Tunica albuginea acellular matrix graft for penile reconstruction in the rabbit: a model for treating Peyronie's disease

Evaluation of Bi-Layer Silk Fibroin Grafts for Penile Tunica Albuginea Repair in a Rabbit Corporoplasty Model

The use of autologous tissue grafts for tunica albuginea repair in Peyronie's disease and congenital chordee is often restricted by limited tissue availability and donor site morbidity, therefore new biomaterial options are needed. In this study, bi-layer silk fibroin (BLSF) scaffolds were investigated to support functional tissue regeneration of tunica albuginea in a rabbit corporoplasty model. Eighteen adult male, New Zealand white rabbits were randomized to nonsurgical controls (NSC, N = 3), or subjected to corporoplasty with BLSF grafts (N = 5); decellularized small intestinal submucosa (SIS) matrices (N = 5); or autologous tunica vaginalis (TV) flaps (N = 5). End-point evaluations were cavernosography, cavernosometry, histological, immunohistochemical, and histomorphometric assessments. Maximum intracorporal pressures (ICP) following papaverine-induced erection were similar between all groups. Eighty percent of rabbits repaired with BLSF scaffolds or TV flaps achieved full rigid erections, compared to 40% of SIS reconstructed animals. Five-minute peak erections were maintained in 60% of BLSF rabbits, compared to 20% of SIS and TV flap reconstructed rabbits. Graft perforation occurred in 60% of TV group at maximum ICP compared to 20% of BLSF cohort. Neotissues supported by SIS and BLSF scaffolds were composed of collagen type I and elastin fibers similar to NSC. SIS and TV flaps showed significantly elevated levels of corporal fibrosis relative to NSC with a corresponding decrease in corporal smooth muscle cells expressing contractile proteins. BLSF biomaterials represent emerging platforms for corporoplasty and produce superior functional and histological outcomes in comparison to TV flaps and SIS matrices for tunica albuginea repair.

Feasibility of Polycaprolactone Scaffolds Fabricated by Three-Dimensional Printing for Tissue Engineering of Tunica Albuginea

PURPOSE

To investigate the feasibility of a polycaprolactone (PCL) scaffold fabricated by three-dimensional (3D) printing for tissue engineering applications for tunica albuginea.

MATERIALS AND METHODS

PCL scaffolds were fabricated by use of a 3D printing system. Two scaffolds were fabricated that differed in the architecture of the lay-down pattern: a 90°PCL scaffold and a 45°PCL scaffold. Mechanical properties were measured to compare tensile strength between the two scaffold types. The scaffolds were characterized by scanning electron microscope (SEM) images. The scaffolds were seeded with fibroblast cells, and the ability of these scaffolds to support the cells was evaluated by immunofluorescence staining.

RESULTS

The PCL scaffolds had well-structured shapes, regular arrays, and good interconnection in SEM images. The horizontal and vertical Young's modulus coefficients were 13 and 12 MPa for the 90°PCL scaffold and 19 and 21 MPa for the 45°PCL scaffold, respectively. Microscopy images revealed that human fibroblast cells covered the entire scaffold surface. Immunofluorescence staining of ER-TR7 confirmed that the fibroblast cells remained viable and proliferated throughout the time course of the culture.

CONCLUSIONS

This preliminary study provides experimental evidence for the feasibility of 3D printing of PCL scaffolds for tissue engineering applications of tunica albuginea.

Tissue engineering for penile surgery: comparative study of noncellular and cell-seeded synthetic grafts for tunica albuginea replacement

INTRODUCTION

Surgical treatment outcomes in Peyronie's disease remain controversial because of high rates of recurrence.

AIM

The aim of this study was to engineer in vitro a new type of tunica albuginea (TA) autologous graft obtained by culture of autologous fibroblast on a polyglycolic acid (PGA) scaffold. This engineering graft was compared with PGA with morphological and functional outcomes for TA replacement, 4 months after graft upon corpus cavernosum in a rat model.

METHODS

Thirty-nine Sprague Dawley adult male rats were divided into four groups: (i) control group (C) with resection and resuture of a 5 mm long and 2 mm large piece of original TA; (ii) PGA scaffold group (P) with the same resection of TA and suture of PGA scaffold; (iii) autologous fibroblast-seeded on PGA scaffold graft after resection of the same piece of TA (F + P); and (iv) sham group for functional and histological comparison.

MAIN OUTCOME MEASURE

The main outcome measure was assessment of graft size variation at 4 months and comparison between the three test groups. The secondary objective is assessment of erectile function by measuring erectile response to cavernous nerve electrical stimulation in each group.

RESULTS

At 4 months, there was a significant difference in graft area retraction between the groups (P = 0.0081) with higher retraction in P group vs. in C or F + P groups. Erectile response to cavernous nerve stimulation significantly differed between the groups and was sham equivalent to C equivalent to F + P superior to P group.

CONCLUSIONS

This study provides experimental evidence for the feasibility and the functionality of fibroblast-seeded scaffold compared with acellular graft for TA replacement.

Human acellular matrix graft of tunica albuginea for penile reconstruction

INTRODUCTION

Penile curvature is one of the most common male conditions, affecting nearly 10% of men, and can impair sexual intercourse. Tunica albuginea (hTA) plays a key role in penile curvature, and reconstructive procedures may be necessary for its substitution. Although several grafts have been proposed for hTA repair, the ideal graft is not yet available.

AIM

The aim of this article is to evaluate a new human tunica albuginea acellular matrix (hTAAM) as potential graft for penile reconstructive procedures.

METHODS

Twelve penises were obtained during sex reassignment surgeries from male-to-female transsexual patients. After dissection, hTAs were assigned into two groups according to the decellularization methods: polyethylene glycol (PEG) 1000 method following ultraviolet-C radiation, and Triton X-100 modified method.

MAIN OUTCOME MEASURES

Structural analyses were assessed by hematoxilin and eosin, Masson's trichrome, Weigert's, and picrosirius-polarization staining methods. Total protein, total glycosaminoglycan (GAG), and nucleic acid (DNA and RNA) concentrations were assessed by specific biochemical analyses. Uniaxial strength tests were performed to evaluate biomechanical properties.

RESULTS

All hTAAMs presented no nuclear or cellular remnants. Total protein concentration was significantly higher in PEG 1000 hTAAM. Despite GAG concentration decreased significantly in hTAAM, Triton X-100 hTAAM retained the highest GAG concentration (1.0 ± 0.42 µg HexUr/mg dry tissue, P > 0.05). All decellularization methods were efficacious to remove nucleic acids. The maximal break point presented no difference between hTA and hTAAM groups (P > 0.05).

CONCLUSIONS

PEG 1000 and Triton X-100 decellularization methods provide equally successful hTAAMs, preserving original structural and biochemical properties.

Surgical option for the correction of Peyronie's disease: an autologous tissue-engineered endothelialized graft

INTRODUCTION

Surgical treatment is indicated in severe cases of Peyronie's disease. Incision of the plaque with subsequent graft material implantation is the option of choice. Ideal graft tissue is not yet available.

AIM

To evaluate the use of an autologous tissue-engineered endothelialized graft by the self-assembly method, for tunica albuginea (TA) reconstruction in Peyronie's disease.

METHODS

Two TA models were created. Human fibroblasts were isolated from a skin biopsy and cultured in vitro until formation of fibroblast sheets. After 4 weeks of maturation, human umbilical vein endothelial cells (HUVEC) were seeded on fibroblasts sheets and wrapped around a tubular support to form a cylinder of about 10 layers. After 21 days of tube maturation, HUVEC were seeded into the lumen of the fibroblast tubes for the endothelialized tunica albuginea (ETA). No HUVEC were seeded into the lumen for the TA model. Both constructs were placed under perfusion in a bioreactor for 1 week.

MAIN OUTCOME MEASURES

Histology, immunohistochemistry, and burst pressure were performed to characterize mature tubular graft. Animal manipulations were also performed to demonstrate the impact of endothelial cells in vivo.

RESULTS

Histology showed uniform multilayered fibroblasts. Extracellular matrix, produced entirely by fibroblasts, presented a good staining for collagen 1. Some elastin fibers were also present. For the TA model, anti-human von Willebrand antibody revealed the endothelial cells forming capillary-like structures. TA model reached a burst pressure of 584 mm Hg and ETA model obtained a burst pressure of 719 mm Hg.

CONCLUSIONS

This tissue-engineered endothelialized tubular graft is structurally similar to normal TA and presents an adequate mechanical resistance. The self-assembly method used and the autologous property of this model could represent an advantage comparatively to other available grafts. Further evaluation including functional testing will be necessary to characterize in vivo implantation and behavior of the graft.

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.

Use of oxidized cellulose for corporal body grafting and suture-less correction of severe penile chordee: an experimental study in rabbits

OBJECTIVE

To evaluate the efficacy of oxidized cellulose, Surgicel(TM) (Johnson & Johnson Medical, New Brunswick, NJ, USA) for patching defects in the tunica albuginea in a rabbit model, with a future application to correct chordee.

MATERIALS AND METHODS

The study comprised nine New Zealand white male rabbits; a rectangular 15 x 5-mm defect was created in the ventral tunica albuginea that was covered by Surgicel. The skin was closed with no catheters left in situ after the procedure. The rabbits were killed in groups of three at 2, 6 and 12 weeks after surgery. The evaluation included cavernosography and histopathological examination of sections of the penis stained with haematoxylin and eosin, and Masson's trichrome.

RESULTS

No deaths were caused by the procedure, and none of the rabbits developed bleeding or haematoma after surgery. Cavernosography at 2 weeks showed contrast medium leaking from the site of the Surgicel, but at 6 and 12 weeks all rabbits had a straight erection with patent corpora and no evidence of narrowing or venous leak. Histopathological evaluation revealed evidence of the remnants of Surgicel surrounded by acute inflammatory cell infiltrate with early neovascularization at 2 weeks. At 6 and 12 weeks, there was complete normal regeneration of the tunica albuginea with no foreign-body reaction.

CONCLUSIONS

In this pilot study, Surgicel had a clear haemostatic effect when covering a defect in the tunica albuginea. Moreover, normal tunica albuginea regenerated by 6 weeks and was maintained at 12 weeks. These results suggest that Surgicel might be considered a safe and effective grafting material for tunica albuginea substitution, including the surgical management of penile chordee.

[Regenerative medicine in andrology: tissue engineering and gene therapy as potential treatment options for penile deformations and erectile dysfunction]

Tissue engineering and gene therapy are currently investigated in animal studies for reconstructing penile tissue or treating erectile dysfunction. This review aims to ecamine these experimental efforts from the last years and tries to give a brief introduction to the basic methodology of these new techniques from the field of regenerative medicine.

The dorsal lamina of the rectus sheath: a suitable grafting material for the penile tunica albuginea in Peyronie's disease?

OBJECTIVE

To estimate the morphological suitability of human connective tissue structures from different regions as graft material in Peyronie's disease, and to present preliminary results from 12 patients with grafting of corporal bodies using autologous rectus sheath.

PATIENTS AND METHODS

In five male cadavers the penile tunica albuginea was compared with the dorsal lamina of the rectus sheath, the palmar aponeurosis, the iliotibial tract and the Achilles tendon by using histological sections stained with haematoxylin and eosin, Crossmon's trichrome stain and resorcin-fuchsin. Surgical results and complication rates were investigated in 12 patients with Peyronie's disease after grafting the corporal bodies with autologous rectus sheath to correct their penile curvature.

RESULTS

On histology, the penile tunica albuginea showed a three-dimensional meshwork of collagenous and elastic fibres. The dorsal lamina of the rectus sheath had a remarkably similar fibre structure. The other tissues had a different histology, with long collagenous fibres in parallel orientation and elastic fibres restricted to the loose connective tissue around blood vessels and nerves. Clinically, the penile deviation was successfully corrected in 10 patients; there were two residual deviations (15 degrees and 35 degrees ). There were minor complications after surgery in six patients, not requiring surgery.

CONCLUSIONS

The dorsal lamina of the rectus sheath has similar morphological characteristics to the tunica albuginea, and therefore represents an ideal autologous graft; the first clinical results are promising.

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.

Effects of renal denervation of the contralateral kidney on blood pressure and sodium and eicosanoid excretion in the chronic phase of two-kidney, one-clip renovascular hypertension in rats

OBJECTIVE

To define the role of the renal nerves of the contralateral kidney in the maintenance of two-kidney, one-clip (2K-1C) renovascular hypertension in rats.

MATERIAL AND METHODS

The contralateral kidney of 2K-1C rats was denervated 6 months after induction of hypertension and 4 weeks after nephrectomy of the clipped kidney. Blood pressure, sodium and potassium balance and eicosanoid excretion were measured.

RESULTS

Denervation of the contralateral kidney induced normalization of blood pressure in post-Goldblatt hypertensive rats. This effect was not mediated by a negative sodium balance. Excretion of prostaglandin E2 and thromboxane B2 increased after denervation of the contralateral kidney in both post-Goldblatt hypertensive and post-Goldblatt normotensive rats, while urine extraction remained unaffected.

CONCLUSION

Afferences from the contralateral kidney appear to participate in the maintenance of 2K-1C renovascular hypertension due to the activation of central mechanisms regulating blood pressure.

[Acellular matrix for functional reconstruction of the urogenital tract. Special form of "tissue engineering"?]

Organ substitution and reconstruction of the urogenital system still poses a problem regarding an adequate substitute. Usually non-organ-specific materials are used for reconstruction (bowl, buccal mucosa). This nonspecific tissue can cause side effects that result from the origin and the natural function. Different groups have shown that an acellular matrix graft in the urinary bladder and the urethra served as a scaffold for complete regeneration of all organ wall components and that this organ-specific regeneration simultaneously facilitates functional restitution. New approaches will presumably effect better regeneration after seeding the matrix with organ-specific cells (i.e., urothelial cells). Smaller studies on genital reconstructive surgery could show that vaginal substitution with an acellular matrix might be possible or that there could be a possible substitute for the tunica during surgical treatment of Peyronie's disease.

Canine ureteral replacement with long acellular matrix tube: is it clinically applicable?

PURPOSE

We evaluated the effectiveness of acellular matrix used as a tube for replacement of a relatively long segment of the canine ureter.

MATERIALS AND METHODS

Acellular matrix was obtained by excision of the whole ureter of donor dogs that were sacrificed and not included in the study group. Retrieved ureters were treated to have complete cell lysis, while maintaining the fiber framework. The study included 10 mongrel dogs in which a 3 cm segment was excised from 1 ureter and replaced by a tube of acellular matrix of the same length and width. The new tube was sutured proximal and distal by watertight interrupted sutures around a 5Fr Double-J stent (Medical Engineering Corp., New York, New York) that remained for 6 weeks. Excretory urography was done 1 and 2 weeks after stent removal and the dogs were then sacrificed. Before sacrifice the ureter was exposed and carefully examined, and the whole specimen was excised for histopathological examination.

RESULTS

All dogs survived surgery except 1, which died 1 week postoperatively of a malpositioned stent and urinary ascites. There was no clinically apparent postoperative complications during the presence or after the removal of the ureteral stents. One week after stent removal excretory urography showed ipsilateral mild to moderate hydroureteronephrosis in 3 dogs and no dye excretion in 6 with a normal contralateral kidney. One week later no dye excretion was detected in all except 1 dog, which showed more radiological deterioration. At the time of sacrifice there was moderate to marked hydroureteronephrosis above the level of the new tube in all dogs. Although the graft was intact in all subjects, marked shrinkage was observed. On ureteral calibration there was significant narrowing of the lumen up to complete occlusion. At 8 weeks histopathological examination showed extensive fibrosis.

CONCLUSIONS

An acellular matrix tube is not able to replace a 3 cm segment of the canine ureter.

Fibrin glue for the suture-less correction of penile chordee: a pilot study in a rabbit model

OBJECTIVE

To evaluate the use of fibrin glue as a scaffold for patching defects in the tunica albuginea in a rabbit model for a future application in correcting chordee.

MATERIALS AND METHODS

Nine New Zealand white male rabbits were utilized. All had a 15 x 5-mm defect created in the ventral tunica albuginea. Fibrin glue (1 mL) was applied to cover the defect in tunica albuginea and the penile skin closed with a continuous 5/0 chromic catgut suture. Animals were killed in groups of three at 2, 6 and 12 weeks afterward. The evaluation included an artificial erection test with intracavernosal injection of prostaglandin E1 (5 microg), cavernosography and histopathological examination of sections of the penis stained with haematoxylin and eosin or Masson trichrome.

RESULTS

None of the rabbits died during the procedure or developed bleeding or haematoma afterward. All animals had straight erections on testing with prostaglandin (5 microg). There was no evidence of corporal narrowing or venous leakage on cavernosography. Histopathological evaluation showed evidence of the fibrin sealant layer, with angiogenesis and a cell infiltrate at 2 weeks. At 6 and 12 weeks there was completely normal regeneration of the tunica albuginea.

CONCLUSIONS

In this pilot study in a rabbit model the haemostatic effect of fibrin glue was confirmed on covering a defect in the tunica albuginea. Moreover, there was regeneration of normal tunica albuginea with no scarring at 6 weeks and maintained at 12 weeks. Further well-controlled studies are required before using fibrin glue for corporal body grafting to treat chordee.

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.

Vaginal and penile reconstruction

PURPOSE OF REVIEW

Reconstructive surgery for patients with genital abnormalities or for patients who require reconstructive efforts is challenging. This review highlights those articles, which are outstanding among all those important papers, which have been published during the last year (2002-2003).

RECENT FINDINGS

A greater understanding of embryonal development improves the success of reconstructive surgery. Other factors, such as the patient's sex, influence the surgical technique used and the degree of invasiveness or complexity. In the adult the pressure to shorten hospital stays has played a big part in the continual modification and enhancement of surgical techniques. In addition to modified techniques, new off-the-shelf materials are introduced to the clinic, which seem to have the potential to improve the surgical outcome and shorten hospital stays.

SUMMARY

With the continued successful basic anatomy and basic research, reconstructive surgery brings higher success rates. Long-term results are still required to validate the reliability of these new surgical techniques and materials.