Use of small intestine submucosa as ureteral allograft in pigs

Comparing Anatomical and Functional Outcomes of Two Neovaginoplasty Techniques for Mayer-Rokitansky-Küster-Hauser Syndrome: A Ten-Year Retrospective Study with Swine Small Intestinal Submucosa and Homologous Skin Grafts

Objective

This study aimed to compare the anatomical and functional outcomes of the modified McIndoe vaginoplasty for Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome using swine small intestinal submucosa (SIS) graft or homologous skin grafts.

Methods

A total of 115 patients with MRKHs who underwent neovaginoplasty between January 2012 and December 2021 were included in the study. Among them, 84 patients received vaginal reconstruction with SIS graft, whereas 31 neovaginoplasty underwent a skin graft procedure. The length and width of the neovagina were measured, and sexual satisfaction was evaluated using the Female Sexual Function Index (FSFI). The operation details, cost, and complications were also assessed.

Results

The SIS graft group had a significantly shorter mean operation time (61.13±7.17min) and less bleeding during the operation (38.57±9.46mL) compared to the skin graft group (92.1±9.47min and 55.81±8.28mL, respectively). The mean length and width of the neovagina in the SIS group were comparable to the skin graft group at 6 months follow-up (7.73±0.57 cm versus 7.6±0.62cm, P=0.32). The SIS group had a higher total FSFI index than the skin graft group (27.44±1.58 versus 25.33±2.16, P=0.001).

Conclusion

The modified McIndoe neovaginoplasty using SIS graft is a safe and effective alternative to homologous skin grafts. It results in comparable anatomical outcomes and superior sexual and functional outcomes. Overall, these results suggest that the modified McIndoe neovaginoplasty using SIS graft is preferred for MRKH patients who require vaginal reconstruction.

Evaluation of Bi-Layer Silk Fibroin Grafts for Tubular Ureteroplasty in a Porcine Defect Model

Ureteral reconstruction with autologous tissue grafts is often limited by tissue availability and donor site morbidity. This study investigates the performance of acellular, bi-layer silk fibroin (BLSF) scaffolds in a porcine model of ureteroplasty. Tubular ureteroplasty with BLSF grafts in combination with transient stenting for 8 weeks was performed in adult female, Yucatan, mini-swine (N = 5). Animals were maintained for 12 weeks post-op with imaging of neoconduits using ultrasonography and retrograde ureteropyelography carried out at 2 and 4 weeks intervals. End-point analyses of ureteral neotissues and unoperated controls included histological, immunohistochemical (IHC), histomorphometric evaluations as well as ex vivo functional assessments of contraction/relaxation. All animals survived until scheduled euthanasia and displayed mild hydronephrosis (Grades 1-2) in reconstructed collecting systems during the 8 weeks stenting period with one animal presenting with a persistent subcutaneous fistula at 2 weeks post-op. By 12 weeks of scaffold implantation, unstented neoconduits led to severe hydronephrosis (Grade 4) and stricture formation in the interior of graft sites in 80% of swine. Bulk scaffold extrusion into the distal ureter was also apparent in 60% of swine contributing to ureteral obstruction. However, histological and IHC analyses revealed the formation of innervated, vascularized neotissues with a-smooth muscle actin+ and SM22α+ smooth muscle bundles as well as uroplakin 3A+ and pan-cytokeratin + urothelium. Ex vivo contractility and relaxation responses of neotissues were similar to unoperated control segments. BLSF biomaterials represent emerging platforms for tubular ureteroplasty, however further optimization is needed to improve in vivo degradation kinetics and mitigate stricture formation.

Onlay Repair Technique for the Management of Ureteral Strictures: A Comprehensive Review

Ureteroplasty using onlay grafts or flaps emerged as an innovative procedure for the management of proximal and midureteral strictures. Autologous grafts or flaps used commonly in ureteroplasty include the oral mucosae, bladder mucosae, ileal mucosae, and appendiceal mucosae. Oral mucosa grafts, especially buccal mucosa grafts (BMGs), have gained wide acceptance as a graft choice for ureteroplasty. The reported length of BMG ureteroplasty ranged from 1.5 to 11 cm with success rates of 71.4%-100%. However, several studies have demonstrated that ureteroplasty using lingual mucosa grafts yields better recipient site outcomes and fewer donor site complications than that using BMGs. In addition, there is no essential difference in the efficacy and complication rates of BMG ureteroplasty using an anterior approach or a posterior approach. Intestinal graft or flap ureteroplasty was also reported. And the reported length of ileal or appendiceal flap ureteroplasty ranged from 1 to 8 cm with success rates of 75%-100%. Moreover, the bladder mucosa, renal pelvis wall, and penile/preputial skin have also been reported to be used for ureteroplasty and have achieved satisfactory outcomes, but each graft or flap has unique advantages and potential problems. Tissue engineering-based ureteroplasty through the implantation of patched scaffolds, such as the small intestine submucosa, with or without cell seeding, has induced successful ureteral regeneration structurally close to that of the native ureter and has resulted in good functional outcomes in animal models.

Mechanical induction of bi-directional orientation of primary porcine bladder smooth muscle cells in tubular fibrin-poly(vinylidene fluoride) scaffolds for ureteral and urethral repair using cyclic and focal balloon catheter stimulation

To restore damaged organ function or to investigate organ mechanisms, it is necessary to prepare replicates that follow the biological role model as faithfully as possible. The interdisciplinary field of tissue engineering has great potential in regenerative medicine and might overcome negative side effects in the replacement of damaged organs. In particular, tubular organ structures of the genitourinary tract, such as the ureter and urethra, are challenging because of their complexity and special milieu that gives rise to incrustation, inflammation and stricture formation. Tubular biohybrids were prepared from primary porcine smooth muscle cells embedded in a fibrin gel with a stabilising poly(vinylidene fluoride) mesh. A mechanotransduction was performed automatically with a balloon kyphoplasty catheter. Diffusion of urea and creatinine, as well as the bursting pressure, were measured. Light and electron microscopy were used to visualise cellular distribution and orientation. Histological evaluation revealed a uniform cellular distribution in the fibrin gel. Mechanical stimulation with a stretch of 20% leads to a circumferential orientation of smooth muscle cells inside the matrix and a longitudinal alignment on the outer surface of the tubular structure. Urea and creatinine permeability and bursting pressure showed a non-statistically significant trend towards stimulated tissue constructs. In this proof of concept study, an innovative technique of intraluminal pressure for mechanical stimulation of tubular biohybrids prepared from autologous cells and a composite material induce bi-directional orientation of smooth muscle cells by locally and cyclically applied mechanical tension. Such geometrically driven patterns of cell growth within a scaffold may represent a key stage in the future tissue engineering of implantable ureter replacements that will allow the active transportation of urine from the renal pelvis into the bladder.

Immediate postoperative evaluation of enteric anastomosis after the use of meloxicam in rats

PURPOSE

To compare ileal anastomoses in the immediate postoperative healing period after meloxicam use.

METHODS

Forty two male Wistar rats were randomly divided into two groups of 21, COX and control group. To COX meloxicam in combination with morphine was given in 3 days period. Control group received only morphine during the same period. Each group was divided into three sub-groups of 7, which were euthanized at 5, 10, and 21 days postoperatively. Comparison was based in histological evaluation of collagen type I and III using sirius red, immunohistochemical through vascular endothelial growth factor and matrix metalloproteinase-9.

RESULTS

Healing process in scheduled periods did not show significant differences (p>0.05) between the COX and control groups during any of the periods.

CONCLUSION

The use of meloxicam in the postoperative period following ileal anastomosis did not affect healing.

Tissue engineering and ureter regeneration: is it possible?

Large ureter damages are difficult to reconstruct. Current techniques are complicated, difficult to perform, and often associated with failures. The ureter has never been regenerated thus far. Therefore the use of tissue engineering techniques for ureter reconstruction and regeneration seems to be a promising way to resolve these problems. For proper ureter regeneration the following problems must be considered: the physiological aspects of the tissue, the type and shape of the scaffold, the type of cells, and the specific environment (urine). 
This review presents tissue engineering achievements in the field of ureter regeneration focusing on the scaffold, the cells, and ureter healing.

Ureteral reconstruction using autologous tubular grafts for the management of ureteral strictures and defects: an experimental study

OBJECTIVE

To investigate whether the peritoneal cavity could function as a bioreactor to produce autologous tubular grafts for ureteral reconstruction in beagles.

MATERIALS AND METHODS

8-Fr Silastic tubes were implanted into the peritoneal cavities of 6 female beagles. At 3 weeks, the tubes were harvested and the tubular tissue covering the tubes was gently everted. A segment 3 cm in length of the right mid-ureter, involving two thirds of its diameter, was removed parallel to the ureteral axis, leaving a third of the ureteral wall. A 5-Fr double-J stent was inserted into the ureter through the created defect, and two thirds of the graft were anastomosed to both edges of the ureteral defect. One third of the graft was overlapped with the retained normal ureter and anastomosed to the external surface of the lumens. Thus, the graft was partly encapsulated by the remainder of ureteral wall. The stent was maintained for 6 weeks and removed. Excretory urography was performed at 8 (n = 3) and 12 weeks (n = 3), postoperatively. Meanwhile, the neoureter was harvested and analyzed. The left ureter served as the control and a simple intubated ureterotomy was performed.

RESULTS

Histological analysis of the tubular tissue demonstrated transversely arranged myofibroblasts and an outer layer of mesothelium. The tissue was easily everted and transplanted as a ureteral graft. Eight weeks postoperatively, the neoureter demonstrated normal ureteral architecture, composed of multilayers of urothelium surrounded by smooth muscle bundles, which became increasingly organized with time. Excretory urography indicated no stenosis or hydronephrosis.

CONCLUSIONS

These results show that autologous tubular tissue grown within the recipients' peritoneal cavity can be used for ureteral reconstruction in the beagle model.

Early experience in reconstruction of long ureteral strictures with allogenic amniotic membrane

OBJECTIVE

To present our experience with the application of human amniotic membrane for the reconstruction of extensive ureteral wall defects.

METHODS

Between 2003 and 2006, 11 patients underwent reconstructive surgery of the ureter. A human amniotic membrane allograft was used to supplement ureteral wall defects. Indications for the procedure included ureteral strictures of a 5.5 cm average (range, 3-8 cm) localized in different parts of the ureter: upper (5), middle (5) and lower (3). The etiology of ureteral loss was: postinflammatory after a complicated stone disease (5), iatrogenic (4) and idiopathic (2). Diagnosis of ureteral stricture was based on antegrade pyelography and excretory urography. Two patients had synchronous treatment for upper and middle ureteral stenosis. Treatment efficacy was assessed by excretory urography and ultrasound.

RESULTS

The mean hospitalization time was 11.9 days, mean operation time 128 min and with an average follow up of 25.2 months. Complications included: stricture recurrence (1) and symptomatic urinary tract infections (2). Excretory urography showed lack of obstruction and normal width of ureters. In one patient, residual hydronephrosis was present on ultrasound.

CONCLUSIONS

The described method seems to be a promising tool in the reconstruction of extensive ureteral strictures.

Study of biocompatibility of small intestinal submucosa (SIS) with Schwann cells in vitro

No satisfactory method currently exists for repairing long peripheral nerve defects. Efforts have been made to fabricate bioactive artificial nerve conduits, comprised of a biomaterial pre-seeded with Schwann cells (SCs), which creating a favorable micro-environment for axonal regeneration, to be an alternative to autografting by means of tissue engineering. Small intestinal submucosa (SIS) possesses special biological characteristics and is comprehensively researched for tissue repairing at varied tissues and organs. This study investigated the biocompatibility of SIS with SCs in vitro. Cultured rat SCs were seeded on SIS. Cell morphology was observed by light microscopy, scanning electron microscopy and transmission electron microscope. The viability of SCs was measured by MTT assay. Secretion of NGF-beta and BDNF was quantitatively assessed by ELISA, and NGF-beta mRNA and BDNF mRNA were semi-quantitatively assessed by RT-PCR. The results indicated that SCs could adhere, migrate and proliferate on the surface of SIS in good condition with productive function of secreting growth factors. SIS has a good biocompatibility with SCs and SIS pre-seeded with SCs has potential to be an alternate candidate of autografting for repairing long peripheral nerve defects.

Education and research using experimental pigs in a medical school

Medium-sized animals such as miniature pigs are considered to be important for education and training in medical schools to master the skills required in surgical treatment. Much still remains to be done to establish total management for animal experiments using pigs. Improvement of the effective utilization of pigs is also required from the economical and ethical points of view. We have been providing a support system at a facility for experimental animals in a medical school for 3 years, and herein we introduce our personal experiments as an instructional lecture. Before starting surgical training using live pigs, sufficient education concerning animal ethics and dry laboratory training was completed. Four kinds of miniature pigs have been used as experimental animals; porcine rearing pens have been improved and a postoperative care system has been implemented. Moreover, staff at the center offer a preoperative service of anesthesia for surgical education, training, and research. Chronic experiments have increased to represent 35% and 48% of experiments using pigs in 2003 and 2004, respectively. Experimental pigs have undergone secondary use after being killed to reduce the number of animals used in experiments. Sharing and reuse have allowed effective use of miniature pig tissues and cells for research, and have reduced the number of animals used. We recommend that researchers consider use of our total systems because they can improve the quality of medical education and research and facilitate effective use of tissues and cells by sharing and reuse among different departments.