Animal model assessment of a new design for a coated mitomycin-eluting biodegradable ureteral stent for intracavitary instillation as an adjuvant therapy in upper urothelial carcinoma.

BACKGROUND: A major limitation in the treatment of upper urinary tract urothelial carcinoma is the limited use of adjuvant therapy due to the drawbacks of current techniques for intracavitary instillation. The aim was to assess, in a large animal model, a biodegradable ureteral stent coated with silk fibroin for mitomycin release, i.e. BraidStent-SF-MMC. METHODS: A total of 14 female pigs with a solitary kidney underwent initial urinalysis, blood chemistry, nephrosonographic, and contrast fluoroscopy assessment of the urinary tract. Later, the BraidStent-SF-MMC was placed retrogradely to assess the mitomycin urine concentration from 0-48 hours. Follow-up was performed weekly until complete stent degradation to assess the macroscopic and microscopic changes in the urinary tract, stent complications. RESULTS: The drug eluting stent released mitomycin for the first 12 h. The main complication was the release of obstructive ureteral coating fragments during the first to third week in 28.5 and 7.1% of animals, respectively, related to urinary pH<7.0, which destabilized the stent coating. Another complication was ureteral strictures between the fourth and sixth week in 21%. The stents were completely degraded by 6-7 weeks. There were no stent-related systemic toxic effects. The success rate was 67.5% and the complication rate was 25.7%. CONCLUSIONS: For the first time, we have shown that a biodegradable anti-cancer drug eluting stent, BraidStent-SF-MMC, provides controlled and well-tolerated release of mitomycin into the upper urinary tract in an animal model. Mitomycin release from a silk fibroin coating could be a compelling approach for adjuvant chemotherapy instillation in upper tract urothelial carcinoma management.

Assessment of silk fibroin for the repair of buccal mucosa in a rat model.

This study evaluated the effectiveness of silk fibroin materials for wound repair confined to the buccal mucosa in a rat model by assessing several key clinical parameters and the associated local and systemic immune response. Ninety male SD rats were subjected to microscopic oral surgery to establish a full thickness wound on the buccal mucosa. Rats were randomly divided into three groups based on the treatments received: group A, covered with polyporous silk fibroin scaffold; group B, repaired with crosslinking silk fibroin film; and group C, control. Visual observation of the wounds suggests that wound shrinkage 5 days after the operation was significantly lower in both silk fibroin repaired groups (A and B) than that in the controls. The distribution of inflammatory neutrophils in group A was significantly lower than those in the control group throughout the entire study. The percentage of fibroblasts and capillary endothelia (CD34(+)), and the subgroups of peripheral lymphocytes (CD3(+), CD4(+), CD8(+)) were similar amongst the groups. The results revealed that placement of silk fibroin in an oral buccal defect can reduce the degree of wound shrinkage and enhance the growth of mucosal epithelial cells without any local or systemic immunological incompatibility.