(Poly)acrylonitrile-based hydrogel as a therapeutic bulking agent in urology

Fabrication of levofloxacin-loaded porcine acellular dermal matrix hydrogel and functional assessment in urinary tract infection

Bacterial cystitis, a commonly occurring urinary tract infection (UTI), is renowned for its extensive prevalence and tendency to recur. Despite the extensive utilization of levofloxacin as a conventional therapeutic approach for bacterial cystitis, its effectiveness is impeded by adverse toxic effects, drug resistance concerns, and its influence on the gut microbiota. This study introduces Lev@PADM, a hydrogel with antibacterial properties that demonstrates efficacy in the treatment of bacterial cystitis. Lev@PADM is produced by combining levofloxacin with decellularized porcine acellular dermal matrix hydrogel and exhibits remarkable biocompatibility. Lev@PADM demonstrates excellent stability as a hydrogel at body temperature, enabling direct administration to the site of infection through intravesical injection. This localized delivery route circumvents the systemic circulation of levofloxacin, resulting in a swift and substantial elevation of the antimicrobial agent's concentration specifically at the site of infection. The in vivo experimental findings provide evidence that Lev@PADM effectively prolongs the duration of levofloxacin's action, impedes the retention and invasion of E.coli in the urinary tract, diminishes the infiltration of innate immune cells into infected tissues, and simultaneously preserves the composition of the intestinal microbiota. These results indicate that, in comparison to the exclusive administration of levofloxacin, Lev@PADM offers notable benefits in terms of preserving the integrity of the bladder epithelial barrier and suppressing the recurrence of urinary tract infections.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

A comprehensive review on hydrogel materials in urology: Problems, methods, and new opportunities

Hydrogel materials provide an extremely promising group of materials that can find an increasingly wide range of use in treating urinary system conditions due to their unique properties. The present review describes achievements to date in terms of the use and development prospects of hydrogel materials applications in the treatment and reconstruction of the urinary system organs, which among others include: hydrogel systems of intravesical drug delivery, ureteral stents design, treatment of vesicoureteral reflux, urinary bladder and urethral defects reconstruction, design of modern urinary catheters and also solutions applied in urinary incontinence therapy (Figure 4). In addition, hydrogel materials find increasingly growing applications in the construction of educational simulation models of organs and specific conditions of the urinary system, which enable the education of medical personnel. Numerous research efforts are underway to expand the existing treatment methods and reconstruction of the urinary system based on hydrogel materials. After conducting the further necessary research, many of the innovative solutions developed to date have high application potential.

Poly(vinyl alcohol)-Poly(ethylene glycol) Double-Network Hydrogel: A General Approach to Shape Memory and Self-Healing Functionalities

A double-network polymer hydrogel composed of chemically cross-linked poly(ethylene glycol) (PEG) and physically cross-linked poly(vinyl alcohol) (PVA) was prepared. When the hydrogel (70 wt % of water) is subjected to freezing/thawing treatment under strain, the enhanced physical network as a result of crystallization of PVA chains can stabilize the hydrogel deformation after removal of the external force at room temperature. Subsequent disruption of the physical network of PVA by heating allows for the recovery of the initial shape of the hydrogel. Moreover, the double-network hydrogel exhibits self-healing capability stemming from the physical network of PVA by virtue of the extensive interchain hydrogen bonding between the hydroxyl side groups. This study thus demonstrates a general approach to imparting both the shape memory and self-healing properties to chemically cross-linked hydrogels that otherwise do not have such functionalities. Moreover, by making use of the fixed hydrogel elongation, the effect of anisotropy arising from chain orientation on the self-healing was also observed.

Combination of calcium hydroxyapatite and autologous blood for endoscopic treatment of vesicoureteral reflux in children

OBJECTIVE

To report the results of endoscopic correction of vesicoureteral reflux (VUR) with concomitant injection of pure calcium hydroxyapatite (CaHA) and autologous blood.

PATIENTS AND METHODS

Records of patients who underwent endoscopic correction of VUR using concomitant injection of CaHA and autologous blood from 2008 through 2010 were retrospectively reviewed. Data regarding patients' demographics, preoperative VUR grades, febrile urinary tract infections, complications of procedure, postoperative VUR grades and cure rates were collected. Voiding cystourethrography was performed 3 months postoperatively.

RESULTS

Total number of 23 children (9 girls and 14 boys) with 40 refluxing ureters were included. The mean age of children was 1.9 ± 0.97 (SD) years. Reflux grades were II to IV in 14, 11 and 15 renal refluxing units (RRUs), respectively. The mean follow-up period was 44 months. VUR was successfully treated in 87.5% of RRUs after three injections. Significant statistical difference was found between VUR grades before and after the first, second and third injections (p < 0.001, p = 0.001 and p = 0.011, respectively). Moreover, there was a significant difference between primary reflux grade and treatment success (p = 0.031). Febrile UTI was resolved in 85% of patients (17 of 20 patients with febrile UTI) after endoscopic treatment which shows significant improvement (p < 0.001). The procedure was uneventful in all patients, and no obstruction was reported during the follow-up period.

CONCLUSION

Concomitant injection of pure CaHA without any additives (hyaluronic acid, etc.) and autologous blood can be an effective, repeatable and cost-benefit approach for the management of children suffering VUR with a success rate of 87.5% after three injections.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed. These materials were investigated for the repair of cartilage, bone, adipose tissue, intervertebral disc, neural, and cardiac tissue. Papers from the last ten years were considered, with a particular focus on the advances of the last five years. A critical discussion is centered on new perspectives and challenges in the regeneration of specific tissues, with the aim of highlighting the limits of current systems and possible future advancements.

In vivo study of an injectable poly(acrylonitrile)-based hydrogel paste as a bulking agent for the treatment of urinary incontinence

Urinary incontinence can be treated by endoscopic injection of bulking agents, however, no optimal therapeutic effect has been achieved upon this treatment yet. In the present study, the development of a injectable poly(acrylonitrile) hydrogel paste is described, and its efficacy and histological behavior, once injected into the submucosal space of the minipig bladder, are evaluated. A device was developed to mix poly(acrylonitrile) hydrogel powder with glycerin, used as carrier, prior to injection into the submucosal space of the bladder. Several paste deposits, depending on the size of the bladder, were injected per animal. The implants were harvested at days 7, 14, 21, 28, 84 and 168 and analyzed morphologically and by histology. The persistence of the implants was demonstrated. However, at later time points the implants were split up and surrounded by granulomatous tissue, which was gradually replaced by histiocytes and adipocytes. Transitory focal urothelial metaplasia was observed only at day 7 and moderate foreign body reaction was detected predominantly between the second and fifth week. This study demonstrated the feasibility to develop an injectable paste of poly(acrylonitrile) hydrogel thought to provide the expected bulking effect, necessary for the treatment of urinary incontinence.

Role of prophylaxis in vesicoureteral reflux

PURPOSE OF REVIEW

Traditional management of vesicoureteral reflux focuses on preventing renal complications associated with ascending urinary tract infection by either providing continuous antibiotic prophylaxis to sterilize the urine and thus prevent recurrent infection, or abolishing reflux via surgical intervention. This review will consider the rationale for antibiotic prophylaxis in light of contemporary data regarding the natural history of vesicoureteral reflux, urinary tract infection and renal scarring, as well as the efficacy of various treatment strategies.

RECENT FINDINGS

Recent studies have shown that in grades I-IV vesicoureteral reflux, open surgical intervention compared with antibiotic prophylaxis is no better at preventing renal complications. Endoscopic subureteral injection of biomaterials has been proposed as a cost-effective, minimally invasive alternative to surgical or medical intervention; however, given the variety of materials and techniques, the literature has yet to achieve consensus on its efficacy. The first study to compare antibiotic prophylaxis with increased surveillance and prompt treatment of urinary tract infection shows no difference between the two approaches in low-grade (grades I-II) vesicoureteral reflux.

SUMMARY

Recent studies have challenged the traditional paradigm of aggressive vesicoureteral reflux management with surgery or antibiotic prophylaxis. In light of these findings, pediatric urologists will need to reexamine treatment modalities for vesicoureteral reflux.