Circulating tumour cells shed large extracellular vesicles in microfluidic capillary models to induce systemic inflammation
File(s)
Author(s)
Vrynas, Angelos
Type
Thesis
Abstract
Tumour cells are often released in the circulation and disseminate through capillary beds to seed eventually metastasis, the major cause of cancer-related deaths. Capillary beds or the microcirculation comprise numerous interconnected non-bifurcated and bifurcated capillaries of narrow sizes and diverse geometries entrapping circulating tumour cells (CTCs), yet the direct impact of capillary bifurcations on CTCs transit remains largely underexplored. In this work, microfluidic technology was utilised to fabricate these geometries, mimicking the conditions met in the microcirculation by CTCs. During CTCs transit, these shed large cytoplasmic microparticles predominately in capillary bifurcations, later verified as large extracellular vesicles (LEVs). Their biogenesis was dependent on multiple parameters, including bifurcations, capillary size, shear, cell size and F-actin. Cell shedding led to reduction of tumour cell volume and protein quantity and enabled faster escape from capillary bifurcations. Successful separation of LEVs from co-transiting tumour cells within the microfluidic devices permitted their downstream investigation. LEVs contained a vast array of proteins, whose role was linked to several pathways that suggested cell reprogramming. Independent co-cultures of LEVs with endothelial cells, monocytes or M1 macrophages revealed internalisation of LEVs by all tested cell types. In respect to endothelial cells, LEVs disrupted endothelial cells’ intercellular junctions, enhancing the permeability against invading cancer cells. Moreover, LEVs promoted the activation of endothelial cells by an increase in expression and production of relevant markers, which in turn led to monocyte stimulation and their attachment. In respect to monocytes, exposure to LEVs led to differentiation of both monocytes and M1 macrophages to pro-metastatic M2 macrophages, validated via typical M2 macrophage markers and enabled enhanced co-interactions with the endothelium and modulation of immune T cells. Altogether, these findings suggest that capillary bifurcations are a favourable location of shedding of LEVs, whose protein diversity enables activation of multiple cell types to promote metastasis.
Version
Open Access
Date Issued
2023-11-20
Date Awarded
01/03/2024
License URL
Advisor
Au, Sam
Publisher Department
Bioengineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)