A silicon nanomembrane platform for the visualization of immune cell trafficking across the human blood–brain barrier under flow

Abstract

Here we report on the development of a breakthrough microfluidic human in vitro cerebrovascular barrier (CVB) model featuring stem cell-derived brain-like endothelial cells (BLECs) and nanoporous silicon nitride (NPN) membranes (µSiM-CVB). The nanoscale thinness of NPN membranes combined with their high permeability and optical transparency makes them an ideal scaffold for the assembly of an in vitro microfluidic model of the blood–brain barrier (BBB) featuring cellular elements of the neurovascular unit (NVU). Dual-chamber devices divided by NPN membranes yield tight barrier properties in BLECs and allow an abluminal pericyte-co-culture to be replaced with pericyte-conditioned media. With the benefit of physiological flow and superior imaging quality, the µSiM-CVB platform captures each phase of the multi-step T-cell migration across the BBB in live cell imaging. The small volume of <100 µL of the µSiM-CVB will enable in vitro investigations of rare patient-derived immune cells with the human BBB. The µSiM-CVB is a breakthrough in vitro human BBB model to enable live and high-quality imaging of human immune cell interactions with the BBB under physiological flow. We expect it to become a valuable new tool for the study of cerebrovascular pathologies ranging from neuroinflammation to metastatic cancer.

Ultrathin Dual‐Scale Nano‐ and Microporous Membranes for Vascular Transmigration Models

“…This suggests a mechanism by which ECs downregulate their interactions with a highly microporous surface. In the context of a microfluidic shear system, this has indirectly been shown to translate to EC loss under physiological levels of flow . This result is undesired, as it greatly disrupts the establishment of a physiological EC barrier.…”

“…It was concluded that an increase in micropore density can result in decreased cell–substrate interactions (as measured by focal adhesion staining) . In a recent study of a blood–brain barrier (BBB) model, ECs were found to detach within minutes of the onset of physiological flow on microporous SiO 2 membranes, ultimately guiding the decision to utilize nanoporous membranes for the BBB model. Importantly, others have reported success in maintaining EC monolayers under shear on track‐etched (TE) and PDMS microporous membranes .…”

Tangential Flow Microfluidics for the Capture and Release of Nanoparticles and Extracellular Vesicles on Conventional and Ultrathin Membranes

“…The system and scheme for particle capture and release is shown in Figure . As in our prior work, we used layer‐by‐layer assembly (Figure A) to construct microfluidic devices (Figure B) with membranes separating top and bottom flow channels. The only difference is that we used a clamped system for both polycarbonate track‐etch (PCTE) systems and NPN systems instead of a fully bonded devices.…”

Biomimetic Nanomembranes: An Overview

“…Some particular application examples include wastewater treatment [7], desalination [8,9], removal of toxic chemicals [10], of bacterial and viral agents [11] and gathering and concentration of targeted species (e.g., precious metals) from seawater [12]. Another wide field of use is biomedicine and life sciences [13], and covers such diverse areas as biointerfaces including brain-machine interfaces [14], scaffolds for tissue growth [15,16], biosensors [17,18], drug delivery and targeting [19], various labs-on-a-chip [20], DNA sequencers [21], etc. A field where the benefits of biomimetic nanomembranes are already starting to lead to large advancements is renewable energy [22].…”