A sequential assessment of the preservation injury in porcine intestines.

BACKGROUND: Clinical and experimental evidence strongly suggest that ischemia-reperfusion injury after intestinal transplantation has deleterious short- and long-term effects and finding means to reduce ischemia-reperfusion injury is a major research area. The anatomical and physiological similarities between the human and porcine digestive tract favor its use as a preclinical model for translational research. Intriguingly, no systematic appraisal of the development of the intestinal preservation injury in pigs is available. MATERIALS AND METHODS: Intestinal procurement was performed in nine pigs using histidine-tryptophan-ketoglutarate solution as preservation fluid. Ileal biopsies were obtained after 8, 14, and 24 h of static cold storage (SCS), and the preservation injury was assessed morphologically (Chiu score) as well as on the molecular level. Tight junction (zonula occludens, claudin-3 and 4, tricellulin, and occludin) and adherens junctions (E-cadherin) proteins were studied using immunofluorescence and Western blot. RESULTS: Eight hours of SCS induced minimal mucosal changes (Chiu grade 1) that advanced to significant subepithelial edema (Chiu grade 3) after 24 h; progressive Goblet cell depletion was also noted. Apoptosis (studied by cleaved caspase-3 staining significantly increased after 24 h of SCS. Significant molecular changes with decreasing expression of zonula occludens, tricellulin, and occludin were evident already after 8 h of SCS and continuously worsened. Claudin-3 and Claudin-4 and E-cadherin expression remained relatively unaltered during SCS. CONCLUSIONS: Important molecular alterations precede histologic changes during SCS of the porcine intestine and may be used as more sensitive injury markers than histologic changes in intestinal ischemia and transplantation.

Assessment of the antimicrobial activity of acellular vascular grafts.

Several studies have reported biological vascular grafts to be more resistant to microbial infection than synthetic counterparts in vivo. Indeed, small intestinal submucosa (SIS) materials have previously been reported to be antimicrobial. The aim of this study was to assess the antimicrobial activity and the ability to resist biofilm formation of a novel acellular vascular graft and compare it to commercially available alternatives using a range of organisms: MRSA, MSSA, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Candida albicans. This was achieved using a modified disk diffusion assay and extraction of the materials into solution followed by minimum inhibitory concentration assays. To assess resistance to biofilm formation a novel biofilm assay was developed which compared the total colony forming units (CFU) recovered from each material and identification of the percentage of CFU which were loosely attached, residing within the biofilm or attached to the biomaterial. The results indicated a lack of antimicrobial activity for all materials tested, including SIS. The biological materials were more resistant to the formation of a biofilm compared to Dacron.

Characterization of small intestinal submucosa regenerated canine detrusor: assessment of reinnervation, in vitro compliance and contractility.

PURPOSE: We characterized small intestinal submucosa regenerated canine bladder. MATERIALS AND METHODS: We subjected 15-month small intestinal submucosa regenerated canine bladder strips to in vitro muscle bath compliance, contractility testing and immunohistochemical staining. RESULTS: Compliance studies demonstrated no significant difference between small intestinal submucosa regenerated and control bladders, which were 30-fold more compliant than native small intestinal submucosal graft material. Contractility studies demonstrated contractile responses and innervation similar to those of normal canine bladder. Afferent nerves were demonstrated through immunohistochemical techniques. CONCLUSIONS: These characteristics further support the regenerative capacity of small intestinal submucosa and its potential use as a bladder augmentation material.

Regenerative urinary bladder augmentation using small intestinal submucosa: urodynamic and histopathologic assessment in long-term canine bladder augmentations.

PURPOSE: To evaluate small intestinal submucosa (SIS) as a possible bladder augmentation material. MATERIALS AND METHODS: Nineteen male dogs underwent 35 to 45% partial cystectomy with immediate augmentation with SIS grafts. All dogs were evaluated pre- and postoperatively with blood chemistries, urine cultures, intravenous urograms, cystograms and cystometrograms. Postoperatively (1 to 15 months), bladders were examined with routine histology and image analysis. RESULTS: All dogs survived their intended survival period without morbidity. All results were normal. Histologically, all 3 layers (mucosa, smooth muscle, serosa) of the normal bladder showed evidence of regeneration. CONCLUSIONS: Small intestinal submucosa acts as a scaffold for bladder augmentation through regeneration and could be a potential option for bladder reconstruction.

Experimental assessment of small intestinal submucosa as a bladder wall substitute.

OBJECTIVES: This study determined the feasibility of promoting urinary bladder regeneration with porcine-derived small intestinal submucosa (SIS). METHODS: Twenty-two Sprague-Dawley rats underwent partial cystectomy with immediate bladder augmentation with SIS. Bladders were harvested for histologic evaluation at 2, 4, 8, 12, 24, and 48 weeks. RESULTS: Histologically at 2 weeks, there was infiltration of the graft material with viable host cells consisting of fibroblasts, macrophages, and blood vessels covered by complete mucosal urothelium comprised of transitional cells. During the next 10 weeks, collagen formation and maturation were noted, and by the end of 12 weeks, the SIS graft was comprised of a mature collagen matrix admixed with thinly scattered disorganized smooth muscle bundles and covered by normal urothelium. At 48 weeks, all three layers of the normal bladder (urothelium, smooth muscle, and serosa) were present and were grossly and microscopically indistinguishable from the normal rat urinary bladder. CONCLUSIONS: This study further supports the concept of bladder regeneration and suggests that SIS may be a viable material for bladder augmentations.