Urinary Stent Development and Evaluation Models: In Vitro, Ex Vivo and In Vivo—A European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS) Initiative

Noor Buchholz*, Alberto Budia, Julia de la Cruz, Wolfgang Kram, Owen Humphreys, Meital Reches, Raquel Valero Boix, Federico Soria Gálvez

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

2 Scopus citations


Background: When trying to modify urinary stents, certain pre-clinical steps have to be followed before clinical evaluation in humans. Usually, the process starts as an in silico assessment. The urinary tract is a highly complex, dynamic and variable environment, which makes a computer simulation closely reflecting physiological conditions extremely challenging. Therefore, the preclinical evaluation needs to go through further steps of in vitro, ex vivo and in vivo assessments. Methods and materials: Within the European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS), the authors summarized and evaluated stent assessment models in silico, in vitro, ex vivo and in vivo. The topic and relevant sub-topics were researched in a systematic literature search in Embase, Scope, Web of Science and PubMed. Clinicaltrials.gov was consulted for ongoing trials. Articles were selected systematically according to guidelines with non-relevant, non-complete, and non-English or Spanish language articles excluded. Results: In the first part of this paper, we critically evaluate in vitro stent assessment models used over the last five decades, outlining briefly their strengths and weaknesses. In the second part, we provide a step-by-step guide on what to consider when setting up an ex vivo model for stent evaluation on the example of a biodegradable stent. Lastly, the third part lists and discusses the pros and cons of available animal models for urinary stent evaluation, this being the final step before human trials. Conclusions: We hope that this overview can provide a practical guide and a critical discussion of the experimental preclinical evaluation steps needed, which will help interested readers in choosing the right methodology from the start of a stent evaluation process once an in silico assessment has been completed. Only a transparent multidisciplinary approach using the correct methodology will lead to a successful clinical implementation of any new or modified stent.

Original languageAmerican English
Article number1641
Issue number9
StatePublished - 1 May 2022

Bibliographical note

Funding Information:
ENIUS (CA16217) is supported by the European Cooperation in Science and Technology (COST). It is a four-year project (COST action). COST is a funding organization by the European Union (EU) for the creation of research networks. This article is based upon work from COST Action CA16217 (European network of multidisciplinary research to improve the urinary stents), supported by COST (European Cooperation in Science and Technology). www.cost.eu (accessed on 2 April 2022).

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • animal models
  • design
  • encrustation
  • evaluation
  • ex vivo
  • in vitro
  • in vivo
  • material
  • urinary stent
  • urinary tract models


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