Microfluidic Tumor Vasculature Model to Recapitulate an Endothelial Immune Barrier Expressing FasL

Abstract

Fas ligand (FasL, CD178) is known to bind to its receptor (Fas, CD95) and mediate cellular apoptosis to maintain immune homeostasis. Recently, it has been recognized that tumor cells and their microenvironments allow an adjacent vascular endothelium to express the FasL on its cell membrane, utilizing the endothelium as an immune barrier to kill antitumor cytotoxic T cells. Here, a microfluidic tumor vasculature model is presented, which enables the recapitulation of an endothelial immune barrier expressing FasL. The in vitro three-dimensional model replicates enhanced endothelial FasL expression under the hypoxic tumor microenvironment. Apoptosis rates of FasL-susceptible target cells are augmented under the microenvironment with upregulated FasL but are consequently abrogated by administrations of pharmacological inhibitions, FasL–Fas blockades. The microfluidic system suggests its promising applications in elucidating complex immunosuppressive mechanisms of the tumor microenvironment and screening of cell-mediated immunotherapies as a preclinical model.

A Robust Method for Perfusable Microvascular Network Formation In Vitro

“…[34][35][36][37] In others, in which the microcirculation self assembles from cells (often ECs and FBs), small-diameter vessels are possible, but even in this case, it is rare to find capillary-sized structures. [3,5,8,9,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] A common reason for this is the need to generate perfusable vessels, and MVNs with larger diameters are more likely to be perfusable. In contrast, narrow, capillary-like vessels are less likely to be perfusable because they fail to open at the interface to the media channel.…”

“…Ensuring perfusability may explain that many published reports show perfusable MVNs with both capillary-like vessels and much larger vessels (Figure S1, Supporting Information). [3,5,8,9,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] To reliably form perfusable MVNs with the desired capillary-like geometry, we investigated the effect of seeding parameters on MVN geometry and, in doing so, established a robust two-step seeding strategy that allows us to provide favorable conditions for open vessels between microposts and capillary-like MVNs throughout the central region.…”

Microfluidic outer blood–retinal barrier model for inducing wet age-related macular degeneration by hypoxic stress

“…12 In vitro models composed of microvessels is one of the most successful research fields, as an application of microfluidic chips. Developing 3D vascularization within the extracellular matrix (ECM) using a microfluidic chip, many and meaningful in vitro microvessel models, including cancer metastasis, [13][14][15][16][17] neural system, 18,19 cardiovascular disease, 20 and even haemostasis 21 and endometrium 22 models, have been proposed. Here, we applied this system to construct an in vitro oBRB model, which has a vascularized ECM layer and epithelial monolayer.…”

Enabling perfusion through multicellular tumor spheroids promoting lumenization in a vascularized cancer model

“…59 This was confirmed in our previous research using monodispersed co-culture of HepG2 and HUVEC. 24 Those breakdowns are known to be a result of vinculin dependent VE-cadherin disassembly. 60,61 The hollow lumen was confirmed by investigating the fluorescent images of fluorescently tagged endothelial cells using confocal z-stack images (Fig.…”

“…[20][21][22] Notably, the microfluidic platform has proven its strength in organ-specific cancer metastasis, tumor immune barrier, and drug efficacy evaluation. [23][24][25][26][27][28] Recently, microfluidic vascularized spheroid models have emerged and replaced the existing dispersed single tumor cell microfluidic models with surrounding vasculature, considering their superiority in recapitulating the tumor characteristics. [29][30][31] Two main strategies exist for generating these models: inducing angiogenic sprouting from the endothelial monolayer towards the tumor spheroid 32,33 and placing the vascular bed prior to the introduction of tumor spheroid.…”