In Vitro BBB Models: Working with Static Platforms and Microfluidic Systems

The Modular µSiM Reconfigured: Integration of Microfluidic Capabilities to Study In Vitro Barrier Tissue Models under Flow

Microfluidic tissue barrier models have emerged to address the lack of physiological fluid flow in conventional "open-well" Transwell-like devices. However, microfluidic techniques have not achieved widespread usage in bioscience laboratories because they are not fully compatible with traditional experimental protocols. To advance barrier tissue research, there is a need for a platform that combines the key advantages of both conventional open-well and microfluidic systems. Here, a plug-and-play flow module is developed to introduce on-demand microfluidic flow capabilities to an open-well device that features a nanoporous membrane and live-cell imaging capabilities. The magnetic latching assembly of this design enables bi-directional reconfiguration and allows users to conduct an experiment in an open-well format with established protocols and then add or remove microfluidic capabilities as desired. This work also provides an experimentally-validated flow model to select flow conditions based on the experimental needs. As a proof-of-concept, flow-induced alignment of endothelial cells and the expression of shear-sensitive gene targets are demonstrated, and the different phases of neutrophil transmigration across a chemically stimulated endothelial monolayer under flow conditions are visualized. With these experimental capabilities, it is anticipated that both engineering and bioscience laboratories will adopt this reconfigurable design due to the compatibility with standard open-well protocols.

An engineered microfluidic blood-brain barrier model to evaluate the anti-metastatic activity of β-boswellic acid

BACKGROUND

The development of anti-cancer drugs with the ability to inhibit brain metastasis through the blood-brain barrier (BBB) is substantially limited due to the lack of reliable in vitro models.

MAIN METHODS

In this study, the Geltrex-based Transwell and microfluidic BBB models were applied to screen the effect of β-boswellic acid (β-BA) on the metastasis of MDA-MB-231 cells through the BBB in static and dynamic conditions, respectively.

MAJOR RESULTS

The toxicity assay revealed that β-BA deteriorates MDA-MB-231 cells, while β-BA had no detectable toxic effects on human umbilical vein endothelial cells (HUVECs) and astrocytes. Trans-endothelial electrical resistance evaluation showed sustainable barrier integrity upon treatment with β-BA. Vimentin expression in HUVECs, evaluated using western blot, confirmed superior barrier integrity in the presence of β-BA. The obtained results were confirmed using an invasion study with a cell tracker and a scanning electron microscope. β-BA significantly inhibited metastasis by 85%, while cisplatin (Cis), a positive control, inhibited cancer cell migration by 12% under static conditions. Upon applying a dynamic BBB model, it was revealed that β-BA-mediated metastasis inhibition was significantly higher than that mediated by Cis.

CONCLUSIONS AND IMPLICATIONS

 In summary, the current study proved the anti-metastatic potential of β-BA in both static and dynamic BBB models.

GRAPHICAL ABSTRACT AND LAY SUMMARY

The development of anti-cancer drugs with the ability to inhibit brain metastasis through the blood-brain barrier (BBB) is substantially limited due to the lack of reliable in vitro models. In this study, the Geltrex-based Transwell and microfluidic BBB models were applied to screen the effect of β-boswellic acid (β-BA) on the metastasis of MDA-MB-231 cells through the BBB in static and dynamic conditions, respectively. In summary, the current study proved the anti-metastatic potential of β-BA in both static and dynamic BBB models.