Simulation, Implementation and Measurement of Defined Sound Fields for Blood-Brain Barrier Opening in Rats.

The blood-brain barrier (BBB) is the most important obstacle to delivery of therapeutics to the central nervous system. Low-intensity pulsed focused ultrasound (FUS) in combination with microbubbles applied under magnetic resonance imaging (MRI) control provides a non-invasive and safe technique for BBB opening (BBBo). In rodent models, however, settings and application protocols differ significantly. Depending on the strain and size, important variables include ultrasound attenuation and sound field distortion caused by the skull. We examined the ultrasound attenuation of the skull of Wistar rats using a targeted FUS system. By modifying the transducer elements and by varying and simulating the acoustic field of the FUS system, we measured a skull attenuation of about 60%. To evaluate potential application of the targeted FUS system in genetically modified animals with increased sensitivity to brain hemorrhage caused by vascular dysfunction, we assessed safety in healthy animals. Histological and MRI analyses of the central nervous system revealed an increase in the number and severity of hyperacute bleeds with focal pressure. At a pressure of 0.4 MPa, no bleeds were induced, albeit at the cost of a weaker hyperintense MRI signal post BBBo. These results indicate a relationship between pressure and the dimension of permeabilization.

Galectin-3 reflects the echocardiographic quantification of right ventricular failure.

Objectives. Galectin-3 (gal-3) is a mediator of extracellular matrix metabolism and reflects an ongoing cardiac fibrotic process. The aim of this study was to determine the potential use of gal-3 in evaluating the structural and functional parameters of the right ventricle as determined by echocardiography. Design. Ninety-one patients undergoing routine echocardiography were prospectively enrolled in this monocentric study. Serum samples for gal-3 and aminoterminal pro-brain natriuretic peptide (NT-proBNP) were collected within 24 h of echocardiographic examination. Patients were arbitrarily divided into subgroups based on right ventricular function as measured by tricuspid annular plane systolic excursion (TAPSE) and these included TAPSE >24 mm (n = 23); TAPSE 18-24 mm (n = 55); TAPSE ≤17 mm (n = 13); permitting the detailed statistical analysis of derived data. Results. Serum levels of gal-3 in all patients correlated with age (r = 0.36. p < .001), creatinine (r = 0.60, p < .001), NT-proBNP (r = 0.53, p < .001), RA area (r = 0.38, p < .001) and TAPSE (r = -0.3. p < .01). The distribution of echocardiographic indices according to TAPSE subgroups revealed an association between gal-3 and its ability to identify patients with right ventricular failure (RVF) as diagnosed by a TAPSE ≤17 mm (r = 0.04, p < .001). The multivariable logistic regression model with adjusted odds ratio showed the ability of gal-3 to identify RVF when adjusted to age and gender (adjusted odds ratio 3.60, 95% CI 1.055-12.282, p < .05). Conclusion. Gal-3 correlated with echocardiographic indices of RVF and could effectively diagnose these patients. The supplementary use of NT-proBNP strengthened the diagnostic capability of each biomarker. Trial Registration: The 'Cardiovascular Imaging and Biomarker Analyses' (CIBER Study), clinicaltrials.gov identifier: NCT03074253. Registered 3/8/2017. https://www.clinicaltrials.gov/ct2/show/NCT03074253.

Intrathecal activation of CD8+ memory T cells in IgG4-related disease of the brain parenchyma.

IgG4-related disease (IgG4-RD) is a fibroinflammatory disorder signified by aberrant infiltration of IgG4-restricted plasma cells into a variety of organs. Clinical presentation is heterogeneous, and pathophysiological mechanisms of IgG4-RD remain elusive. There are very few cases of IgG4-RD with isolated central nervous system manifestation. By leveraging single-cell sequencing of the cerebrospinal fluid (CSF) of a patient with an inflammatory intracranial pseudotumor, we provide novel insights into the immunopathophysiology of IgG4-RD. Our data illustrate an IgG4-RD-associated polyclonal T-cell response in the CSF and an oligoclonal T-cell response in the parenchymal lesions, the latter being the result of a multifaceted cell-cell interaction between immune cell subsets and pathogenic B cells. We demonstrate that CD8+ T effector memory cells might drive and sustain autoimmunity via macrophage migration inhibitory factor (MIF)-CD74 signaling to immature B cells and CC-chemokine ligand 5 (CCL5)-mediated recruitment of cytotoxic CD4+ T cells. These findings highlight the central role of T cells in sustaining IgG4-RD and open novel avenues for targeted therapies.

Tissue Sodium Concentration within White Matter Correlates with the Extent of Small Vessel Disease.

INTRODUCTION: Sodium MRI (23Na MRI) derived biomarkers such as tissue sodium concentration (TSC) provide valuable information on cell function and brain tissue viability and has become a reliable tool for the assessment of brain tumors and ischemic stroke beyond pathoanatomical morphology. Patients with major stroke often suffer from different degrees of underlying white matter lesions (WMLs) attributed to chronic small vessel disease. This study aimed to evaluate the WM TSC in patients with an acute ischemic stroke and to correlate the TSC with the extent of small vessel disease. Furthermore, the reliability of relative TSC (rTSC) compared to absolute TSC in these patients was analyzed. METHODOLOGY: We prospectively examined 62 patients with acute ischemic stroke (73 ± 13 years) between November 2016 and August 2019 from which 18 patients were excluded and thus 44 patients were evaluated. A 3D 23Na MRI was acquired in addition to a T2-TIRM and a diffusion-weighted image. Coregistration and segmentation were performed with SPM 12 based on the T2-TIRM image. The extension of WM T2 hyperintense lesions in each patient was classified using the Fazekas scale of WMLs. The absolute TSC in the WM region was correlated to the Fazekas grades. The stroke region was manually segmented on the coregistered absolute diffusion coefficient image and absolute, and rTSC was calculated in the stroke region and compared to nonischemic WM region. Statistical significance was evaluated using the Student t-test. RESULTS: For patients with Fazekas grade I (n = 25, age: 68.5 ± 15.1 years), mean TSC in WM was 55.57 ± 7.43 mM, and it was not statistically significant different from patients with Fazekas grade II (n = 7, age: 77.9 ± 6.4 years) with a mean TSC in WM of 53.9 ± 6.4 mM, p = 0.58. For patients with Fazekas grade III (n = 9, age: 81.4 ± 7.9 years), mean TSC in WM was 68.7 ± 10.5 mM, which is statistically significantly higher than the TSC in patients with Fazekas grade I and II (p < 0.001 and p = 0.05, respectively). There was a positive correlation between the TSC in WM and the Fazekas grade with r = 0.48 p < 0.001. The rTSC in the stroke region was statistically significant difference between low (0 and I) and high (2 and 3) Fazekas grades (p = 0.0353) whereas there was no statistically significant difference in absolute TSC in the stroke region between low (0 and I) and high (2 and 3) Fazekas grades. CONCLUSION: The significant difference in absolute TSC in WM in patients with severe small vessel disease; Fazekas grade 3 can lead to inaccuracies using rTSC quantification for evaluation of acute ischemic stroke using 23 Na MRI. The study, therefore, emphasizes the importance of absolute tissue sodium quantification.

[Acute ischemic stroke and elevated troponin: Diagnostic work-up and therapeutic consequences]. / Akuter ischämischer Schlaganfall und Troponinerhöhung: Diagnostische Abklärung und therapeutische Konsequenzen.

Elevated troponin values are frequently detected in patients with acute ischemic stroke, requiring adequate diagnostic work-up due to the high cardiac mortality after stroke. Since dual platelet inhibition can cause secondary intracerebral hemorrhage careful consideration of invasive coronary intervention is mandatory. Based on three case reports, this review article presents a diagnostic algorithm taking into account latest findings from the literature.

Copeptin reliably reflects longitudinal right ventricular function.

BACKGROUND: Data is limited evaluating novel biomarkers in right ventricular dysfunction. Normal right heart function improves the prognosis of patients with heart failure. Therefore, this study investigates the association between the novel biomarker copeptin and right heart function compared to NT-proBNP. METHODS: Patients undergoing routine echocardiography were enrolled prospectively. Right ventricular function was assessed by tricuspid annular plane systolic excursion (TAPSE) and further right ventricular and atrial parameters. Exclusion criteria were age under 18 years, left ventricular ejection fraction < 50% and moderate to severe valvular heart disease. Blood samples were taken for biomarker measurements within 72 h of echocardiography. RESULTS: Ninety-one patients were included. Median values of copeptin increased significantly according to decreasing values of TAPSE (P = 0.001; right heart function grade I: tricuspid annular plane systolic excursion; TAPSE > 24 mm: 5.20 pmol/L; grade II: TAPSE 18-24 mm: 8.10 pmol/L; grade III: TAPSE < 18 mm: 26.50 pmol/L). Copeptin concentrations were able to discriminate patients with decreased right heart function defined as TAPSE < 18 mm (area under the curves [AUC]: copeptin: 0.793; P = 0.001; NT-proBNP: 0.805; P = 0.0001). Within a multivariable linear regression model, copeptin was independently associated with TAPSE (copeptin: T: -4.43; P = 0.0001; NT-proBNP: T: -1.21; P = 0.23). Finally, copeptin concentrations were significantly associated with severely reduced right heart function (TAPSE < 18 mm) within a multivariate logistic regression model (copeptin: odds ratio: 0.94; 95% confidence interval: 0.911-0.975; P = 0.001). CONCLUSIONS: This study demonstrates that the novel biomarker copeptin reflects longitudinal right heart function assessed by standardized transthoracic echocardiography compared with NT-proBNP.

23 Na MRI in ischemic stroke: Acquisition time reduction using postprocessing with convolutional neural networks.

Quantitative 23 Na magnetic resonance imaging (MRI) provides tissue sodium concentration (TSC), which is connected to cell viability and vitality. Long acquisition times are one of the most challenging aspects for its clinical establishment. K-space undersampling is an approach for acquisition time reduction, but generates noise and artifacts. The use of convolutional neural networks (CNNs) is increasing in medical imaging and they are a useful tool for MRI postprocessing. The aim of this study is 23 Na MRI acquisition time reduction by k-space undersampling. CNNs were applied to reduce the resulting noise and artifacts. A retrospective analysis from a prospective study was conducted including image datasets from 46 patients (aged 72 ± 13 years; 25 women, 21 men) with ischemic stroke; the 23 Na MRI acquisition time was 10 min. The reconstructions were performed with full dataset (FI) and with a simulated dataset an image that was acquired in 2.5 min (RI). Eight different CNNs with either U-Net-based or ResNet-based architectures were implemented with RI as input and FI as label, using batch normalization and the number of filters as varying parameters. Training was performed with 9500 samples and testing included 400 samples. CNN outputs were evaluated based on signal-to-noise ratio (SNR) and structural similarity (SSIM). After quantification, TSC error was calculated. The image quality was subjectively rated by three neuroradiologists. Statistical significance was evaluated by Student's t-test. The average SNR was 21.72 ± 2.75 (FI) and 10.16 ± 0.96 (RI). U-Nets increased the SNR of RI to 43.99 and therefore performed better than ResNet. SSIM of RI to FI was improved by three CNNs to 0.91 ± 0.03. CNNs reduced TSC error by up to 15%. The subjective rating of CNN-generated images showed significantly better results than the subjective image rating of RI. The acquisition time of 23 Na MRI can be reduced by 75% due to postprocessing with a CNN on highly undersampled data.

A High Output Method to Isolate Cerebral Pericytes from Mouse.

In recent years, cerebral pericytes have become the focus of extensive research in vascular biology and pathology. The importance of pericytes in blood brain barrier formation and physiology is now demonstrated but its molecular basis remains largely unknown. As the pathophysiological role of cerebral pericytes in neurological disorders is intriguing and of great importance, the in vitro models are not only sufficiently appropriate but also able to incorporate different techniques for these studies. Several methods have been proposed as in vitro models for the extraction of cerebral pericytes, although an antibiotic-free protocol with high output is desirable. Most importantly, a method that has increased output per extraction reduces the usage of more animals. Here, we propose a simple and efficient method for extracting cerebral pericytes with sufficiently high output. The mouse brain tissue homogenate is mixed with a BSA-dextran solution for the separation of the tissue debris and microvascular pellet. We propose a three-step separation followed by filtration to obtain a microvessel rich filtrate. With this method, the quantity of microvascular fragments obtained from 10 mice is sufficient to seed 9 wells (9.6 cm2 each) of a 6-well plate. Most interestingly with this protocol, the user can obtain 27 pericyte rich wells (9.6 cm2 each) in passage 2. The purity of the pericyte cultures are confirmed with the expression of classical pericyte markers: NG2, PDGFR-ß and CD146. This method demonstrates an efficient and feasible in vitro tool for physiological and pathophysiological studies on pericytes.

Extending thrombolysis to 4·5-9 h and wake-up stroke using perfusion imaging: a systematic review and meta-analysis of individual patient data.

BACKGROUND: Stroke thrombolysis with alteplase is currently recommended 0-4·5 h after stroke onset. We aimed to determine whether perfusion imaging can identify patients with salvageable brain tissue with symptoms 4·5 h or more from stroke onset or with symptoms on waking who might benefit from thrombolysis. METHODS: In this systematic review and meta-analysis of individual patient data, we searched PubMed for randomised trials published in English between Jan 1, 2006, and March 1, 2019. We also reviewed the reference list of a previous systematic review of thrombolysis and searched ClinicalTrials.gov for interventional studies of ischaemic stroke. Studies of alteplase versus placebo in patients (aged ≥18 years) with ischaemic stroke treated more than 4·5 h after onset, or with wake-up stroke, who were imaged with perfusion-diffusion MRI or CT perfusion were eligible for inclusion. The primary outcome was excellent functional outcome (modified Rankin Scale [mRS] score 0-1) at 3 months, adjusted for baseline age and clinical severity. Safety outcomes were death and symptomatic intracerebral haemorrhage. We calculated odds ratios, adjusted for baseline age and National Institutes of Health Stroke Scale score, using mixed-effects logistic regression models. This study is registered with PROSPERO, number CRD42019128036. FINDINGS: We identified three trials that met eligibility criteria: EXTEND, ECASS4-EXTEND, and EPITHET. Of the 414 patients included in the three trials, 213 (51%) were assigned to receive alteplase and 201 (49%) were assigned to receive placebo. Overall, 211 patients in the alteplase group and 199 patients in the placebo group had mRS assessment data at 3 months and thus were included in the analysis of the primary outcome. 76 (36%) of 211 patients in the alteplase group and 58 (29%) of 199 patients in the placebo group had achieved excellent functional outcome at 3 months (adjusted odds ratio [OR] 1·86, 95% CI 1·15-2·99, p=0·011). Symptomatic intracerebral haemorrhage was more common in the alteplase group than the placebo group (ten [5%] of 213 patients vs one [<1%] of 201 patients in the placebo group; adjusted OR 9·7, 95% CI 1·23-76·55, p=0·031). 29 (14%) of 213 patients in the alteplase group and 18 (9%) of 201 patients in the placebo group died (adjusted OR 1·55, 0·81-2·96, p=0·66). INTERPRETATION: Patients with ischaemic stroke 4·5-9 h from stroke onset or wake-up stroke with salvageable brain tissue who were treated with alteplase achieved better functional outcomes than did patients given placebo. The rate of symptomatic intracerebral haemorrhage was higher with alteplase, but this increase did not negate the overall net benefit of thrombolysis. FUNDING: None.

Extending the time window for intravenous thrombolysis in acute ischemic stroke using magnetic resonance imaging-based patient selection.

BACKGROUND: Intravenous thrombolysis with alteplase within a time window up to 4.5 h is the only approved pharmacological treatment for acute ischemic stroke. We studied whether acute ischemic stroke patients with penumbral tissue identified on magnetic resonance imaging 4.5-9 h after symptom onset benefit from intravenous thrombolysis compared to placebo. METHODS: Acute ischemic stroke patients with salvageable brain tissue identified on a magnetic resonance imaging were randomly assigned to receive standard dose alteplase or placebo. The primary end point was disability at 90 days assessed by the modified Rankin scale, which has a range of 0-6 (with 0 indicating no symptoms at all and 6 indicating death). Safety end points included death, symptomatic intracranial hemorrhage, and other serious adverse events. RESULTS: The trial was stopped early for slow recruitment after the enrollment of 119 (61 alteplase, 58 placebo) of 264 patients planned. Median time to intravenous thrombolysis was 7 h 42 min. The primary endpoint showed no significant difference in the modified Rankin scale distribution at day 90 (odds ratio alteplase versus placebo, 1.20; 95% CI, 0.63-2.27, P = 0.58). One symptomatic intracranial hemorrhage occurred in the alteplase group. Mortality at 90 days did not differ significantly between the two groups (11.5 and 6.8%, respectively; P = 0.53). CONCLUSIONS: Intravenous alteplase administered between 4.5 and 9 h after the onset of symptoms in patients with salvageable tissue did not result in a significant benefit over placebo. (Supported by Boehringer Ingelheim, Germany; ISRCTN 71616222).

Influence of Gadolinium-Based Contrast Agents on Tissue Sodium Quantification in Sodium Magnetic Resonance Imaging.

OBJECTIVES: Sodium magnetic resonance (MR) imaging provides noninvasive insights to cellular processes by measuring tissue sodium concentration (TSC). Many clinical studies combine sodium MR imaging with clinical standard MR procedures, in which contrast media is frequently administered. This work investigates the influence of gadolinium-based contrast agents on quantification of TSC. Thus, either scan pauses between early and late contrast-enhanced acquisitions can be used efficiently or sodium imaging can be performed as the final scan after dynamic contrast-enhanced acquisition. MATERIALS AND METHODS: For this study, 2 gadolinium-based contrast agents, Dotarem and Gadovist, were diluted with saline solution covering contrast agent concentrations in a clinical range. In addition, agarose-based sample series were created to simulate tissue relaxation time behavior. In vivo, the influence of Dotarem on sodium acquisition and TSC quantification was investigated in 1 ischemic stroke patient. RESULTS: Proton relaxation times decreased for increasing contrast agent concentrations as hyperbolic functions. Sodium relaxation times displayed a negative slope in regression analysis in most cases. The largest influence (-1.52 milliseconds per mmol/L contrast agent) was measured for sodium T1. Worst case calculations in ultrashort echo time sequence signal analysis showed a signal drop of (1.21% ± 0.56%) on tissue sodium quantification. In vivo sodium brain acquisitions of a stroke patient before and after Dotarem injection resulted in statistically nonsignificant differences in TSC quantification of relevant tissues and stroke areas (P > 0.05). CONCLUSIONS: Our study showed a quantitative influence of Dotarem and Gadovist on sodium relaxation times. However, quantification of TSC was not impaired, which was proven by worst case calculations and nonsignificant differences in vivo in an ischemic stroke patient. We suggest performing sodium imaging in useful clinical positions in protocols regardless of included Dotarem or Gadovist administrations. Being flexible in the study protocol design will strengthen ongoing sodium imaging investigations for various pathologies.

Off-label use of IV t-PA in patients with intracranial neoplasm and cavernoma.

BACKGROUND: The safety of systemic thrombolysis in patients with intracranial tumor and cavernoma are unknown. So far evidence is limited to a number of case reports and few case series or unspecified data based on population-based analysis. Our aim was to comprehend the risk of systemic thrombolysis in these patients. METHODS: Patients with additional evidence of intracranial tumor or cavernoma who received IV tissue plasminogen activator (t-PA) treatment at our comprehensive stroke center over a period of 7 years were identified in our stroke database and compared to the same number of matched control subjects without any evidence of intracranial tumor and cavernoma. Clinical history and imaging patterns before and after t-PA therapy were individually reviewed for each patient. RESULTS: Thirty-four patients with additional evidence of meningioma (19/34), cavernoma (13/34) or malignant intracranial neoplasm (2/34) were identified. The incidence of secondary intracranial hemorrhage observed showed no difference between control subjects (9/34, 26%) and patients (6/34, 18%; p = 0.56). Symptomatic hemorrhage in patients with meningioma or cavernoma could not be observed. Likewise, the prevalence of stroke mimics showed no difference between patients (8/34, 24%) and control subjects (5/34, 15%; p = 0.54). However, both patients with malignant intracranial neoplasm presented with a stroke mimic and intracranial hemorrhage was observed in one of them. CONCLUSIONS: In compliance with existing evidence, treatment in patients with meningioma and cavernoma appears to be safe and reasonable, while the therapy should be avoided in patients with malignant intracranial neoplasm with blood-brain barrier disruption.

Analysis of the vasculature by immunohistochemistry in paraffin-embedded brains.

The brain vasculature can be investigated in different ways ranging from in vivo to biochemical analysis. Immunohistochemistry is a simple and powerful technique that can also be applied to archival tissues. However, staining of brain vessels on paraffin sections has been challenging. In this study, we developed an optimized method that can be used in paraffin-embedded mouse and human brain tissues derived from healthy controls and neurological disorders such as Alzheimer's disease. We subsequently showed that this method is fully compatible with the detection of glial cells and key markers of Alzheimer's disease including amyloid beta and phosphorylated Tau protein. Furthermore, we observed that the length of microvasculature in hippocampus of TgCRND8 Alzheimer's disease mouse model is reduced, which is correlated with the decreased blood flow in hippocampus as determined by arterial spin labeling perfusion magnetic resonance imaging. Finally, we determined that the microvasculature length in two other Alzheimer's disease mouse models, APP and PS1 double-transgenic mice and P301S Tau-transgenic mice, is also shortened in the dentate gyrus. Thus, we have established a new, simple and robust method to characterize the brain vasculature in the mouse and human brain.

Intravenous treatment with human recombinant ApoA-I Milano reduces beta amyloid cerebral deposition in the APP23-transgenic mouse model of Alzheimer's disease.

Beyond the crucial role of apolipoprotein A-I (ApoA-I) on peripheral cholesterol metabolism, this apolipoprotein has also been implicated in beta amyloid (Aß)-related neuropathologies. ApoA-I-Milano (M) is a mutated variant, which showed increased vasoprotective properties compared to ApoA-I-wild type in models of atherosclerosis and cardiovascular damage. We speculated that ApoA-I-M may also protect Aß-affected vasculature and reverse some of the pathological features associated with Alzheimer's disease (AD). For this purpose, we produced and characterized human recombinant ApoA-I-wild type and ApoA-I-M proteins. Both of them were able to avoid the aggregation of Aß in vitro, even though recombinant ApoA-I-M was significantly more effective in protecting endothelial cells from Aß(1-42)-toxicity. Next, we determined the effect of chronic intravenous administration of rApoA-I-M in the APP23-transgenic mouse model of AD. We found reduced cerebral Aß levels in mice that received rApoA-I-M, which were accompanied by a lower expression of astrocyte and microglia neuroinflammatory markers. Our results suggest an applicability of this molecule as a therapeutic candidate for protecting the brain in AD.

Cerebral Microbleeds in Murine Amyloid Angiopathy: Natural Course and Anticoagulant Effects.

BACKGROUND AND PURPOSE: Cerebral microbleeds (CMBs) predispose patients to intracerebral hemorrhage. Preclinical models to examine the effects of antithrombotic treatments on the development of clinically overt intracerebral hemorrhage are needed. We examined the natural course of CMB development and the effects of long-term anticoagulation with warfarin or dabigatran on cerebral micro- and macrohemorrhage in mice overexpressing the APP23 (amyloid precursor protein). METHODS: Repeated susceptibility-weighted magnetic resonance imaging was performed in APP23 mice at the age of 18 and 21 months, respectively. After establishing stable long-term anticoagulation effects of warfarin and dabigatran on number and total volume of CMBs, the outcome parameters were compared with nonanticoagulated control. RESULTS: CMBs were equally located in lobar and deep brain regions, and number and total volume of CMBs increased over time. Anticoagulation with either warfarin or dabigatran did not increase CMBs in APP23 significantly. Mice treated with warfarin numerically had a higher mortality (nonanticoagulated: 31%; dabigatran: 35% versus warfarin: 55%; P=0.21). In postmortem brains of prematurely dying animals warfarin caused significantly more frequently large intracerebral hemorrhage than control and dabigatran. CONCLUSIONS: Anticoagulation with warfarin or dabigatran for 3 to 4 months does not promote the formation of CMBs in aged APP23 mice. Nevertheless, warfarin but not dabigatran is associated with a higher risk of extensive intracerebral hemorrhage, suggesting that this model may allow preclinical safety evaluation of antithrombotic therapies.

HIV-Associated Cerebellar Dysfunction and Improvement with Aminopyridine Therapy: A Case Report.

Apart from infectious causes and cerebellar dysfunction associated with acquired immune deficiency syndrome dementia or HIV-associated neurocognitive disorder, cerebellar dysfunction in HIV-positive individuals has been ascribed to granule cell neuronopathy as well as primary cerebellar atrophy without identifiable etiology. We report the case of a patient with progressive cerebellar dysfunction as the primary manifestation of HIV infection. No symptom improvement was seen under combination antiretroviral therapy, which had been established upon diagnosis, but the patient improved rapidly under 4-aminopyridine treatment, which was recommended 1 year later. Our report, adding to the rather small number of reports of HIV-associated cerebellar atrophy and dysfunction as a primary manifestation of HIV infection, draws attention to HIV as a possible differential etiology of a cerebellar syndrome. Further, rapid improvement of symptom severity under 4-aminopyridine treatment warrants further investigation with longer-term follow-up into the effectiveness of this compound in gait disorder associated with HIV infection.

The effect of adipose tissue-derived stem cells in a middle cerebral artery occlusion stroke model depends on their engraftment rate.

BACKGROUND: In the field of experimental stem cell therapy, intra-arterial (IA) delivery yields the best results concerning, for example, migrated cell number at the targeted site. However, IA application also appears to be associated with increased mortality rates and infarction. Since many rodent studies systemically apply 1 × 106 cells, this could also be a consequence of engrafted cell number. The aim of this study was therefore to investigate the effect of different doses of adipose tissue-derived stem cells (ASCs) on engraftment rates and stroke outcome measured in vivo using 9.4-T high-field magnetic resonance imaging (MRI). METHODS: Male Wistar rats (n = 43) underwent a middle cerebral artery occlusion (MCAo) for 45 or 90 min, followed by IA delivery of either saline or 1 × 106, 3 × 105, or 5 × 104 ASCs pre-labelled with very small superparamagnetic iron oxide particles (VSOPs). MRI (9.4-T) analysis was performed 48 h and 9 days post-MCAo. Lesion volumes were assessed by analysis of T2-weighted images and cell signal tracking showing cell engraftment and active cell migration by an improved T2*-analysis. RESULTS: The ASC-derived signal intensity increased in the affected hemisphere 48 h post MCAo with injected cell number (p < 0.05). The analysis of stroke volumes revealed an increased infarction after injection of 1 × 106 ASCs compared to controls or application of 5 × 104 ASCs (p < 0.05). At 9 days post-MCAo, injection of 3 × 105 ASCs resulted in reduced infarct volumes (p < 0.05). Correspondingly, MRI analysis revealed no changes in cell numbers between both MRI examinations but showed active ASC migration to the site of infarction. CONCLUSION: Our results confirm that IA injection is an efficient way of targeting damaged brain tissue but its usefulness strongly depends on the right dose of delivered stem cells since this factor has a strong influence on migration rate and infarct volume, with better results for doses below 1 × 106 cells. Future challenges will include the determination of therapeutic doses for best cellular engraftment and stroke outcome.