Application of Transmural Flow Across In Vitro Microvasculature Enables Direct Sampling of Interstitial Therapeutic Molecule Distribution

Abstract

In vitro prediction of physiologically relevant transport of therapeutic molecules across the microcirculation represents an intriguing opportunity to predict efficacy in human populations. On‐chip microvascular networks (MVNs) show physiologically relevant values of molecular permeability, yet like most systems, they lack an important contribution to transport: the ever‐present fluid convection through the endothelium. Quantification of transport through the MVNs by current methods also requires confocal imaging and advanced analytical techniques, which can be a bottleneck in industry and academic laboratories. Here, it is shown that by recapitulating physiological transmural flow across the MVNs, the concentration of small and large molecule therapeutics can be directly sampled in the interstitial fluid and analyzed using standard analytical techniques. The magnitudes of transport measured in MVNs reveal trends with molecular size and type (protein versus nonprotein) that are expected in vivo, supporting the use of the MVNs platform as an in vitro tool to predict distribution of therapeutics in vivo.

Glycocalyx-Mediated Vascular Dissemination of Circulating Tumor Cells

“…Over 43 seven days, the ECs self-assembled into perfusable, interconnected vascular networks. In addition to 44 recapitulating in vivo microvascular geometry and functionality as detailed elsewhere 29,31 , the ECs 45 formed an intact endothelium that expressed major components of the GCX: HA, CS, and HS ( Fig. 46 1a).…”

“…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 .…”

“…formation, GCX removal, and permeability321 MVNs were cultured using Vasculife Endothelial Medium (LL-0003, Lifeline) and pooled HUVECs 322 (GFP-expressing, Angio-Proteomie, 6 million ml -1 after five passages) and nHLFs (Lonza, 2 million mL -1 323 also after five passages) in fibrin hydrogel exactly as previously described31 , including seeding of the 324 endothelial monolayer on the sides of the hydrogel at day 4 of culture and use at day 7. Enzymatic 325 removal of GCX components was achieved using hyaluronidase (H3631, Sigma Aldrich, used at 150 326 units mL -1 ), chondroitinase (C3667, Sigma Aldrich, used at 0.5 units mL -1 ), and heparinase (H8891,327 Sigma Aldrich, used at 0.5 units mL -1 ) in Vasculife, exposing either the MVNs (through perfusion) or328 the TCs for 10 minutes before washing with Vasculife twice.…”

Vascularized organoids on a chip: strategies for engineering organoids with functional vasculature

“…19,55,69,70 Transcytosis across the endothelium of large molecules has also been demonstrated and measured with such 3D perfusable microvascular networks. 70,71 To further replicate in vivo functionality, organotypic vasculatures have been engineered through self-organizing approach by coculturing relevant types of cells. Campisi et al developed a human BBB microvascular model with a tri-culture system consisting of iPSC-derived endothelial cells and primary brain pericytes and astrocytes in fibrin gel.…”

The effects of luminal and trans-endothelial fluid flows on the extravasation and tissue invasion of tumor cells in a 3D in vitro microvascular platform

“…In the circulation, TCs are subjected to fluid shear forces that affect their ability to adhere to the endothelial surface and alter their behavior through mechanicallyactivated signaling pathways. In addition to luminal flow, transmural or trans-endothelial (TE) flow occurs from the blood vessels into the surrounding matrix as interstitial flow, until its uptake by lymphatic vessels, which recirculates it to blood vessels 9,10 . These complex flow profiles in the circulation and surrounding tissues can result in significant biomechanical forces that have been shown to affect remodeling and angiogenesis 11 .…”