Competitive ELISA assay to measure the HA shedding from HUVEC monolayer Introduction The endothelial glycocalyx is a dense layer of proteoglycans, glycoproteins, and glycosaminoglycans (GAGs) that helps maintain the integrity of the endothelial cell (EC) barrier.1 The main GAGs are heparan sulfate (HS), chondroitin sulfate, and hyaluronic acid (HA), among which HS and HA are…
Motivation We have discussed the optimization of our in situ permeability assay at length. This assay relies on confocal microscopy, which may not be accessible to all users of the µSiM. Therefore, we developed an alternative permeability assay in the µSiM that is an endpoint, sampling assay. The protocol for this assay can be found…
Introduction & Motivation A subset of cancer cells has mutations that generate proteins recognized by the immune system as foreign, triggering the immune-mediated clearance of those cells. To avoid this fate, cancer cells can evolve mechanisms to suppress this antitumor response via the regulation of immune checkpoint pathways. Immune checkpoints describe mechanisms that are in…
Although most previous studies suggest a weakened cell-substrate interaction over porous membranes, there are variations in the observed cell responses, likely due to the use of different cell types, substrate materials, and experimental methods. We are seeking to develop a computational model using the Active Brownian Particle (ABP) approach to study the role of pore…
The development of the μSiM-DX has been swift and focused, as discussed in these previous blog posts: https://trace-bmps.org/beadazzled-laying-the-foundation-of-the-%ce%bcsim-dx-fouling-based-sensor/ and https://trace-bmps.org/vindictive-virus-capture-testing-the-%ce%bcsim-dx-with-vaccinia-virus-towards-a-modular-virus-diagnostic/. To provide a greater understanding of the inner workings of the device, I have done a few calculations regarding some of its working properties related to microfluidics. The three I present here are about the relationship…
One of the many contributions Alec S. made to our group is to help us appreciate the importance of the apicobasal (A/B) polarity of endothelial cells. The effects of A/B polarity were demonstrated in his paper: Integrative Biology (2020), 12(11),275–289 where he showed that stimulation of ECs with TNFα from the abluminal chamber caused an…
After completing proof of concept testing with polystyrene beads and with the goal of creating a SARS-CoV-2 sensor (Discussed in this post: https://trace-bmps.org/beadazzled-laying-the-foundation-of-the-%ce%bcsim-dx-fouling-based-sensor/), we sought to test the performance of the system with a target more similar to the SARS-CoV-2 virus. We found this target in vaccinia virus. As we did with the polystyrene beads,…
Starting in December of 2019, we began capturing fluorescent beads on microslit silicon nanomembranes as an illustrative representation of particle capture within our microfluidic devices. From then until now we have successfully used this method within gasket made TFAC devices and uSiM ALine devices using a range of micropore sizes/shapes and bead sizes. These experiments…
Introduction In addition to in situ measurements of small molecule permeability (Parts 1, 2 and 3), we wish to enable an assessment of permeability by sampling from the abluminal chamber of the µSiM in a manner similar to what is done with Transwells®-style devices. To begin this, we need to review the methods used with…
Introduction Proliferation, invasion and metastasis of cancer cells require bidirectional cell-cell communication. Cell-cell communication involves the secretion of oncoproteins, mRNAs, RNAs and DNA fragments by cancer cells. The particles that get secreted by these cancer cells are encapsulated in extracellular vesicles (EVs), which include exosomes. Since evidence suggests that cancer cells secrete more EVs than…