Smooth Muscle Precursor Cells Derived from Human Pluripotent Stem Cells for Treatment of Stress Urinary Incontinence

Strategies of Bladder Reconstruction after Partial or Radical Cystectomy for Bladder Cancer

The standard strategy is to reconstruct bladder by use of bowel segments as material in bladder cancer with radical cystectomy clinically. Both natural derived and non natural derived materials are investigated in bladder reconstruction. Studies on mechanical bladder, bladder transplantation and bladder xenotransplantation are currently limited although heart and kidney transplantation or xenotransplantation are successful to a certain extent, and bone prostheses are applied in clinical contexts. Earlier limited number of studies associated with bladder xenograft from animals to humans were not particular promising in results. Although there have been investigations on pig to human cardiac xenotransplantation with CRISPR Cas9 gene editing, the CRISPR Cas technique is not yet widely researched in porcine bladder related gene editing for the potential of human bladder replacement for bladder cancer. The advancement of technologies such as gene editing, bioprinting and induced pluripotent stem cells allow further research into partial or whole bladder replacement strategies. Porcine bladder is suggested as a potential source material for bladder reconstruction due to its alikeness to human bladder. Challenges that exist with all these approaches need to be overcome. This paper aims to review gene editing technology such as the CRISPR Cas systems as tools in bladder reconstruction, bladder xenotransplantation and hybrid bladder with technologies of induced pluripotent stem cells and genome editing, bioprinting for bladder replacement for bladder reconstruction and to restore normal bladder control function after cystectomy for bladder cancer.

Adipose-derived stem cells loaded photocurable and bioprintable bioinks composed of GelMA, HAMA and PEGDA crosslinker to differentiate into smooth muscle phenotype

Developing a polymer-based photocrosslinked 3D printable scaffolds comprised of gelatin methacryloyl (G) and hyaluronic acid methacryloyl (H) incorporated with two molecular weights of polyethylene glycol diacrylate (P) of various concentrations that enables rabbit adipose-derived stem cells (rADSCs) to survive, grow, and differentiate into smooth muscle cells (SMCs). Then, the chemical modification and physicochemical properties of the PGH bioinks were evaluated. The cell viability was assessed via MTT, CCK-8 assay and visualized employing Live/Dead assay. In addition, the morphology and nucleus count of differentiated SMCs were investigated by adopting TRAP (tartrate-resistant acid phosphatase) staining, and quantitative RT-PCR analysis was applied to detect gene expression using two different SMC-specific gene markers α-SMA and SM-MHC. The SMC-specific protein markers namely α-SMA and SM-MHC were applied to investigate SMC differentiation ability by implementing Immunocytofluorescence staining (ICC) and western blotting. Moreover, the disk, square, and tubular cellular models of PGH7 (GelMA/HAMA=2/1) + PEGDA-8000 Da, 3% w/v) hybrid bioink were printed using an extrusion bioprinting and cell viability of rADSCs was also analysed within 3D printed square construct practising Live/Dead assay. The results elicited the overall viability of SMCs, conserving its phenotype in biocompatible PGH7 hybrid bioink revealing its great potential to regenerate SMCs associated organs repair.

Differentiation of patient-specific void urine-derived human induced pluripotent stem cells to fibroblasts and skeletal muscle myocytes

Cell-based therapy is a major focus for treatment of stress urinary incontinence (SUI). However, derivation of primary cells requires tissue biopsies, which often have adverse effects on patients. A recent study used human induced pluripotent stem cells (iPSC)-derived smooth muscle myocytes for urethral sphincter regeneration in rats. Here, we establish a workflow using iPSC-derived fibroblasts and skeletal myocytes for urethral tissue regeneration: (1) Cells from voided urine of women were reprogrammed into iPSC. (2) The iPSC line U1 and hESC line H9 (control) were differentiated into fibroblasts expressing FSP1, TE7, vinculin, vimentin, αSMA, fibronectin and paxillin. (3) Myogenic differentiation of U1 and H9 was induced by small molecule CHIR99021 and confirmed by protein expression of myogenic factors PAX7, MYOD, MYOG, and MF20. Striated muscle cells enriched by FACS expressed NCAM1, TITIN, DESMIN, TNNT3. (4) Human iPSC-derived fibroblasts and myocytes were engrafted into the periurethral region of RNU rats. Injected cells were labelled with ferric nanoparticles and traced by Prussian Blue stain, human-specific nuclear protein KU80, and human anti-mitochondria antibody. This workflow allows the scalable derivation, culture, and in vivo tracing of patient-specific fibroblasts and myocytes, which can be assessed in rat SUI models to regenerate urethral damages and restore continence.

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Sources, Selection, and Microenvironmental Preconditioning of Cells for Urethral Tissue Engineering

Urethral stricture is a common urinary tract disorder in men that can be caused by iatrogenic causes, trauma, inflammation, or infection and often requires reconstructive surgery. The current therapeutic approach for complex urethral strictures usually involves reconstruction with autologous tissue from the oral mucosa. With the goal of overcoming the lack of sufficient autologous tissue and donor site morbidity, research over the past two decades has focused on cell-based tissue-engineered substitutes. While the main focus has been on autologous cells from the penile tissue, bladder, and oral cavity, stem cells from sources such as adipose tissue and urine are competing candidates for future urethral regeneration due to their ease of collection, high proliferative capacity, maturation potential, and paracrine function. This review addresses the sources, advantages, and limitations of cells for tissue engineering in the urethra and discusses recent approaches to improve cell survival, growth, and differentiation by mimicking the mechanical and biophysical properties of the extracellular environment.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.

Muscle-derived Stem Cells Combined With Nerve Growth Factor Transplantation in the Treatment of Stress Urinary Incontinence

OBJECTIVE

To investigate the efficacy of muscle-derived stem cells (MDSCs) combined with nerve growth factor (NGF) in the treatment of stress urinary incontinence (SUI) METHODS: MDSCs were isolated and extracted from 90 SD rats, and the stem cell characteristics of the cells were identified using flow cytometry. NGF overexpression (oe-NGF) plasmid was coated with adenovirus and qRT-PCR was applied to verify adenovirus transfection efficiency. The rat models of SUI were constructed and randomly divided into 5 groups: control group, phosphate buffer (PBS) group, MDSCs + oe-NGF group, MDSCs + vector group, and MDSCs group. After 8 weeks of feeding, the leakage point pressure (LPP) rats, and Masson staining of rat urethral sections were detected. The expression of NGF and vascular endothelial growth factor (VEGF) was detected by western blot and IHC staining.

RESULTS

Compared with the control group, the LPP and the ratio of muscle fibers/collagen fibers were significantly increased in the MDSCs treated groups, with the highest increase in the MDSCs + oe-NGF group. Western blot and IHC results showed that the expression of NGF and VEGF in the urethral tissues in the MDSCs treated groups were significantly up-regulated comparing with the control group, with the highest increase in the MDSCs + oe-NGF group.

CONCLUSION

MDSCs alone can relieve SUI, while MDSCs combined with NGF is more effective, which may be related to the up-regulating of VEGF.

Combination of PD98059 and TGF-β1 Efficiently Differentiates Human Urine-Derived Stem Cells into Smooth Muscle Cells

Pluripotent adult stem cells have potential applications in cell therapy and tissue engineering. Urine-derived stem cells (UDSCs) differentiate into various cell types. Here, we attempted to differentiate human UDSCs (hUDSCs) into smooth muscle cells (SMCs) using transforming growth factor-beta 1 (TGF-β1) and/or PD98059, an extracellular signal-regulated kinase (ERK) inhibitor. Both quantitative polymerase chain reaction (qPCR) and Western blot analysis showed that the expression of messenger ribonucleic acid (mRNA) and proteins for alpha-smooth muscle actin (α-SMA), calponin (CNN1), and smooth muscle myosin heavy chain (SM-MHC), which are specific markers for SMCs, increased on day 9 after differentiation and again on day 14. The differentiated cells from human UDSCs (hUDSCs) with a combination of TGF-β1 and PD98059 showed the highest expression of SMC marker proteins. Immunocytochemical staining performed to assess the molecular expression revealed CNN and α-SMA colocalizing in the cytoplasm. The cells that differentiated from hUDSCs with a combination of TGF-β1 and PD98059 showed the strongest expression for CNN1, α-SMA, and SM-MHC. Functional testing of the differentiated cells revealed a stronger contractile capacity for the cells differentiated with a combination of PD98059 and TGF-β1 than those differentiated with a single factor. These results suggest the combination of PD98059 and TGF-β1 to be a more effective differentiation method and that differentiated SMCs could be used for restoring the functions of the sphincter muscle or bladder.

Generation and Characterization of Human Mesenchymal Stem Cell-Derived Smooth Muscle Cells

Cardiovascular diseases are the leading cause of death worldwide. A completely autologous treatment can be achieved by using elastogenic mesenchymal stem cell (MSC)-derived smooth muscle cells (SMC) at the affected tissue site of vascular diseases such as abdominal aortic aneurysms (AAA). Thus, our work focused on evaluating the efficacy of (a) the combination of various growth factors, (b) different time periods and (c) different MSC lines to determine the treatment combination that generated SMCs that exhibited the greatest elastogenicity among the tested groups using Western blotting and flow cytometry. Additionally, total RNA sequencing was used to confirm that post-differentiation cells were upregulating SMC-specific gene markers. Results indicated that MSCs cultured for four days in PDGF + TGFβ1 (PT)-infused differentiation medium showed significant increases in SMC markers and decreases in MSC markers compared to MSCs cultured without differentiation factors. RNA Seq analysis confirmed the presence of vascular smooth muscle formation in MSCs differentiated in PT medium over a seven-day period. Overall, our results indicated that origin, growth factor treatment and culture period played a major role in influencing MSC differentiation to SMCs.

Current Applications and Future Directions of Bioengineering Approaches for Bladder Augmentation and Reconstruction

End-stage neurogenic bladder usually results in the insufficiency of upper urinary tract, requiring bladder augmentation with intestinal tissue. To avoid complications of augmentation cystoplasty, tissue-engineering technique could offer a new approach to bladder reconstruction. This work reviews the current state of bioengineering progress and barriers in bladder augmentation or reconstruction and proposes an innovative method to address the obstacles of bladder augmentation. The ideal tissue-engineered bladder has the characteristics of high biocompatibility, compliance, and specialized urothelium to protect the upper urinary tract and prevent extravasation of urine. Despite that many reports have demonstrated that bioengineered bladder possessed a similar structure to native bladder, few large animal experiments, and clinical applications have been performed successfully. The lack of satisfactory outcomes over the past decades may have become an important factor hindering the development in this field. More studies should be warranted to promote the use of tissue-engineered bladders in clinical practice.

Secretomes of human pluripotent stem cell-derived smooth muscle cell progenitors upregulate extracellular matrix metabolism in the lower urinary tract and vagina

BACKGROUND

Adult mesenchymal stem cells (MSCs) have been studied extensively for regenerative medicine; however, they have limited proliferation in vitro, and the long culture time induces cell senescence. MSCs also contribute to tissue repair through their paracrine function. In this study, we sought to examine the paracrine effects of human smooth muscle cell progenitors (pSMC) on the urethra and adjacent vagina of stress urinary incontinence rodents. We use human pluripotent stem cell (PSC) lines to derive pSMCs to overcome the issue of decreased proliferation in tissue culture and to obtain a homogenous cell population.

METHOD

Three human PSC lines were differentiated into pSMCs. The conditioned medium (CM) from pSMC culture, which contain pSMC secretomes, was harvested. To examine the effect of the CM on the extracellular matrix of the lower urinary tract, human bladder smooth muscle cells (bSMCs) and vaginal fibroblasts were treated with pSMC-CM in vitro. Stress urinary incontinence (SUI) was induced in rats by surgical injury of the urethra and adjacent vagina. SUI rats were treated with pSMC-CM and monitored for 5 weeks. Urethral pressure testing was performed prior to euthanasia, and tissues were harvested for PCR, Western blot, and histological staining. Kruskal-Wallis one-way ANOVA test and Student t test were used for statistical comparisons.

RESULTS

pSMC-CM upregulated MMP-2, TIMP-2, collagen, and elastin gene expression, and MMP-9 activity in the human bladder and vaginal cells consistent with elastin metabolism modulation. pSMC-CM treatment in the SUI rat improved urethral pressure (increase in leak point pressure compared to intact controls, p < 0.05) and increased collagen and elastin expression in the urethra and the adjacent vagina.

CONCLUSION

Conditioned media from smooth muscle cell progenitors derived from human pluripotent stem cells improved urethral leak point pressure and collagen and elastin content in the SUI rat. These findings suggest a novel therapeutic potential for PSC-based treatments for SUI and pelvic floor disorders where tissues are affected by collagen, elastin, and smooth muscle loss.

Frontiers in urethra regeneration: current state and future perspective

Despite the positive achievements attained, the treatment of male urethral strictures and hypospadiases still remains a challenge, particularly in cases of severe urethral defects. Complications and the need for additional interventions in such cases are common. Also, shortage of autologous tissue for graft harvesting and significant morbidity in the location of harvesting present problems and often lead to staged treatment. Tissue engineering provides a promising alternative to the current sources of grafts for urethroplasty. Since the first experiments in urethral substitution with tissue engineered grafts, this topic in regenerative medicine has grown remarkably, as many different types of tissue-engineered grafts and approaches in graft design have been suggested and testedin vivo. However, there have been only a few clinical trials of tissue-engineered grafts in urethral substitution, involving hardly more than a hundred patients overall. This indicates that the topic is still in its inception, and the search for the best graft design is continuing. The current review focuses on the state of the art in urethral regeneration with tissue engineering technology. It gives a comprehensive overview of the components of the tissue-engineered graft and an overview of the steps in graft development. Different cell sources, types of scaffolds, assembling approaches, options for vascularization enhancement and preclinical models are considered.

Combined Treatment With CCR1-Overexpressing Mesenchymal Stem Cells and CCL7 Enhances Engraftment and Promotes the Recovery of Simulated Birth Injury-Induced Stress Urinary Incontinence in Rats

Objective: To observe whether urethral injection of chemokine (c-c motif) ligand 7 (CCL7) and overexpressing CC receptor 1 (CCR1) in mesenchymal stem cells (MSCs) can promote their homing and engraftment to the injured tissue, and improve the recovery of simulated birth injury-induced stress urinary incontinence (SUI) in rats.

Methods: Female rats underwent a dual injury consisting of vaginal distension (VD) and pudendal nerve crush (PNC) to induce SUI. Bone marrow-derived MSCs were transduced with lentivirus carrying CCR1 (MSC-CCR1) and green fluorescent protein (GFP). Forty virgin Sprague–Dawley rats were evenly distributed into four groups: sham SUI + MSC-CCR1+CCL7, SUI + MSCs, SUI + MSC-CCR1, and SUI + MSC-CCR1+CCL7 group. The engrafted MSCs in urethra were quantified. Another three groups of rats, including sham SUI + sham MSC-CCR1+CCL7 treatment, SUI + sham MSC-CCR1+CCL7 treatment, and SUI + MSC-CCR1+CCL7 treatment group, were used to evaluate the functional recovery by testing external urethral sphincter electromyography (EUS EMG), pudendal nerve motor branch potentials (PNMBP), and leak point pressure (LPP) 1 week after injury and injection. Urethra and vagina were harvested for histological examination.

Results: The SUI + MSC-CCR1+CCL7 group received intravenous injection of CCR1-overexpressing MSCs and local injection of CCL7 after simulated birth injury had the most engraftment of MSCs to the injured tissues and best functional recovery from SUI compared to other groups. Histological examination showed a partial repair in the SUI + MSC-CCR1+CCL7 group.

Conclusions: Our study demonstrated combined treatment with CCR1-overexpressing MSCs and CCL7 can increase engraftment of MSCs and promote the functional recovery of simulated birth trauma-induced SUI in rats, which could be a new therapeutic strategy for SUI.

Episomal Induced Pluripotent Stem Cells: Functional and Potential Therapeutic Applications

The term episomal induced pluripotent stem cells (EiPSCs) refers to somatic cells that are reprogrammed into induced pluripotent stem cells (iPSCs) using non-integrative episomal vector methods. This reprogramming process has a better safety profile compared with integrative methods using viruses. There is a current trend toward using episomal plasmid reprogramming to generate iPSCs because of the improved safety profile. Clinical reports of potential human cell sources that have been successfully reprogrammed into EiPSCs are increasing, but no review or summary has been published. The functional applications of EiPSCs and their potential uses in various conditions have been described, and these may be applicable to clinical scenarios. This review summarizes the current direction of EiPSC research and the properties of these cells with the aim of explaining their potential role in clinical applications and functional restoration.

Tissue Engineering and Stem Cell Therapy in Pediatric Urology

The rapidly expanding field of tissue engineering along with stem cell therapy has a promising future in pediatric urological conditions. The initial struggle seemed difficult in renal regeneration but a functional biounit has been developed. Urine excretion has been demonstrated successfully from stem cell-generated embryonic kidneys. Three-dimensional (3D) stem cell-derived organoids are the new paradigm in research. Techniques to regenerate bladder tissue have reached the clinic, and the urethra is close behind. 3D bioprinted urethras would soon be available. Artificial germ cells produced from mouse pluripotent stem cells have been shown to give rise to live progeny. Myoblast and fibroblast therapy has been safely and effectively used for urinary incontinence. Stress urinary incontinence has been clinically treated with muscle-derived stem cells. Skeletal muscle-derived stem cells have been shown to get converted into smooth muscle cells when implanted into the corpora cavernosa in animal models. This review encompasses the various experimental and clinical developments in this field that can benefit pediatric urological conditions with the contemporary developments in the field.

Microenergy acoustic pulses induced myogenesis of urethral striated muscle stem/progenitor cells

Background

Stress urinary incontinence (SUI) is a common disorder with high prevalence in women across their life span, but there are no non-surgical curative options for the condition. Stem cell-based therapy, especially endogenous stem cell therapy may be a potential treatment method for SUI. The aims of this study are to identify, isolate, and assay the function of urethral striated muscle derived stem/progenitor cells (uMDSCs) and to assess uMDSC response to microenergy acoustic pulses (MAP).

Methods

Urethral striated muscle was identified utilizing 3D imaging of solvent organs (3DISCO) and immunofluorescence (IF). uMDSCs were isolated and purified from Zucker Lean (ZL) (ZUC-LEAN) (ZUC-Leprfa 186) rats, with magnetic-activated cell sorting (MACS) and pre-plating methods. The stemness and differentiation potential of the uMDSCs were measured by cell proliferation, EdU, flow cytometry, IF, and Western blot.

Results

Comparison of the cell proliferation assays between MACS and pre-plating reveals the advantage of MACS over pre-plating. In addition, the study reveals that uMDSCs form myotubes when treated with MAP.

Conclusions

The uMDSCs within female rat urethral striated muscle could be a therapeutic target of MAP in managing SUI.

Recent advances in pelvic floor repair

Stress urinary incontinence (SUI) and pelvic organ prolapse (POP) are conditions which result in significant physical, mental and social consequences for women worldwide. The high rates of recurrence reported with primary repair for POP led to the use of synthetic mesh to augment repairs in both primary and secondary cases following failed previous POP repair. The widely reported, unacceptably high rates of complications associated with the use of synthetic, transvaginal mesh in pelvic floor repair have severely limited the treatment options that surgeons can offer. This article summarises the recent advances in pelvic floor repair, such as improved quantification and modelling of the biomechanics of the pelvic floor and the developing technology within the field of tissue engineering for treatment of SUI/POP, including biomaterials and cell-based therapies. Finally, we will discuss the issues surrounding the commercial introduction of synthetic mesh for use within the pelvic floor and what lessons can be learned for the future as well as the current guidance surrounding treatment for SUI/POP.

Engineered Microenvironment for Manufacturing Human Pluripotent Stem Cell-Derived Vascular Smooth Muscle Cells

Human pluripotent stem cell-derived vascular smooth muscle cells (hPSC-VSMCs) are of great value for disease modeling, drug screening, cell therapies, and tissue engineering. However, producing a high quantity of hPSC-VSMCs with current cell culture technologies remains very challenging. Here, we report a scalable method for manufacturing hPSC-VSMCs in alginate hydrogel microtubes (i.e., AlgTubes), which protect cells from hydrodynamic stresses and limit cell mass to <400 μm to ensure efficient mass transport. The tubes provide cells a friendly microenvironment, leading to extremely high culture efficiency. We have shown that hPSC-VSMCs can be generated in 10 days with high viability, high purity, and high yield (∼5.0 × 108 cells/mL). Phenotype and gene expression showed that VSMCs made in AlgTubes and VSMCs made in 2D cultures were similar overall. However, AlgTube-VSMCs had higher expression of genes related to vasculature development and angiogenesis, and 2D-VSMCs had higher expression of genes related to cell death and biosynthetic processes.

Do Induced Pluripotent Stem Cell Characteristics Correlate with Efficient In Vitro Smooth Muscle Cell Differentiation? A Comparison of Three Patient-Derived Induced Pluripotent Stem Cell Lines

Human induced pluripotent stem cells (iPSCs) have the potential to repair/regenerate smooth muscle cells (SMCs) in different organs. However, there are many challenges in their translation to clinical therapies. In this study, we describe our observations of in vitro SMC differentiation in three iPSC lines derived from human fibroblasts using retroviral, episomal, and mRNA/miRNA reprogramming methods. We sought to elucidate correlations between differentiation characteristics and efficiencies that can facilitate large-scale production of differentiated cells for clinical applications, and to report differences in pluripotency marker expression in differentiated cells from different iPSC lines. A standardized SMC differentiation protocol was used to induce the CD31⁺/CD34⁺ vascular progenitor cell phenotype. These were sorted by magnetic-activated (MACS) and fluorescence-activated cell sorting (FACS), and then treated with PDGF-BB and smooth muscle growth medium for further differentiation into smooth muscle progenitor cells (pSMCs). The expression of SMC and pluripotency markers in early- and late-passage (P1 and P4) pSMCs was analyzed. A total of 36 differentiation runs was performed on the three patient iPSC lines. All pSMC populations expressed SMC markers and Ki67 consistent with the progenitor phenotype. Initial iPSC density correlated positively with the sorted cell FACS efficiency, and this correlation could be fit to a quadratic equation. We also observed that a specific "honeycomb" pattern of the starting cultured iPSCs cultured correlated with higher efficiency in all three iPSC lines. Pluripotency marker expression decreased significantly to nearly undetectable levels in all three lines. There was no significant change in SMC and pluripotent marker expression between passage 1 and 4. In summary, our observations suggest that the method of iPSC reprogramming does not affect iPSC differentiation into pSMCs. Protocol efficiency can be modeled mathematically and coupled with the initial "honeycomb" cell pattern to optimize production of large cell numbers for clinical therapies.

Bioengineering Approaches for Bladder Regeneration

Current clinical strategies for bladder reconstruction or substitution are associated to serious problems. Therefore, new alternative approaches are becoming more and more necessary. The purpose of this work is to review the state of the art of the current bioengineering advances and obstacles reported in bladder regeneration. Tissue bladder engineering requires an ideal engineered bladder scaffold composed of a biocompatible material suitable to sustain the mechanical forces necessary for bladder filling and emptying. In addition, an engineered bladder needs to reconstruct a compliant muscular wall and a highly specialized urothelium, well-orchestrated under control of autonomic and sensory innervations. Bioreactors play a very important role allowing cell growth and specialization into a tissue-engineered vascular construct within a physiological environment. Bioprinting technology is rapidly progressing, achieving the generation of custom-made structural supports using an increasing number of different polymers as ink with a high capacity of reproducibility. Although many promising results have been achieved, few of them have been tested with clinical success. This lack of satisfactory applications is a good reason to discourage researchers in this field and explains, somehow, the limited high-impact scientific production in this area during the last decade, emphasizing that still much more progress is required before bioengineered bladders become a commonplace in the clinical setting.

Human induced pluripotent stem cell-derived vascular smooth muscle cells: differentiation and therapeutic potential

Cardiovascular diseases remain the leading cause of death worldwide and current treatment strategies have limited effect of disease progression. It would be desirable to have better models to study developmental and pathological processes and model vascular diseases in laboratory settings. To this end, human induced pluripotent stem cells (hiPSCs) have generated great enthusiasm, and have been a driving force for development of novel strategies in drug discovery and regenerative cell-therapy for the last decade. Hence, investigating the mechanisms underlying the differentiation of hiPSCs into specialized cell types such as cardiomyocytes, endothelial cells, and vascular smooth muscle cells (VSMCs) may lead to a better understanding of developmental cardiovascular processes and potentiate progress of safe autologous regenerative therapies in pathological conditions. In this review, we summarize the latest trends on differentiation protocols of hiPSC-derived VSMCs and their potential application in vascular research and regenerative therapy.

Tissue engineering in pediatric urology - a critical appraisal

Tissue engineering is defined as the combination of biomaterials and bioengineering principles together with cell transplantation or directed growth of host cells to develop a biological replacement tissue or organ that can be a substitute for normal tissue both in structure and function. Despite early promising preclinical studies, clinical translation of tissue engineering in pediatric urology into humans has been unsuccessful both for cell-seeded and acellular scaffolds. This can be ascribed to various factors, including the use of only non-diseased models that inaccurately describe the structural and functional modifications of diseased tissue. The paper addresses potential future strategies to overcome the limitations experienced in clinical applications so far. This includes the use of stem cells of various origins (mesenchymal stem cells, hematopoietic stem/progenitor cells, urine-derived stem cells, and progenitor cells of the urothelium) as well as the need for a deeper understanding of signaling pathways and directing tissue ingrowth and differentiation through the concept of dynamic reciprocity. The development of smart scaffolds that release trophic factors in a set and timely manner will probably improve regeneration. Modulation of innate immune response as a major contributor to tissue regeneration outcome is also addressed. It is unlikely that only one of these strategies alone will lead to clinically applicable tissue engineering strategies in pediatric urology. In the meanwhile, the fundamental new insights into regenerative processes already obtained in the attempts of tissue engineering of the lower urogenital tract remain our greatest gain.

Stem Cells for Urinary Incontinence: Functional Differentiation or Cytokine Effects?

Minimally invasive stem cell therapy for stress urinary incontinence may provide an effective nonsurgical treatment for this common condition. Clinical trials of periurethral stem cell injection have been under way, and basic science research has demonstrated the efficacy of both local and systemic stem cell therapies. Results differ as to whether stem cells have a therapeutic effect by differentiating into permanent, functional tissues or exert benefits through a transient presence and the secretion of regenerative factors. This review explores the fate of therapeutic stem cells for stress urinary incontinence and how this may relate to their mechanism of action.

The utility of stem cells in pediatric urinary bladder regeneration

Pediatric patients with a neurogenic urinary bladder, caused by developmental abnormalities including spina bifida, exhibit chronic urological problems. Surgical management in the form of enterocystoplasty is used to enlarge the bladder, but is associated with significant clinical complications. Thus, alternative methods to enterocystoplasty have been explored through the incorporation of stem cells with tissue engineering strategies. Within the context of this review, we will examine the use of bone marrow stem cells and induced pluripotent stem cells (iPSCs), as they relate to bladder regeneration at the anatomic and molecular levels. The use of bone marrow stem cells has demonstrated significant advances in bladder tissue regeneration as multiple aspects of bladder tissue have been recapitulated including the urothelium, bladder smooth muscle, vasculature, and peripheral nerves. iPSCs, on the other hand, have been well characterized and used in multiple tissue-regenerative settings, yet iPSC research is still in its infancy with regards to bladder tissue regeneration with recent studies describing the differentiation of iPSCs to the bladder urothelium. Finally, we examine the role of the Sonic Hedgehog signaling cascade that mediates the proliferative response during regeneration between bladder smooth muscle and urothelium. Taken together, this review provides a current, comprehensive perspective on bladder regeneration.

Cell sex affects extracellular matrix protein expression and proliferation of smooth muscle progenitor cells derived from human pluripotent stem cells

Background

Smooth muscle progenitor cells (pSMCs) differentiated from human pluripotent stem cells (hPSCs) hold great promise for treating diseases or degenerative conditions involving smooth muscle pathologies. However, the therapeutic potential of pSMCs derived from men and women may be very different. Cell sex can exert a profound impact on the differentiation process of stem cells into somatic cells. In spite of advances in translation of stem cell technologies, the role of cell sex and the effect of sex hormones on the differentiation towards mesenchymal lineage pSMCs remain largely unexplored.

Methods

Using a standard differentiation protocol, two human embryonic stem cell lines (one male line and one female line) and three induced pluripotent stem cell lines (one male line and two female lines) were differentiated into pSMCs. We examined differences in the differentiation of male and female hPSCs into pSMCs, and investigated the effect of 17β-estradiol (E2) on the extracellular matrix (ECM) metabolisms and cell proliferation rates of the pSMCs. Statistical analyses were performed by using Student’s t test or two-way ANOVA, p < 0.05.

Results

Male and female hPSCs had similar differentiation efficiencies and generated morphologically comparable pSMCs under a standard differentiation protocol, but the derived pSMCs showed sex differences in expression of ECM proteins, such as MMP-2 and TIMP-1, and cell proliferation rates. E2 treatment induced the expression of myogenic gene markers and suppressed ECM degradation activities through reduction of MMP activity and increased expression of TIMP-1 in female pSMCs, but not in male pSMCs.

Conclusions

hPSC-derived pSMCs from different sexes show differential expression of ECM proteins and proliferation rates. Estrogen appears to promote maturation and ECM protein expression in female pSMCs, but not in male pSMCs. These data suggest that intrinsic cell-sex differences may influence progenitor cell biology.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0606-2) contains supplementary material, which is available to authorized users.

Efficacy and Safety of Immuno-Magnetically Sorted Smooth Muscle Progenitor Cells Derived from Human-Induced Pluripotent Stem Cells for Restoring Urethral Sphincter Function

Human-induced pluripotent stem cells (hiPSCs)-based cell therapy holds promise for treating stress urinary incontinence (SUI). However, safety concerns, especially tumorgenic potential of residual undifferentiated cells in hiPSC derivatives, are major barriers for its clinical translation. An efficient, fast and clinical-scale strategy for purifying committed cells is also required. Our previous studies demonstrated the regenerative effects of hiPSC-derived smooth muscle progenitor cells (pSMCs) on the injured urethral sphincter in SUI, but the differentiation protocol required fluorescence-activated cell sorting (FACS) which is not practical for autologous clinical applications. In this study, we examined the efficacy and safety of hiPSC-derived pSMC populations sorted by FDA-approved magnetic-activated cell sorting (MACS) using cell-surface marker CD34 for restoring urethral sphincter function. Although the heterogeneity of MACS-sorted pSMCs was higher than that of FACS-sorted pSMCs, the percentage of undifferentiated cells dramatically decreased after directed differentiation in vitro. In vivo studies demonstrated long-term cell integration and no tumor formation of MACS-sorted pSMCs after transplantation. Furthermore, transplantation of MACS-sorted pSMCs into immunodeficient SUI rats was comparable to transplantation with FACS-sorted pSMCs for restoration of the extracellular matrix metabolism and function of the urethral sphincter. In summary, purification of hiPSC derivatives using MACS sorting for CD34 expression represent an efficient approach for production of clinical-scale pSMCs for autologous stem cell therapy for regeneration of smooth muscle tissues. Stem Cells Translational Medicine 2017;6:1158-1167.

A genetic female mouse model with congenital genitourinary anomalies and adult stages of urinary incontinence

AIMS

To characterize the urinary incontinence observed in adult Gli2^+/- ; Gli3^Δ699/+ female mice and identify the defects underlying the condition.

METHODS

Gli2^+/- and Gli3^Δ699/+ mice were crossed to generate: wild-type, mutant Gli2 (Gli2^+/- ), mutant Gli3 (Gli3^Δ699/+ ), and double mutant (Gli2^+/- ; Gli3^Δ699/+ ) female mice, verified via Polymerase Chain Reactions. Bladder functional studies including cystometrogram (CMG), leak point pressure (LPP), and voiding testing were performed on adult female mice. Female bladders and urethras were also analyzed via ink injection and histological assays.

RESULTS

CMG tracing showed no signal corresponding to the filling of the Gli2^+/- ; Gli3^Δ699/+ bladders. LPP were significantly reduced in Gli2^+/- ; Gli3^Δ699/+ mice compared to wild-type mice. CMG studies revealed a decrease in peak micturition pressure values in Gli2^+/- ; Gli3^Δ699/+ mice compared with all other groups. No significant differences between mutant and wild-type mice were detected in urinary output. Histological analyses revealed Gli2^+/- ; Gli3^Δ699/+ mice exhibited a widened urethra and a decrease in smooth muscle layer thickness in the bladder outlet and urethra, with increased mucosal folding.

CONCLUSIONS

Gli2^+/- ; Gli3^Δ699/+ adult female mice display persistent urinary incontinence due to the malformation of the bladder outlet and urethra. This presents a consistent and reliable genetic mouse model for female urinary incontinence and alludes to the key role of genetic factors involved in the condition.

Smooth Muscle Progenitor Cells Derived From Human Pluripotent Stem Cells Induce Histologic Changes in Injured Urethral Sphincter

: Data suggest that myoblasts from various sources, including bone marrow, skeletal muscle, and adipose tissue, can restore muscle function in patients with urinary incontinence. Animal data have indicated that these progenitor cells exert mostly a paracrine effect on the native tissues rather than cell regeneration. Limited knowledge is available on the in vivo effect of human stem cells or muscle progenitors on injured muscles. We examined in vivo integration of smooth muscle progenitor cells (pSMCs) derived from human pluripotent stem cells (hPSCs). pSMCs were derived from a human embryonic stem cell line (H9-ESCs) and two induced pluripotent stem cell (iPSC) lines. pSMCs were injected periurethrally into urethral injury rat models (2 × 10⁶ cells per rat) or intramuscularly into severe combined immunodeficiency mice. Histologic and quantitative image analysis revealed that the urethras in pSMC-treated rats contained abundant elastic fibers and thicker muscle layers compared with the control rats. Western blot confirmed increased elastin/collagen III content in the urethra and bladder of the H9-pSMC-treated rats compared with controls. iPSC-pSMC treatment also showed similar trends in elastin and collagen III. Human elastin gene expression was not detectable in rodent tissues, suggesting that the extracellular matrix synthesis resulted from the native rodent tissues rather than from the implanted human cells. Immunofluorescence staining and in vivo bioluminescence imaging confirmed long-term engraftment of pSMCs into the host urethra and the persistence of the smooth muscle phenotype. Taken together, the data suggest that hPSC-derived pSMCs facilitate restoration of urethral sphincter function by direct smooth muscle cell regeneration and by inducing native tissue elastin/collagen III remodeling.

SIGNIFICANCE

The present study provides evidence that a pure population of human smooth muscle progenitor cells (pSMCs) derived from human pluripotent stem cells (hPSCs) (human embryonic stem cells and patient induced pluripotent stem cells) restores urethral sphincter function by two mechanisms: modulation of extracellular matrix protein metabolism in vivo and pSMC proliferation and differentiation into smooth muscle cells to regenerate the muscle layer in the lower urinary tract. These findings on the in vivo effects of human pSMCs should aid in optimizing regenerative therapies using human myoblasts.