Schwann cell seeded guidance tubes restore erectile function after ablation of cavernous nerves in rats

Icariside II facilitates the differentiation of ADSCs to schwann cells and restores erectile dysfunction through regulation of miR-33/GDNF axis

BACKGROUND

Adipose derived stem cells (ADSCs) have the property to differentiate into neuron-like cells, which may provide a novel insight for the restoration of erectile dysfunction (ED) mainly induced by cavernous nerve injury. Icariside II (ICA II) has been reported to play a key role in the regulation of erectile function via stimulating the differentiation of ADSCs to Schwann Cells (SCs). However, the function and molecular mechanisms of ICA II in ED remains to be further clarified.

METHODS

The expression of S100, P75, GDNF and miR-33 was detected by qRT-PCR. And the relative proteins expression was determined by western blot. Cell viability was measured by Cell Counting Kit-8 (CCK-8) assay. Bioinformatics, luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to verify the interaction between miR-33 and GDNF. Intracavernosal pressure (ICP), the ratio of ICP and mean arterial pressure (MAP), as well as nNOS expression were examined to evaluate the erectile function of SD rats with bilateral cavernous nerve injury (BCNI).

RESULTS

ICA II and miR-33 respectively promoted and inhibited the differentiation of ADSCs to SCs. MiR-33 could negatively regulate P75 and GDNF expression. ICA II exerted promotion effects on differentiation of ADSCs to SCs via regulating miR-33. GDNF was identified to be a target of miR-33. MiR-33 overexpression abrogated the stimulatory effect of ICA II on ADSCs' differentiation, which was blocked by GDNF overexpression. treated with ICA II recovered the erectile function of BCNI model rats through regulation of miR-33.

CONCLUSION

ICA II contributed to the differentiation of ADSCs to SCs viamiR-33/GDNF axis, contributing to the recovery of erectile function in BCNI rats.

Recovery of erectile function comparing autologous nerve grafts, unseeded conduits, Schwann-cell-seeded guidance tubes and GDNF-overexpressing Schwann cell grafts

Dissection of the cavernous nerves during radical prostatectomy for prostate cancer eliminates spontaneous erections. Using the rat as an experimental model, we compared the regenerative capacity of autologous nerve grafts and Schwann-cell-seeded nerve guides. After bilateral excision of cavernous nerve segments, cavernous nerves were reconstructed using unseeded silicon tubes, nerve autografts and silicon tubes seeded with either Glial-cell-line-derived (GDNF)-overexpressing or green fluorescent protein (GFP)-expressing Schwann cells (SCs) (16 study nerves per group). Control groups underwent either a sham operation or bilateral excision of cavernous nerve segments without repair. After 12 weeks erectile function was assessed by neurostimulation and intracavernous pressure (ICP) measurement. The reconstructed nerve segments were excised and histologically analyzed. We demonstrated an intact erectile response upon neurostimulation in 25% (4/16) of autologous nerve grafts, in 50% (8/16) of unseeded tubes, in 75% (12/16) of the Schwann-cell-GFP group and in 93.75% (15/16) of the GDNF group. ICP was significantly increased when comparing the Schwann-cell-GFP group with nerve autografts, unseeded conduits and negative controls (P<0.005). In conclusion, Schwann-cell-seeded scaffolds combined with neurotrophic factors are superior to unseeded tubes and autologous nerve grafts. They present a promising therapeutic approach for the repair of erectile nerve gaps.

Tonsil-Derived Mesenchymal Stem Cells Differentiate into a Schwann Cell Phenotype and Promote Peripheral Nerve Regeneration

Schwann cells (SCs), which produce neurotropic factors and adhesive molecules, have been reported previously to contribute to structural support and guidance during axonal regeneration; therefore, they are potentially a crucial target in the restoration of injured nervous tissues. Autologous SC transplantation has been performed and has shown promising clinical results for treating nerve injuries and donor site morbidity, and insufficient production of the cells have been considered as a major issue. Here, we performed differentiation of tonsil-derived mesenchymal stem cells (T-MSCs) into SC-like cells (T-MSC-SCs), to evaluate T-MSC-SCs as an alternative to SCs. Using SC markers such as CAD19, GFAP, MBP, NGFR, S100B, and KROX20 during quantitative real-time PCR we detected the upregulation of NGFR, S100B, and KROX20 and the downregulation of CAD19 and MBP at the fully differentiated stage. Furthermore, we found myelination of axons when differentiated SCs were cocultured with mouse dorsal root ganglion neurons. The application of T-MSC-SCs to a mouse model of sciatic nerve injury produced marked improvements in gait and promoted regeneration of damaged nerves. Thus, the transplantation of human T-MSCs might be suitable for assisting in peripheral nerve regeneration.

Hierarchically structured nerve guidance channels based on poly-3-hydroxybutyrate enhance oriented axonal outgrowth

Traumatic peripheral nerve lesions can cause local anesthesia, paralysis and loss of autonomic control. Reconstruction using engineered nerve guidance conduits (NGCs) is rarely successful due to the sub-optimal characteristics of the conduits. To address the demands of clinical practice, we developed a hierarchically structured NGC from slowly resorbing poly(3-hydroxybutyric acid) (P3HB). The NGC consists of a permeable single-lumen tube and melt-spun fibrillar lumen fillers. Permeable tubes were constructed from P3HB/poly(ɛ-caprolactone) (PCL) blends or poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid) (P(3HB-co-4HB)). Polyvinylpyrrolidone was used as a porogen in solvent-free thermoplastic processing, followed by selective polymer leaching. All tested material compositions showed hydrolytic degradation after 16weeks in phosphate buffered saline, whereas P3HB/PCL tubes maintained mechanical strength compared to (P(3HB-co-4HB)). The porous scaffolds allowed diffusion of large molecules (∼70kDa). In vitro studies demonstrated that mouse fibroblasts survived and proliferated inside closed porous tubes. An in vitro model of axonal regeneration using dorsal root ganglia and sympathetic cervical ganglia demonstrated that the NGCs successfully supported neuron survival and neurite outgrowth. The introduction of fibrillar lumen fillers promoted oriented neurite growth and coating with extracellular matrix proteins further increased ganglia attachment and cell migration. In this study we show that P3HB-based NGCs scaffolds have potential in long gap peripheral nerve repair strategies.

Schwann cell-mediated delivery of glial cell line-derived neurotrophic factor restores erectile function after cavernous nerve injury

OBJECTIVES

To evaluate the time-course of functional recovery after cavernous nerve injury using glial cell line-derived neurotrophic factor-transduced Schwann cell-seeded silicon tubes.

METHODS

Sections of the cavernous nerves were excised bilaterally (5 mm), followed by immediate bilateral surgical repair. A total of 20 study nerves per group were reconstructed by interposition of empty silicon tubes and silicon tubes seeded with either glial cell line-derived neurotrophic factor-overexpressing or green fluorescent protein-expressing Schwann cells. Control groups were either sham-operated or received bilateral nerve transection without nerve reconstruction. Erectile function was evaluated by relaparotomy, electrical nerve stimulation and intracavernous pressure recording after 2, 4, 6, 8 and 10 weeks. The animals underwent re-exploration only once, and were killed afterwards. The nerve grafts were investigated for the maturation state of regenerating nerve fibers and the fascular composition.

RESULTS

Recovery of erectile function took at least 4 weeks in the current model. Glial cell line-derived neurotrophic factor-transduced Schwann cell grafts restored erectile function better than green fluorescent protein-transduced controls and unseeded conduits. Glial cell line-derived neurotrophic factor-transduced grafts promoted an intact erectile response (4/4) at 4, 6, 8 and 10 weeks that was overall significantly superior to negative controls (P < 0.001). Maximum intracavernous pressure on electrostimulation was significantly elevated using glial cell line-derived neurotrophic factor-transduced grafts compared with negative controls (P = 0.018) and unseeded tubes (P = 0.034). Return of function was associated with the electron microscopic evidence of preganglionic myelinated nerve fibers and postganglionic unmyelinated axons.

CONCLUSIONS

Schwann cell-mediated delivery of glial cell line-derived neurotrophic factor presents a viable approach for the treatment of erectile dysfunction after cavernous nerve injury.

Sonic Hedgehog regulates brain-derived neurotrophic factor in normal and regenerating cavernous nerves

INTRODUCTION

The cavernous nerve (CN) is commonly injured during prostatectomy. Manipulation of the nerve microenvironment is critical to improve regeneration and develop novel erectile dysfunction therapies. Sonic hedgehog (SHH) treatment promotes CN regeneration. The mechanism of how this occurs is unknown. Brain-derived neurotrophic factor (BDNF) facilitates return of erectile function after CN injury and it has been suggested in cortical neurons and the sciatic nerve that BDNF may be a target of SHH.

AIM

To determine if SHH promotes CN regeneration through a BDNF-dependent mechanism.

METHODS

Sprague Dawley rats underwent (i) bilateral CN crush (N = 15); (ii) SHH treatment of pelvic ganglia (PG)/CN (N = 10); (iii) SHH inhibition in PG/CN (N = 14 rats); (iv) CN crush with SHH treatment of PG/CN (N = 10 rats); (v) CN crush with SHH treatment and BDNF inhibition (N = 14 rats); and (vi) CN injury and SHH treatment of the penis (N = 23).

MAIN OUTCOME MEASURES

BDNF and glial fibrillary acidic protein were quantified in PG/CN by Western, and a t-test was used to determine differences.

RESULTS

In normal rats SHH inhibition in the PG/CN decreased BDNF 34% and SHH treatment increased BDNF 36%. BDNF was increased 44% in response to SHH treatment of crushed CNs, and inhibition of BDNF in crushed CNs treated with SHH protein hampers regeneration.

CONCLUSIONS

SHH regulates BDNF in the normal and regenerating PG/CN. BDNF is part of the mechanism of how SHH promotes regeneration, thus providing an opportunity to further manipulate the nerve microenvironment with combination therapy to enhance regeneration.

Emerging tools for erectile dysfunction: a role for regenerative medicine

Erectile dysfunction (ED) is the most common sexual disorder reported by men to their health-care providers and the most investigated male sexual dysfunction. Currently, the treatment of ED focuses on 'symptomatic relief' of ED and, therefore, tends to provide temporary relief rather than providing a cure or reversing the cause. The identification of a large population of "difficult-to-treat" patients has triggered researchers to identify novel treatment approaches, which focus on cure and restoration of the underlying cause of ED. Regenerative medicine has developed extensively in the past few decades and preclinical trials have emphasized the benefit of growth factor therapy, gene transfer, stem cells and tissue engineering for the restoration of erectile function. Development of clinical trials involving immunomodulation in postprostatectomy ED patients and the use of maxi-K channels for gene therapy are illustrative of the advances in the field. However, the search for novel treatment targets and a wealth of preclinical studies represent a dynamic and continuing field of enquiry.

Advances in the study of the peripheral nervous system for erection in animals and humans

Introduction

Since Walsh first emphasized the importance of preserving the neurovascular bundle n to protect the cavernous nerve during pelvic surgery, patients' sexual life quality has dramatically improved. Today, nerve-sparing radical prostatectomy is the established gold standard for organ-confined prostate cancer patients. Recent technical advances in functional assessment such as intraoperative electrical stimulation have unveiled new anatomical features and physiological roles. Basic research has advanced understanding of cavernous nerve function, while molecular biology has uncovered the crucial role of neuronal nitric oxide in mediating erection, and has led to new treatments such as phosphodiesterase type-5 inhibitors. A recent focus in cavernous nerve research concerns the nerve distribution external to the neurovascular bundle. The cavernous nerves in humans appear to be distributed more widely beneath the lateral pelvic fascia than in other animals, and electrical stimulation studies suggest possible involvement of these nerves in erection. These findings have prompted new surgical techniques such as the "veil of Aphrodite", or "intrafascial nerve-sparing" procedures.

Materials and Methods

These recent anatomical and physiological studies in humans and animals and their impact are reviewed in this article.

Conclusions

Further investigation should stimulate future advances in strategies to preserve erectile function in RP patients.

Tissue engineering and stem cells: basic principles and applications in urology

To overcome problems of damaged urinary tract tissues and complications of current procedures, tissue engineering (TE) techniques and stem cell (SC) research have achieved great progress. Although diversity of techniques is used, urologists should know the basics. We carried out a literature review regarding the basic principles and applications of TE and SC technologies in the genitourinary tract. We carried out MEDLINE/PubMed searches for English articles until March 2010 using a combination of the following keywords: bladder, erectile dysfunction, kidney, prostate, Peyronie's disease, stem cells, stress urinary incontinence, testis, tissue engineering, ureter, urethra and urinary tract. Retrieved abstracts were checked, and full versions of relevant articles were obtained. Scientists have achieved great advances in basic science research. This is obvious by the tremendous increase in the number of publications. We divided this review in two topics; the first discusses basic science principles of TE and SC, whereas the second part delineates current clinical applications and advances in urological literature. TE and SC applications represent an alternative resource for treating complicated urological diseases. Despite the paucity of clinical trials, the promising results of animal models and continuous work represents the hope of treating various urological disorders with this technology.

Regeneration of the cavernous nerve by Sonic hedgehog using aligned peptide amphiphile nanofibers

SHH plays a significant role in peripheral nerve regeneration and has clinical potential to be used as a regenerative therapy for the CN in prostatectomy patients and in other patients with neuropathy of peripheral nerves. Efforts to regenerate the cavernous nerve (CN), which provides innervation to the penis, have been minimally successful, with little translation into improved clinical outcomes. We propose that, Sonic hedgehog (SHH), is critical to maintain CN integrity, and that SHH delivered to the CN by novel peptide amphiphile (PA) nanofibers, will promote CN regeneration, restore physiological function, and prevent penile morphology changes that result in erectile dysfunction (ED). We performed localization studies, inhibition of SHH signaling in the CN, and treatment of crushed CNs with SHH protein via linear PA gels, which are an innovative extended release method of delivery. Morphological, functional and molecular analysis revealed that SHH protein is essential to maintain CN architecture, and that SHH treatment promoted CN regeneration, suppressed penile apoptosis and caused a 58% improvement in erectile function in less than half the time reported in the literature. These studies show that SHH has substantial clinical application to regenerate the CN in prostatectomy and diabetic patients, that this methodology has broad application to regenerate any peripheral nerve that SHH is necessary for maintenance of its structure, and that this nanotechnology method of protein delivery may have wide spread application as an in vivo delivery tool in many organs.

Sonic hedgehog, apoptosis, and the penis

INTRODUCTION

Smooth muscle apoptosis in the penis is common in prostatectomy patients and animal models of erectile dysfunction (ED). A critical regulator of smooth muscle apoptosis in the penis is the secreted protein Sonic hedgehog (SHH). Since SHH protein treatment of the penis prevents cavernous nerve (CN) injury-induced apoptosis, SHH has the potential to treat post-prostatectomy apoptosis. However, little is known about how SHH signaling is regulated in the adult penis.

AIM

The goal of this review is to examine what is known about SHH signaling in the penis, to offer insight as to how SHH inhibition induces apoptosis in penile smooth muscle, and to define the role of the SHH pathway in maintaining CN integrity.

METHODS

Information presented in this review was derived from a literature search using the National Library of Medicine PubMed Services. Search terms included SHH, apoptosis, smooth muscle, penis, ED, pelvic ganglia, corpora cavernosa, CN, regeneration, Schwann cell, neural activity, and transport.

RESULTS

In this review, we have discussed the role of the CN in regulation of SHH abundance and apoptosis induction in the penis, and have examined the function and localization of SHH signaling in the CN.

CONCLUSION

There is substantial potential to develop SHH for delivery to the penis of prostatectomy patients at the time of surgery in order to prevent apoptosis induction and long-term ED development. Studies are in progress that will identify if SHH may be used as a regenerative therapy to speed CN regeneration.

The development of a rat model of erectile dysfunction after radical prostatectomy: preliminary findings

OBJECTIVE

To develop a rat model of erectile dysfunction (ED) after cavernous nerve injury.

MATERIALS AND METHODS

Given the great similarity between the anatomical structure of the cavernous nerve in rats and humans, 24 rats underwent dissections and the cavernous nerves were identified with the aid of an operating microscope. Then the rats were randomized into two groups: sham-operated controls and a bilateral cavernous nerve section group. At 3 months after surgery, the rats were evaluated for their response to an apomorphine challenge.

RESULTS

The erectile response after an apomorphine challenge was normal in all the control rats, while there were no erections in the bilateral injured group.

CONCLUSION

The rat major autonomic ganglion and its cavernous nerve can be identified with the aid of a microscope. Rats are inexpensive and easy to handle, thus a good animal for developing an ED model of cavernous nerve injury. In the present study, the rats with cavernous nerve injury lost erectile capacity in a reliable and reproducible fashion. Because of the great similarity between the cavernous nerve of rats and humans, one may consider this technique as a reliable experimental model for studying ED after radical prostatectomy.

Neural influences on sonic hedgehog and apoptosis in the rat penis

The role of sonic hedgehog (SHH) in maintaining corpora cavernosal morphology in the adult penis has been established; however, the mechanism of how SHH itself is regulated remains unclear. Since decreased SHH protein is a cause of smooth muscle apoptosis and erectile dysfunction (ED) in the penis, and SHH treatment can suppress cavernous nerve (CN) injury-induced apoptosis, the question of how SHH signaling is regulated is significant. It is likely that neural input is involved in this process since two models of neuropathy-induced ED exhibit decreased SHH protein and increased apoptosis in the penis. We propose the hypothesis that SHH abundance in the corpora cavernosa is regulated by SHH signaling in the pelvic ganglia, neural activity, or neural transport of a trophic factor from the pelvic ganglia to the corpora. We have examined each of these potential mechanisms. SHH inhibition in the penis shows a 12-fold increase in smooth muscle apoptosis. SHH inhibition in the pelvic ganglia causes significantly increased apoptosis (1.3-fold) and decreased SHH protein (1.1-fold) in the corpora cavernosa. SHH protein is not transported by the CN. Colchicine treatment of the CN resulted in significantly increased smooth muscle apoptosis (1.2-fold) and decreased SHH protein (1.3-fold) in the penis. Lidocaine treatment of the CN caused a similar increase in apoptosis (1.6-fold) and decrease in SHH protein (1.3-fold) in the penis. These results show that neural activity and a trophic factor from the pelvic ganglia/CN are necessary to regulate SHH protein and smooth muscle abundance in the penis.

[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.

Neuromodulatory Therapy to Improve Erectile Function Recovery Outcomes After Pelvic Surgery

PURPOSE

Erectile dysfunction is a recognized, common adverse consequence of radical prostatectomy as well as various other pelvic surgeries. While a host of management options have been considered to decrease this complication, neuromodulatory therapy has recently been advanced as an intervention that may be applied for this purpose. We evaluated concepts regarding the neuropathic basis for erectile dysfunction following pelvic surgery, principles for establishing neuromodulatory therapy in this clinical context, evidence from preclinical studies supporting neuromodulatory approaches as a therapeutic strategy and the progress of early clinical developments in this field.

MATERIALS AND METHODS

The exercise principally consisted of a current literature search using the National Library of Medicine PubMed Services, a survey of recent abstract proceedings from national meetings relevant to the topic and an Internet online search for current information on federally and privately supported clinical trials specific to this topic. References were made to such key words as neuroprotection, nerve regeneration, nerve growth factors, neurotrophic factors, cavernous nerves, nerve guides and penile erection.

RESULTS

Basic science research and clinical studies support the concept that erectile loss after pelvic surgery is frequently related to neuropathic effects, resulting in penile vascular impairment. An assortment of neurobiological studies using rodent models of cavernous nerve injury have shown nerve reconstitutive actions for a host of neurotrophic substances, including classic neurotrophins, growth hormone, cytokines and atypical neurotrophic mediators. Clinical trials of several proposed neuroprotective and neurotrophic applications have been done or are in progress.

CONCLUSIONS

Erectile dysfunction is a well recognized and yet ineffectively averted complication of pelvic surgery. Neuromodulatory therapy offers a therapeutic approach for addressing the neuropathic changes of the penis that occurs in this context with the goal of maximally preserving erectile function postoperatively. While several specific neuromodulatory applications have gained interest for their potential benefit with pelvic surgery, determining their actual roles awaits the completion of controlled clinical trials.

Update on erectile dysfunction in prostate cancer patients

PURPOSE OF REVIEW

Evolution in the management of prostate cancer includes increased attention being paid to patient quality of life after treatment, specifically with issues related to sexual function. Erectile dysfunction is one of the major concerns of patients undergoing treatment for prostate cancer. There are several recognized factors that determine the postoperative incidence of erectile difficulties, including patient age, degree of cavernosal nerve sparing during surgery, cancer stage, and associated vascular comorbidities. Early initiation of rehabilitation protocols after radical prostatectomy has been advocated to promote the speed and degree of recovery of erectile function. The aim of this communication is to review recent initiatives in erectile dysfunction restoration after prostate cancer therapy.

RECENT FINDINGS

In recognition of the neurogenic basis of erectile dysfunction after radical prostatectomy, new strategies have been devised to initiate the rehabilitation process. Type 5 phosphodiesterase inhibitors, vacuum erection devices, and intracavernosal and intraurethral application of vasoactive agents have all been reported in a positive light in recent studies. Developments in cavernous nerve graft interposition procedures, perioperative neuroprotection measures, and postoperative neurotrophic treatments aim to preserve prostate cancer patients' qualities of life.

SUMMARY

Data generated from a number of clinical investigations document that pharmacologic rehabilitation programs provide a higher rate of recovery of erectile function following radical prostatectomy. Both intracavernosal and intraurethral applications of vasoactive agents and vacuum devices can speed the recovery period for return of erectile function. Various neuroprotective and neurotrophic approaches are thought to provide integral roles for the maintenance of sexual function in men undergoing prostate cancer therapy.

Hope springs eternal: cavernosal nerve regeneration

Erectile dysfunction after radical prostatectomy for prostate cancer remains a significant morbidity for a large group of patients. A large body of work suggests that disrupting the cavernosal nerves is central as a causative factor. Extensive research has focused on ways to increase potency rates after surgery, either by preserving neuro-integrity, or attempting to restore it using various approaches. Herein we discuss the neurophysiology of nerve injury and regeneration, and review the work to date on cavernosal nerve regeneration.

Plasticity of pelvic autonomic ganglia and urogenital innervation

Pelvic ganglia contain a mixture of sympathetic and parasympathetic neurons and provide most of the motor innervation of the urogenital organs. They show a remarkable sensitivity to androgens and estrogens, which impacts on their development into sexually dimorphic structures and provide an array of mechanisms by which plasticity of these neurons can occur during puberty and adulthood. The structure of pelvic ganglia varies widely among species, ranging from rodents, which have a pair of large ganglia, to humans, in whom pelvic ganglion neurons are distributed in a large, complex plexus. This plexus is frequently injured during pelvic surgical procedures, yet strategies for its repair have yet to be developed. Advances in this area will come from a better understanding of the effects of injury on the cellular signaling process in pelvic neurons and also the role of neurotrophic factors during development, maintenance, and repair of these axons.

Nerve Replacement Strategies for Cavernous Nerves

OBJECTIVE

This article reviews novel restorative therapies for cavernous nerves that may be used to replace resected cavernous nerves at the time of pelvic surgery.

METHODS

A literature-based presentation (Medline search) on current nerve replacement strategies was conducted with emphasis on neurobiological factors contributing to the restoration of erectile function after cavernous nerve injuries.

RESULTS

A promising alternative to autologous nerve grafts for extending the length of successful nerve regeneration are artificial nerve guides. The addition of neurotrophic factors, extracellular matrix components and Schwann cells has been shown to promote cavernous nerve regeneration. Neurotrophic factors can be incorporated in the scaffold or can be supplied by cells seeded into the stroma. The regenerative capacity of these cells can be further enhanced by genetic modification with neurotrophic factor encoding genes.

CONCLUSIONS

Artificial nerve guides, especially biodegradable ones containing growth-promoting factors or cells, are a promising option for the repair of cavernous nerve lesions.

[Nerve repair strategies for restoration of erectile function after radical pelvic surgery]

Iatrogenic cavernous nerve lesions occurring during radical pelvic surgery often lead to irreversible erectile dysfunction. The nerve defects after excision of the neurovascular bundles must be reconstructed by interposition grafting to supply a permissive scaffold for oriented axonal regrowth. The use of autologous nerve grafts for the repair of human cavernous nerves during radical prostatectomy has been controversial regarding the limited success achieved with bilateral nerve grafting. Artificial nerve guides consisting of natural or synthetic materials have been successfully used for bridging peripheral nerve defects. The combination with Schwann cells, neurotrophic factors and extracellular matrix components has been shown to promote cavernous nerve regeneration.

Tissue Engineering erektiler Nerven

Dissection of the cavernous nerves eliminates spontaneous erections and may lead to irreversible erectile dysfunction due to degeneration of cavernous tissue. Novel procedures to reconstruct penile innervation include cavernous nerve interposition grafting and neurotrophic treatments to revitalize penile neural input, evaluated thus far in various preclinical models of cavernous nerve injury. Schwann cells crucially contribute to successful axonal regeneration by mechanical and paracrine mechanisms in the injured nerve, and Schwann cells seeded into guidance channels have been successfully employed to support regeneration in animal models of cavernous nerve injury. Gene therapy, tissue engineering, and reconstructive techniques have been combined to deliver neurotrophic factors and recover erectile function.