An on-chip model of protein paracellular and transcellular permeability in the microcirculation

Abstract

Recent therapeutic success of large-molecule biologics has led to intense interest in assays to measure with precision their transport across the vascular endothelium and into the target tissue. Most current in vitro endothelial models show unrealistically large permeability coefficients due to a non-physiological paracellular transport. Thus, more advanced systems are required to better recapitulate and discern the important contribution of transcellular transport (transcytosis), particularly of pharmaceutically-relevant proteins. Here, a robust platform technology for the measurement of transport through a human endothelium is presented, which utilizes in vitro microvascular networks (MVNs). The self-assembled MVNs recapitulate the morphology and junctional complexity of in vivo capillaries, and express key endothelial vesicular transport proteins. This results in measured permeabilities to large molecules comparable to those observed in vivo, which are orders of magnitude lower than those measured in transwells. The permeability of albumin and immunoglobulin G (IgG), biopharmaceutically-relevant proteins, is shown to occur primarily via transcytosis, with passage of IgG regulated by the receptor FcRn. The physiological relevance of the MVNs make it a valuable tool to assess the distribution of biopharmaceuticals into tissues, and may be used to prioritize candidate molecules from this increasingly important class of therapeutics.

Modeling Nanocarrier Transport across a 3D In Vitro Human Blood‐Brain–Barrier Microvasculature

“…Previous authors also reported one order of magnitude lower permeability values in a 3D model compared with a 2D transwell model. [ 51 ] In the 3D in vitro model, transcytosis possibly played a more important role compared to paracellular transport. Conversely, in the 2D transwell set‐up, transcytosis effects were possibly inferior and paracellular transport prevailed.…”

“…The above‐described measurements were derived based on the 3D analysis of the confocal image stacks of the microvasculature as previously described. [ 51 ]…”

Pericytes Contribute to Dysfunction in a Human 3D Model of Placental Microvasculature through VEGF‐Ang‐Tie2 Signaling

“…[27] Following stabilization (≈2-3 min), time-lapse confocal volumes were captured (3 × 5 min intervals). At day 7, devices were perfused with 10 kDa anionic Cascade-blue dextran (ThermoFisher) by a temporary drop in pressure across the gel region (complete removal of media followed by introduction of 40 µL of fluorescent solute into one channel).…”

“…[23,24] Consistent with their importance in vessel function, our group and others have shown that fibroblasts and pericytes are necessary for the maintenance and long-term growth of in vitro 3D microvessels. [21,26] After design and fabrication of the devices (see [27] for details), we set out to establish successful 3D in vitro microvessel generation in the presence or absence of human placental pericytes (HPPs). Using similar microscale devices, we have shown that microvessel formation occurs in a process akin to vasculogenesis (neo-vessel formation) within 1 week and allows for morphological and functional studies of human microvasculature.…”

Glycocalyx-Mediated Vascular Dissemination of Circulating Tumor Cells

“…Therefore, in order to assess relevant TC extravasation 27 mechanisms, advanced experimental systems are required to recapitulate human physiology while 28 allowing for high spatiotemporal resolution imaging of cell interactions 14,25,26 . Our research group has 29 developed and used perfusable microvascular networks (MVNs) self-assembled from human ECs and 30 stromal cells within microfluidic devices 27 , which have been employed in the past to explore the role 31 of specific adhesion molecules, such as integrins, expressed on TCs 28 . The MVNs possess 32 morphological similarities to the human microvasculature in vivo and express a functional GCX 29 .…”