Fluid flow rate dictates the efficacy of low‐intensity anti‐vascular ultrasound therapy in a microfluidic model

Abstract

Objective Low‐intensity anti‐vascular ultrasound therapy is an effective means of disrupting the blood supply in the tumor microenvironment. Its diminished effect on the surrounding vasculature is thought to be due to higher blood flow rates outside the tumor that decreases the interaction time between the endothelial lining and the microbubbles, which transduce acoustic energy to thermal heat. However, investigating the effect of circulation rate on the response to low‐intensity ultrasound is complicated by the heterogeneity of the in vivo vascular microenvironment. Here, a 3D microfluidic model is used to directly interrogate the dynamics of ultrasound stimulation. Methods A 3D in vitro vessel consisting of LifeACT transfected endothelial cells facilitate real‐time analysis of actin dynamics during ultrasound treatment. Using an integrated testing platform, both the flow rate of microbubbles within the vessel and the magnitude of insonation can be varied. Results Morphological measurements and dextran transport assays indicate that lower flow rates exacerbate the effect of low‐intensity ultrasound on vessel integrity. Additionally, immunostaining for VE‐cadherin and transmission electron microscopy provide further insight into structural changes in cell‐cell junctions following insonation. Conclusions Overall, these results reveal that blood flow rate is an important parameter to consider during the refinement of anti‐vascular low‐intensity ultrasound therapies.

The SARS-CoV-2 spike protein alters barrier function in 2D static and 3D microfluidic in-vitro models of the human blood–brain barrier

“…Following exposure to the viral protein, vessels were either placed in fixative or prepared for permeability testing. To quantify localization of ZO-1 to the cell-cell junction in these vessels, the fluorescence intensities along representative 100-μm sections of both the control and spike protein-treated condition were plotted as described in a previous study( DeOre et al, 2019 ). The variance of both these intensity plots were calculated, and the percent difference was calculated to quantify the reduction in localization of ZO-1 to the cell-cell junctions.…”

A 3D printable perfused hydrogel vascular model to assay ultrasound-induced permeability

“…This biological phenomena has been studied with terminal immunostaining, 76 as well as with real-time imaging during ultrasound application. 12 The VE-cadherin complex consists of the transmembrane protein VE-cadherin, and the intracellular proteins that link VE-cadherin to the F-actin cytoskeleton, 77 which implies that rearrangement of the F-actin cytoskeleton will also affect barrier function and the organization of VE-cadherin. Thus, efforts have been underway to assess the effects of ultrasound on VE-cadherin morphology.…”

“…Time-lapsed acquisitions of the fluorescent molecule channel were used to calculate the apparent permeability coefficient with the equation below,where P is the apparent permeability coefficient, d I /d t is the change in fluorescence intensity of the dye over time, r is the radius of the endothelialized channel, and I 0 is the maximum fluorescence intensity inside the lumen. 12 The change in fluorescence intensity (d I /d t ) was determined by monitoring a region outside the channel at a fixed distance from the channel edge and the maximum fluorescence intensity ( I 0 ) was determined by the fluorescence intensity of the dye within the lumen at a time before the diffusion of the dye out of the gel occurs. The image processing used to determine each of these variables is described in more detail in the following section.…”

Comprehensive Development in Organ-On-A-Chip Technology

“…47 A liver-on-a-chip platform consisting of parenchymal and non-parenchymal cells has successfully developed to understand the intercellular communication between various types of hepatic cells in ALD progression. 48 Brain-on-a-chip Furthermore, physiologically relevant reconstruction of blood brain barrier (BBB) allows an understanding of various mechanisms involved in the drug-delivery applications, including receptor-mediated transport, 49 adsorptive-mediated transport, 50 inhibition of efflux transport 51 and various BBB disruption techniques such as sonoporation 52 and electroporation. 53 The brain-on-a-chip model is an in vitro brain model to evaluate a drug's neurotoxicity and to study the mechanism of neurological diseases.…”