A 3D microvascular network model to study the impact of hypoxia on the extravasation potential of breast cell lines

Abstract

Hypoxia is a common feature of the tumor microenvironment. Accumulating evidence has demonstrated hypoxia to be an important trigger of tumor cell invasion or metastasizes via hypoxia-signaling cascades, including hypoxia-inducible factors (HIFs). Microfluidic model can be a reliable in vitro tool for systematically interrogating individual factors and their accompanying downstream effects, which may otherwise be difficult to study in complex tumor tissues. Here, we used an in vitro model of microvascular networks in a microfluidic chip to measure the extravasation potential of breast cell lines subjected to different oxygen conditions. Through the use of HIF-1α knock-down cell lines, we also validated the importance of HIF-1α in the transmigration ability of human breast cell lines. Three human breast cell lines derived from human breast tissues (MCF10A, MCF-7 and MDA-MB-231) were used in this study to evaluate the role of hypoxia in promoting metastasis at different stages of cancer progression. Under hypoxic conditions, HIF-1α protein level was increased, and coincided with changes in cell morphology, viability and an elevated metastatic potential. These changes were accompanied by an increase in the rate of extravasation compared to normoxia (21% O2). siRNA knockdown of HIF-1α in hypoxic tumors significantly decreased the extravasation rates of all the cell lines tested and may have an effect on the function of metastatic and apoptotic-related cellular processes.

The Use of Microfluidic Platforms to Probe the Mechanism of Cancer Cell Extravasation

“…This platform facilitated observation of cancer cell adhesion, transmigration, invasion, and proliferation in a vascular network that mimicked the microvasculature in vivo. Thus, cancer cell motility on the endothelium, transendothelial migration, and extravascular motility in capillary networks that mimic the microcirculation in vivo were observed using this platform in this and several other studies (Table ) . Noteworthy exception included observation of cancer cell capture and lodging during cancer cell infusion and visualization of cancer cell capture, motility, transmigration under flow (Table ) …”

“…For example, pretreatment of microvascular networks with mouse splenocyte conditioned media increased MDA‐MB‐231 breast cancer cell extravasation by accelerating the emergence of surface protrusions . Similarly, prolonged culture of MDA‐MB‐231 cells under hypoxic conditions increased the percentage of extravasated cells over cells cultured under normoxic conditions . Activated neutrophils in the vasculature (Figure 4F) increased the percentage of extravasated MDA‐MB‐231 and A375 melanoma cells.…”

Mimicking tumor hypoxia and tumor-immune interactions employing three-dimensional in vitro models

“…Microfluidic 3D model platforms contribute to solid tumor hypoxia studies by supplementing a much-needed fluid-flow aspect achieved through cleverly designed micro-channels. Song et al developed a microfluidic model that can systematically evaluate individual TME molecular factors and their relative downstream pathological effects, which is otherwise challenging to study in complex in vivo tumor samples [122]. In this study, the researchers measured the extravasation potential of different breast cancer cell lines after subjecting them to variable oxygen conditions, which include normoxic culture conditions reflected by incubation in 21% oxygen and hypoxic culture conditions reflected by incubation in either 3% or 1% oxygen.…”

The Tumor-on-Chip: Recent Advances in the Development of Microfluidic Systems to Recapitulate the Physiology of Solid Tumors

“…Three-dimensionality has been confirmed to have a paramount importance in the proper understanding of tumor dynamics. For instance, recently published literature discusses the role of the size of a tumor (and the associated hypoxia levels) on its aggressiveness [81,82,83,84,85] and on the efficacy of drug delivery to it [84,86,87].…”