First Prize: Chitosan and the Urothelial Barrier: Effects on Ureteral Intraluminal Drug Penetration and Peristalsis

Pick, Donald L.; Shelkovnikov, S. A.; Canvasser, Noah; Louie, Michael K.; Tongson-Ignacio, Jane; McDougall, Elspeth M.; Clayman, Ralph V.

doi:10.1089/end.2010.0205

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…Chitosan is the material of choice for this first exploration of a freeze-cast, porous stent design because it offers additional parameters for the custom-design of scaffold properties: such as the molecular weight and degree of deacetylation. [48][49][50][51][52][53][54] Another advantage is that it is a naturally antimicrobial [55,56] and biodegradable [57][58][59] material, properties that reduce and possibly prevent biofilm formation, preventing stone formation by surface degradation, enable controlled drug release and enhance penetration, [60][61][62][63][64][65] and the selfremoval of the stent [66][67][68].…”

Section: Introductionmentioning

confidence: 99%

Freeze-casting porous chitosan ureteral stents for improved drainage

2019

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As a new strategy for improved urinary drainage in parallel to the potential for additional functions such as drug release and self-removal, highly porous chitosan stents are manufactured by radial, bi-directional freeze-casting. Inserting the porous stent in a silicone tube to emulate its placement in the ureter shows that it is shape conforming and remains safely positioned in place, also during flow tests, including those performed in a peristaltic pump. Cyclic compression tests on fullyhydrated porous stents reveal high stent resilience and close to full elastic recovery upon unloading. The drainage performance of the chitosan stent is evaluated, using effective viscosity in addition to volumetric flow and flux; the porous stent's performance is compared to that of the straight portion of a commercial 8 Fr double-J stent which possesses, in its otherwise solid tube wall, regularly spaced holes along its length. Both the porous and the 8 Fr stent show higher effective viscosities when tested in the silicone tube. The performance of the porous stent improves considerably more (47.5%) than that of the 8 Fr stent (30.6%) upon removal from the tube, illustrating the effectiveness of the radially aligned porosity for drainage. We conclude that the newly-developed porous chitosan ureteral stent merits further in vitro and in vivo assessment of its promise as an alternative and complement to currently available medical devices.

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Section: Introductionmentioning

confidence: 99%

Freeze-casting porous chitosan ureteral stents for improved drainage

2019

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“…By pretreating the intraluminal surface of the ureter with chitosan, which increases urothelial permeability, nifedipine blocks ureteral peristalsis at low concentrations. 13 They found chitosan changes ureteral urothelial permeability without barrier disruption and had no observed effect on ureteral contraction.…”

Section: Animal Studiesmentioning

confidence: 98%

Understanding the Ureter: Challenges and Opportunities

Park

Venkatesh

2016

Journal of Endourology

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The ureter is possibly the least studied and most poorly understood organ of the urinary tract. The pathophysiologic basis underlying the use of a-blockers to improve ureteral stone passage or to treat ureteral stent symptoms is poorly understood. This, in part, may explain why clinical studies of medical expulsive therapy for ureteral stone passage are fraught with conflicting data. Methods to study human ureter in vivo are few and challenging. The findings of many of the ureteral studies are from observational in vitro studies and were evaluated in other animal species that may not be applicable in human beings. There are few mechanistic studies evaluating the underlying molecular pathophysiologic mechanisms of human ureter. This is critical to our understanding and treatment of stent symptoms, including the development of a patient friendly ureteral stent and for the pharmacologic modulation of ureteral activity. The following is an overview of some of the observational and mechanistic ureteral studies evaluating the pharmacologic and stent effects, including potential areas for further research.

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“…Chitosan has known time-and concentration-dependent exfoliative effects on murine and porcine urothelium related to its electrostatic effect with negatively charged integrins on the cell surface 16 , with applications in drug delivery 17 and treatment of urinary tract infections 18 . Notably, previous studies have shown rapid and complete functional recovery of the urothelium after chitosan exposure [19][20][21] .…”

Section: Magstone Designmentioning

confidence: 99%

A magnetic hydrogel for the efficient retrieval of kidney stone fragments during ureteroscopy

Roquero

Holton

et al. 2022

Preprint

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Surgical management of stone disease aims for complete clearance, yet only 60–75% of ureteroscopic laser lithotripsy treatments achieve complete stone-free status. Up to 30% patients with residual fragments < 2 mm in size experience stone-related complications. We demonstrate a method of stone fragment retrieval in which fragments are coated with a magnetic hydrogel and retrieved en masse with a magnetic guidewire. The magnetic hydrogel facilitated robust in vitro capture of stone fragments up to 4 mm in size across a wide range of stone compositions. The components exhibited no cytotoxicity in cell culture and only superficial effects on the urothelium in ex vivo human urothelium and in vivo mouse bladders. Furthermore, the hydrogel demonstrated antimicrobial activity against common uropathogens on par with that of common antibiotics. By enabling the efficient retrieval of kidney stone fragments, our method could lead to improved stone-free rates and patient outcomes.

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First Prize: Chitosan and the Urothelial Barrier: Effects on Ureteral Intraluminal Drug Penetration and Peristalsis

Abstract: By pretreating the intraluminal surface of the ureter with chitosan, nifedipine blocks ureteral peristalsis at low concentrations. Chitosan changes ureteral urothelial permeability without barrier disruption and has no observed effect on ureteral contraction.

Cited by 8 publications

References 21 publications

Freeze-casting porous chitosan ureteral stents for improved drainage

Freeze-casting porous chitosan ureteral stents for improved drainage

Understanding the Ureter: Challenges and Opportunities

A magnetic hydrogel for the efficient retrieval of kidney stone fragments during ureteroscopy

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