Regenerative medicine in urology

Development of a porcine acellular bladder matrix for tissue-engineered bladder reconstruction

PURPOSE

Enterocystoplasty is adopted for patients requiring bladder augmentation, but significant long-term complications highlight need for alternatives. We established a protocol for creating a natural-derived bladder extracellular matrix (BEM) for developing tissue-engineered bladder, and investigated its structural and functional characteristics.

METHODS

Porcine bladders were de-cellularised with a dynamic detergent-enzymatic treatment using peristaltic infusion. Samples and fresh controls were evaluated using histological staining, ultrastructure (electron microscopy), collagen, glycosaminoglycans and DNA quantification and biomechanical testing. Compliance and angiogenic properties (Chicken chorioallantoic membrane [CAM] assay) were evaluated. T test compared stiffness and glycosaminoglycans, collagen and DNA quantity. p value of < 0.05 was regarded as significant.

RESULTS

Histological evaluation demonstrated absence of cells with preservation of tissue matrix architecture (collagen and elastin). DNA was 0.01 μg/mg, significantly reduced compared to fresh tissue 0.13 μg/mg (p < 0.01). BEM had increased tensile strength (0.259 ± 0.022 vs 0.116 ± 0.006, respectively, p < 0.0001) and stiffness (0.00075 ± 0.00016 vs 0.00726 ± 0.00216, p = 0.011). CAM assay showed significantly increased number of convergent allantoic vessels after 6 days compared to day 1 (p < 0.01). Urodynamic studies showed that BEM maintains or increases capacity and compliance.

CONCLUSION

Dynamic detergent-enzymatic treatment produces a BEM which retains structural characteristics, increases strength and stiffness and is more compliant than native tissue. Furthermore, BEM shows angiogenic potential. These data suggest the use of BEM for development of tissue-engineered bladder for patients requiring bladder augmentation.

Efficacy of combination therapy with pentosan polysulfate sodium and adipose tissue-derived stem cells for the management of interstitial cystitis in a rat model

We evaluated the synergistic effects of pentosan polysulfate sodium (PPS) and mesenchymal stem cells (MSCs) in an interstitial cystitis (IC) rat model. After generation of the IC rat model, the rats were divided into 4 groups according to the treatment they received: phosphate-buffered saline injection into bladder submucosa, daily oral PPS feeding, MSC injection into bladder submucosa, or MSC injection into bladder submucosa with daily oral PPS feeding. After treatment, conscious cystometry and pain scale measurement were performed and their bladders were obtained for histological and proinflammatory-related gene expression analysis. On cystometric analysis, all treatment groups showed significantly increased intercontraction intervals and lower pain scores compared to those of the control group. Histological analysis revealed regenerated urothelium, less fibrosis, and decreased mast cell infiltration in all treatment groups compared to the control group. Significantly lower expression of TNF-α, IFN-γ, MCP, IL-6, TLR2, and TLR11 was observed in the PPS with MSC group compared to the other groups. Combination therapy with PPS and MSCs showed histological and functional effects in an IC rat model, including synergistic effects leading to increased intercontraction interval and decreased inflammatory reactions.

Verification of mesenchymal stem cell injection therapy for interstitial cystitis in a rat model

Objective

Interstitial cystitis (IC) is a chronic intractable disease. Recently, the potential application of stem cell (SC) therapy was suggested for IC management. This study aimed to establish an optimal SC source and verify the efficacy and safety of SC injection therapy in an IC rat model.

Design

After IC animal model induction, urine-derived stem cells (USCs), adipose tissue-derived stem cells (ADSCs), bone marrow-derived stem cells (BMSCs) and amniotic fluid-derived stem cells (AFSCs) were injected into the bladder submucosa. The following parameters were analysed: 1) functional improvement of bladder via cystometry, 2) histological changes and 3) inflammatory gene expression and regenerative potential of damaged bladder tissues. Additionally, an optimal method for SC introduction in terms of effective bladder regeneration was analysed.

Results

Intercontraction interval was significantly increased and inflammatory reactions and fibrotic changes were decreased in all of the SC-injected groups than in the control group. PCR analysis revealed that inflammatory gene expression significantly decreased in the USC-treated group than in the other groups. To confirm the optimal SC injection route in the IC rat model, group was divided according to the following criteria: 1) direction of SC injection into the bladder submucosa, 2) injection via tail vein, 3) transurethral instillation. In each analysis, the groups in which SCs were injected into the bladder submucosa showed significantly longer intercontraction interval, better morphologic regeneration and inhibition of bladder inflammatory reaction compared with the other groups.

Conclusion

Regardless of the cell source, human tissue-derived mesenchymal SCs regenerated damaged bladder tissue, promoted functional recovery and inhibited inflammatory cell accumulation in an IC rat model; particularly, USC had the highest inhibitory effect on inflammation. Additionally, direct USC injection into the bladder submucosa was expected to have the best therapeutic effect, which will be an important factor for clinical applications in the future.

Longitudinal intravital imaging of transplanted mesenchymal stem cells elucidates their functional integration and therapeutic potency in an animal model of interstitial cystitis/bladder pain syndrome

Rationale: Mesenchymal stem cell (MSC) therapy may be a novel approach to improve interstitial cystitis/bladder pain syndrome (IC/BPS), an intractable disease characterized by severe pelvic pain and urinary frequency. Unfortunately, the properties of transplanted stem cells have not been directly analyzed in vivo, which hampers elucidation of the therapeutic mechanisms of these cells and optimization of transplantation protocols. Here, we monitored the behaviors of multipotent stem cells (M-MSCs) derived from human embryonic stem cells (hESCs) in real time using a novel combination of in vivo confocal endoscopic and microscopic imaging and demonstrated their improved therapeutic potency in a chronic IC/BPS animal model.

Methods: Ten-week-old female Sprague-Dawley rats were instilled with 10 mg of protamine sulfate followed by 750 μg of lipopolysaccharide weekly for 5 weeks. The sham group was instilled with phosphate-buffered saline (PBS). Thereafter, the indicated dose (0.1, 0.25, 0.5, and 1×10⁶ cells) of M-MSCs or PBS was injected once into the outer layer of the bladder. The distribution, perivascular integration, and therapeutic effects of M-MSCs were monitored by in vivo endoscopic and confocal microscopic imaging, awake cystometry, and histological and gene expression analyses.

Results: A novel combination of longitudinal intravital confocal fluorescence imaging and microcystoscopy in living animals, together with immunofluorescence analysis of bladder tissues, demonstrated that transplanted M-MSCs engrafted following differentiation into multiple cell types and gradually integrated into a perivascular-like structure until 30 days after transplantation. The beneficial effects of transplanted M-MSCs on bladder voiding function and the pathological characteristics of the bladder were efficient and long-lasting due to the stable engraftment of these cells.

Conclusion: This longitudinal bioimaging study of transplanted hESC-derived M-MSCs in living animals reveals their long-term functional integration, which underlies the improved therapeutic effects of these cells on IC/BPS.

The Therapeutic Effect of Human Embryonic Stem Cell-Derived Multipotent Mesenchymal Stem Cells on Chemical-Induced Cystitis in Rats

Purpose

To evaluate the therapeutic effect of human embryonic stem cell (hESC)-derived multipotent mesenchymal stem cells (M-MSCs) on ketamine-induced cystitis (KC) in rats.

Methods

To induce KC, 10-week-old female rats were injected with 25-mg/kg ketamine hydrochloride twice weekly for 12 weeks. In the sham group, phosphate buffered saline (PBS) was injected instead of ketamine. One week after the final injection of ketamine, the indicated doses (0.25, 0.5, and 1×10⁶ cells) of M-MSCs (KC+M-MSC group) or PBS vehicle (KC group) were directly injected into the bladder wall. One week after M-MSC injection, the therapeutic outcomes were evaluated via cystometry, histological analyses, and measurement of gene expression. Next, we compared the efficacy of M-MSCs at a low dose (1×10⁵ cells) to that of an identical dose of adult bone marrow (BM)-derived MSCs.

Results

Rats in the KC group exhibited increased voiding frequency and reduced bladder capacity compared to rats of the sham group. However, these parameters recovered after transplantation of M-MSCs at all doses tested. KC bladders exhibited markedly increased mast cell infiltration, apoptosis, and tissue fibrosis. Administration of M-MSCs significantly reversed these characteristic histological alterations. Gene expression analyses indicated that several genes associated with tissue fibrosis were markedly upregulated in KC bladders. However the expression of these genes was significantly suppressed by the administration of M-MSCs. Importantly, M-MSCs ameliorated bladder deterioration in KC rats after injection of a low dose (1×10⁵) of cells, at which point BM-derived MSCs did not substantially improve bladder function.

Conclusions

This study demonstrates for the first time the therapeutic efficacy of hESC-derived M-MSCs on KC in rats. M-MSCs restored bladder function more effectively than did BM-derived MSCs, protecting against abnormal changes including mast cell infiltration, apoptosis and fibrotic damage.

Biomaterial Scaffolds for Reproductive Tissue Engineering

The reproductive system usually involves gamete producing gonads, a series of specialized ducts, accessory glands and the external genitalia. Despite there are many traditional methods such as hormonal and surgical approaches, at present no effective treatments exist to help patients suffering from serious diseases of reproductive system, including congenital and acquired abnormalities, malignant tumor, traumatic, infectious etiologies, inflammation and iatrogenic injuries. Tissue engineering holds promise for reproductive medicine through the development of biological alternative. Till now, a diverse range of biomaterials have been utilized as suitable substrates to match both the mechanical and biological context of reproductive tissues. The current review will focus mainly on the applications of biomaterial scaffolds and their major achievements in each region of reproductive systems.

Mesenchymal stem cells protect against the tissue fibrosis of ketamine-induced cystitis in rat bladder

Abuse of the hallucinogenic drug ketamine promotes the development of lower urinary tract symptoms that resemble interstitial cystitis. The pathophysiology of ketamine-induced cystitis (KC) is largely unknown and effective therapies are lacking. Here, using a KC rat model, we show the therapeutic effects of human umbilical cord-blood (UCB)-derived mesenchymal stem cells (MSCs). Daily injection of ketamine to Sprague-Dawley rats for 2-weeks resulted in defective bladder function, indicated by irregular voiding frequency, increased maximum contraction pressure, and decreased intercontraction intervals and bladder capacity. KC bladders were characterized by severe mast-cell infiltration, tissue fibrosis, apoptosis, upregulation of transforming growth factor-β signaling related genes, and phosphorylation of Smad2 and Smad3 proteins. A single administration of MSCs (1 × 10(6)) into bladder tissue not only significantly ameliorated the aforementioned bladder voiding parameters, but also reversed the characteristic histological and gene-expression alterations of KC bladder. Treatment with the antifibrotic compound N-acetylcysteine also alleviated the symptoms and pathological characteristics of KC bladder, indicating that the antifibrotic capacity of MSC therapy underlies its benefits. Thus, this study for the first-time shows that MSC therapy might help to cure KC by protecting against tissue fibrosis in a KC animal model and provides a foundation for clinical trials of MSC therapy.

Stem Cell Therapy for Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a disease characterized by pelvic pain, usually with urinary frequency. These symptoms make patients suffer from a poor quality of life. However, there is still a lack of consensus on the pathophysiology and curable treatment of IC/BPS. We have reviewed several candidates for the pathophysiology of this disease and also treatments that have been used. Although several oral medications, bladder instillation therapies, fulguration for Hunner's lesion, and hydrodistention have been tried as IC/BPS treatments, their outcomes have not been satisfactory. As the application of stem cell therapy is expanding into the urologic field, innovative strategies have been tested with animal models of IC/BPS and have shown promising therapeutic effects for reversing the symptoms of this disorder. Although several concerns about stem cell sources and their safety should be addressed before initiating human clinical trials, we introduce stem cell therapy as a valuable future treatment approach for IC/BPS.

Vascularization strategies for tissue engineers

All tissue-engineered substitutes (with the exception of cornea and cartilage) require a vascular network to provide the nutrient and oxygen supply needed for their survival in vivo. Unfortunately the process of vascular ingrowth into an engineered tissue can take weeks to occur naturally and during this time the tissues become starved of essential nutrients, leading to tissue death. This review initially gives a brief overview of the processes and factors involved in the formation of new vasculature. It then summarizes the different approaches that are being applied or developed to overcome the issue of slow neovascularization in a range of tissue-engineered substitutes. Some potential future strategies are then discussed.

Mesenchymal Stem Cell Therapy Alleviates Interstitial Cystitis by Activating Wnt Signaling Pathway

Interstitial cystitis (IC) is a syndrome characterized by urinary urgency, frequency, pelvic pain, and nocturia in the absence of bacterial infection or identifiable pathology. IC is a devastating disease that certainly decreases quality of life. However, the causes of IC remain unknown and no effective treatments or cures have been developed. This study evaluated the therapeutic potency of using human umbilical cord-blood-derived mesenchymal stem cells (UCB-MSCs) to treat IC in a rat model and to investigate its responsible molecular mechanism. IC was induced in 10-week-old female Sprague-Dawley rats via the instillation of 0.1 M HCl or phosphate-buffered saline (PBS; sham). After 1 week, human UCB-MSC (IC+MSC) or PBS (IC) was directly injected into the submucosal layer of the bladder. A single injection of human UCB-MSCs significantly attenuated the irregular and decreased voiding interval in the IC group. Accordingly, denudation of the epithelium and increased inflammatory responses, mast cell infiltration, neurofilament production, and angiogenesis observed in the IC bladders were prevented in the IC+MSC group. The injected UCB-MSCs successfully engrafted to the stromal and epithelial tissues and activated Wnt signaling cascade. Interference with Wnt and epidermal growth factor receptor activity by small molecules abrogated the benefits of MSC therapy. This is the first report that provides an experimental evidence of the therapeutic effects and molecular mechanisms of MSC therapy to IC using an orthodox rat animal model. Our findings not only provide the basis for clinical trials of MSC therapy to IC but also advance our understanding of IC pathophysiology.

New advances in the pathophysiologic and radiologic basis of the exstrophy spectrum

The exstrophy-epispadias complex is a rare spectrum of anomalies affecting the genitourinary system, anterior abdominal wall, and pelvis. Recent advances in the repair of classic bladder exstrophy (CBE) and cloacal exstrophy (CE) have resulted in significant changes in outcomes of surgical management (including higher continence rate, fewer surgical complications, and better cosmesis) and health-related quality of life in these patients. These noteworthy changes resulted from advances in the pathophysiological and genetic backgrounds of this disease and better radiologic assessment of the three-dimensional anatomy of the bony pelvis and its musculature. A PubMed search was performed with the keyword exstrophy. The resulting literature pertaining to genetics, stem cells, imaging, tissue engineering, epidemiology, and endocrinology was reviewed. The following represents an overview of the advances in basic science understanding and imaging of the exstrophy-epispadias spectrum and discusses their possible and future effects on the management of CBE and CE.

Plasticity of in vitro-generated urothelial cells for functional tissue formation

Tissue-engineering and regenerative medicine strategies for the bladder and urinary tract are dependent on the ability to generate adequate numbers of differentiation-competent uro-epithelial cells. In situ, urothelium is a mitotically quiescent, but highly regenerative epithelium. Although evidence supports a resident, basally located urothelial progenitor population, no specific stem cell has been identified. Our aim was to isolate basal and suprabasal urothelial subpopulations and characterize their regenerative and differentiation potentials in vitro. We showed that the low-affinity nerve growth factor receptor (NGFR) is a cell surface-expressed marker that is restricted to basal cells in normal human and porcine urothelia in situ. We used NGFR immunoseparation and differential adherence to collagen to isolate subpopulations of urothelial cells for culture. Isolated basal-derived porcine NGFR⁺ urothelial cells initially showed a higher proliferative and clonogenic phenotype than their suprabasal NGFR⁻ counterparts in vitro. However, after a short period of adaptation to culture, both NGFR⁺ and NGFR⁻ subpopulations became indistinguishable and displayed similar long-term growth and differentiation potentials. Both populations generated hierarchically organized, differentiated tissue equivalents similar to native urothelium, including a fully reconstituted NGFR⁺ basal cell layer by the NGFR⁻ suprabasal-derived population. Similarly, slow collagen-adherent human urothelial cells initially displayed a longer lag phase than rapid-adherent cultures, but after adaptation, both populations showed similar long-term proliferation, exponential growth rates, and capacity to form a functional barrier urothelium. Our results support a model where urothelial cell phenotype is plastic and determined by the niche or local environment. This has direct implications for tissue-engineering strategies requiring urothelial cell expansion and provides a new perspective toward understanding urothelial regeneration and differentiated tissue hierarchy.

The paracrine effects of mesenchymal stem cells stimulate the regeneration capacity of endogenous stem cells in the repair of a bladder-outlet-obstruction-induced overactive bladder

Overactive bladder (OAB), which is characterized by the sudden and uncomfortable need to urinate with or without urinary leakage, is a challenging urological condition. The insufficient efficacy of current pharmacotherapies that uses antimuscarinic agents has increased the demand for novel long-term/stable therapeutic strategies. Here, we report the superior therapeutic efficacy of using mesenchymal stem cells (MSCs) for the treatment of OAB and a novel therapeutic mechanism that activates endogenous Oct4(+) primitive stem cells. We induced OAB using bladder-outlet-obstruction (BOO) in a rat model and either administered a single transplantation of human adipose-derived MSCs or daily intravenous injections of solifenacin, an antimuscarinic agent, for 2 weeks. Within 2 weeks, both the MSC- and solifenacin-treated groups similarly demonstrated relief from BOO-induced detrusor overactivity, hypertrophic smooth muscle, and neurological injuries. In contrast with the solifenacin-treated groups, a single transplantation of MSCs improved most OAB parameters to normal levels within 4 weeks. Although the transplanted human MSCs were hardly engrafted into the damaged bladders, the bladder tissues transplanted with MSCs increased rat sequence-specific transcription of Oct4, Sox2, and Stella, which are surrogate markers for primitive pluripotent stem cells. In addition, MSCs enhanced the expression of several genes, responsible for stem cell trafficking, including SDF-1/CXCR4, HGF/cMet, PDGF/PDGFR, and VEGF/VEGFR signaling axis. These changes in gene expression were not observed in the solifenacin-treated group. Therefore, we suggest the novel mechanisms for the paracrine effect of MSCs as unleashing/mobilizing primitive endogenous stem cells, which could not only explain the long-term/stable therapeutic efficacy of MSCs, but also provide promising new therapies for the treatment of OAB.

[An introduction to biomaterials in urology]

Aim of this paper is to provide a brief introduction on the biomaterials used in urology, discussing issues of biocompatibility and biomaterials available for use. Information will moreover be provided on basic elements of Tissue engineering and Regenerative medicine, rapidly advancing technologies that could finally shift in the next future from the laboratory to clinical practice, with special interest to possible urological applications.

Delivery of growth factors for tissue regeneration and wound healing

Growth factors are soluble secreted proteins capable of affecting a variety of cellular processes important for tissue regeneration. Consequently, the self-healing capacity of patients can be augmented by artificially enhancing one or more processes important for healing through the application of growth factors. However, their application in clinics remains limited due to lack of robust delivery systems and biomaterial carriers. Interestingly, all clinically approved therapies involving growth factors utilize some sort of a biomaterial carrier for growth factor delivery. This suggests that biomaterial delivery systems are extremely important for successful usage of growth factors in regenerative medicine. This review outlines the role of growth factors in tissue regeneration, and their application in both pre-clinical animal models of regeneration and clinical trials is discussed. Additionally, current status of biomaterial substrates and sophisticated delivery systems such as nanoparticles for delivery of exogenous growth factors and peptides in humans are reviewed. Finally, issues and possible future research directions for growth factor therapy in regenerative medicine are discussed.

Tissue engineering potential of urothelial cells from diseased bladders

PURPOSE

We examined the suitability of urothelium from patients with abnormal bladders for use in surgical reconstruction using a tissue engineering approach that would require autologous urothelium to be expanded by propagation in cell culture.

MATERIALS AND METHODS

Resection specimens from 8 children (median age 9.8 years) with abnormal bladders (neuropathic in 4, posterior urethral valves in 2, epispadias in 1, nonneurogenic in 1) were collected with informed parental consent during planned urological procedures. Six patients had recurrent urinary tract infections and 7 underwent frequent intermittent catheterization. A representative sample was immunohistologically processed to assess urothelial proliferation and differentiation status, and the remaining 7 cases were processed for urothelial cell culture. Five normal adult urothelial samples were included as controls.

RESULTS

Immunohistological assessment indicated that 3 of 8 samples lacked urothelial differentiation associated expression of UPK3a or CK20. Four of 7 samples resulted in successful primary culture, with 1 sample lost to underlying infection and 2 not surviving in culture. All 4 cultures grew beyond passage 3 before senescence but all showed reduced proliferation capacity and a compromised ability to form a barrier urothelium compared to controls.

CONCLUSIONS

While normal human urothelium is highly regenerative and derived cells are highly proliferative in culture, our results with urothelium from abnormal pediatric bladders indicate a reduced capacity for proliferation and differentiation in vitro. This finding may indicate a need to identify alternative cell sources for engineered bladder reconstruction.