Persistence and survival of autologous muscle derived cells versus bovine collagen as potential treatment of stress urinary incontinence

Periurethral cellular injection: comparison of muscle-derived progenitor cells and fibroblasts with regard to efficacy and tissue contractility in an animal model of stress urinary incontinence

OBJECTIVES

To compare muscle-derived cells (MDCs) and fibroblasts with regard to their potential for restoration of urethral function on injection in a previously established animal model of stress urinary incontinence.

METHODS

The animals were divided into four (dosage) or five (cell concentration) experimental groups: normal, nontreated controls (normal group) or bilateral sciatic nerve transection with either periurethral injection of saline (saline group), MDCs (MDC group), fibroblasts (fibroblast group), or MDC/fibroblast mixture (mixed group). At 4 weeks after injection, the leak point pressure (LPP) was measured and contractility testing and histologic analysis were performed.

RESULTS

The histologic examination demonstrated muscular atrophy in the saline group and new striated muscle fibers at the sites of MDC injection in the MDC group, but not in the fibroblast group. Denervation of the urethra resulted in a significant decrease of maximal fast-twitch muscle contraction amplitude to only 9% of normal. MDC injection into the denervated urethra significantly improved the fast-twitch muscle contraction amplitude to 73% of normal. The LPP of the normal, saline, MDC, fibroblast, and mixed groups at 4 weeks after treatment was 43.3 +/- 2.5, 25.8 +/- 1.4, 38.2 +/- 4.2, 38.3 +/- 1.2, and 34.5 +/- 3.3 cm H2O, respectively. In the cell dosage experiment, the LPP increased with increases in the injected cell number. Evidence of obstruction was observed in the high-dose (1 x 10(7) cells) fibroblast group.

CONCLUSIONS

Although both MDCs and fibroblast injection increased the LPP in a stress urinary incontinence rat model, only MDCs significantly improved urethral muscle strip contractility. Moreover, urinary retention developed with high-dose fibroblast injection, but not with MDC injection.

Injection of skeletal muscle-derived cells into the penis improves erectile function

We investigated the effect of intrapenile injection of muscle-derived cells (MDC) on the erectile function in rats with bilateral cavernous nerve injury. Rat MDC were harvested and transduced with a retrovirus expressing the lacZ gene. Hanks' balanced salt solution (HBSS) (20 microl) or MDC (1 x 10(6) cells/side) were injected in each corpora cavernosa immediately before bilateral cavernous nerve transection. Intracavernous pressures (ICP) were measured 2 or 4 weeks after surgery with electrical stimulation of the pelvic nerves. Mean maximal ICP of sham group was significantly lower than that of control group both at 2 and 4 weeks after surgery. When MDC were injected into the penis, ICP improved over the sham-injected group at both 2 and 4 weeks after surgery. Percent area of PGP 9.5 staining was significantly greater in MDC-injected penis than in sham-injected at 2 and 4 weeks. Penile MDC injection can facilitate recovery of injured penile innervation and improve erectile function.

Processed lipoaspirate cells for tissue engineering of the lower urinary tract: implications for the treatment of stress urinary incontinence and bladder reconstruction

PURPOSE

We performed a pilot study to investigate the ability of human adipose derived, multipotent stem cells to be delivered to and survive within bladder and urethral smooth muscle.

MATERIALS AND METHODS

Lipoaspirate was acquired from female patients undergoing liposuction. The lipoaspirate was processed to yield a pluripotent population of processed lipoaspirate (PLA) cells. For tissue delivery PLA cells were fluorescent labeled and suspended in Hanks' balanced salt solution (Sigma Chemical Co., St. Louis, Missouri). To assess PLA viability in multiple animal models 8 Rnu athymic rats (Charles River, Wilmington, Massachusetts) and 6 SCID mice (Taconic Farms, Oxnard, California) underwent laparotomy and injection of PLA cells into the bladder and urethra. An additional 8 rats underwent sham injection of Hanks' balanced salt solution alone. Experimental and control animals were sacrificed 2, 4, 8 and 12 weeks after injection, and the bladders and urethras were analyzed.

RESULTS

Self-regenerating, pluripotent PLA cells were easily isolated from human adipose tissue. Evaluation 2, 4, 8 and 12 weeks after injection demonstrated PLA cell viability and incorporation into the recipient smooth muscle. Eight weeks following injection PLA cells demonstrated in vivo expression of alpha-smooth muscle actin, an early marker of smooth muscle differentiation.

CONCLUSIONS

PLA cells are an easily accessible source of pluripotent cells, making them ideal for tissue regeneration. PLA cells remain viable up to 12 weeks in the lower urinary tract. Human PLA cells injected into the urinary tract show morphological and phenotypic evidence of smooth muscle incorporation and differentiation with time. PLA cells may provide a feasible and cost-effective cell source for urinary tract reconstruction.

Fate of implanted syngenic muscle precursor cells in striated urethral sphincter of female rats: perspectives for treatment of urinary incontinence

OBJECTIVES

To analyze the outcome of syngenic skeletal muscle precursor cells (MPCs) after implantation in the striated urethral sphincter of the female rat.

METHODS

MPCs were isolated from the striated muscles of the lower limbs and infected with a retrovirus carrying the gene for green fluorescent protein. Approximatively 10(5) cells were injected longitudinally in the striated urethral sphincter of 24 animals using a 10-muL Hamilton syringe. The whole urethra was excised at 0, 1, 7, 10, 14, 30, and 90 days after implantation for histologic study and fluorescence analysis of the transections.

RESULTS

At days 0 and 1, some small, round, fluorescent MPCs were observed at the injection site. At day 7, significant MPC persistence was noted, with infiltration of inflammatory cells in the whole urethral wall (striated muscle layer, smooth muscle layer, and connective tissue). At day 10, some fusiform cells appeared in the striated muscle layer, suggesting the incorporation of MPCs into the striated myofibers. Inflammatory cells were no longer visible. At day 14, the fusiform cells tended to be larger. The small, round cells were no longer seen. At days 30 and 90, all myofibers of the striated muscle layer were strongly fluorescent, and no fluorescence was detectable in the smooth muscle layer.

CONCLUSIONS

Implantation of skeletal MPCs in the urethral sphincter resulted in selective incorporation into striated myofibers. Muscle-derived cell autografting could represent a new approach for the treatment of urinary incontinence in humans.

Neurologic recovery and improved detrusor contractility using muscle-derived cells in rat model of unilateral pelvic nerve transection

OBJECTIVES

To create a model of peripheral neuropathy and explore the potential of using muscle-derived cells (MDCs) to facilitate the regeneration of autonomic nerves and improve bladder function. Damage to the peripheral nerves that innervate the bladder from radical pelvic surgery is refractory to the currently available treatments.

METHODS

Rat MDCs were isolated from the gastrocnemius muscle using the preplate technique. The unilateral pelvic nerve was cut in female Sprague-Dawley rats. Three experimental groups were included: control (n = 5); unilateral pelvic nerve transected with sham injection (n = 5); and unilateral pelvic nerve transected with injection of MDC (3 x 10(5) cells/site; n = 5). Two weeks after injection, the intravesical pressures were measured during electrical stimulation of the proximal transected preganglionic nerve. The contralateral major pelvic ganglion was excised to ensure that any observed bladder activity was due exclusively to inputs on the unilateral side. The rats were killed, the experimental side major pelvic ganglion was removed, and enkephalin immunoreactivity was counted.

RESULTS

After unilateral pelvic nerve transection, no change occurred in bladder weight or capacity or postvoid residual urine volume. The maximal intravesical pressures for the control, sham, and MDC groups, after the contralateral pelvis had been cut, was 31.7 +/- 10.3, 9.6 +/- 4.5, and 15.2 +/- 7.7 cm H2O, respectively (P <0.05). After transecting the preganglionic pelvic nerve, the intensity of pericellular enkephalin immunoreactivity varicosities was significantly decreased in the sham group but unchanged in the MDC group compared with the control group.

CONCLUSIONS

MDCs can promote peripheral autonomic nerve regeneration. The morphologic changes correlated with the functional neurologic recovery effect of MDCs. The underlying neurologic recovery mechanisms of MDCs need to be exploited.

Chondrogenic differentiation of human mesenchymal stem cells using a thermosensitive poly(N-isopropylacrylamide) and water-soluble chitosan copolymer

Poly(N-isopropylacrylamide) (PNIPAAm) is known to be thermally responsive material and has a lower critical solution temperature (LCST, 32 degrees C) at which a macromolecular transition from a hydrophilic to a hydrophobic structure occurs. Chitosan is a useful natural polymeric biomaterial due to its biocompatibility and biodegradable properties. It has good characteristics for cell attachment, proliferation and viability. The aim of this study was to assess the ability to differentiate from mesenchymal stem cells (MSCs) to chondrocytes and mass formation using a newly developed injectable material, a thermosensitive (water-soluble chitosan-g-PNIPAAm) gel, and evaluate cartilage formation in vivo after injecting a cell-thermosensitive gel complex. The MSCs were cultured in the chitosan-PNIPAAm in vitro. Fluorescence-activated cell sort analysis, viability test, collagen type I, II, X formation and the aggrecan levels were examined. These cultured cells can be easily recovered from a copolymer gel by simply lowering the temperature. An animal study was performed to assess cartilage formation in the submucosal layer of the bladder of rabbits. The cartilage formation could be detected. This can be used to treat vesicoureteral reflux or reflux esophagitis by the effective mass effect. This is a simple method (sol-gel technique in LCST), and good cartilage formation occurs in the bladder tissue.

A model of intrinsic sphincteric deficiency in the rat: electrocauterization

AIMS

Intrinsic sphincteric deficiency (ISD) denotes a malfunction of the distal urethral sphincter. Our objective was to produce a durable model of ISD in the rat.

METHODS

Surrounding tissues lateral to the mid-urethra were cauterized to produce sphincteric injury in 24 adult female Sprague-Dawley rats. The rats were divided into four groups of six rats each and followed for 2, 4, 6, and 16 weeks. Sphincteric function was studied by using the vertical tilt table/intravesical pressure clamp model to measure leak point pressures (LPPs). Muscle and nerve damage were assessed with hematoxylin and eosin (H&E) and anti-protein gene product (PGP) 9.5 staining, respectively. As a control, 12 rats underwent a sham operation and subsequent LPP testing at 2, 4, 6, and 16 weeks.

RESULTS

The mean LPPs of the rats 2, 4, 6, and 16 weeks after cauterization were 18.7 +/- 0.8 cm H2O, 27.6 +/- 1.6 cm H2O, 24.3 +/- 1.7 cm H2O, and 19.1 +/- 2.2 cm H2O, respectively. The mean LPPs of the rats 2, 4, 6, and 16 weeks after the sham operation were 49.8 +/- 1.3 cm H2O, 51.2 +/- 1.5 cm H2O, 51.6 +/- 2.0 cm H2O, and 49.7 +/- 0.6 cm H2O, respectively. When compared to time-matched control groups, the decreased LPPs in each cauterized group were significantly lower (P < 0.001). Histological analysis showed muscle damage and fewer nerves in all cauterized groups.

CONCLUSIONS

Cauterization of tissues lateral to the mid-urethra decreased LPP without affecting bladder function. This electrocauterization model produced low LPPs that, after 2 weeks, were maintained for up to 16 weeks. Histology suggests that damage to striated muscle and nerves might have contributed to the change in LPP in this model for ISD.

Intraurethral muscle-derived cell injections increase leak point pressure in a rat model of intrinsic sphincter deficiency

OBJECTIVES

To determine whether allogenic muscle-derived cells (MDCs) could restore sphincter function in rats with intrinsic sphincter deficiency (ISD). ISD denotes a malfunction of the urethral sphincter.

METHODS

ISD was produced in 25 adult female Sprague-Dawley rats by cauterizing tissues lateral to the mid-urethra. One week after cauterization, 1.5 x 10(6) MDCs, genetically engineered for beta-galactosidase expression, was injected into the mid-urethra in 16 rats. Another 9 rats were injected with Hanks' balanced salt solution after cauterization. As a control, 9 normal rats underwent a sham operation. Sphincter function was studied using the vertical tilt table/intravesical pressure clamp technique to measure leak point pressures (LPPs). The fate of the MDCs was assessed using LacZ staining.

RESULTS

The injection of MDCs increased the LPP without affecting bladder function. The mean LPP of the control rats 2, 4, and 6 weeks after the sham operation was 49.8 +/- 1.3, 51.2 +/- 1.5, and 51.6 +/- 2.0 cm H2O, respectively. The mean LPP of the rats 2, 4, and 6 weeks after cauterization and Hanks' balanced salt solution injection was 17.2 +/- 1.4, 26.9 +/- 1.9, and 25.5 +/- 1.3 cm H2O, respectively. The mean LPP of the rats 2, 4, and 6 weeks after cauterization and MDC injection was 38.2 +/- 2.2, 43.1 +/- 2.6, and 51.5 +/- 0.9 cm H2O, respectively. LacZ staining confirmed that MDC had integrated within the striated muscle layer of the cauterized urethra.

CONCLUSIONS

The injection of intraurethral MDCs improved sphincter function in rats with ISD and may provide an attractive alternative to current treatments.

Improved sphincter contractility after allogenic muscle-derived progenitor cell injection into the denervated rat urethra

OBJECTIVES

To study the physiologic outcome of allogenic transplant of muscle-derived progenitor cells (MDPCs) in the denervated female rat urethra.

METHODS

MDPCs were isolated from muscle biopsies of normal 6-week-old Sprague-Dawley rats and purified using the preplate technique. Sciatic nerve-transected rats were used as a model of stress urinary incontinence. The experimental group was divided into three subgroups: control, denervated plus 20 microL saline injection, and denervated plus allogenic MDPCs (1 to 1.5 x 10(6) cells) injection. Two weeks after injection, urethral muscle strips were prepared and underwent electrical field stimulation. The pharmacologic effects of d-tubocurare, phentolamine, and tetrodotoxin on the urethral strips were assessed by contractions induced by electrical field stimulation. The urethral tissues also underwent immunohistochemical staining for fast myosin heavy chain and CD4-activated lymphocytes.

RESULTS

Urethral denervation resulted in a significant decrease of the maximal fast-twitch muscle contraction amplitude to only 8.77% of the normal urethra and partial impairment of smooth muscle contractility. Injection of MDPCs into the denervated sphincter significantly improved the fast-twitch muscle contraction amplitude to 87.02% of normal animals. Immunohistochemistry revealed a large amount of new skeletal muscle fiber formation at the injection site of the urethra with minimal inflammation. CD4 staining showed minimal lymphocyte infiltration around the MDPC injection sites.

CONCLUSIONS

Urethral denervation resulted in near-total abolishment of the skeletal muscle and partial impairment of smooth muscle contractility. Allogenic MDPCs survived 2 weeks in sciatic nerve-transected urethra with minimal inflammation. This is the first report of the restoration of deficient urethral sphincter function through muscle-derived progenitor cell tissue engineering. MDPC-mediated cellular urethral myoplasty warrants additional investigation as a new method to treat stress urinary incontinence.

Restoration of functional motor units in a rat model of sphincter injury by muscle precursor cell autografts1

BACKGROUND

Urinary incontinence is a debilitating condition that affects primarily elderly individuals. One major mechanism results from chronic denervation of the striated urethral sphincter with associated fibrosis. The authors investigated the fate of muscle precursor cells (MPC) injected into a model of striated urethral sphincter injury that reproduces the histopathologic changes of sphincter insufficiency.

METHODS

The striated urethral sphincter of older male rats was damaged by electrocoagulation. MPC were isolated from limb myofiber explants, infected with an adenovirus carrying the transgene encoding beta-galactosidase, and injected into the sphincter of the same animal 37 days after injury. Animals were killed 5 and 30 days after injection for assessment of sphincter function and the formation of motor units.

RESULTS

Electrocoagulation resulted in an irreversible destruction of both sphincteric myofibers and nerve endings, with a functional incapacity of the damaged sphincter to sustain an increase in bladder pressure; atrophy and fibrosis developed after 1 month. Injection of MPC resulted in the formation of beta-galactosidase-expressing myotubes in the sphincter that persisted beyond 30 days. The regenerated myotubes carried acetylcholine receptors associated with a nerve ending and were thus considered to form anatomic motor units. Urodynamic studies confirmed the restoration of 41% of sphincter function 1 month after MPC injection.

CONCLUSIONS

The authors showed that MPC isolated from limb muscles of an older animal can recapitulate a myogenic program when injected into an irreversibly injured sphincter. The maturation of MPC activates nerve regeneration and restores functional motor units.

Muscle-derived cell-mediated ex vivo gene therapy for urological dysfunction

We have tested the feasibility of muscle-based gene therapy and tissue engineering for urological dysfunction using highly purified muscle-derived cells (MDC) that display stem cell characteristics. We then explored the potential use of these MDC as an alternative therapy for the treatment of impaired detrusor contractility. The MDC were genetically engineered to express the gene encoding beta-galactosidase and injected into the bladder walls of SCID mice. The injected bladders were harvested at various time-points after injection and assayed for beta-galactosidase activity; the presence of myofibers within the injected tissue was determined by detection of fast myosin heavy chain isoform (MyHCs). We have demonstrated that the injected MDC are capable of not only surviving in the lower urinary tract, but also improving the contractility of the bladder following an induced injury. Two potential mechanisms can be used to explain this finding. First, we have observed that some of the beta-galactosidase-expressing cells expressed alpha-smooth muscle actin, suggesting a differentiation into smooth muscle. Second, a stain for acetylcholine receptors (AChRs), which identifies the location of neuromuscular junctions, revealed that the myofibers derived from the doner cells became innervated into the bladder as early as 2 weeks after injection. These results suggest that gene therapy and tissue engineering based on MDC potentially can be used for urological dysfunction.

Current and future pharmacological treatment for overactive bladder

PURPOSE

Urinary incontinence and overactive bladder are important and common conditions that have received little general medical attention. We reviewed the magnitude and impact of these conditions, and discuss pharmacotherapy as well as new drugs under investigation.

MATERIALS AND METHODS

The main emphasis of this review is pharmacological therapy for the bladder. We discuss currently available agents, drugs under development and pharmacological targets that would be suitable targets for treating overactive bladder. Drugs such as duloxetine that target not bladder smooth muscle, but rather central nervous system control of the micturition reflex are undergoing clinical trials. We also discuss intravesical therapy and alternative drug delivery methods, such as intravesical capsaicin and botulinum toxin, with special emphasis on approaches to modulate bladder afferent nerve function for preventing overactive bladder.

RESULTS

There are many advantages to advanced drug delivery systems, including long-term therapeutic efficacy, decreased side effects and improved patient compliance. Future speculation such as gene therapy holds great promise for overactive bladder because it is possible to access all genitourinary organs via endoscopy and other minimally invasive techniques that are ideally suited for gene therapy.

CONCLUSIONS

Traditional anticholinergic therapies are limited in their effectiveness. There is great hope for future research regarding voiding dysfunction and urinary incontinence through a focus on afferent nerve intervention for preventing overactive bladder.

Beyond collagen: injectable therapies for the treatment of female stress urinary incontinence in the new millennium

Previous experience with GAX-collagen has shown that the endoscopic correction of female SUI is both possible and effective. It is clear, however, that durability remains a primary concern when implementing this approach to treatment. The availability of recently developed and newly emerging materials, carefully designed using the tenets and techniques of biotechnology and materials science, may provide solutions to some of the difficulties beleaguering this treatment option. Results with currently available injectables are summarized in Table 1. Careful review and critical analysis of new bulking agents will soon reveal which materials approach the therapeutic ideal. It is likely that the ultimate choice of a particular substance, synthetic or biologic, may best be determined by the clinical circumstances involving the individual patient.

Gene therapy and tissue engineering for urologic dysfunction: status and prospects

This article reviews the recent advances in gene therapy and tissue engineering for urologic dysfunction. Although the number of gene therapy-based clinical trials has increased dramatically in the field of urologic oncology, such trials are still few within the neurourologic field. Recently, new biologic approaches employing growth factors have been utilized to treat various pathological conditions. Among them, transfer of genes such as those encoding growth factors represents a promising way to deliver therapeutic proteins to malfunctioning tissues, which leads to the improvement of organ function. Tissue engineering, which may eventually be combined with gene therapy, also offers the potential to create new functional genitourinary tissue for regeneration and replacement of tissue lost as a consequence of disease. Thus, both tissue engineering and gene therapy may hold promising new solutions in the urologic field.

Bladder instability: a re-appraisal of classical experimental approaches and development of new therapeutic strategies

1 Despite the growing social interest in human urinary tract disorders, the aetiology of detrusor instability remains poorly understood. Myogenic and neural impairment of detrusor activity caused by CNS or autonomic injuries can results in dysfunctions of normal voiding of the bladder such as urinary incontinence. 2 The contractility of human detrusor smooth muscle is critically dependent on acetylcholine-induced muscarinic receptor activation. Biochemical and functional in vivo and in vitro studies suggest the presence of an heterogeneous population of muscarinic receptor subtypes (M1-M4) localized at muscular and neutral sites. There is increasing evidence on the prejunctional auto- and hetero-regulation of acetylcholine release from parasympathetic nerve endings in modulating detrusor muscle contraction during micturition. 3 Activation of P2X purinoreceptors closely associated with the parasympathetic varicosities seems to be implicated to varying extent in the contractility in normal or instable human detrusor. Interestingly, P2X(1) subtype expression on smooth muscle increases considerably in the symptomatically obstructed bladder. A striking absence of P2X(3) and P2X(5) subtypes was observed in the cholinergic innervation of detrusor from patients with urgent incontinence. Thus, it is likely that alteration of the neural acetylcholine control can play a critical role in pathological states. 4 If the failures in storage and voiding can be recognized urodynamically, considerable difficulties remain in investigating the underlying functional changes especially because the study of the pathophysiology requires techniques that can be justified in animals but not in humans. 5 Recently, to solve this problem an alternative technique using human smooth muscle cells in culture has been developed. Human cell lines may be relevant in investigating the molecular pathways in physiological and pathological conditions. 6 The potential development of novel molecular therapeutic strategies such as gene therapy and tissue engineering is also discussed.

Gene therapy strategies for urological dysfunction

Novel molecular techniques such as conventional and ex vivo gene therapy, and tissue engineering have only recently been introduced to the field of urology. The lower urinary tract is ideally suited for minimally invasive therapy, and also ex vivo approaches would limit the risk of systemic side effects. Muscle-derived stem cells have been used successfully to treat stress incontinence, and rats with diabetic bladder dysfunction benefited from nerve growth factor (NGF)-based gene therapy. Nitric oxide synthase and capase-7 might provide suitable gene therapy targets for erectile dysfunction and benign prostatic hyperplasia, respectively.

Detection of a progesterone-dependent secretory protein synthesized by cat endometrium

Uterine flushings and culture media from endometrial explants incubated in the presence of radiolabeled amino acids were analyzed using one-(1-D) and two-dimensional (2-D) gel electrophoresis to identify proteins synthesized by the endometrium and subsequently released into the uterine lumen. 1-D and 2-D analyses of uterine flushings and culture media of endometrial explants obtained from 7- to 11-day pregnant cats (pre-implantation) showed a Mr 30,000 protein that appeared on 2-D gels as a family of macromolecules with isoelectric points between 6.5 and 7.0. This family of macromolecules was also present in the culture media of implantation-site tissue obtained from 12- to 16-day pregnant cats and of nonimplantation-site endometrium obtained form 12- to 28-day pregnant cats. The Mr 30,000 protein was absent in uterine flushings and culture media from estrous and 3- to 5-day-pregnant cats. In ovariectomized, steroid-treated animals, the Mr 30,000 protein was only detected in flushings and media from those animals treated with progesterone, regardless of the presence or absence of estradiol-priming and/or simultaneous estradiol treatment. In daily flushings obtained from ovariectomized, steroid-treated cats equipped with an indwelling uterine catheter, the Mr 30,000 protein was absent during the 14 days of estradiol treatment and was first detected 3-4 days after the onset of estradiol plus progesterone treatment. This protein was not detected in serum from estrous, 9-day pregnant, ovariectomized, and ovariectomized, steroid-treated animals. This study shows that 1) a progesterone-dependent protein, with an approximate molecular weight of 30,000 and an isoelectric point of 6.5-7.0, first appears within the uterine lumen soon after the arrival of the blastocyst and continues to be present during implantation; 2) the synthesis and release of the Mr 30,000 protein is dependent on progesterone regardless of the presence or absence of estradiol; and 3) the onset of secretion of the Mr 30,000 protein requires 3-4 days of continuous progesterone treatment in the estradiol-primed cat.