Reversible Cavitation‐Induced Junctional Opening in an Artificial Endothelial Layer

Abstract

Targeting pharmaceuticals through the endothelial barrier is crucial for drug delivery. In this context, cavitation‐assisted permeation shows promise for effective and reversible opening of intercellular junctions. A vessel‐on‐a‐chip is exploited to investigate and quantify the effect of ultrasound‐excited microbubbles—stable cavitation—on endothelial integrity. In the vessel‐on‐a‐chip, the endothelial cells form a complete lumen under physiological shear stress, resulting in intercellular junctions that exhibit barrier functionality. Immunofluorescence microscopy is exploited to monitor vascular integrity following vascular endothelial cadherin staining. It is shown that microbubbles amplify the ultrasound effect, leading to the formation of interendothelial gaps that cause barrier permeabilization. The total gap area significantly increases with pressure amplitude compared to the control. Gap opening is fully reversible with gap area distribution returning to the control levels 45 min after insonication. The proposed integrated platform allows for precise and repeatable in vitro measurements of cavitation‐enhanced endothelium permeability and shows potential for validating irradiation protocols for in vivo applications.

Mechanical Stimulation: A Crucial Element of Organ-on-Chip Models

“…Fluid Flow: 10 nL/min-10 µL/min Fluid shear: 0.001-2 Pa Blood-brain barrier (Prabhakarpandian et al, 2013;Deosarkar et al, 2015;Tang et al, 2018;Brown et al, 2019;Da Silva-Candal et al, 2019) Blood vessel (Silvani et al, 2019) Blood vessel: Microvascular network (Rosano et al, 2009;Prabhakarpandian et al, 2011;Lamberti et al, 2013) Cancer models (Tang et al, 2017;Terrell-Hall et al, 2017;Vu et al, 2019) Lung (Kolhar et al, 2013;Liu et al, 2019;Soroush et al, 2020) TissUse https://www.tissuse.com/en/ Fluid shear: 0.02-2 Pa Multi-tissue models: Intestine-Liver-Brain-Kidney (Ramme et al, 2019) Intestine-Liver-Skin-Kidney (Maschmeyer et al, 2015b) Liver-Brain (Materne et al, 2015) Liver-Intestine (Maschmeyer et al, 2015a) Liver-Kidney (Lin et al, 2020) Liver-Lung (Schimek et al, 2020) Liver-Pancreatic islets (Bauer et al, 2017) (Continued) Liver-Skin (Wagner et al, 2013) Liver-Skin-Vasculature (Maschmeyer et al, 2015a) Liver-Testis (Baert et al, 2020) Skin-Lung cancer (Hubner et al, 2018) Single tissue models: Blood vessels (Schimek et al, 2013;Maschmeyer et al, 2015b) Blood vessels: Micro capillaries (Hasenberg et al, 2015) Bone marrow (Sieber et al, 2018) Brain (Materne et al, 2015) Hair follicle biopsies (Atac et al, 2013) Intestine (Maschmeyer et al, 2015a) Kidney (Ramme et al, 2019) Liver (Maschmeyer et al, 2015a;Materne et al, 2015;…”

Cellular Interactions of Liposomes and PISA Nanoparticles during Human Blood Flow in a Microvascular Network

“…[ 45–47 ] The flow in these micro‐channels was designed to mimic various shear rates of blood flow. [ 48–50 ] However, the commercial microvascular network microchip is not coated with endothelial cells and importantly, to the best of our knowledge, this microfluidic chip has not been previously used to study interactions of nanoparticles with fresh human blood. Therefore, we not only needed to culture endothelial cells inside the microchip prior to use but also developed a method to employ for the first time fresh whole human blood and a synthetic microvascular network to analyze the cellular interactions during flow conditions.…”

A Microfluidic Platform for Cavitation-Enhanced Drug Delivery

“…This effect, already considerable when the endothelium is treated with US alone, is intensified by the presence of MBs, with an increase of the total gap area of 360% with respect to the control condition (i.e., non treated mature endothelium). Moreover, when the endothelium was exposed to physiological levels of shear stress (10 dyn cm −2 ) upon US irradiation, total recovery of tissue integrity was registered after 45 min, with the closure of the gaps formed by cavitation [35].…”

“…Microfluidic platforms allowed to highlight the importance of physiological shear stress (1-12 dyn cm −2 in microvasculature) for the formation of a mature vascular lumen, favouring streamwise cell elongation and stabilising junction proteins [25,[33][34][35]. Upon endothelial maturation, barrier permeability can be characterised through different approaches [36].…”

“…In this scenario, our group recently employed a blood vessel-on-chip model, originally developed in [25], to characterise cavitation-enhanced endothelial permeability [35,72]. The purpose of the present paper is to describe details concerning the set-up, its design and fabrication procedure, together with providing examples of application of the device to cavitation-enhanced endothelial layer permeability through the formation of interendothelial gaps.…”