1.55+/-0.14), with a further significant (P<0.01) increase at 8 h in the immediate persistent paralysis group (1.76+/-0.07).

CONCLUSIONS

Findings on MR imaging can differentiate clinical outcomes in this experimental model of spinal cord ischemia. While further studies are required, MR could be useful in predicting which patients are at risk for delayed paraplegia after TAA repair.

Impact of the endoplasmic reticulum stress response in spinal cord after transient ischemia

BACKGROUND

Delayed paraplegia after operation of the thoracic aorta is considered to be related to vulnerability of motor neurons to ischemia. Recently, endoplasmic reticulum (ER) stress has been reported to participate in neuronal cell death. In the present study, we investigate the expression of ER stress-related molecules and discuss the relationship between neuronal vulnerability and ER stress after transient ischemia in the spinal cord.

METHODS

A rabbit spinal cord ischemia model was generated using a balloon catheter. In this model, spinal motor neurons show selectively delayed neuronal death whereas other spinal neuron, such as interneurons, survive. Immunohistochemical analysis and Western blotting for ER stress-related molecules, including phosphorylated eukaryotic initiation factor 2 alpha (p-eIF2alpha), activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and inositol-requiring ER transmembrane RNAse alpha isoform (IRE1alpha), were examined.

RESULTS

P-eIF2alpha, which inhibits protein synthesis and modulates ER stress, was induced only in interneurons after 6 h of reperfusion. ATF4, which is specifically activated by PERK-eIF2alpha, was induced only in interneurons between 6 h and 1 day after reperfusion. GRP78 was induced strongly both in interneurons and motor neurons at an early stage of reperfusion, but prolonged expression was observed only in interneurons. IRE1alpha, which is supposed to transduce an ER stress-related death signal, was expressed more strongly and over a more prolonged period in motor neurons.

CONCLUSIONS

These results indicate that the vulnerability of motor neurons in the spinal cord might be partially attributed to an ER stress response to transient ischemia.

[The reperfusion injury model improvement and the tolerance time investigation of rabbit spinal cord ischemia under normothermia]

OBJECTIVE

This study is designed to improve the rabbit model of ischemic- reperfusion injury and determine the safe clamping duration relevant to the spinal cord tolerance to ischemia at normothermia.

METHODS

50 New Zealand white rabbits were assigned randomly to 5 groups (Group C20, C25, C30, C40 and C60, 10 rabbits in each group) according to different clamping durations, ranging from 20 min to 60 min. The rabbits were endotracheally intubated for ventilation, and their left ear arteries were catheterized for monitoring the mean artery pressure. The spinal cord ischemia was induced by infrarenal aorta occlusion. A catheter was inserted into the aorta distal clamped site for monitoring the distal artery pressure. The neurological functional status of animal was assessed with the Tarlov scale system (0 or 1 meaning the rabbit paraplegia), at the moment of revival, 6 h, 24 h, and 48 h after the reperfusion. After last scoring, the lumbar segments of spinal cord (L4-L6) were removed for pathological examination, and the normal motor neurons of anterior horn were counted.

RESULTS

Forty-eight hours after the infusion, the severe neurological impairments were not detected in the rabbits whose aorta were only clamped for 20 min (Group C20). However, the rabbits in Group CSO became totally paraplegic, and the rabbits in Group C25 C30 or C40 developed the paraplegia at 30% , 80% or 90% respectively. The median number of normal motor neuron was 12. 5, 10 or 2 respectively in Group C20, C25 or C30, and 0 median number resulted in Group C40 and C60.

CONCLUSION

The rabbit model of ischemic-reperfusion injury is successfully improved, of which the safe clamping duration without spinal cord injury is not more than 20 min at normothermia.

Functional recovery in rats with ischemic paraplegia after spinal grafting of human spinal stem cells

Transient spinal cord ischemia in humans can lead to the development of permanent paraplegia with prominent spasticity and rigidity. Histopathological analyses of spinal cords in animals with ischemic spastic paraplegia show a selective loss of small inhibitory interneurons in previously ischemic segments but with a continuing presence of ventral alpha-motoneurons and descending cortico-spinal and rubro-spinal projections. The aim of the present study was to examine the effect of human spinal stem cells (hSSCs) implanted spinally in rats with fully developed ischemic paraplegia on the recovery of motor function and corresponding changes in motor evoked potentials. In addition the optimal time frame for cell grafting after ischemia and the optimal dosing of grafted cells were also studied. Spinal cord ischemia was induced for 10 min using aortic occlusion and systemic hypotension. In the functional recovery study, hSSCs (10,000-30,000 cells/0.5 mul/injection) were grafted into spinal central gray matter of L2-L5 segments at 21 days after ischemia. Animals were immunosuppressed with Prograf (1 mg/kg or 3 mg/kg) for the duration of the study. After cell grafting the recovery of motor function was assessed periodically using the Basso, Beattie and Bresnahan (BBB) scoring system and correlated with the recovery of motor evoked potentials. At predetermined times after grafting (2-12 weeks), animals were perfusion-fixed and the survival, and maturation of implanted cells were analyzed using antibodies recognizing human-specific antigens: nuclear protein (hNUMA), neural cell adhesion molecule (hMOC), neuron-specific enolase (hNSE) and synapthophysin (hSYN) as well as the non-human specific antibodies TUJ1, GFAP, GABA, GAD65 and GLYT2. After cell grafting a time-dependent improvement in motor function and suppression of spasticity and rigidity was seen and this improvement correlated with the recovery of motor evoked potentials. Immunohistochemical analysis of grafted lumbar segments at 8 and 12 weeks after grafting revealed intense hNSE immunoreactivity, an extensive axo-dendritic outgrowth as well as rostrocaudal and dorsoventral migration of implanted hNUMA-positive cells. An intense hSYN immunoreactivity was identified within the grafts and in the vicinity of persisting alpha-motoneurons. On average, 64% of hSYN terminals were GAD65 immunoreactive which corresponded to GABA immunoreactivity identified in 40-45% of hNUMA-positive grafted cells. The most robust survival of grafted cells was seen when cells were grafted 21 days after ischemia. As defined by cell survival and laminar distribution, the optimal dose of injected cells was 10,000-30,000 cells per injection. These data indicate that spinal grafting of hSSCs can represent an effective therapy for patients with spinal ischemic paraplegia.

Neurological Complications Following Endoluminal Repair of Thoracic Aortic Disease

Open surgery for thoracic aortic disease is associated with significant morbidity and the reported rates for paraplegia and stroke are 3%-19% and 6%-11%, respectively. Spinal cord ischemia and stroke have also been reported following endoluminal repair. This study reviews the incidence of paraplegia and stroke in a series of 186 patients treated with thoracic stent grafts. From July 1997 to September 2006, 186 patients (125 men) underwent endoluminal repair of thoracic aortic pathology. Mean age was 71 years (range, 17-90 years). One hundred twenty-eight patients were treated electively and 58 patients had urgent procedures. Anesthesia was epidural in 131, general in 50, and local in 5 patients. Seven patients developed paraplegia (3.8%; two urgent and five elective). All occurred in-hospital apart from one associated with severe hypotension after a myocardial infarction at 3 weeks. Four of these recovered with cerebrospinal fluid (CSF) drainage. One patient with paraplegia died and two had permanent neurological deficit. The rate of permanent paraplegia and death was 1.6%. There were seven strokes (3.8%; four urgent and three elective). Three patients made a complete recovery, one had permanent expressive dysphasia, and three died. The rate of permanent stroke and death was 2.1%. Endoluminal treatment of thoracic aortic disease is an attractive alternative to open surgery; however, there is still a risk of paraplegia and stroke. Permanent neurological deficits and death occurred in 3.7% of the patients in this series. We conclude that prompt recognition of paraplegia and immediate insertion of a CSF drain can be an effective way of recovering spinal cord function and improving the prognosis.

[Protective effect of ferulic acid on neuronal apoptosis of spinal cord subsequent to aortic blood cross-clamping in rabbits]

OBJECTIVE

To investigate the protective effect of ferulic acid on neuronal apoptosis of the spinal cord after aortic blood cross-clamping and its mechanism in rabbits.

METHODS

Twenty-four rabbits were randomly divided into sham operation group, ischemia/reperfusion (I/R) injury group and ferulic acid group. Spinal cord I/R injury model was replicated by clamping blood of the infrarenal aorta for 40 minutes followed reperfusion for 7 days. Ferulic acid 50 mg/kg was injected 15 minutes before aortic clamping in ferulic acid group. The aorta was not clamped in sham operation group. Contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in plasma were assayed at 10 minutes before clamping (C-10), before removal of occlusion (C40), at 60 minutes (R60) and on the 7 th day (R7d) after reperfusion. Apoptosis of neurones of spinal cord and the expressions of Bax and Bcl-2 protein were assayed by immunohistochemical technique. Neurologic function score of hind limb was observed after operation.

RESULTS

(1)The activity of MDA after I/R in I/R injury group was increased significantly compared with those before clamping and those in sham operation group (P<0.05 or P<0.01). The activity of MDA in ferulic acid group was significantly higher than that at C-10 (P<0.05), while significantly lower than those in I/R injury group at any time point (P<0.05 or P<0.01), but showed no significant difference compared with sham operation group. Changes in SOD activities were opposite to that of MDA. (2)The expression of Bax protein in I/R injury group was increased significantly (P<0.05), but the expression of Bcl-2 protein was decreased significantly compared with that in sham operation group (P<0.01). In ferulic acid group, the expression of Bax protein was significantly lower than that in I/R injury group and higher than that in sham operation group (P<0.01 and P<0.05), and the expression of Bcl-2 protein was higher than those in I/R injury group and sham operation group (both P<0.01). (3)The index of neuronal apoptosis in I/R injury group was significantly higher than that in sham operation group (P<0.01), and that in ferulic acid group was much lower than that in I/R injury group, but higher than sham operation group (P<0.01 and P<0.05). (4)The degree of paralysis in ferulic acid group was significantly lower than that in I/R injury group, and a higher neurologic score was observed (both P<0.01).

CONCLUSION

Ferulic acid can reduce the spinal cord neuronal apoptosis as a result of aortic occlusion in rabbits. The possible mechanism is that it decreases protein expression of Bax, increases that of Bcl-2 and enhances antioxidation.

Therapeutic Benefit of Intrathecal Injection of Marrow Stromal Cells on Ischemia-Injured Spinal Cord

BACKGROUND

Prophylactic transplantation of marrow stromal cells (MSCs) before spinal cord ischemia has been shown to attenuate neurologic injures. We sought to investigate the therapeutic effect of MSCs on ischemia-injured spinal cord.

METHODS

Marrow stromal cells were expanded in vitro and prelabeled with bromodeoxyuridine. Spinal cord ischemia was induced in rabbits by infrarenal aortic occlusion for 30 minutes. Four groups were enrolled. About 1 x 10(8) MSCs were intrathecally injected 2 hours (group MSC-2h), 24 hours (group MSC-24h), or 48 hours (group MSC-48h) after spinal cord ischemia, respectively. The control group received intrathecal injection of medium alone. Hind-limb motor function was assessed during a 28-day recovery period with Tarlov criteria, and then histologic examination was performed.

RESULTS

Marrow stromal cells still could be found in the spinal cord 4 weeks after transplantation. The capillary density in the ventral gray matter was significantly increased in the three MSC-treated groups (p < 0.01 versus control group, respectively). After a 28-day recovery, marked functional improvement was detected in group MSC-2h (from day 1 to 28, p < 0.05, versus control group, respectively) and group MSC-24h (from day 14 to 28, p < 0.05, versus control group, respectively), but not in group MSC-48h. The number of intact motor neurons was much greater in group MSC-2h (p < 0.05, versus control group).

CONCLUSIONS

Intrathecal injection of MSCs enhances angiogenesis in the host spinal cord and improves the motor functional recovery after spinal cord ischemia. The therapeutic time window is critical for the therapeutic effect of MSCs.

Erythropoietin attenuates neuronal injury and potentiates the expression of pCREB in anterior horn after transient spinal cord ischemia in rats

BACKGROUND

Recent studies have suggested that EPO activates the CREB transcription pathway and increases BDNF expression and production, which contributes to EPO-mediated neuroprotection. We investigated whether EPO has a neuroprotective effect against ISCI in rats and examined the involvement of CREB protein phosphorylation in this process.

METHODS

Spinal cord ischemia was produced by balloon occlusion of the abdominal aorta below the branching point of the left subclavian artery for 5 minutes, and rHu-EPO (1000 U/kg BW) was administered intravenously after the onset of the reperfusion. Neurologic status was assessed at 1, 24, and, 48 hours. After the end of 48 hours, spinal cords were harvested for histopathologic analysis and immunohistochemistry for pCREB.

RESULTS

All sham-operated rats had a normal neurologic outcome, whereas all ischemic rats suffered severe neurologic deficits after ISCI. Erythropoietin treatment was found to accelerate recovery of motor deficits and prevent the loss of motoneurons in the spinal cord after transient ischemia. Ischemic spinal cord injury induced the phosphorylation of pCREB at the anterior horn of the spinal cord, and EPO treatment significantly potentiated expression of pCREB increase at the anterior horn of the spinal cord.

CONCLUSIONS

These results demonstrate that a single dose of EPO given before ISCI provides significant neuroprotection and potentiates the expression of pCREB in this region.

Activation of ASK1 during reperfusion of ischemic spinal cord

Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK), which plays a pivotal role in cell apoptosis. To determine the mechanism of ASK1 induction during reperfusion of ischemic spinal tissue, we used a model of rabbit spinal cord ischemia and reperfusion. To assess the role of ASK1 in spinal cord ischemia-reperfusion injuries, we examined alterations in spinal tissue morphology, protein-protein interactions, and activation of key members of the ASK1-mediated signaling pathway. Changes in spinal cord morphology were observed with hematoxylin and eosin (H&E) staining and electron microscopy. The phosphorylation levels of ASK1, JNK, and p38 were assessed by immunoblotting proteins from animals that received 30 min of ischemia followed by 1 or 24h of reperfusion. We observed increased phosphorylation of ASK1, JNK, and p38 after reperfusing ischemic spinal cords. Immunohistochemical studies were performed to determine the cellular localization of phosphorylated ASK1 (pASK1) and 14-3-3. Following reperfusion for 24h, we observed increased cytoplasmic localization of pASK1 and decreased cytoplasmic localization of 14-3-3. Immunoprecipitation analyses suggested that 14-3-3 dissociates from ASK1 during reperfusion of ischemic spinal cords. These results indicate that activation of ASK1 may play an important role in the apoptotic signaling mechanisms that occur in reperfused spinal cord injuries.

Effects of intrathecal bupivacaine in conjunction with hypothermia on neuronal protection against transient spinal cord ischemia in rats

BACKGROUND

Excitotoxic neuronal injury from ischemia may be reduced by local anesthetics. We investigated the neuroprotective effects of intrathecally administered bupivacaine and hypothermia in a rat model of transient spinal cord ischemia.

METHODS

PE-10 intrathecal catheter-implanted male Sprague-Dawley rats were randomly assigned to one of four groups: normothermia (NT) and hypothermia (HT) groups (given 15 microl of normal saline) and bupivacaine (B) and bupivacaine-hypothermia (BHT) groups (given 15 mul of 0.5% bupivacaine). Transient spinal cord ischemia was induced by inflation of a 2F Fogarty catheter placed in the aortic arch for 12 min. The rectal temperature was maintained at 37.0 +/- 0.5 degrees C for the NT and B groups, and at 34.5 +/- 0.5 degrees C for the HT and BHT groups. Motor and sensory deficit scores were assessed 2 and 24 h after reperfusion. Lumbar spinal cords were harvested for histopathology and immunoreactivity of heat shock protein 70 (HSP70).

RESULTS

After reperfusion, the motor and sensory deficit scores of the NT group were significantly higher than those of the HT (P < 0.05) and BHT (P < 0.001) groups. Significant differences were evident in the motor and sensory deficit scores between the HT and BHT groups at 24 h (P < 0.05). Neuronal cell death and immunoreactivity of HSP70 were frequently observed in the NT and BT groups, but not in the HT and BHT groups.

CONCLUSIONS

These results collectively suggest that intrathecal bupivacaine does not provide neuroprotection during normothermic transient spinal cord ischemia in rats, but enhances the neuroprotective effects of hypothermia.

Isoflurane produces delayed preconditioning against spinal cord ischemic injury via release of free radicals in rabbits

BACKGROUND

Whether isoflurane preconditioning produces delayed neuroprotection in the spinal cord is unclear. The authors tested the hypothesis that isoflurane produces delayed preconditioning against spinal cord ischemic injury and, further, that the beneficial effect is dependent on free radicals.

METHODS

In experiment 1, 63 rabbits were randomly assigned to seven groups (n = 9 each): Animals in the control group only underwent spinal cord ischemia without pretreatment; animals in the Iso24h, Iso48h, and Iso72h groups received 40 min of 1.0 minimum alveolar concentration isoflurane in 100% oxygen each day for 5 consecutive days, with the last pretreatment at 24, 48, and 72 h, respectively, before spinal cord ischemia; animals in the O2 24h, O2 48h, and O2 72h groups received 40 min of 100% oxygen each day for 5 consecutive days, with the last pretreatment at 24, 48, and 72 h, respectively, before spinal cord ischemia. In experiment 2, 48 rabbits were randomly assigned into four groups (n = 12 each): Animals in the O2 and Iso groups received 3 ml/kg saline intraperitoneally 1 h before each session of oxygen pretreatment and isoflurane pretreatment, respectively. In the DMTU+Iso and DMTU+O2 groups, 10% dimethylthiourea (DMTU, a potent free radical scavenger) dissolved in saline (3 ml/kg) was administered at the same time point. Twenty-four hours after the last pretreatment, animals were subjected to spinal cord ischemia. Spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min. Forty-eight hours after reperfusion, neurologic function and histopathology of the spinal cord were examined.

RESULTS

In experiment 1, the neurologic and histopathologic outcomes in the Iso24h and Iso48h groups were better than those in the control group (P < 0.005 for each comparison); the neurologic and histopathologic outcomes in the control group showed no significant differences in comparison with the O2 24h, O2 48h, O2 72h, and Iso72h groups (P > 0.05 for each comparison). In experiment 2, the neurologic and histopathologic outcomes in the Iso group were better than those in the DMTU+Iso, O2, and DMTU+O2 groups (P < 0.01 for each comparison); there were no significant differences in the neurologic and histopathologic outcomes among the DMTU+Iso, O2, and DMTU+O2 groups (P > 0.05 for each comparison).

CONCLUSIONS

Isoflurane produces delayed preconditioning against spinal cord ischemic injury, and the beneficial effect may be dependent on the release of free radicals.

Neuronal damage in rat brain and spinal cord after cardiac arrest and massive hemorrhagic shock*

OBJECTIVE

Severe global ischemia often results in severe damage to the central nervous system of survivors. Hind-limb paralysis is a common deficit caused by global ischemia. Until recently, most studies of global ischemia of the central nervous system have examined either the brain or spinal cord, but not both. Spinal cord damage specifically after global ischemia has not been studied in detail. Because the exact nature of the neuronal damage to the spinal cord and the differences in neuronal damage between the brain and spinal cord after global ischemia are poorly understood, we developed a new global ischemia model in the rat and specifically studied spinal cord damage after global ischemia. Further, we compared the different forms of neuronal damage between the brain and spinal cord after global ischemia.

DESIGN

Randomized, controlled study using three different global ischemia models in the rat.

SETTING

University research laboratory.

SUBJECTS

Male, adult Sprague-Dawley rats (300 g).

INTERVENTIONS

Animals were divided into three experimental groups, group A (n = 6, survived for 7 days), 12 mins of hemorrhagic shock; group B (n = 6, survived for 7 days), 5 mins of cardiac arrest; or group C (n = 6, each for 6 hrs, 12 hrs, 1 day, 3 days, and 7 days), 7 mins of hemorrhagic shock and 5 mins of cardiac arrest. Motor deficit of the hind limbs was studied 6 hrs to 7 days after resuscitation. Also, nonoperated animals (n = 6) were used as the control. Histologic analysis (hematoxylin and eosin, Fluoro-Jade B, terminal deoxynucleotidyl transferase- mediated dUTP end-labeling [TUNEL], Klüver-Barrera) and ultrastructural analysis using electron microscopy were performed on samples from the CA1 region of the hippocampus and lumbar spinal cord. Demyelination of the white matter of the lumbar spinal cord was analyzed semiquantitatively using Scion Image software.

MAIN RESULTS

No paraplegic animals were observed in either group A or B. All group C animals showed severe hind-limb paralysis. Severe neuronal damage was found in the CA1 region of the hippocampus in all groups, and the state of delayed neuronal cell death was similar among the three groups. Neuronal damage in the lumbar spinal cord was detected only in group C animals, mainly in the dorsal horn and intermediate gray matter. Demyelination was prominent in the ventral and ventrolateral white matter in group C. A significant difference was observed between control and group C rats with Scion Image software. Ultrastructural analysis revealed extensive necrotic cell death in the intermediate gray matter in the lumbar spinal cord in group C rats.

CONCLUSION

The combination in the global ischemia model (i.e., hemorrhagic shock followed by cardiac arrest) caused severe neuronal damage in the central nervous system. Thereby, hind-limb paralysis after global ischemia might result from spinal cord damage. These results suggest that therapeutic strategies for preventing spinal cord injury are necessary when treating patients with severe global ischemia.

[Histological evaluation of ischemic injury to the spinal cord. Experimental study in the rabbit]

Sometimes in clinical practice the spinal cord is subjected to a more or less prolonged period of ischemia, after which cellular lesions may occur, causing paraplegia. The purpose of this paper is to quantify morphologically the damage of the spinal cord after an induced ischemia. Seventy male adult rabbits were used. They were divided into three groups: one group was used for evaluation of spinal cord ischemia at 3 hours, the second at 12 hours and the third at 24 hours. The recovery periods ranged from 3, to 12 and 24 hours. At the end of this period, the animals were anesthetized and killed. A clinical evaluation was made using the Tarlov method and criteria. The spinal cord was subjected to a histological evaluation. The results revealed different changes according to the multiple groups of study. The authors discuss the data of the present study and compare to the reports published in the bibliography on the subject.