Bioresorbable ureteral stents from natural origin polymers

Abstract

In this work, stents were produced from natural origin polysaccharides. Alginate, gellan gum, and a blend of these with gelatin were used to produce hollow tube (stents) following a combination of templated gelation and critical point carbon dioxide drying. Morphological analysis of the surface of the stents was carried out by scanning electron microscopy. Indwelling time, encrustation, and stability of the stents in artificial urine solution was carried out up to 60 days of immersion. In vitro studies carried out with simulated urine demonstrated that the tubes present a high fluid uptake ability, about 1000%. Despite this, the materials are able to maintain their shape and do not present an extensive swelling behavior. The bioresorption profile was observed to be highly dependent on the composition of the stent and it can be tuned. Complete dissolution of the materials may occur between 14 and 60 days. Additionally, no encrustation was observed within the tested timeframe. The ability to resist bacterial adherence was evaluated with Gram‐positive Staphylococcus aureus and two Gram‐negatives Escherichia coli DH5 alpha and Klebsiella oxytoca. For K. oxytoca, no differences were observed in comparison with a commercial stent (Biosoft® duo, Porges), although, for S. aureus all tested compositions had a higher inhibition of bacterial adhesion compared to the commercial stents. In case of E. coli, the addition of gelatin to the formulations reduced the bacterial adhesion in a highly significant manner compared to the commercial stents. The stents produced by the developed technology fulfill the requirements for ureteral stents and will contribute in the development of biocompatible and bioresorbable urinary stents. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 608–617, 2015.

Hybrid Alginate‐Based Cryogels for Life Science Applications

“…Equilibrium water uptake was found to be around 3000 wt % for all tested formulations. Another study with alginate hydrogel demonstrated similar values [47]. The samples were found to be stable in PBS solution and degraded after 21 days.…”

Gelatin-based biodegradable ureteral stents with enhanced mechanical properties

“…This helps to understand that with higher amounts of gelatin in the formulation a faster degradation will take place. In our previous study, the alginate-based ureteral stents showed a slower degradation comparing with this work, for the same reason [16]. The polymer blend with the alginate is however unknown and hence difficult to establish a work correlation compared with our formulation.…”

“…Other studies using poly(lactic-co-glycolic acid)-based ureteral stents reported favorable radiopaque and drainage properties, but the biocompatibility was compromised, according to what is reported in the literature [5,[13][14][15]. The degradation of the ureteral stents must be uniform and homogenous or dissolving based on directionality, preventing the formation of fragments during the degradation process that can block the ureter [1,6,16]. Uriprene stent (Poly-Med, USA), a radiopaque, glycolic-lactic acid based stent has been designed to degrade in the direction of the bladder coil to renal coil preventing ureteral obstruction secondary to degrading stent fragments [1].…”

“…The in vivo pig model studies of Uriprene reported a good stability and biocompatibility, with a predictable degradation during 2-4 weeks while maintaining drainage. In our previous study, we reported an ureteral stent produced with natural based polymers processed by critical point drying with carbon dioxide [16]. This study was however not the first in literature to report alginate-polymer-based temporary ureteral stents.…”

“…The bacterial adhesion of Gram-positive and Gramnegative was assed and compared with a commercial stent (Biosoft® duo, Porges, Coloplast) showed a decrease of adhesion. The biodegradation profile was observed to be highly dependent on the composition of the stent, with a complete dissolution of alginate-based during 14 days and the gellan gum-based up to 60 days [16]. A firstgeneration of biodegradable ureteral stents based on natural origin polymers developed previously has proven to be an interesting alternative, but it has however demonstrated to have mechanical properties upon the first in vivo validation.…”