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Extracellular vesicles (EVs), nanovesicles released by cells to effectively exchange biological information, are gaining interest as drug delivery system. Yet, analogously to liposomes, they show short blood circulation times and accumulation in the liver and the spleen. For tissue specific delivery, EV surfaces will thus have to be functionalized. We present a novel platform for flexible modification of EVs with target-specific ligands based on the avidin-biotin system. Genetic engineering of donor cells with a glycosylphosphatidylinositol-anchored avidin (GPI-Av) construct allows the isolation of EVs displaying avidin on their surface, functionalized with any biotinylated ligand. For proof of concept, GPI-Av EVs were modified with i) a biotinylated antibody or ii) de novo designed and synthesized biotinylated ligands binding carbonic anhydrase IX (CAIX), a membrane associated enzyme overexpressed in cancer. Functionalized EVs showed specific binding and uptake by CAIX-expressing cells, demonstrating the power of the system to prepare EVs for cell-specific drug delivery.

Aim The aim of the present analysis is to confirm or refute the association of neck pain to migraine or tension-type headache and to assess whether this association is independent of other risk factors for headache. Methods Secondary school students were invited to complete a questionnaire on headache and lifestyle factors in a cross-sectional study. Neck pain was assessed via (a) a screening question concerning neck pain and (b) denoting affected areas in schematic drawings of the human body. Results Absolute increment in prevalence of headache with pain in the shoulder-neck region was between 7.5% and 9.6%. Gender, grade, stress and lifestyle factors were assessed as potential confounding factors. Nearly all factors were associated with shoulder-neck pain and most with headache. After adjustment for confounders, the association of neck pain with headache was almost completely confined to migraine (OR 2.39; 95% CI 1.48–3.85) and migraine + tension-type headache (OR 2.12; 95% CI 1.50–2.99), whereas the association with isolated tension-type headache was negligible (OR 1.22, 95% CI 0.87–1.69). Conclusion Neck pain is associated with migraine but not with tension-type headache. A possible link between migraine and neck pain may be the cervico-trigeminal convergence of neck and meningeal sensory afferents or a disturbed descending inhibition in migraine.

Item does not contain fulltext With the emergence of multimodal imaging strategies, genetically encoded reporters that can be flexibly combined with any imaging modality become highly attractive. Here we describe the use of glycosylphosphatidylinositol (GPI)-anchored avidin, an avidin moiety targeted to the extracellular side of cell membranes via a GPI anchor, as a reporter for in vivo imaging. Being present on the outside of cells, avidin can be visualized with any type of biotinylated imaging agent, without the requirement that the probe be membrane-permeable. We used the avidin-GPI system to monitor the activity of hypoxia-inducible factors (HIFs)-oxygen-sensing transcription factors, which play a major role in regulating cancer progression-in a mouse tumor allograft model. METHODS: Mouse C51 cells were stably transfected with pH3SVG, a reporter construct driving the expression of avidin-GPI from an HIF-sensitive promoter. The transfected cells were subcutaneously implanted into BALB/c nude mice. At 10 d after tumor inoculation, mice received an intravenous injection of either alexa-594-biocytin or (67)Ga-DOTA-biotin, and tumor HIF activity was imaged using fluorescence reflectance imaging or SPECT. RESULTS: In vitro cell experiments demonstrated the functionality and HIF-dependent regulation of the avidin-GPI reporter construct. In vivo, avidin-GPI was targeted specifically in allograft tumors with biotinylated imaging probes using both fluorescence imaging and SPECT. Analysis of the reporter expression pattern on ex vivo tumor tissue sections indicated a good overlap, with areas of hypoxia. CONCLUSION: We have demonstrated the utility of avidin-GPI as a reporter for multimodal in vivo imaging using both a fluorescence and a SPECT approach to assess intracellular oxygen signaling in a mouse tumor model. 01 maart 2011