Small intestinal submucosa as a tunica albuginea graft material

Rabbit Ear Cartilage Regeneration With a Small Intestinal Submucosa Graft

OBJECTIVES/HYPOTHESIS

The objective was to demonstrate that interpositional grafting with porcine small intestinal submucosa promotes cartilage regeneration following excision of rabbit auricular cartilage.

STUDY DESIGN

Blinded, controlled study.

METHODS

Eight New Zealand white rabbits underwent excision of auricular cartilage on two sites with and two sites without preservation of perichondrium. Porcine small intestinal submucosa was implanted into one site with and one site without intact perichondrium. Remaining sites served as control sites. Histological assessment was performed at 3 (n = 4) and 6 (n = 3) months and at 1 year (n = 1) after grafting.

RESULTS

Histological evaluation showed cartilage regeneration accompanied by chronic inflammation in areas in which porcine small intestinal submucosa was implanted between layers of intact perichondrium. Other sites failed to show significant cartilage regeneration.

CONCLUSION

The results of the study using porcine small intestinal submucosa as a bioscaffold for cartilage regeneration are promising and justify further animal and human studies.

Crural Tunica Albuginea Autograft for Corporoplasty: An Experimental Animal Study of Hemodynamic, Histopathological, and Molecular Effects in the Long Term

INTRODUCTION

Correction of penile deformity caused by Peyronie's disease by a variety of grafts varies in success. A long-term follow-up shows a significant number of graft scarring and erectile dysfunction. The clinical success of autologous crural tunica albuginea graft (TAG) has not resulted in wide application.

AIM

To identify in healthy baboons the limitations and merits of autologous crural TAG over 1 year in a way difficult to pursue in humans.

METHODS

Under general anesthesia, eight sexually active adult baboons underwent pharmacological cavernosometry (CM) and cavernosography. TAG from crus was implanted in the distal penile shaft. After 6 months, six animals were reevaluated and two were sacrificed, and the penises were excised. After 1 year, the remaining six animals were evaluated and sacrificed. The TAG and underlying corpus cavernosum (CC) were examined histologically and by Western blot analysis for nitric oxide synthase (NOS), neuronal (nNOS), endothelial (eNOS) and inducible (iNOS) isoforms, and transforming growth factor-beta1 (TGF-beta1).

MAIN OUTCOME MEASURES

Sexual activity, CM, cavernosography, histopathology, and Western blot analysis.

RESULTS

All animals resumed normal sexual activity 1 month postsurgery. Cavernous pressure was comparable before, at 6 months, and 1 year after surgery. A cavernovenous insufficiency developed in four animals at 6 months, and ceased in two at 1 year. Penile angulation (<20 degrees) was seen in three animals at 6 months, and an additional two at 1 year. Histologically, TAG was indistinguishable from the adjacent tunica with no fibrosis. In CC, iNOS and nNOS decreased at 1 year, whereas there was no change in TGF-beta1 levels. In TAG, there was no significant change in TGF-beta1 and eNOS levels, but there was a significant decrease in iNOS at 1 year.

CONCLUSION

Autologous free TAG is associated with normal sexual activity, minimal hemodynamic changes, excellent histological outcome, and no rise in iNOS or TGF-beta1. However, cavernovenous insufficiency, mild penile angulation, and decreased nNOS persisted at 1 year.

Graft Materials in Peyronie's Disease Surgery: A Comprehensive Review

OBJECTIVE

To discuss the currently used graft materials in Peyronie's surgery.

METHODS

A MEDLINE search was conducted till the end of September 2006 on the surgical treatment of Peyronie's disease, and all aspects of the graft materials used for Peyronie's surgery were examined.

RESULTS

Currently available interposing graft materials may be classified in three categories: autologous tissues, extracellular matrix (ECM) tissues, and synthetic materials. Each grafting material in these categories has its own advantages and drawbacks in terms of tissue properties, antigenicity, availability, and cost-effectiveness. Saphenous vein grafts are the most widely used among autologous grafts, with acceptable functional outcomes in the long term. Other graft materials include tunica vaginalis, fascia lata, rectus fascia, and buccal mucosa, with variable results. Despite numerous advantages in terms of tissue compatibility, the major drawback of autologous grafts is tissue harvesting that to morbidities and longer operative durations. For this reason, the use of readily available ECM tissues as the products of tissue engineering is recommended by some authors. Among ECM grafts, cadaveric and bovine pericardia have satisfactory mid-term outcomes. However, longer follow-ups with an adequate number of patients are lacking. On the other hand, recent evidence suggests that small intestinal submucosa may be associated with high rate of operative failure and complications. Generally, synthetic materials are no longer used in grafting procedures in Peyronie's surgery because of their antigenicity and inappropriate functional properties. For prosthesis surgery, pericardia as well as autologous rectus fascia grafts are probably the most suitable graft materials because of their suitable tissue characteristics that satisfy the mechanical demands of the prosthesis.

CONCLUSION

Saphenous vein grafting from autologous tissues and pericardium from ECM tissues have satisfactory results. However, further research and clinical studies are needed in order to determine the optimal graft material.

Surgical outcomes and patient satisfaction after dermal, pericardial, and small intestinal submucosal grafting for Peyronie's disease

INTRODUCTION

Peyronie's disease, a localized fibrosis of the tunica albuginea surrounding the penile corpora, results in penile curvature and sexual dysfunction. Surgical management involving grafting to straighten the penis is the treatment of choice in conditions unresponsive to conservative therapy where penile length preservation is important.

AIM

To determine surgical outcomes and patient satisfaction after dermal, pericardial, and small intestinal submucosal grafting for Peyronie's disease.

MAIN OUTCOME MEASURES

The International Index of Erectile Function (IIEF), postoperative self-reports, patient satisfaction, and clinical characteristics were used to measure outcomes.

METHODS

We retrospectively reviewed charts of 36 patients who underwent surgery for Peyronie's disease requiring grafting from 1999 to 2005. Follow-up to subjectively assess outcomes was conducted.

RESULTS

Average patient age at surgery was 55 +/- 1 years. Body mass indexes were similar among all groups. Erectile dysfunction risk factors were comparable with 36% reporting hypertension and 22% hypercholesterolemia. Overall patient follow-up time was 673 +/- 98 days. Self-reported resolution of penile curvature was noted in 60% of dermal, 100% of Tutoplast, and 76.9% of Stratasis graft recipients. Stratasis patients maintained presurgery length (54%) and rigidity (77%) more so than dermal (30%, 60%) and Tutoplast (23%, 39%) patients. Assessment of erectile dysfunction using the IIEF-5 captured significant improvements in patients receiving Stratasis grafts (preoperative: 10.1 +/- 1.1 vs. postoperative: 17 +/- 1.6). Overall, 89% of patients reported satisfaction following surgical intervention.

CONCLUSIONS

Surgical management of Peyronie's disease results in correction of penile curvatures and high rates of patient satisfaction. Loss of penile length and decreased rigidity occurred to a lesser degree with Stratasis grafts. While detailed informed consent is essential in this patient population, novel materials such as Tutoplast and Stratasis grafts improve outcomes following surgical correction of Peyronie's disease.

Characterization of Muscarinic Receptor Subtypes in Human Ureter

BACKGROUND AND PURPOSE

To date, the subtypes of muscarinic receptors in the human ureter have not been characterized. Recently, several clinical studies have suggested enhanced passage of ureteral stones after relaxation of the ureter using adrenergic antagonists. However, there is a paucity of information on ureteral receptors and their role in ureteral motility. The objective of our study was to evaluate whether all five of the known subtypes of muscarinic receptors are present in the human ureter and to determine the relative distribution of these subtypes.

MATERIALS AND METHODS

Four ureters from human patients undergoing radical nephrectomy were paraffin tissue sectioned (5 microm) and applied to charged slides, deparaffinized, and hydrated. These sections underwent immunocytochemical (ICC) analysis of the density of each of the muscarinic receptor subtypes (M1-M5) with respect to the total area of ureteral tissue (I/A) present in every sample. Three ureters were harvested for reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of muscarinic receptor subtypes.

RESULTS

All five receptor subtypes were present in the human ureter on ICC analysis. However, on RT-PCR analysis, only subtypes 2, 3, and 5 were present.

CONCLUSIONS

The results of our study demonstrate that muscarinic receptors are present in the human ureter. A novel finding is the identification of relatively high levels of M5 by both ICC and RT-PCR.

Use of rectus fascia graft for corporeal reconstruction during placement of penile implant

OBJECTIVES

To report on the technique of using autologous rectus fascia graft for corporeal and tunica reconstruction during placement of an inflatable penile prosthesis. Reconstructing the corpora cavernosa and closing the tunica albuginea over an inflatable penile prosthesis can be challenging when severe fibrosis is encountered.

METHODS

Fifteen patients with severe fibrosis of the corpora or tunica were included in this study. Eight patients had severe corporeal fibrosis secondary to an infected or malfunctioned penile prosthesis that had been previously removed, and seven had severe penile curvature secondary to tunical fibrosis with concomitant erectile dysfunction. All patients underwent corporeal or tunica reconstruction using autologous rectus fascia after placement of an inflatable penile prosthesis. Postoperatively, patients were evaluated at 1, 6, 12, and 24 months. Data on patient satisfaction, graft function, and complications were recorded.

RESULTS

At a mean follow-up of 18 months (range 12 to 64), augmentation of the tunica or corporeal defect using autologous rectus fascia graft was successful in all patients. The penile prostheses were functioning properly with no evidence of graft infection, erosion, or abdominal wall hematoma. Patients demonstrated good results, with return to sexual intercourse at a mean of 9 weeks postoperatively (range 8 to 10).

CONCLUSIONS

Use of an autologous rectus fascia graft for coverage of a tunical or corporeal defect during penile prosthesis placement in patients with corporeal or tunica fibrosis is surgically feasible, safe, and efficacious. Long-term follow-up of this reconstructive technique has demonstrated excellent clinical results with no morbidity related to the rectus fascia graft harvesting.

Resorbable extracellular matrix grafts in urologic reconstruction

PURPOSE

There is an increasingly large body of literature concerning tissue-engineering products that may be used in urology. Some of these are quite complex (such as multilayer patient-specific cell-seeded implants) yet the most simple and successful products to date are also the most uncomplicated: resorbable acellular extra-cellular matrices (ECMs) harvested from animals. ECMs have been used in a variety of difficult urologic reconstruction problems, and this review is intended to summarize this complex literature for the practicing urologist.

METHODS

Medline search of related terms such as "SIS, small intestinal submucosa, ECM, extracellular matrix, acellular matrix and urologic reconstruction". Manuscripts missed in the initial search were taken from the bibliographies of the primary references.

RESULTS

Full review of potential clinical uses of resorbable extra-cellular matrices in urologic reconstruction.

CONCLUSIONS

Currently, the "state of the art" in tissue engineering solutions for urologic reconstruction means resorbable acellular xenograft matrices. They show promise when used as a pubovaginal sling or extra bolstering layers in ureteral or urethral repairs, although recent problems with inflammation following 8-ply pubovaginal sling use and failures after 1- and 4-ply SIS repair of Peyronie's disease underscore the need for research before wide adoption. Preliminary data is mixed concerning the potential for ECM urethral patch graft, and more data is needed before extended uses such as bladder augmentation and ureteral replacement are contemplated. The distant future of ECMs in urology likely will include cell-seeded grafts with the eventual hope of producing "off the shelf" replacement materials. Until that day arrives, ECMs only fulfill some of the requirements for the reconstructive urologist.

Penile enhancement using a porcine small intestinal submucosa graft in a rat model

Several biodegradable materials have been experimented for penile enhancement, but none show the potential for clinical use. This study was designed to use porcine small intestinal submucosa (SIS) augmenting the normal tunica albuginea to increase the functional girth of the rat penis. In all, 20 adult male Sprague-Dawley rats constituted the study population. The animals were divided into two groups: group 1 consisted of the control (n=10) and group 2 (n=10) consisted of rats that underwent penile enhancement by a longitudinal I-shaped incision of the tunica albuginea on both sides, and the dissection of the plane between tunica albuginea and cavernosal tissue was carried out (n=10). The incision was then patched with a 3 x 10 mm2 piece of SIS, using a 6/0 nylon suture material. The penile length and mid-circumference were then measured using a Vernier Caliper before and 2 months after surgery. All rat penises underwent histological examination using Masson's trichome and Verhoff's van Giesen's stain for collagen and elastic fibers. The penile length, mid-circumference and degree of fibrosis score were expressed as mean+/-s.e. (standard error) and analyzed using a Wilcoxon rank-sum test. A statistical significance was accepted at P-value < or =0.05. Our results showed similar preoperative penile length and circumference in both groups. However, 2 months after the surgery, the mean penile circumference of the SIS group has grown significantly larger than the control group, while the mean penile length remained unchanged. The histological study of the rat penises revealed minimal amounts of fibrosis under the graft, and the elastic fibers of the graft showed orientation in a circular manner. In conclusion, SIS appears promising for material use in a penile enhancement.

Single-layer small intestinal submucosa or tunica vaginalis flap for correcting penile chordee

OBJECTIVE

To evaluate the use of single-layer small intestinal submucosa (SIS) and tunica vaginalis flap (TVF) for covering defects in the ventral surface of the tunica albuginea to correct severe penile chordee.

MATERIALS AND METHODS

In all, 24 New Zealand white rabbits had a rectangular area excised from the ventral surface of tunica albuginea. In 12 rabbits TVF was used to cover the defect and in the remaining animals single-layer SIS was used. Animals were killed in groups of four at 2-, 6- and 12-week intervals after surgery. Before death in the 12-week group, an artificial erection was induced and cavernosography performed. Transverse sections of the penis at the graft site were stained with haematoxylin and eosin and Masson's trichrome, and examined microscopically.

RESULTS

None of the animals developed haematoma or bleeding. The mean operative duration for TVF and SIS grafts were 56 and 29 min, respectively (P < 0.001). At the time of autopsy, there was no contracture in any of the rabbits. Of the 8 rabbits assessed, all had a straight rigid erection and cavernosography showed evidence of an intact corporal veno-occlusive mechanism. Histologically at 6 and 12 weeks, the mesothelial layers of the TVF and the SIS graft were completely replaced by well-collagenized tissue similar to that of normal tunica albuginea, with no inflammatory infiltrate.

CONCLUSIONS

Both the TVF and single-layer SIS graft are viable comparable options for corporal body grafting. The 'off-the-shelf' availability, significantly quicker operation and absence of donor site morbidity make single-layer SIS better than TVF for correcting chordee.

Critical analysis of surgery for Peyronieʼs disease

PURPOSE OF REVIEW

This review focuses on the surgical management of Peyronie's disease in the light of recent published reports from 2003 and 2004.

RECENT FINDINGS

Although there have been a number of non-surgical innovations in this field, the surgical treatment of Peyronie's disease still remains the only alternative for patients not responding to other therapies. Various surgical modalities have recently been promulgated, however the ideal surgical procedure is still not perfected, particularly in cases of severe and complex penile curvature. The recent results of various surgical approaches have engendered concern about their long term benefits.

SUMMARY

The initial management of the acute presentation of Peyronie's disease is conservative and non-surgical. Surgery for Peyronie's disease is contemplated only after stabilization of the fibrotic process, and is generally reserved for men with severe penile deformities that impede satisfactory sexual intercourse. If there is ample penile length and the deformity is mild to moderate in severity, a variety of plication techniques may be considered to provide a straight and functional penis. In patients with larger plaques, severe curvature, complete or hourglass deformities, then incision or excision of the plaque and the placement of a graft are recommended. Most authorities currently favor non-synthetic graft materials whose properties resemble the anatomy and functionality of the tunica albuginea. The implantation of a penile prosthesis, with or without excision/incision of the diseased tunica albuginea, is reserved for patients with erectile dysfunction who have not responded to medical therapies. Manual modeling of the deformed penis over a penile prosthesis may prevent some patients from needing more complex surgical grafting procedures.

Functional Tissue Engineering of Autologous Tunica Albuginea: A Possible Graft for Peyronie’s Disease Surgery

OBJECTIVES

The aim of the present study was to generate a tissue engineered type of mechanically stable graft suitable for surgical replacement of the tunica albuginea penis.

METHODS

Porcine fibroblasts isolated from open fascia biopsies were seeded on decellularized collagen matrices and then cultivated in a bioreactor under continuous multiaxial stress for up to 21 days (n=12). Static cultures without mechanical stress served as controls. Cell proliferation, cell alignment, and de novo synthesis of extracellular matrix proteins (proteoglycans, procollagen I, elastin) in these grafts was evaluated by hematoxylin-eosin, pentachrome, and immuno-staining. Additionally, the enzymatic isolation of porcine fibroblasts from X4mm skin punch biopsies (n=8) was evaluated.

RESULTS

Mechanically strained cultures of fibroblasts showed a homogeneous multilayer matrix infiltration and a regular cell alignment in the direction of strain axis after 7 days, as well as a de novo production of extracellular matrix proteins compared to the static control. A large amount of viable fibroblasts was easily obtained from small skin punch biopsies.

CONCLUSION

This study shows that continuous multiaxial stimuli improve proliferation and extracellular matrix synthesis of mature fibroblasts reseeded on a biological matrix making this a feasible autologous tissue engineered graft for penile surgery. For the clinical setting fibroblasts harvested from small skin biopsies can be a comfortable cell source.

Tissue engineering in urology: where are we going?

Tissue engineering in urology is a broad term used to describe the development of alternative tissue sources for diseased or dysfunctional native urologic tissue. This article reviews the recently published techniques involving synthetic and natural biodegradable matrices alone, known as "unseeded" scaffolds, and the latest data on "seeded" scaffolds, which are impregnated with cultured cells from urologic organs. Recent discoveries in reporter gene labeling of urologic tissue are discussed as a new method to identify and track the fates of these transplanted cells in vivo. This article also investigates how these bioengineering techniques are applied to synthetic and natural scaffolds, such as polyglycolic acid and porcine small intestine submucosa, to increase bladder capacity, repair urethral strictures, and replace corporal plaques in Peyronie's disease. Furthermore, recently published reports that these materials have been seeded with chondrocytes to create corporal rods for penile prostheses and stents for ureteral and urethral stricture disease are discussed. With these latest developments as a foundation, the future directions of tissue engineering in urology are presented.