Multiphoton microscopy for pre-clinical evaluation of flow-diverter stents for treating aneurysms

BackgroundConventional histological analyses are the gold standard for the study of aneurysms and vascular pathologies in pre-clinical research. Over the past decade, in vivo and ex vivo imaging using multiphoton microscopy have emerged as powerful pre-clinical tools for detailed tissue analyses that can assess morphology, the extracellular matrix (ECM), cell density and vascularisation. Multiphoton microscopy allows for deeper tissue penetration with minor phototoxicity.ObjectiveThe present study aimed to demonstrate the current status of multimodality imaging, including multiphoton microscopy, for detailed analyses of neo-endothelialisation and ECM evolution after flow-diverter stent (FDS) treatment in an experimental rabbit model of aneurysms.MethodsMultiphoton microscopy tools for assessing autofluorescence and second harmonic generation (SHG) signals from biological tissues were used to evaluate the endovascular treatment of intracranial aneurysms in an animal model of aneurysms (pig, rabbit). Results from multiphoton microscopy were compared to those from standard histology, electronic and bright field microscopy.ConclusionsThe present study describes novel evaluation modes based on multiphoton microscopy for visualising tissue morphology (e.g., collagen, elastin, and cells) to qualify and quantify the extent of neo-intimal formation of covered arteries and device integration into the arterial wall using a rabbit model of intracranial aneurysms treated with FDS.     

VERIDICAL AND FALSE MEMORIES IN HEALTHY OLDER ADULTS AND IN DEMENTIA OF THE ALZHEIMER'S TYPE

Five groups of participants (young, healthy old, healthy old-old, very mild Dementia of the Alzheimer's Type, Mild Dementia of the Alzheimer's Type) studied and were tested on six 12-item lists of words selected from the DRM (Deese, 1959; Roediger & McDermott, 1995) materials. These lists of words strongly converged semantically on a nonpresented critical word. The results indicated that both veridical recall and recognition performance decreased both as a function of age of the participants and as a function of dementia severity. However, the recall and recognition of the highly related nonpresented items actually increased as a function of age, and only slightly decreased as a function of DAT. When false memory was considered as a proportion of veridical memory, there was a clear increase as a function of both age of the participants and as a function of disease severity. The results are discussed in terms of (a) age and DAT-related changes in attention and memory performance, and (b) the underlying mechanisms that produce false memories in the DRM paradigm.     

Migraine and cluster headache – the common link

Although clinically distinguishable, migraine and cluster headache share prominent features such as unilateral pain, common pharmacological triggers such glyceryl trinitrate, histamine, calcitonin gene-related peptide (CGRP) and response to triptans and neuromodulation. Recent data also suggest efficacy of anti CGRP monoclonal antibodies in both migraine and cluster headache. While exact mechanisms behind both disorders remain to be fully understood, the trigeminovascular system represents one possible common pathophysiological pathway and network of both disorders. Here, we review past and current literature shedding light on similarities and differences in phenotype, heritability, pathophysiology, imaging findings and treatment options of migraine and cluster headache. A continued focus on their shared pathophysiological pathways may be important in paving future treatment avenues that could benefit both migraine and cluster headache patients.     

An ultra-high-affinity small organic ligand of fibroblast activation protein for tumor-targeting applications

We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP in order to study biodistribution properties and tumor-targeting performance in preclinical models. Fluorescent derivatives selectively localized in FAP-positive tumors implanted in nude mice with a rapid and homogeneous penetration within the neoplastic tissue. Quantitative in vivo biodistribution studies with a lutetium-177–labeled derivative of OncoFAP revealed a preferential localization in tumors at doses of up to 1,000 nmol/kg. More than 30% of the injected dose had already accumulated in 1 g of tumor 10 min after intravenous injection and persisted for at least 3 h with excellent tumor-to-organ ratios. OncoFAP also served as a modular component for the generation of nonradioactive therapeutic products. A fluorescein conjugate mediated a potent and FAP-dependent tumor cell killing activity in combination with chimeric antigen receptor (CAR) T cells specific to fluorescein. Similarly, a conjugate of OncoFAP with the monomethyl auristatin E-based Vedotin payload was well tolerated and cured tumor-bearing mice in combination with a clinical-stage antibody-interleukin-2 fusion. Collectively, these data support the development of OncoFAP-based products for tumor-targeting applications in patients with cancer.

Small organic ligands which selectively bind with high affinity to tumor-associated antigens are increasingly applied as targeting delivery vehicles of small payloads such as radionuclides (1, 2), drugs (3–5), and fluorophores (6, 7) to tumor sites. In principle, the use of small ligands for targeting applications offers several advantages compared to intact immunoglobulins, including superior penetration of solid neoplastic lesions (8), lower immunogenicity (9), and a reduced cost of goods (10). Low molecular weight compounds may reach their target in vivo in a matter of seconds, thanks to rapid extravasation after intravenous administration (8). A strikingly selective accumulation of small ligands in neoplastic masses has been demonstrated for a small number of targets including somatostatin receptor type 2 (SSTR-2) (11), prostate-specific membrane antigen (PSMA) (12), and carbonic anhydrase IX (CAIX) (13), for which high-affinity small organic ligands are available. Those ligands are typically specific for defined tumor entities, such as neuroendocrine tumors (11), prostate cancer (3), and clear cell renal cell carcinoma (2).¹⁷⁷Lu-DOTATATE (Lutathera), a small-molecule product targeting SSTR-2, has been approved based on phase III data in which a clinically meaningful 82% reduction in the risk of disease progression or death was demonstrated in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) (14). Similar data are expected from the currently ongoing phase III VISION trial for ¹⁷⁷Lu-PSMA-617 (clinical trial no. {"type":"clinical-trial","attrs":{"text":"NCT03511664","term_id":"NCT03511664"}}NCT03511664), a radiolabeled small molecule that binds with high affinity to PSMA and that enables targeted beta particle therapy in metastatic castration-resistant prostate cancer patients (15). PHC-102, a ^99mTc-labeled small-molecule derivative targeting CAIX, exhibited favorable uptake in primary and metastatic lesions in patients with renal cell carcinoma (RCC) (2). In light of the promising performance of small organic ligands, it would be desirable to discover and develop small molecules with a broader tumor-targeting potential, therefore covering multiple cancer types.Fibroblast activation protein (FAP) is a type II integral membrane serine protease which is abundantly expressed in the stroma of more than 90% of the epithelial cancers, including malignant breast, colorectal, skin, prostate, and pancreatic cancers (16, 17), while exhibiting a restricted expression in normal adult tissues (18, 19). Haberkorn and coworkers (1, 20, 21) have recently described a series of FAP ligands capable of selective accumulation in FAP-positive tumors in mice and in patients. One of these products (named FAPI-04) showed impressive tumor to background ratios at early time points (i.e., few hours after administration) in a broad range of different cancer types in patients. More than 28 tumor types including breast, lung, pancreatic, head and neck, esophagus, and colorectal cancer presented a remarkably high uptake of a FAP-targeted small molecule labeled with gallium-68 (1, 20, 21). For this reason, FAP has recently been dubbed as “the next billion-dollar target for theranostic products” (22).Here, we describe how the chemical modification of a quinoline moiety in position 8 led to the discovery of OncoFAP, a small organic FAP ligand with a dissociation constant in the subnanomolar concentration range. OncoFAP exhibited a strikingly selective and efficient tumor-targeting performance when equipped with various types of payloads, including radionuclides, fluorophores, and cytotoxic drugs. The targeting delivery of radionuclides to solid tumors is rapidly gaining in popularity, as it may open theranostic opportunities, associated with the use of gallium-68 for positron emission tomography (PET) imaging and of lutetium-177 for therapeutic applications (23). The delivery of fluorescein to tumors enables the conditional activation of chimeric antigen receptor (CAR) T cells, which display a potent biocidal activity only in the presence of fluorescein-labeled adaptor molecules specific to a tumor antigen (24, 25). Finally, small-molecule–drug conjugates (SMDCs) promise to represent a valid alternative to antibody–drug conjugates for cancer therapy, with better tumor penetration and a lower cost of goods (8, 26, 27).     

Atherosclerosis in light of the evidence from large statin trials

The results of the large trials with the inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (or statins) in terms of clinical benefits in patients with coronary artery disease indicate that these drugs act in a complex way on several pathways involved in the atherosclerotic process. Beyond their lipid-lowering activity, statins appear to modify many characteristics of the arterial wall, resulting in protection against the progression of plaque growth and/or the precipitation of acute events. The so called "pleiotropic" effects of statins, such as the restoration of endothelial activity, the antioxidant potential or the antiproliferative effect on smooth muscle cells, have been investigated mainly in in vitro experiments. In the near future, it will be necessary to unravel the biological significance and the clinical relevance of these effects, which also involve other pathological conditions such as cancer and osteoporosis. Furthermore, lessons from the trials with statins have allowed a better understanding of the mechanisms leading to atherosclerosis which is now considered as an inflammatory process affecting the vascular wall. This has opened new perspectives in the search for the development of newer and more targeted anti-atherogenic drugs.