Rob Parton @robparton.bsky.social · 22/01/20269. Altogether, we show that trans-endothelial transport of PEG-based nanoparticles is size-dependent, dictating intracellular or intercellular routes, and further constrained by vesicle size limits and the level of activity of distinct intracellular pathways. 000
Rob Parton @robparton.bsky.social · 22/01/20268. Cavin1 paralog is widely expressed across the zebrafish vasculature up to 15 dpf. Examination on Cavin1 double KOs show that caveolae do not mediate PEG-based NP transvascular transport in the zebrafish, and caveola loss similarly does not alter NP biodistribution in mice. 100
Rob Parton @robparton.bsky.social · 22/01/20267. As the PEG-based micelles increased in size to 109 nm, low basal macropinocytosis becomes the dominant trans-endothelial transport pathway, with minimal dynamin-dependent contribution, likely due to vesicle size constraints. 100
Rob Parton @robparton.bsky.social · 22/01/20266. We then examined the trans-endothelial transport pathways of 32 to 81 nm PEG-based micelles. These NPs extravasate via dynamin-dependent pathways, with some contribution from the macropinocytic pathway. 100
Rob Parton @robparton.bsky.social · 22/01/20265. Having mapped these physiological pathways, we injected zebrafish embryos and juveniles with PEG-based NPs. Small (3-7 nm) PEG-based hyperbranched polymers (HBPs) rapidly extravasate via paracellular routes as determined by cAMP treatment, with minimal intracellular contributions. 100
Rob Parton @robparton.bsky.social · 22/01/20264. Next, we identified steady-state extravasation pathways by priming vessels with inhibitors and using a Cavin1 KO. Fluid-phase solutes cross the embryonic endothelium via paracellular routes (≤15 nm), dynamin-dependent mechanisms, and low basal macropinocytosis, with minimal caveola contribution. 100
Rob Parton @robparton.bsky.social · 22/01/20263. We discovered that trans-endothelial transport involves dynamic intracellular vesicles within intersegmental vessels (ISVs). These endocytic vesicles localize to venous ISVs and appear influenced by arterial-venous mechanical diffs, which we probed by modulating shear stress with epinephrine. 100
Rob Parton @robparton.bsky.social · 22/01/20262. Co-injecting 2000 kDa dextran with NPs allowed us to 1. control injection variability, 2. flag embryos with abnormal leakage, 3. parse vascular vs EVS regions and 4. provide a normalization reference for unbiased quantitation. As a proof of concept, we quantified 40 kDa dextran extravasation. 100
Rob Parton @robparton.bsky.social · 22/01/20261. First, we set up a standardized protocol to assess trans-endothelial transport. We looked at NP signal changes in the blood vessels and extravascular space (EVS) and thought that co-injecting a tracer would be an ideal control. We surveyed dextran tracers across a range of sizes. 100
Rob Parton @robparton.bsky.social · 22/01/20264. The high specificity of caveospheres in delivering highly toxic molecules to tumor cells in mice highlights the potential for utilizing caveospheres in chemotherapeutic targeting of cancer cells as well as in imaging and diagnosis. 000
Rob Parton @robparton.bsky.social · 22/01/20263. The caveospheres can be further engineered to mimic virus particles, with the spike protein of SARS-Cov-2 used to target a human bronchial epithelial cell line. 100
Rob Parton @robparton.bsky.social · 22/01/20262. The Z-domain displayed on the surface of caveospheres provides a specific antibody-binding site, allowing modular labelling and targeting to defined cell types, including hard-to-transfect T cells. 100
Rob Parton @robparton.bsky.social · 22/01/20261. Caveospheres can incorporate genetically-encoded cargo proteins without protein purification or can be loaded with RNA, DNA, proteins, drugs. 110