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Open AccessFeature PaperEditor’s ChoiceArticle

A Microfluidic-Based Investigation of Bacterial Attachment in Ureteral Stents

1
Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, UK
2
Institute for Life Sciences (IfLS), University of Southampton, Southampton SO17 1BJ, UK
3
Center for Biofilm Engineering and Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, USA
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(4), 408; https://doi.org/10.3390/mi11040408
Received: 29 March 2020 / Revised: 9 April 2020 / Accepted: 10 April 2020 / Published: 13 April 2020
(This article belongs to the Special Issue 10th Anniversary of Micromachines)
Obstructions of the ureter lumen can originate from intrinsic or extrinsic factors, such as kidney stones, tumours, or strictures. These can affect the physiological flow of urine from the kidneys to the bladder, potentially causing infection, pain, and kidney failure. To overcome these complications, ureteral stents are often deployed clinically in order to temporarily re-establish urinary flow. Despite their clinical benefits, stents are prone to encrustation and biofilm formation that lead to reduced quality of life for patients; however, the mechanisms underlying the formation of crystalline biofilms in stents are not yet fully understood. In this study, we developed microfluidic-based devices replicating the urodynamic field within different configurations of an occluded and stented ureter. We employed computational fluid dynamic simulations to characterise the flow dynamic field within these models and investigated bacterial attachment (Pseudomonas fluorescens) by means of crystal violet staining and fluorescence microscopy. We identified the presence of hydrodynamic cavities in the vicinity of a ureteric occlusion, which were characterised by low levels of wall shear stress (WSS < 40 mPa), and observed that initiation of bacterial attachment occurred in these specific regions of the stented ureter. Notably, the bacterial coverage area was directly proportional to the number of cavities present in the model. Fluorescence microscopy confirmed that the number density of bacteria was greater within cavities (3 bacteria·mm−2) when compared to side-holes of the stent (1 bacterium·mm−2) or its luminal surface (0.12 bacteria·mm−2). These findings informed the design of a novel technological solution against bacterial attachment, which reduces the extent of cavity flow and increases wall shear stress over the stent’s surface. View Full-Text
Keywords: ureteral obstruction; ureteral stent; microfluidics; stent-on-a-chip; bacterial attachment; biofilm formation; cavity flow; wall shear stress; CFD simulations ureteral obstruction; ureteral stent; microfluidics; stent-on-a-chip; bacterial attachment; biofilm formation; cavity flow; wall shear stress; CFD simulations
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MDPI and ACS Style

De Grazia, A.; LuTheryn, G.; Meghdadi, A.; Mosayyebi, A.; Espinosa-Ortiz, E.J.; Gerlach, R.; Carugo, D. A Microfluidic-Based Investigation of Bacterial Attachment in Ureteral Stents. Micromachines 2020, 11, 408.

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