Proteomics and transcriptomics of peripheral nerve tissue and cells unravel new aspects of the human Schwann cell repair phenotype

The remarkable feature of Schwann cells (SCs) to transform into a repair phenotype turned the spotlight on this powerful cell type. SCs provide the regenerative environment for axonal re‐growth after peripheral nerve injury (PNI) and play a vital role in differentiation of neuroblastic tumors into a benign subtype of neuroblastoma, a tumor originating from neural crest‐derived neuroblasts. Hence, understanding their mode‐of‐action is of utmost interest for new approaches in regenerative medicine, but also for neuroblastoma therapy. However, literature on human SCs is scarce and it is unknown to which extent human SC cultures reflect the SC repair phenotype developing after PNI in patients. We performed high‐resolution proteome profiling and RNA‐sequencing on highly enriched human SC and fibroblast cultures, control and ex vivo degenerated nerve explants to identify novel molecules and functional processes active in repair SCs. In fact, we found cultured SCs and degenerated nerves to share a similar repair SC‐associated expression signature, including the upregulation of JUN, as well as two prominent functions, i.e., myelin debris clearance and antigen presentation via MHCII. In addition to myelin degradation, cultured SCs were capable of actively taking up cell‐extrinsic components in functional phagocytosis and co‐cultivation assays. Moreover, in cultured SCs and degenerated nerve tissue MHCII was upregulated at the cellular level along with high expression of chemoattractants and co‐inhibitory rather than ‐stimulatory molecules. These results demonstrate human SC cultures to execute an inherent program of nerve repair and support two novel repair SC functions, debris clearance via phagocytosis‐related mechanisms and type II immune‐regulation. GLIA 2016;64:2133–2153     

体外诱导骨髓间充质干细胞向神经元样细胞分化的机制研究

目的体外诱导成人骨髓间充质干细胞(MSCs)向神经元样细胞分化,并探讨分化过程中多效蛋白(PTN)mRNA的表达,以了解MSCs向神经元样细胞分化的特性和机制。方法密度梯度离心加贴壁培养法分离成人MSCs,原代和传代培养。取第6代MSCs设对照和试验组进行诱导,诱导后30 min至3 d,观察细胞形态并计数。免疫细胞化学法和反转录-聚合酶链反应(RT-PCR)法测定分化后细胞神经细胞特异性表面标志神经元烯醇化酶(NSE)、微管相关蛋白(MAP)-2,胶原酸性蛋白(GFAP)和诱导前、诱导后12 h PTN mRNA的表达。结果接种24 h后MSCs开始贴壁,呈圆形或椭圆形。3 d后可见梭状细胞呈集落状生长,10～14 d融合。第5～6代时呈现较均一的成纤维细胞样形态。诱导后胞体向胞核收缩;出现双极及多极细胞。12 h变形细胞增多,细长突起相互连接。24 h后变形细胞增多不明显。诱导后12 h大部分细胞表达NSE(64.79±0.07)%、MAP-2(60.05±0.09)%,未检测到GFAP的表达,RT-PCR半定量检测有NSE mRNA的表达(0.66±0.15)。实验组诱导后12 h细胞有PTN mRNA的表达(0.689±0.017)。结论建立了稳定的成人MSCs培养增殖体系,MSCs可体外诱导分化为神经元样细胞,在分化过程中有外观形态变化和特异性标志物NSE和MAP-2的表达,同时有PTN mRNA的表达,提示PTN可能参与调控了MSCs向神经元样细胞的分化。     

Safety of endovascular treatment of intracranial aneurysms with a new,complex shaped Guglielmi detachable coil

Introduction The Guglielmi detachable coil (GDC) 360°, a new complex shaped bare platinum coil, became available in Europe for aneurysm treatment in September 2005. The purpose of this study was to assess the feasibility and safety of selective embolization of intracranial aneurysms with the GDC 360° in 52 consecutive patients. Methods All patients included in this study were registered in a prospectively maintained database. We assessed the patient clinical history, aneurysm shape and dimensions, technical details and complications of the procedures, degree of aneurysm occlusion, and clinical findings upon discharge. In all patients, the first coil deployed was a GDC 360°. Results Over a 6-month period, we intended to treat 52 aneurysms with the GDC 360° in 52 patients. Of these 52 patients, 42 (81%) were treated in the context of subarachnoid haemorrhage. In 51 of 52 patients, the underlying aneurysm was successfully treated by coil embolization. Six procedures (11.5%) were complicated by the formation of thrombus in the parent artery during the intervention. One patient suffered a stroke related to the procedure. Angiograms obtained immediately after the procedure showed complete occlusion of the aneurysmal sac in 38 of 51 procedures (74.5%), a neck remnant in 11 (21.6%), and a residual aneurysm in 2 (3.9%). In 43 of 51 patients (84.3%), clinical assessment demonstrated independent clinical status, whereas 7 patients (13.7%) required assistance in the activities of daily living upon hospital discharge. One patient (2.0%) died after development of a severe vasospasm 10 days after the endovascular procedure. Conclusion The GDC 360° can be safely used for the endovascular occlusion of intracranial aneurysms.     

Interobserver Agreement in Scoring Angiographic Results of Basilar Artery Occlusion Stroke Therapy

BACKGROUND AND PURPOSE:The modified TICI Infarction grading system is a metric currently used to evaluate angiographic results of thrombectomy for large-vessel occlusion in ischemic stroke. Originally designed for evaluating MCA territories, it is currently used for other vessel occlusions, including the posterior circulation. We postulate that the modified TICI use for the posterior circulation is not accurate due to the different vascular territories supplied by vertebrobasilar vasculature, making grading more complex.MATERIALS AND METHODS:We collected angiographic results from 30 patients who presented with acute posterior circulation occlusions between 2015 and 2018 and underwent thrombectomy in our institution. Eight observers were asked to evaluate the TICI scores before and after thrombectomy. The multirater statistics were computed using Fleiss κ analysis. Further data were collected regarding the potential brain territories at risk and the existence of atherosclerotic disease in the basilar artery.RESULTS:The overall agreement κ reached 0.277 (SD, 0.013), which suggests a “fair” agreement among the raters. On average, 45% of observers achieved a high accuracy in predicting brain areas at risk of ischemia. As for the existence of basilar atherosclerotic disease, a high agreement (defined as at least 5 of 6 observers) was seen in 20 of the 30 patients.CONCLUSIONS:Despite TICI being ubiquitous in stroke diagnostics, the high variability of posterior circulation TICI scores calls into question its use in these strokes. Other methods should be developed to assess recanalization in the posterior circulation.

The TICI grading system is a metric developed by Higashida et al¹ to evaluate the response of thrombolytic agents in acute ischemic strokes. Following the demonstration in controlled randomized studies that mechanical thrombectomy is superior to pharmacologic management in anterior ischemic strokes, the 5-point modified TICI (mTICI) scale became instrumental in analyzing pre- and postintervention cerebral perfusion and assessing procedural effectiveness. In the anterior circulatory system, the mTICI score may be a bona fide metric, which strongly correlates with the patient''s prognosis and can be effectively used as a guide for clinical decision-making. However, does it make sense to talk about mTICI score in basilar artery occlusions?Recent advances in endovascular therapies for stroke treatment allow rapid clot retrieval and restoration of perfusion to ischemic brain tissue.² While patient recovery depends on myriad factors such as the time to reperfusion, the size of the infarct, and the location of the occluded vessel, the ability to achieve rapid and complete flow restoration to ischemic tissues is currently the primary goal of stroke treatment. The assessment of vessel patency not only guides the physician''s operative plan, namely deciding on additional attempts at extracting clot versus ending the procedure, but is also a metric used posttreatment to gauge the patient''s prognosis and the efficacy of the treatment.^3,4 The mTICI scoring system is widely used to encode and compare angiographic results in acute stroke therapies.⁵ Despite much debate regarding its accuracy and precision and although modifications were suggested, the mTICI score is still the most widely used metric among interventional neuroradiologists.^6,7While the mTICI scoring system is mostly used to assess recanalization in the anterior circulation, recent technologic advances, such as low-profile stent retrievers and hypercompliant, atraumatic aspiration systems, have helped improve the effectiveness of mechanical thrombectomy in the posterior circulation.^8-11 Although not yet demonstrated in a randomized trial, posterior vessel thrombectomy is promising, and several trials of the efficacy and safety of thrombectomy for acute basilar artery occlusions are ongoing.For a lack of a better metric, the mTICI score is widely used for the assessment of the anterior and posterior circulation, but its popularity hides an ugly truth: The mTICI framework is an ill-adapted yardstick in the evaluation of the posterior circulation because the cerebrovascular anatomy is too convoluted, too diverse, and often incompletely rendered by conventional imaging to achieve either accuracy or precision. In the anterior system, some major interobserver variability is reported¹² and the posterior side is even more complex. First, within posterior occlusions, there is ample variability, depending on the location of the occlusion, that translates into a variety of clinical presentations and, in turn, causes difficulty in scoring blood flow. For example, there are some critical differences between proximal and distal occlusions of the basilar artery. The prognosis of lateral medullary infarction due to PICA occlusion is more benign, mainly due to the absence of important motor dysfunction.¹³ Persistent top of the basilar occlusion after a failed thrombectomy attempt might lead to downward extension of thrombi, resulting in catastrophic bilateral midbrain or pontine infarction.¹⁴Second, the multiple etiologies of the posterior circulation stroke¹⁵ add a layer of complexity in the scoring. Acute on chronic occlusion of a severely atherosclerotic basilar artery might be more difficult to treat, while it is less clinically devastating due to the development of collaterals.¹⁶ Cardioembolic basilar strokes typically lead to larger infarcts, due to larger clots and insufficiently developed collateral circulation.¹⁷ Third, often the severity of the disease does not follow the intuition gained from imaging, rendering the scoring moot. For example, the lack of the posterior cerebral artery on angiographic images might lead the operator to assign a low mTICI score because the posterior cerebral artery is a major artery of the posterior system and predicts a devastating stroke. However, the occlusions of the basilar perforators, which look more benign and would be scored higher on the mTICI scale, lead to far more serious conditions. We postulate that these major considerations are regarded differently by different operators, resulting in different mTICI grading.The aim of this work was to examine whether the mTICI score is a bona fide metric of posterior vascularization states and whether it can reliably guide the clinical intent: attempt another pass for better recanalization or stop. Even though numerous outside parameters can influence the progression of the disease postintervention, we framed the decision to continue to treat or stop as a prediction of the likely course of postendovascular treatment. To test our hypotheses, we measured the interobserver reliability with the Fleiss κ of mTICI scoring of 8 trained raters in adjudicating outcomes of endovascular treatment for ischemic strokes of the posterior circulation.     

Mechanism of human accommodation as analyzed by nonlinear finite element analysis

Results of nonlinear finite element analysis support the Schachar theory of accommodation and demonstrate that the long-held Helmholtz theory of accommodation is impossible.     

Chagas' disease diagnosis: evaluation of several tests in blood bank screening

Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease.