Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

Clinical outcome and local profile after lumbar spine fusion surgery

Einleitung: Fusionen der lumbalen Wirbelsäule sind eine anerkannte Therapie, wenn konservative Behandlungsmöglichkeiten bei Erkrankungen der Wirbelsäule ausgeschöpft wurden. Aufgrund steigender OP-Zahlen, neuen Erkenntnissen auf dem Gebiet des sagittalen Profils sowie der Einführung neuer Methoden wie intraoperativer Navigation, wurde auf dem Gebiet der Wirbelsäulenchirurgie in den letzten Jahren viel geforscht. Die Ziele dieser Studie waren, klinische sowie radiologische Ergebnisse von Fusionen der Lendenwirbelsäule zu beschreiben. Ein Schwerpunkt lag auf der Beschreibung der postoperativen Veränderungen des lokalen Profils, also der lumbalen Lordose, der segmentale Lordose sowie der Spondylolisthese. Da vor kurzem ein intraoperatives CT mit der Möglichkeit zur intraoperativen Navigation eingerichtet wurde, lag ein weiterer Schwerpunkt in der Evaluierung etwaiger Unterschiede zwischen Patienten die konventionell operiert wurden, sowie Patienten, die iCT-navigiert operiert wurden. Methoden: Die Studie wurde als prospektive Kohortenstudie durchgeführt. Einschlusskriterien waren ein Alter zwischen 18 und 85, das Vorliegen einer Instabilität oder Deformität der Wirbelsäule, eine Fusion der Wirbelsäule mit mindestens einem Segment der LWS, sowie die Durchführung der OP zwischen 1.2.2017 und 1.2.2018. Erhoben wurden Daten bezüglich des Geschlechts, dem Alter bei Operation, Body Mass Index, Diagnose, Operationstyp, Operationszeiten, Anzahl der fusionierten Segmente, Komplikationen, Spitalsaufenthaltsdauer, Anzahl der iCT Scans, Durchleuchtungsdauer, Dosislängenprodukt, Dosisflächenprodukt, Effektive Dosis, Schraubenlage, Lumbale Lordose, Segmentale Lordose, Thorakale Kyphose, Sacral Slope, Pelvic Tilt, Pelvic Incidence, C7 Lot und Listhese. Resultate: 30 Patienten wurden eingeschlossen. Bei allen Patienten wurde eine TLIF Operation durchgeführt. 18 (60%) Patienten wurden mit Durchleuchtung operiert, 9 (30%) mittels iCT basierter Navigation. Bei 3 (10%) Patienten wurde das iCT nur zur Lage der Pedikelschrauben verwendet. Die gesamte OP Zeit war im Durchschnitt um 61,94 Minuten länger bei der navigierten Patientengruppe (330 min.) als bei der konventionell operierten Gruppe (268,06 min.). Die durchschnittliche effektive Dosis betrug 0,316 mSv in der Durchleuchtungsgruppe und 11,56 mSv in der Navigationsgruppe. Die Gesamtrate an Komplikationen betrug 20%. 4 (13,3%) neurologische Komplikationen, 1 (3,3%) postoperatives Hämatom sowie 1 (3,3%) postoperative Infektionen traten auf. Revisions-Operationen wurden bei 2 (6,6%) Patienten durchgeführt. In der Navigationsgruppe zeigte sich eine intrapedikuläre Lage von 79,41% aller Schrauben, eine leichte Dislokation in 11,76%, eine moderate in 5,88% und eine schwere in 2,94%. Die durchschnittliche Listhese war postoperativ signifikant geringer, während bei lumbaler Lordose und segmentaler Lordose nur ein insignifikanter Anstieg beobachtet werden konnte. Fazit: Bezüglich der postoperativen Veränderungen des lokalen Profils konnten nur im Falle der Listhese signifikante Veränderungen beobachtet werden. Die Mittelwerte von lumbaler Lordose und segmentaler Lordose zeigten jedoch zumindest einen leichten postoperativen Anstieg, was als Verbesserung des lokalen Profils gewertet werden kann. Der Einsatz einer iCT basierten Navigation muss skeptisch betrachtet werden, da sich keine wesentlich besseren Ergebnisse bezüglich Komplikationen, Schraubenlage oder lokalem Profil zeigten, jedoch durchschnittliche Operationszeit sowie effektive Dosis signifikant höher waren als bei konventionellen Operationen. Allerdings wurden in dieser Studie nur die ersten 9 Patienten, die mittels iCT Navigation operiert wurden, betrachtet. Es ist daher zu erwarten, dass mit steigender Vertrautheit zum Verfahren auch die Ergebnisse verbessert werden. Zudem muss erwähnt werden, dass die Studie durch eine niedrige Fallzahl sowie hohe Drop-Out Raten deutlich eingeschränkt war.Introduction: Lumbar spine fusion is a widely accepted treatment option in patients where conservative treatment of the underlying spine is not sufficient anymore. In the last years, research on spine fusion surgery increased due to growing numbers of performed surgeries, new findings in different research fields like the sagittal profile, and due to the introduction of new technical possibilities like navigated surgery. The goal of this diploma thesis study was to describe the clinical and radiographic outcome of lumbar spine fusion surgeries performed between February 2017 and February 2018 at the University Clinics for Orthopaedics and Traumatology at the General Hospital Vienna. One main focus of this thesis was to describe the change of the local profile, including lumbar lordosis, segmental lordosis and spondylolisthesis, due to surgery. As recently an intraoperative CT scanner with the possibility of intraoperative navigation was installed, another main focus of this work was to evaluate eventual differences in the outcome of patients who underwent conventional, fluoroscopy assisted surgery, and patients who underwent iCT navigated surgery. Methods: This study was carried out as a prospective cohort study. Inclusion criteria were an age between 18-85 years, the presence of an instability or deformity of the spine, leading to fusion surgery including at least one lumbar spine level, and a surgery date between 1/2/2017 and 1/2/2018. Assessed parameters were gender, age at operation, body mass index, diagnosis, operation type, operative times, number of fused segments, complications, length of hospital stay, number of iCT scans, time of fluoroscopy, dose length product, dose area product, effective dose, screw position, lumbar lordosis, segmental lordosis, thoracic kyphosis, sacral slope, pelvic tilt, pelvic incidence, C7 sagittal vertical axis and spondylolisthesis. Results: 30 Patients were included to this study. All patients underwent TLIF. 18 (60%) Patients underwent conventional, fluoroscopy assisted surgery, 9 (30%) patients iCT navigated surgery, and 3 (10%) patients underwent surgery where iCT was only used for control of the pedicle screw position. Mean total operative time was by averagely 61,94 minutes significantly higher in the navigated group (330,0 min.) than in the fluoroscopy group (268,06 min.). Mean effective dose in the fluoroscopy group was 0,316mSv and in the iCT navigated group 11,56 mSv. Total complication rate was 20% due to 4 (13,3%) neurological complications, 1 (3,3%) postoperative haematoma and 1 (3,3%) postoperative infection. Revision surgery was performed in 2 cases (6,6%). In the navigated group, 79,41% of all screws were located intrapedicular; a minor violation was seen in 11,76%, a moderate violation in 5,88% and a severe violation in 2,94%. Spondylolisthesis decreased significantly due to operation, while lumbar lordosis and segmental lordosis showed only a non-significant postoperative increase. Conclusion: Regarding a change of the local profile due to surgery, significant changes could only be seen in the postoperative decrease of spondylolisthesis. Mean values of lumbar lordosis and segmental lordosis of all included patients however showed at least a decent postoperative increase, which can be considered as improvement of the local profile. Benefit of iCT navigated surgery is ambiguous, as no substantial better outcome regarding complications, screw placement, and improvement of local profile were observed, while mean operation time and effective dose were significantly higher than in conventional surgery. It must be considered though that these were the very first patients at our clinics who underwent iCT navigated surgery, and with increasing familiarity to the procedure also an improvement of the results is expected. Also to be mentioned, we encountered several limitations, like a primarily low case number and a high drop-out rate.eingereicht von Stefan AspalterAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersMedizinische Universität Wien, Diplomarb., 2019(VLID)357426

Machine learning based outcome prediction of microsurgically treated unruptured intracranial aneurysms

Abstract Machine learning (ML) has revolutionized data processing in recent years. This study presents the results of the first prediction models based on a long-term monocentric data registry of patients with microsurgically treated unruptured intracranial aneurysms (UIAs) using a temporal train-test split. Temporal train-test splits allow to simulate prospective validation, and therefore provide more accurate estimations of a model’s predictive quality when applied to future patients. ML models for the prediction of the Glasgow outcome scale, modified Rankin Scale (mRS), and new transient or permanent neurological deficits (output variables) were created from all UIA patients that underwent microsurgery at the Kepler University Hospital Linz (Austria) between 2002 and 2020 (n = 466), based on 18 patient- and 10 aneurysm-specific preoperative parameters (input variables). Train-test splitting was performed with a temporal split for outcome prediction in microsurgical therapy of UIA. Moreover, an external validation was conducted on an independent external data set (n = 256) of the Department of Neurosurgery, University Medical Centre Hamburg-Eppendorf. In total, 722 aneurysms were included in this study. A postoperative mRS > 2 was best predicted by a quadratic discriminant analysis (QDA) estimator in the internal test set, with an area under the receiver operating characteristic curve (ROC-AUC) of 0.87 ± 0.03 and a sensitivity and specificity of 0.83 ± 0.08 and 0.71 ± 0.07, respectively. A Multilayer Perceptron predicted the post- to preoperative mRS difference > 1 with a ROC-AUC of 0.70 ± 0.02 and a sensitivity and specificity of 0.74 ± 0.07 and 0.50 ± 0.04, respectively. The QDA was the best model for predicting a permanent new neurological deficit with a ROC-AUC of 0.71 ± 0.04 and a sensitivity and specificity of 0.65 ± 0.24 and 0.60 ± 0.12, respectively. Furthermore, these models performed significantly better than the classic logistic regression models (p  2, a pre- and postoperative difference in mRS > 1 point and a GOS < 5. Therefore, generalizability of the models could not be demonstrated in the external validation. A SHapley Additive exPlanations (SHAP) analysis revealed that this is due to the most important features being distributed quite differently in the internal and external data sets. The implementation of newly available data and the merging of larger databases to form more broad-based predictive models is imperative in the future

Endothelial cells dynamically compete for the tip cell position during angiogenic sprouting

Sprouting angiogenesis requires the coordinated behaviour of endothelial cells, regulated by Notch and vascular endothelial growth factor receptor (VEGFR) signalling. Here, we use computational modelling and genetic mosaic sprouting assays in vitro and in vivo to investigate the regulation and dynamics of endothelial cells during tip cell selection. We find that endothelial cells compete for the tip cell position through relative levels of Vegfr1 and Vegfr2, demonstrating a biological role for differential Vegfr regulation in individual endothelial cells. Differential Vegfr levels affect tip selection only in the presence of a functional Notch system by modulating the expression of the ligand Dll4. Time-lapse microscopy imaging of mosaic sprouts identifies dynamic position shuffling of tip and stalk cells in vitro and in vivo, indicating that the VEGFR-Dll4-Notch signalling circuit is constantly re-evaluated as cells meet new neighbours. The regular exchange of the leading tip cell raises novel implications for the concept of guided angiogenic sprouting.