Comparison of high-dose intracisterna magna and lumbar puncture intrathecal delivery of AAV9 in mice to treat neuropathies.

Gene therapy clinical trials for neurological disorders are ongoing using intrathecal injection of adeno-associated virus (AAV) vector directly into the cerebral spinal fluid. Preliminary findings from these trials and results from extensive animal studies provides compelling data supporting the safety and benefit of intrathecal delivery of AAV vectors for inherited neurological disorders. Intrathecal delivery can be achieved by a lumbar puncture (LP) or intracisterna magna (ICM) injection, although ICM is not commonly used in clinical practice due to increased procedural risk. Few studies directly compared these delivery methods and there are limited reports on transduction of the PNS. To further test the utility of ICM or LP delivery for neuropathies, we performed a head to head comparison of AAV serotype 9 (AAV9) vectors expressing GFP injected into the cisterna magna or lumbar subarachnoid space in mice. We report that an intrathecal gene delivery of AAV9 in mice leads to stable transduction of neurons and glia in the brain and spinal cord and has a widespread distribution that includes components of the PNS. Vector expression was notably higher in select brain and PNS regions following ICM injection, while higher amounts of vector was found in the lower spinal cord and peripheral organs following LP injection. These findings support that intrathecal AAV9 delivery is a translationally relevant delivery method for inherited neuropathies.

Flow of cerebrospinal fluid is driven by arterial pulsations and is reduced in hypertension.

Flow of cerebrospinal fluid (CSF) through perivascular spaces (PVSs) in the brain is important for clearance of metabolic waste. Arterial pulsations are thought to drive flow, but this has never been quantitatively shown. We used particle tracking to quantify CSF flow velocities in PVSs of live mice. CSF flow is pulsatile and driven primarily by the cardiac cycle. The speed of the arterial wall matches that of the CSF, suggesting arterial wall motion is the principal driving mechanism, via a process known as perivascular pumping. Increasing blood pressure leaves the artery diameter unchanged but changes the pulsations of the arterial wall, increasing backflow and thereby reducing net flow in the PVS. Perfusion-fixation alters the normal flow direction and causes a 10-fold reduction in PVS size. We conclude that particle tracking velocimetry enables the study of CSF flow in unprecedented detail and that studying the PVS in vivo avoids fixation artifacts.

An applicable method of drawing cerebrospinal fluid in rats.

BACKGROUND: Component analysis of cerebrospinal fluid (CSF) is frequently required to probe the causes and pathologic mechanisms of disease and effective drugs in experimental studies of the central nervous system. Rat and mouse are two kinds of most frequently used animals in experimental studies. Rats are considered to be the most suitable animal for experimental analysis of CSF both on cost and manipulability as mice are too small for drawing CSF. However, drawing CSF from rats is still not easy, which makes many researchers choose bigger animals, such as rabbits. This paper introduced a highly applicable technique of CSF collection from cerebellomedullary cistern (CC) in rats. METHODS: CSF collection with this technique was performed by direct CC puncture using a collection apparatus with negative pressure. The apparatus consists of a 1ml syringe, a disposable intravenous infusion needle and a clip. The needle was cut and made less sharp than the original one to avoid injury to the brain and spinal cord. RESULTS: We have collected CSF multiple times from each rat with this approach and the collection lasted less than 30s each time on average. The length of the collection needles of the CSF was conformed to the different body sizes (weight) of the rats in the 3 groups. Compared with currently existing methods, this is faster, safer, simpler and repeatable. CONCLUSIONS: CSF collection by CC puncture using a negative pressure collection apparatus is fast to operate, safe to the rats, and maximum amount of CSF can be collected.

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique.

PURPOSE: We compared the depiction of pulsatile CSF motion obtained by 4-dimensional phase-contrast velocity mapping (4D-VM) with that by time-spatial labeling inversion pulse (time-SLIP) technique in the presence of membrane structures. MATERIALS AND METHODS: We compared the 2 techniques using a flow phantom comprising tubes with and without a thin rubber membrane and applied the techniques to 6 healthy volunteers and 2 patients to analyze CSF dynamics surrounding thin membrane structures, such as the Liliequist membrane (LM), or the wall of an arachnoid cyst. RESULTS: Phantom images exhibited propagation of the flow and pressure gradient beyond the membrane in the tube. In contrast, fluid labeled by the time-SLIP technique showed little displacement from the blockage of spin travelling by the membrane. A similar phenomenon was observed around the LM in healthy volunteers and the arachnoid cyst wall in a patient. CONCLUSION: Four-dimensional phase-contrast velocity mapping permitted visualization of the propagation of CSF pulsation through the intracranial membranous structures. This suggests that 4D-VM and the time-SLIP technique provide different information on flow and that both techniques are useful for classifying the pathophysiological status of CSF and elucidating the propagation pathway of CSF pulsation in the cranium.

High performance collection of cerebrospinal fluid in rats: evaluation of erythropoietin penetration after osmotic opening of the blood-brain barrier.

An important issue to be considered when studying a new drug for treatment of central nervous system (CNS) diseases is its ability to cross the blood-brain barrier (BBB) and distribute throughout the brain. As cerebrospinal fluid (CSF) has demonstrated to be an invaluable reservoir to study CNS availability of therapeutic proteins, we have developed an improved method for CSF sampling from the cisterna magna of rats. The technique enables the simple and rapid collection of adequate quantities (50-75 µl) of blood-free CSF, rendering a high percentage of animal survival (99%) without clinic or neurological consequences. Its success in avoiding blood contamination of CSF lays in the use of a mixture of lidocaine/ephinephrine topically injected in the rat's suboccipital area and neck. Another relevant feature of the methodology is its low cost, since the puncture device can be easily assembled with cheap and available materials and, more importantly, neither expensive stereotaxic equipment nor frame is required. The present method is demonstrated by studying the CSF pharmacokinetics of recombinant human erythropoietin (rhEPO), a well-studied therapeutic candidate for neurological diseases. Moreover, we applied this technique to evaluate a strategy of osmotic disruption of the BBB to achieve a faster delivery of rhEPO into the CNS.

Novel modified method for injection into the cerebrospinal fluid via the cerebellomedullary cistern in mice.

A modified method of injection into the cerebellomedullary (CM) cistern of mice was developed based on fixation of the mouse with a special mask under inhalation anesthesia, and exposure of the sagittal suture of the cranium and midline of the nape to allow us to visualize injection point directly. The accuracy of the modified method was evaluated using the temporal and spatial intracranial distribution of dye by intracisternal injection of 6- microliter methylene blue aqueous solution. A high concentration of dye was found in the CM cistern, the ventral cisterns, and intracranial proximal portion of the main cranial nerves at 1 hour after injection. The color of the dye in the CM cistern and the ventral cisterns was lighter, and the dye had reached the intracranial distal portion of the main cranial nerves at 6 hours after injection. The dye was completely eliminated by cerebrospinal fluid (CSF) circulation at 24 hours after injection. No severe brain injury was found in any of the 20 mice. Intracisternal injection was successful in all 14 mice sacrificed 1 hour or 6 hours after injection according to the confirmation of dye distribution. The effects of central administration of endothelin-1 (ET1) were evaluated on cerebral blood supply, constriction of cerebral arteries, and change of respiration in mice. Three doses of ET1 were studied: 2 micrograms (0.8 nmol), 4 micrograms (1.6 nmol), and 6 micrograms (2.4 nmol). Cerebral blood flow (CBF) was monitored for 60 minutes following injection using a laser Doppler probe. Intracisternal ET1 injection induced dose-dependent reduction of CBF, constriction of cerebral arteries, and respiratory depression in mice. This modified method of injection into the CM cistern under direct visualization provides accurate and reproducible injection into the CSF, and can be used to investigate the effects of various chemical substances on the central nervous system in mice.

Fractalkine signaling in microglia contributes to ectopic orofacial pain following trapezius muscle inflammation.

Fractalkine (FKN) signaling is involved in mechanical allodynia in the facial skin following trapezius muscle inflammation. Complete Freund's adjuvant (CFA) injection into the trapezius muscle produced mechanical allodynia in the ipsilateral facial skin that was not associated with facial skin inflammation and resulted in FKN but not FKN receptor (CX3CR1) expression, and microglial activation was enhanced in trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal cord (C1-C2). Intra-cisterna magna anti-CX3CR1 or anti-interleukin (IL)-1ß neutralizing antibody administration decreased the enhanced excitability of Vc and C1-C2 neurons in CFA-injected rats, whereas intra-cisterna magna FKN administration induced microglial activation and mechanical allodynia in the facial skin. IL-1ß expression and p38 mitogen-activated protein kinase phosphorylation were enhanced in activated microglia after CFA injection. The excitability of neurons whose receptive fields was located in the facial skin was significantly enhanced in CFA-injected rats, and the number of cells expressing phosphorylated extracellular signal-regulated kinase (pERK) following noxious mechanical stimulation of the facial skin was significantly increased in Vc and C1-C2. We also observed mechanical allodynia of the trapezius muscle as well as microglial activation and increased pERK expression in C2-C6 after noxious stimulation of the trapezius muscle in facial skin-inflamed rats. These findings suggest that FKN expression was enhanced in Vc and C1-C2 or C2-C6 following trapezius muscle or facial skin inflammation, microglia are activated via FKN signaling, IL-1ß is released from the activated microglia, and the excitability of neurons in Vc and C1-C2 or C2-C6 is enhanced, resulting in the ectopic mechanical allodynia.

The neuro-behavioral profile in rats after subarachnoid hemorrhage.

Despite significant advancements in the understanding of the pathophysiological mechanisms of subarachnoid hemorrhage (SAH), little is known about the emotional consequences. The primary goal of this study was to describe the locomotor and behavioral patterns in rats following both a single-injection and double-injection model of SAH. In 48 rats, SAH was induced by injecting 0.3 ml of autologous arterial blood into the cisterna magnum (single-hemorrhagic model). In 24 of these rats, post-SAH vasospasm was induced by a repeated injection of blood into the cisterna magnum 24h later (double-hemorrhagic model). In 24 additional rats, 0.3 ml of saline was injected into the cisterna magnum (sham group). Neurological performance was assessed at 24, 48 h, 1, 2 and 3 weeks after SAH. Four behavioral tests were performed for 3 weeks after SAH for the duration of 6 consequent days, in the following order: open field test, sucrose preference test, elevated plus maze test and forced swimming test. Following both, a single and double-hemorrhagic models of SAH, rats were found to have significant behavioral abnormalities on the open field test, sucrose preference test, elevated plus maze test, and forced swimming test. A more prominent disability was found in rats that underwent the double-hemorrhagic model of SAH than rats that underwent the single-hemorrhagic model. Both a single and double injection model of rats SAH are associated with significant behavioral disturbances including locomotor abnormalities, depressive behavior and increased anxiety, even as early as 3 weeks after SAH.

A new percutaneous model of Subarachnoid Haemorrhage in rats.

OBJECTIVE: Describe the results obtained with a new percutaneous, intracisternal model of Subarachnoid Haemorrhage (SAH) in Wistar rats by a single injection of non-heparinised, autologous blood. METHODS: Once anaesthetized the rat was fixed prone in a stereotaxic frame. After identifying the projection of the occipital bone, the needle of the stereotaxic frame aspirated towards the foramen magnum until it punctured through the atlanto-occipital membrane and obtained cerebrospinal fluid. Autologous blood (100 µl) was withdrawn from the tail and injected intracisternally. This procedure was repeated in the sham group, injecting 100 µl of isotonic saline. On the fifth day post-intervention, the rats were anaesthetized and the brain was exposed. After a lethal injection of ketamine the brain was explanted and fixed in paraformaldehyde. Gross and microscopic inspection of the slices revealed the existence or non-existence of pathological findings. RESULTS: A total of 26 rats were operated on (13 in the SAH group/13 in the sham group). The average time between obtaining the blood and the start of the intracisternal injection was 10 (±1.2)s. The mortality rate was 16.12%. Intra- and extraparenchymal ischemic-haemorrhagic lesions were found in three animals (23.07%)--all from the SAH group--with ischemic neuronal cell injury detected in two of the three. CONCLUSIONS: The new murine model of SAH is easy to perform, with low mortality, minimally invasive, which makes it interesting for future studies on vasospasm-related delayed SAH complications.

Cisterna magna cannulated repeated CSF sampling rat model--effects of a gamma-secretase inhibitor on Aß levels.

Cerebrospinal fluid (CSF) provides a window into central nervous system (CNS) physiology and pathophysiology in human neurodegenerative conditions such as Alzheimer's disease. Changes in CSF bioanalytes also provide a direct readout of target engagement in the CNS following pharmacological interventions in clinical trials. Given the importance of tracking CNS bioanalytes in drug discovery, we have developed a novel cisterna magna cannulated rat model for repeated CSF sampling and used it to assess an amyloid beta (Aß) lowering agent. The surgically implanted cisterna magna cannula was patent over a period of 1-2 weeks and enabled repeated sampling of CSF (volume of ∼30-50µL/sample) from each rat. CSF Aß40 levels showed good intra-animal variability across time points and inter-animal variability within a time point. Peripheral treatment with a gamma-secretase inhibitor (GSI) led to a rapid and robust decline in CSF Aß40 levels that returned to baseline over 24-96h after dosing. Terminal brain, CSF and plasma Aß levels measured at 24h after dosing demonstrated robust Aß lowering and showed excellent correlation across these compartments. These results are the first pharmacological validation of the repeated CSF sampling rat model for Aß lowering agents. This model can have broad applicability in pharmacological evaluation for diverse CNS targets.

Effects of intracisternal administration of cannabidiol on the cardiovascular and behavioral responses to acute restraint stress.

Systemic administration of cannabidiol (CBD), a non-psychotomimetic compound from Cannabis sativa, attenuates the cardiovascular and behavioral responses to restraint stress. Although the brain structures related to CBD effects are not entirely known, they could involve brainstem structures responsible for cardiovascular control. Therefore, to investigate this possibility the present study verified the effects of CBD (15, 30 and 60 nmol) injected into the cisterna magna on the autonomic and behavioral changes induced by acute restraint stress. During exposure to restraint stress (1h) there was a significant increase in mean arterial pressure (MAP) and heart rate (HR). Also, 24h later the animals showed a decreased percentage of entries onto the open arms of the elevated plus-maze. These effects were attenuated by CBD (30 nmol). The drug had no effect on MAP and HR baseline values. These results indicate that intracisternal administration of CBD can attenuate autonomic responses to stress. However, since CBD decreased the anxiogenic consequences of restraint stress, it is possible that the drug is also acting on forebrain structures.

Median aperture of the fourth ventricle revisited.

BACKGROUND: The median aperture of Magendie is the largest of three openings of the fourth ventricle and thus it forms the main path for the outflow of the cerebrospinal fluid from the ventricle. The Magendie aperture connects the fourth ventricle with the cisterna magna and makes a natural corridor for neurosurgical approach and inspection of the ventricle and its floor. The purpose of this study was to give a contemporary anatomical view of this structure in the context of historical data. MATERIAL AND METHODS: The Magendie foramen was studied in 30 fixed specimens of human brainstems with cerebella. The microdissection technique was used. Measurements were taken with a microscope ocular ruler. RESULTS: The aperture is limited by the following structures: obex and gracile tubercles inferiorly, and tela choroidea with choroid plexus superolaterally. Obex tubercles usually have the form of a piece of neural tissue bridging two halves of the brainstem above the entrance to the central canal. Gracile tubercles together are 8.15 mm wide and the maximal width of the foramen is 6.53 mm. Tela choroidea attaches laterally at both sides to the inferior medullary velum. In most cases the right and left choroid plexus are connected to each other with a triangular membrane of tela choroidea, which protrudes through the median foramen and attaches to the vermis at a highly variable level. CONCLUSIONS: We hope that the presented description of anatomical relations around the Magendie aperture, with its new measurements, will be helpful for those operating in the area and will explain some of the inaccuracies found in literature.

The influence of cisternal and ventricular lavage on cerebral vasospasm in patients suffering from subarachnoid hemorrhage: analysis of effectiveness.

OBJECTIVE: within the last decades several clinical trials were performed to analyze the effectiveness of cisternal and ventricular lavage on cerebral vasospasm in patients suffering from subarachnoid hemorrhage. Aim of the present analysis was to review and summarize all documented clinical studies using cisternal or ventricular lavage to prevent vasospasm. METHODS: the MEDLINE Web site ( www.pub.med.com ) was searched using the clinical query function optimized for clinical therapy. Search terms were subarachnoid hemorrhage, vasospasm, cisternal and ventricular lavage. Results were divided into cisternal and ventricular lavage therapies alone and its combination with additional treatment modalities. RESULTS: so far the literature search revealed a total of nine clinical trials using cisternal or ventricular lavage alone in patients suffering from subarachnoid hemorrhage. The patients were treated using urokinase or recombinant tissue plasminogen activator. A metaanalysis, investigating a total of 652 included patients revealed a significant reduction of delayed neurological deficits, a significant increase of outcome and a significant decrease of mortality in the treatment group. Additional there was no difference of effectiveness or side effects using urokinase or recombinant tissue plasminogen activator. Hence, only one of these studies was based on a prospective, randomized study design. A combination of cisternal or ventricular lavage with some sort of kinetic treatment was documented in a total of three studies. All of them were designed prospectively. The combined application demonstrated reduced delayed neurological deficits, reduced vasospasm and better outcome in two studies for the treatment group. One study was stopped early due to unexpected complication. CONCLUSIONS: In conclusion, there is strong evidence that cisternal or ventricular lavage alone and in combination with kinetic therapy lead to a reduction of cerebral vasospasm and better outcome in patients suffering from subarachnoid hemorrhage. As a consequence a prospective randomized study would be of great interest.

Optimal cerebrospinal fluid magnesium ion concentration for vasodilatory effect and duration after intracisternal injection of magnesium sulfate solution in a canine subarachnoid hemorrhage model.

OBJECT: The optimal CSF Mg(++) concentration for vasodilation of spastic cerebral arteries after subarachnoid hemorrhage (SAH) and its duration are unknown. The temporal profile of the vasodilatory effect and optimal CSF Mg(++) concentration after the intracisternal injection of MgSO(4) solution were investigated in an SAH model in canines. METHODS: Cerebral vasospasm was induced by experimental SAH using a 2-hemorrhage model in 26 female beagles. On Day 7, 0.5 ml/kg of 15, 10, 5, or 0 mmol/L MgSO(4) in Ringer solution was injected into the cerebellomedullary cistern. Angiography was performed on Day 1 (before SAH) and before and 1, 3, and 6 hours after the intracisternal injection on Day 7 to measure arterial diameters of the basilar artery (BA), superior cerebellar artery (SCA), and vertebral artery (VA). Cerebrospinal fluid Mg(++) was also measured at the same time. RESULTS: Arterial diameters of the BA, SCA, and VA were significantly decreased by vasospasm on Day 7. Arterial diameter ratios (ratio of arterial diameter after MgSO(4) injection to diameter before injection on Day 7) of the BA and SCA at 1 and 3 hours after and the VA at 1 hour after intracisternal injection of the MgSO(4) solution were positively correlated with the CSF Mg(++) concentration. All arterial diameter ratios, except 1 point of the SCA, exceeded 1 if the CSF Mg(++) concentration was > 3 mEq/L at 1 hour after injection. Animals with CSF Mg(++) concentrations > 3 mEq/L at 1 hour after injection (11 dogs) showed significantly increased arterial diameters of the BA at 1 and 3 hours after and of the SCA and VA at 1, 3, and 6 hours after injection, as compared with the diameters before injection. The CSF Mg(++) concentration significantly increased at 1 hour (3.73 ± 0.69 mEq/L, p < 0.01) and 3 hours (2.05 ± 0.35 mEq/L, p < 0.01) after the intracisternal injection as compared with the baseline value (1.41 ± 0.20 mEq/L). CONCLUSIONS: The reversible effect of an intracisternal injection of MgSO(4) solution on the spastic artery requires CSF Mg(++) concentrations > 3 mEq/L. The vasodilatory effect continues for 3-6 hours after injection. These results suggest that the continuous infusion or intermittent intracisternal injection of MgSO(4) is needed to maintain the optimal CSF Mg(++) concentration and constantly ameliorate cerebral vasospasm.

Microsurgical and endoscopic anatomy of the supratentorial arachnoidal membranes and cisterns.

OBJECTIVE: A limitation of previous studies of the arachnoid cisterns and membranes is that the act of opening the sylvian and interhemispheric fissures and basal arachnoid often led to destruction of the cisternal compartments and their membranous walls. The goal of this study was to overcome this limitation by combining the surgical microscope and endoscope for the examination of the cisternal compartments and their membranous walls. METHODS: The supratentorial cisterns were examined in 22 cadaveric brains using both the operating microscope and the endoscope. RESULTS: There are 2 types of arachnoid membranes: outer and inner. The outer arachnoidal membrane surrounds the whole brain, and the inner membranes divide the subarachnoid space into cisterns. Twelve inner arachnoid membranes were identified in the supratentorial area: diencephalic, mesencephalic, medial carotid, intracarotid, intracrural, olfactory, medial and lateral lamina terminalis, and proximal, medial, intermediate, and lateral sylvian membranes. These membranes partially or completely separate the subarachnoid space into 9 supratentorial cisterns: sylvian, carotid, chiasmatic, lamina terminalis, pericallosal, crural, ambient, oculomotor, and interpeduncular. There is a confluent area between the carotid, interpeduncular, and crural cisterns, which frequently has no membrane separating these cisterns. CONCLUSION: Twelve inner arachnoid membranes and 9 cisterns were identified in this study.

Intracisternal infusion of magnesium sulfate solution improved reduced cerebral blood flow induced by experimental subarachnoid hemorrhage in the rat.

Magnesium has neuroprotective and antivasospastic properties in the presence of subarachnoid hemorrhage (SAH). The present study investigated the effect of intracisternal administration of magnesium on cerebral vasospasm in the experimental SAH rat model. The rat double-SAH model (0.2 mL autologous blood injected twice into the cisterna magna) was used. Normal saline (SAH group, N=8) or 10 mmol/L magnesium sulfate in normal saline (SAH + MG group, N=8) was infused into the cisterna magna at 1.5 microL/min for 30 min on day 5. Control rats without SAH also received intracisternal infusion of normal saline (control group, N=6). Local cerebral blood flow (CBF) at 24 locations and the weighted average were quantitatively measured by the autoradiographic technique using [(14)C]iodoantipyrine during infusion. The weighted average CBF was significantly reduced (P<0.01, Student's t-test) in the SAH group (0.78+/-0.16 mL g(-1) min(-1)) compared to the control group (1.0+/-0.15 mL g(-1) min(-1)) and was significantly improved (P<0.01, Student's t-test) in the SAH + MG group (0.98+/-0.18 mL g(-1) min(-1)). Local CBF was significantly reduced (P<0.05, unpaired t test) in 16 locations in the SAH group and significantly improved (P < 0.05, unpaired t test) in 12 locations in the SAH + MG group. Intracisternal infusion of magnesium sulfate significantly improved reduced CBF induced by experimental SAH in the rat.

Teflon sponge shunt for recurrent arachnoid cyst.

A 50-year-old female presented with complaints of progressive ataxia. Investigations showed a large intradural arachnoid cyst located anterior to the brainstem. Following marsupialization of the cyst she improved remarkably in her symptoms. The symptoms recurred nine months later and investigations revealed recurrence of the cyst. The cyst was evacuated again and two Teflon sponge sheets were placed such that they traversed the length of the cyst cavity and extended into the cisterna magna. At follow-up after 25 months, there has been no recurrence of symptoms or the cyst. The role and advantages of Teflon sponge in such cases is evaluated.

Intrathecal application of neuroectodermally converted stem cells into a mouse model of ALS: limited intraparenchymal migration and survival narrows therapeutic effects.

Stem and progenitor cells provide a promising therapeutic strategy for amyotrophic lateral sclerosis (ALS). To comparatively evaluate the therapeutic potentials of human bone marrow-derived mesodermal stromal cells (hMSCs) and umbilical cord blood cells (hUBCs) in ALS, we transplanted hMSCs and hUBCs and their neuroectodermal derivatives (hMSC-NSCs and hUBC-NSCs) into the ALS mouse model over-expressing the G93A mutant of the human SOD1 gene. We used a standardized protocol similar to clinical studies by performing a power calculation to estimate sample size prior to transplantation, matching the treatment groups for gender and hSOD-G93A gene content, and applying a novel method for directly injecting 100,000 cells into the CSF (the cisterna magna). Ten days after transplantation we found many cells within the subarachnoidal space ranging from frontal basal cisterns back to the cisterna magna, but only a few cells around the spinal cord. hMSCs and hMSC-NSCs were also located within the Purkinje cell layer. Intrathecal cell application did not affect survival times of mice compared to controls. Consistently, time of disease onset and first pareses, death weight, and motor neuron count in lumbar spinal cord did not vary between treatment groups. Interestingly, transplantation of hMSCs led to an increase of pre-symptomatic motor performance compared to controls in female animals. The negative outcome of the present study is most likely due to insufficient cell numbers within the affected brain regions (mainly the spinal cord). Further experiments defining the optimal cell dose, time point and route of application and particularly strategies to improve the homing of transplanted cells towards the CNS region of interest are warranted to define the therapeutic potential of mesodermal stem cells for the treatment of ALS.

Effect of graded hyperventilation on cerebral metabolism in a cisterna magna blood injection model of subarachnoid hemorrhage in rats.

In subarachnoid hemorrhage (SAH) with cerebrovascular instability, hyperventilation may induce a risk of inducing or aggravating cerebral ischemia. We measured cerebral blood flow (CBF) and cerebral metabolic rates of oxygen (CMRO2), glucose (CMRglc), and lactate (CMRlac) at different PaCO2 levels after experimental SAH in rats (injection of 0.07 mL of autologous blood into the cisterna magna). Four groups of Sprague-Dawley male rats were studied at predetermined PaCO2 levels: group A: normocapnia (5.01-5.66 kPa [38.0-42.0 mm Hg]); group B: slight hyperventilation (4.34-5.00 kPa [32.5-37.5 mm Hg]); group C: moderate hyperventilation (3.67-4.33 kPa [27.5-32.4 mm Hg]); group D: profound hyperventilation (3.00-3.66 kPa [22.5-27.4 mm Hg]). Each of the four groups included eight rats with SAH and eight sham-operated controls. CBF was determined by the intracarotid Xe method; CMRo2, CMRglc, and CMRlac were obtained by cerebral arteriovenous differences. In both SAH rats and controls, hyperventilation decreased CBF in proportion to the decrement in PaCO2 without affecting either CMRO2, CMRglc, or CMRlac. In groups C and D, CBF decreased by 20%-35%, but CMRs were maintained by a compensatory increase in oxygen extraction fraction (OEF). The results show that even profound hyperventilation in this model of SAH is associated with an adequate increase in OEF so that CMRs of oxygen, glucose, and lactate remain similar to levels observed in normocapnic conditions.