Bone marrow mesenchymal stem cells differentiate into urothelial cells and the implications for reconstructing urinary bladder mucosa

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.

A Novel Hybrid Membrane for Urinary Conduit Substitutes Based on Small Intestinal Submucosa Coupled with Two Synthetic Polymers

Among the urinary tract's malignancies, bladder cancer is the most frequent one: it is at the tenth position of most common cancers worldwide. Currently, the gold standard therapy consists of radical cystectomy, which results in the need to create a urinary diversion using a bowel segment from the patient. Nevertheless, due to several complications associated with bowel resection and anastomosis, which significantly affect patient quality of life, it is becoming extremely important to find an alternative solution. In our recent work, we proposed the decellularized porcine small intestinal submucosa (SIS) as a candidate material for urinary conduit substitution. In the present study, we create SIS-based hybrid membranes that are obtained by coupling decellularized SIS with two commercially available polycarbonate urethanes (Chronoflex AR and Chronoflex AR-LT) to improve SIS mechanical resistance and impermeability. We evaluated the hybrid membranes by means of immunofluorescence, two-photon microscopy, FTIR analysis, and mechanical and cytocompatibility tests. The realization of hybrid membranes did not deteriorate SIS composition, but the presence of polymers ameliorates the mechanical behavior of the hybrid constructs. Moreover, the cytocompatibility tests demonstrated a significant increase in cell growth compared to decellularized SIS alone. In light of the present results, the hybrid membrane-based urinary conduit can be a suitable candidate to realize a urinary diversion in place of an autologous intestinal segment. Further efforts will be performed in order to create a cylindrical-shaped hybrid membrane and to study its hydraulic behavior.

The urothelium: a multi-faceted barrier against a harsh environment

All mucosal surfaces must deal with the challenge of exposure to the outside world. The urothelium is a highly specialized layer of stratified epithelial cells lining the inner surface of the urinary bladder, a gruelling environment involving significant stretch forces, osmotic and hydrostatic pressures, toxic substances, and microbial invasion. The urinary bladder plays an important barrier role and allows the accommodation and expulsion of large volumes of urine without permitting urine components to diffuse across. The urothelium is made up of three cell types, basal, intermediate, and umbrella cells, whose specialized functions aid in the bladder's mission. In this review, we summarize the recent insights into urothelial structure, function, development, regeneration, and in particular the role of umbrella cells in barrier formation and maintenance. We briefly review diseases which involve the bladder and discuss current human urothelial in vitro models as a complement to traditional animal studies.

Hydrogel composite scaffolds achieve recruitment and chondrogenesis in cartilage tissue engineering applications

BACKGROUND

The regeneration and repair of articular cartilage remains a major challenge for clinicians and scientists due to the poor intrinsic healing of this tissue. Since cartilage injuries are often clinically irregular, tissue-engineered scaffolds that can be easily molded to fill cartilage defects of any shape that fit tightly into the host cartilage are needed.

METHOD

In this study, bone marrow mesenchymal stem cell (BMSC) affinity peptide sequence PFSSTKT (PFS)-modified chondrocyte extracellular matrix (ECM) particles combined with GelMA hydrogel were constructed.

RESULTS

In vitro experiments showed that the pore size and porosity of the solid-supported composite scaffolds were appropriate and that the scaffolds provided a three-dimensional microenvironment supporting cell adhesion, proliferation and chondrogenic differentiation. In vitro experiments also showed that GelMA/ECM-PFS could regulate the migration of rabbit BMSCs. Two weeks after implantation in vivo, the GelMA/ECM-PFS functional scaffold system promoted the recruitment of endogenous mesenchymal stem cells from the defect site. GelMA/ECM-PFS achieved successful hyaline cartilage repair in rabbits in vivo, while the control treatment mostly resulted in fibrous tissue repair.

CONCLUSION

This combination of endogenous cell recruitment and chondrogenesis is an ideal strategy for repairing irregular cartilage defects.

Non-Muscular Invasive Bladder Cancer: Re-envisioning Therapeutic Journey from Traditional to Regenerative Interventions

Non-muscular invasive bladder cancer (NMIBC) is one of the most common cancer and major cause of economical and health burden in developed countries. Progression of NMIBC has been characterized as low-grade (Ta) and high grade (carcinoma in situ and T1). The current surgical intervention for NMIBC includes transurethral resection of bladder tumor; however, its recurrence still remains a challenge. The BCG-based immunotherapy is much effective against low-grade NMIBC. BCG increases the influx of T cells at bladder cancer site and inhibits proliferation of bladder cancer cells. The chemotherapy is another traditional approach to address NMIBC by supplementing BCG. Notwithstanding, these current therapeutic measures possess limited efficacy in controlling NMIBC, and do not provide comprehensive long-term relief. Hence, biomaterials and scaffolds seem an effective medium to deliver therapeutic agents for restructuring bladder post-treatment. The regenerative therapies such as stem cells and PRP have also been explored for possible solution to NMIBC. Based on above-mentioned approaches, we have comprehensively analyzed therapeutic journey from traditional to regenerative interventions for the treatment of NMIBC.

Therapeutic potential of adipose-derived mesenchymal stem cell exosomes in tissue-engineered bladders

Mesenchymal stem cells (MSCs) are a therapeutic tool for tissue engineering. However, many studies have recently shown that the therapeutic effects of MSCs are mediated by paracrine signaling and their secretory factors rather than their multidirectional differentiation ability. Exosomes isolated from the conditioned medium of MSCs are considered the main intercellular communication medium between MSCs and their target cells. Exosomes have been utilized in a novel cell-free therapy strategy that has attracted much attention. In this study, we evaluated the effects of a new cell-free tissue-engineered bladder (bladder acellular matrix combined with adipose-derived mesenchymal stem cell exosomes (AMEs)) in vivo and in vitro to prove that AMEs promoted tissue regeneration and functional recovery in a rat bladder replacement model.

Tissue-engineered autologous peritoneal grafts for bladder reconstruction in a porcine model

Ileal neobladder construction is a common treatment for patients with bladder cancer after radical cystectomy. However, metabolic disorders caused by transposed bowel segments occur frequently. Bladder tissue engineering is a promising alternative approach. Although numerous studies have reported bladder reconstruction using acellular and cellular scaffolds, there are also disadvantages associated with these methods, such as immunogenicity of synthetic grafts and incompatible mechanical properties of the biomaterials. Here, we engineered an autologous peritoneal graft consisting of a peritoneal sheet and the seromuscular layer from the ileum. Three months after the surgery, compared with the neobladder made from the ileum, the reconstructed neobladder using our new method showed normal function and better gross morphological characteristics. Moreover, histopathological and transcriptomic analysis revealed urothelium-like cells expressing urothelial biomarkers appeared in the neobladder, while no such changes were observed in the control group. Overall, our study provides a new strategy for bladder tissue engineering and informs a variety of future research prospects.

Application of Adult and Pluripotent Stem Cells in Interstitial Cystitis/Bladder Pain Syndrome Therapy: Methods and Perspectives

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic disease without definite etiology characterized by bladder-related pelvic pain. IC/BPS is associated with pain that negatively affects the quality of life. There are various therapeutic approaches against IC/BPS. However, no efficient therapeutic agent against IC/BPS has been discovered yet. Urothelium dysfunction is one of the key factors of IC/BPS-related pathogenicity. Stem cells, including adult stem cells (ASCs) and pluripotent stem cells (PSCs), such as embryonic stem cells (ESCs) and induced PSCs (iPSCs), possess the abilities of self-renewal, proliferation, and differentiation into various cell types, including urothelial and other bladder cells. Therefore, stem cells are considered robust candidates for bladder regeneration. This review provides a brief overview of the etiology, pathophysiology, diagnosis, and treatment of IC/BPS as well as a summary of ASCs and PSCs. The potential of ASCs and PSCs in bladder regeneration via differentiation into bladder cells or direct transplantation into the bladder and the possible applications in IC/BPS therapy are described in detail. A better understanding of current studies on stem cells and bladder regeneration will allow further improvement in the approaches of stem cell applications for highly efficient IC/BPS therapy.

Urine as a Main Effector in Urological Tissue Engineering-A Double-Edged Sword

In order to reconstruct injured urinary tract tissues, biodegradable scaffolds with autologous seeded cells are explored in this work. However, when cells are obtained via biopsy from individuals who have damaged organs due to infection, congenital disorders, or cancer, this can result in unhealthy engineered cells and donor site morbidity. Thus, neo-organ construction through an alternative cell source might be useful. Significant advancements in the isolation and utilization of urine-derived stem cells have provided opportunities for this less invasive, limitless, and versatile source of cells to be employed in urologic tissue-engineered replacement. These cells have a high potential to differentiate into urothelial and smooth muscle cells. However, urinary tract reconstruction via tissue engineering is peculiar as it takes place in a milieu of urine that imposes certain risks on the implanted cells and scaffolds as a result of the highly cytotoxic nature of urine and its detrimental effect on both growth and differentiation of these cells. Both of these projections should be tackled thoughtfully when designing a suitable approach for repairing urinary tract defects and applying the needful precautions is vital.

Direct conversion of fibroblasts into urothelial cells that may be recruited to regenerating mucosa of injured urinary bladder

Urothelial cells play essential roles in protection of urine exudation and bacterial invasion at the urothelial mucosa, so that defect or damage of urothelial cells associated with urinary tract diseases may cause serious problems. If a sufficient number of functional urothelial cells are prepared in culture and transplanted into the damaged urothelial lesions, such technology may provide beneficial effects to patients with diseases of the urinary tract. Here we found that human adult dermal fibroblasts were converted into urothelial cells by transducing genes for four transcription factors, FOXA1, TP63, MYCL and KLF4 (FTLK). The directly converted urothelial cells (dUCs) formed cobblestone-like colonies and expressed urothelium-specific markers. dUCs were successfully expanded and enriched after serial passages using a specific medium that we optimized for the cells. The passaged dUCs showed similar genome-wide gene expression profiles to normal urothelial cells and had a barrier function. The FTLK-transduced fibroblasts were also converted into urothelial cells in vivo and recruited to the regenerating urothelial tissue after they were transplanted into the bladder of mice with interstitial cystitis. Our technology may provide a promising solution for a number of patients with urinary tract disorders.

Urethroplasty performed with an autologous urothelium-vegetated collagen fleece to treat urethral stricture in the minipig model

INTRODUCTION AND OBJECTIVE

Tissue-engineered materials in urethral reconstructive surgeries are a promising field for innovative therapy. Collagen matrices increase stability of cell-based implants and can promote viability and proliferation of urothelial cells. In this study, a collagen type I-based cell carrier (CCC) with stratified multi-layer autologous urothelium was used for urethroplasty after induction of urethral stricture in eight minipigs.

MATERIALS AND METHODS

Minipigs underwent surgical procedures to induce urethral stricture by thermocoagulation. Simultaneously, bladder tissue was harvested. Urothelial cells were expanded, labeled with PKH26 and seeded onto CCC in high density. 3 weeks after strictures were induced and verified by urethrography, minipigs underwent urethroplasty using the seeded CCC. Two animals were euthanized after 1, 2, 4, and 24 weeks. Urethras were histologically examined for integration and survival of seeded CCC. In vivo phenotype of multi-layered urothelium matrix constructs was characterized via immunofluorescence staining with pancytokeratin, CK20, p63, E-cadherin and ZO-1.

RESULTS

Seeded CCCs showed excellent stability and suturability after manipulation and application. Transplanted cells were detected using positive PKH26 fluorescence up to 6 months after labeling. Urothelium matrix implants integrated well into the host tissue without sign of inflammation. Animals showed no sign of rejection or stricture recurrence (urethrography) at any time during experimental period. Immunofluorescence analysis confirmed epithelial phenotype, junction formation and differentiation after 2 weeks.

CONCLUSION

CCC can be suitable for urologic reconstructive surgeries and represents a promising option for clinical application. Longer follow-up results are required to exclude re-occurrence of stricture reformation.

Urethroplasty with a bilayered poly-D,L-lactide-co-ε-caprolactone scaffold seeded with allogenic mesenchymal stem cells

Reconstructive surgery for urethral defects employing tissue-engineered scaffolds represents an alternative treatment for urethroplasty. The aim of this study was to compare the therapeutic efficacy of the bilayer poly-D,L-lactide/poly-ε-caprolactone (PL-PC) scaffold seeded with allogenic mesenchymal stem cells (MSCs) for urethra reconstruction in a rabbit model with conventional urethroplasty employing an autologous buccal mucosa graft (BG). The inner layer of the scaffold based on poly-D,L-lactic acid (PL) was seeded with MSCs, while the outer layer, prepared from poly-ε-caprolactone, protected the surrounding tissues from urine. To track the MSCs in vivo, the latter were labeled with superparamagnetic iron oxide nanoparticles. In rabbits, a dorsal penile defect was reconstructed employing a BG or a PL-PC graft seeded with nanoparticle-labeled MSCs. In the 12-week follow-up period, no complications were detected. Subsequent histological analysis demonstrated biointegration of the PL-PC graft with surrounding urethral tissues. Less fibrosis and inflammatory cell infiltration were observed in the experimental group as compared with the BG group. Nanoparticle-labeled MSCs were detected in the urothelium and muscular layer, co-localizing with the urothelium cytokeratin marker AE1/AE3, indicating the possibility of MSC differentiation into neo-urothelium. Our results suggest that a bilayer MSCs-seeded scaffold could be efficiently employed for urethroplasty.

Mesenchymal Stem Cells: Miraculous Healers or Dormant Killers?

Mesenchymal Stem Cells (MSCs) are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency to differentiate into mesodermal cell lineages. The use of MSCs in clinical settings began with high enthusiasm and the number of MSC-based clinical trials has been rising ever since. However; the very unique characteristics of MSCs that made them suitable to for therapeutic use, might give rise to unwanted outcomes, including tumor formation and progression. In this paper, we present a model of carcinogenesis initiated by MSCs, which chains together the tissue organization field theory, the stem cell theory, and the inflammation-cancer chain. We believe that some tissue resident stem cells could be leaked cells from bone marrow MSC pool to various injured tissue, which consequently transform and integrate in the host tissue. If the injury persists or chronic inflammation develops, as a consequence of recurring exposure to growth factors, cytokines, etc. the newly formed tissue from MSCs, which still has conserved their mesenchymal and stemness features, go through rapid population expansion, and nullify their tumor suppressor genes, and hence give rise to neoplastic cell (carcinomas, sarcomas, and carcino-sarcomas). Considering the probability of this hypothesis being true, the clinical and therapeutic use of MSCs should be with caution, and the recipients' long term follow-up seems to be insightful.

Urothelium with barrier function differentiated from human urine-derived stem cells for potential use in urinary tract reconstruction

Background

Autologous urothelial cells are often obtained via bladder biopsy to generate the bio-engineered urethra or bladder, while urine-derived stem cells (USC) can be obtained by a non-invasive approach. The objective of this study is to develop an optimal strategy for urothelium with permeability barrier properties using human USC which could be used for tissue repair in the urinary tract system.

Methods

USC were harvested from six healthy adult individuals. To optimize urothelial differentiation, five different differentiation methods were studied. The induced cells were assessed for gene and protein expression markers of urothelial cells via RT-PCR, Western blotting, and immunofluorescent staining. Barrier function and ultrastructure of the tight junction were assessed with permeability assays and transmission electron microscopy (TEM). Induced cells were both cultured on trans-well membranes and small intestinal submucosa, then investigated under histology analysis.

Results

Differentiated USC expressed significantly higher levels of urothelial-specific transcripts and proteins (Uroplakin III and Ia), epithelial cell markers (CK20 and AE1/AE3), and tight junction markers (ZO-1, ZO-2, E-cadherin, and Cingulin) in a time-dependent manner, compared to non-induced USC. In vitro assays using fluorescent dye demonstrated a significant reduction in permeability of differentiated USC. In addition, transmission electron microscopy confirmed appropriate ultrastructure of urothelium differentiated from USC, including tight junction formation between neighboring cells, which was similar to positive controls. Furthermore, multilayered urothelial tissues formed 2 weeks after USC were differentiated on intestine submucosal matrix.

Conclusion

The present study illustrates an optimal strategy for the generation of differentiated urothelium from stem cells isolated from the urine. The induced urothelium is phenotypically and functionally like native urothelium and has proposed uses in in vivo urological tissue repair or in vitro urethra or bladder modeling.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1035-6) contains supplementary material, which is available to authorized users.

Differential transcription factor expression by human epithelial cells of buccal and urothelial derivation

Identification of transcription factors expressed by differentiated cells is informative not only of tissue-specific pathways, but to help identify master regulators for cellular reprogramming. If applied, such an approach could generate healthy autologous tissue-specific cells for clinical use where cells from the homologous tissue are unavailable due to disease. Normal human epithelial cells of buccal and urothelial derivation maintained in identical culture conditions that lacked significant instructive or permissive signaling cues were found to display inherent similarities and differences of phenotype. Investigation of transcription factors implicated in driving urothelial-type differentiation revealed buccal epithelial cells to have minimal or absent expression of PPARG, GATA3 and FOXA1 genes. Retroviral overexpression of protein coding sequences for GATA3 or PPARy1 in buccal epithelial cells resulted in nuclear immunolocalisation of the respective proteins, with both transductions also inducing expression of the urothelial differentiation-associated claudin 3 tight junction protein. PPARG1 overexpression alone entrained expression of nuclear FOXA1 and GATA3 proteins, providing objective evidence of its upstream positioning in a transcription factor network and identifying it as a candidate factor for urothelial-type transdifferentiation or reprogramming.

Stem cell in urology-are we at the cusp of a new era?

Stem cell therapy can potentially disrupt conventional medicine as we practice it today. Stem cells can self-renew and differentiate and by this, repair and in certain conditions regenerate damaged tissue. In the past two decades, there has been significant research into its value in several chronic urological conditions for which conventional therapy is unsatisfactory. Stem cell therapy has been tried on animal models of bladder dysfunction, stress urinary incontinence (SUI), erectile dysfunction and urethral injury and certain preclinical studies have had very encouraging results. Yet despite this explosion of knowledge about the nature and value of stem cells, translation of research into the clinical domain has been slow. In addition, lack of regulation of stem cell therapy has resulted in indiscriminate, unscientific administration of stem cell therapy to patients. This review looks into the advances in the use of stem cells in urological practice, the recent regulatory guidelines that have been introduced and what the future holds for this exciting branch.

The Current Use of Stem Cells in Bladder Tissue Regeneration and Bioengineering

Many pathological processes including neurogenic bladder and malignancy necessitate bladder reconstruction, which is currently performed using intestinal tissue. The use of intestinal tissue, however, subjects patients to metabolic abnormalities, bladder stones, and other long-term sequelae, raising the need for a source of safe and reliable bladder tissue. Advancements in stem cell biology have catapulted stem cells to the center of many current tissue regeneration and bioengineering strategies. This review presents the recent advancements in the use of stem cells in bladder tissue bioengineering.

Differentiate into urothelium and smooth muscle cells from adipose tissue-derived stem cells for ureter reconstruction in a rabbit model

Ureter reconstruction is still a tough task for urologist. Cell-based tissue engineering serves a better technique for patients with long segments of ureter defect who need ureter reconstruction. In this study, we sought to evaluate the differentiation potential of adipose derived stem cells (ADSCs) into urothelial lineage and smooth muscle lineage and to assess the possibility of ureter reconstruction using differentiated cells seeded vessel extracellular matrix (VECM) in a rabbit model. ADSCs were isolated from adipose tissue and identified in vitro. Subsequently, they were cultured with induction medium for urothelium and smooth muscle phenotypes differentiation. After 14 days inducing, differentiation was evaluated by Quantitative PCR and western blot studies. After fluorescent protein labeling, the differentiated cells were seeded onto VECM and cultured under dynamic conditions in vitro. After 7 days culturing, the cell-seeded graft was tubularized and wrapped by two layers of the omentum in a rabbit. Three weeks later, the maturated graft was used for ureter reconstruction in vivo. The ADSCs were isolated and cultured in vitro. Flow cytometry demonstrated that the ADSCs expressed CD29 and CD90, but did not express CD34. After induction, urothelium phenotypes gene (cytokeratin 7) and smooth muscle expression gene (a-SMA and SM-MHC) was confirmed in mRNA and protein level. After cells seeding onto VECM, the induced urothelium cells formed a single epithelial layer, and the induced smooth muscle cells formed a few cell layers during dynamic culture. After 3 weeks of omental maturation, tubular graft was vascularized and comprised epithelial layer positively with cytokeratin 7, cytokeratin 20 on the luminal aspect. At 8 weeks post ureter reconstruction, histological evaluation showed a clearly layered structure of ureter with terminally differentiated multilayered urothelium positively with cytokeratin 20 and uroplakin III over connective smooth muscle tissue positively with a-SMA and SM-MHC. The labeled induced cells could be observed in the reconstructed ureter. We demonstrated that ADSCs could differentiate into urothelial and smooth muscle lineage. Tissue engineered graft by these differentiated cells seeded on VECM could be employed to long segments ureter reconstruction after omental maturation in vivo.

Experimental bladder regeneration using a poly-l-lactide/silk fibroin scaffold seeded with nanoparticle-labeled allogenic bone marrow stromal cells

In the present study, a poly-l-lactide/silk fibroin (PL-SF) bilayer scaffold seeded with allogenic bone marrow stromal cells (BMSCs) was investigated as a potential approach for bladder tissue engineering in a model of partial bladder wall cystectomy in rabbits. The inner porous layer of the scaffold produced from silk fibroin was designed to promote cell proliferation and the outer layer produced from poly-l-lactic acid to serve as a waterproof barrier. To compare the feasibility and efficacy of BMSC application in the reconstruction of bladder defects, 12 adult male rabbits were divided into experimental and control groups (six animals each) that received a scaffold seeded with BMSCs or an acellular one, respectively. For BMSC tracking in the graft in in vivo studies using magnetic resonance imaging, cells were labeled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated high intracellular incorporation of nanoparticles and the absence of a toxic influence on BMSC viability and proliferation. Following implantation of the graft with BMSCs into the bladder, we observed integration of the scaffold with surrounding bladder tissues (as detected by magnetic resonance imaging). During the follow-up period of 12 weeks, labeled BMSCs resided in the implanted scaffold. The functional activity of the reconstructed bladder was confirmed by electromyography. Subsequent histological assay demonstrated enhanced biointegrative properties of the PL-SF scaffold with cells in comparison to the control graft, as related to complete regeneration of the smooth muscle and urothelium tissues in the implant. Confocal microscopy studies confirmed the presence of the superparamagnetic iron oxide nanoparticle-labeled BMSCs in newly formed bladder layers, thus indicating the role of stem cells in bladder regeneration. The results of this study demonstrate that application of a PL-SF scaffold seeded with allogenic BMSCs can enhance biointegration of the graft in vivo and support bladder tissue regeneration and function.

Production of urothelium from pluripotent stem cells for regenerative applications

As bladder reconstruction strategies evolve, a feasible and safe source of transplantable urothelium becomes a major consideration for patients with advanced bladder disease, particularly cancer. Pluripotent stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are attractive candidates from which to derive urothelium as they renew and proliferate indefinitely in vitro and fulfill the non-autologous and/or non-urologic criteria, respectively, that is required for many patients. This review presents the latest advancements in differentiating urothelium from pluripotent stem cells in vitro in the context of current bladder tissue engineering strategies.

Myocardin-related transcription factor-A-overexpressing bone marrow stem cells protect cardiomyocytes and alleviate cardiac damage in a rat model of acute myocardial infarction

Myocardin-related transcription factor-A (MRTF-A) can transduce biomechanical and humoral signals, which can positively modulate cardiac damage induced by acute myocardial infarction (AMI). In the clinic, bone marrow stem cell (BMSC) therapy is being increasingly utilized for AMI; however, the effects of BMSC transplantation remain to be optimized. Therefore, a novel strategy to enhance BMSC‑directed myocardial repair is particularly important. The present study was performed to assess the efficacy of MRTF‑A-overexpressing BMSCs in a rat model of AMI. Primary cardiomyocytes were prepared from neonatal Sprague-Dawley rats and BMSCs were isolated from male Sprague-Dawley rats (aged 8-12 weeks). Annexin V-phycoerythrin/7-actinomycin D staining was used to evaluate BMSC and cardiomyocyte survival after exposure to hydrogen peroxide in vitro. B-cell lymphoma 2 (Bcl-2) protein expression was measured by flow cytometric and western blot analyses. The effects of MRTF-A‑overexpressing BMSCs in a rat model of AMI were investigated by hematoxylin and eosin staining and western blot analysis of Bcl-2 expression in myocardial tissue sections. MRTF-A enhanced the migration of BMSCs, and overexpression of MRTF-A in BMSCs prevented hydrogen peroxide-induced apoptosis in primary cardiomyocytes ex vivo. In addition, co-culture of cardiomyocytes with MRTF‑A-overexpressing BMSCs inhibited hydrogen peroxide-induced apoptosis and the enhanced expression of Bcl-2. Furthermore, in vivo, enhanced cell survival was observed in the MRTF-A-modified BMSC group compared with that in the control group. These observations indicated that MRTF-A-overexpressing BMSCs have the potential to exert cardioprotective effects against hydrogen peroxide-induced injury and that treatment with MRTF‑A‑modified BMSCs is able to reverse cardiac dysfunction after AMI.

Dynamic reciprocity in cell-scaffold interactions

Tissue engineering in urology has shown considerable promise. However, there is still much to understand, particularly regarding the interactions between scaffolds and their host environment, how these interactions regulate regeneration and how they may be enhanced for optimal tissue repair. In this review, we discuss the concept of dynamic reciprocity as applied to tissue engineering, i.e. how bi-directional signaling between implanted scaffolds and host tissues such as the bladder drives the process of constructive remodeling to ensure successful graft integration and tissue repair. The impact of scaffold content and configuration, the contribution of endogenous and exogenous bioactive factors, the influence of the host immune response and the functional interaction with mechanical stimulation are all considered. In addition, the temporal relationships of host tissue ingrowth, bioactive factor mobilization, scaffold degradation and immune cell infiltration, as well as the reciprocal signaling between discrete cell types and scaffolds are discussed. Improved understanding of these aspects of tissue repair will identify opportunities for optimization of repair that could be exploited to enhance regenerative medicine strategies for urology in future studies.

Urine-derived stem cells for potential use in bladder repair

Engineered bladder tissues, created with autologous bladder cells seeded on biodegradable scaffolds, are being developed for use in patients who need cystoplasty. However, in individuals with organ damage from congenital disorders, infection, irradiation, or cancer, abnormal cells obtained by biopsy from the compromised tissue could potentially contaminate the engineered tissue. Thus, an alternative cell source for construction of the neo-organ would be useful. Although other types of stem cells have been investigated, autologous mesenchymal stem cells (MSCs) are most suitable to use in bladder regeneration. These cells are often used as a cell source for bladder repair in three ways - secreting paracrine factors, recruiting resident cells, and trans-differentiation, inducing MSCs to differentiate into bladder smooth muscle cells and urothelial cells. Adult stem cell populations have been demonstrated in bone marrow, fat, muscle, hair follicles, and amniotic fluid. These cells remain an area of intense study, as their potential for therapy may be applicable to bladder disorders. Recently, we have found stem cells in the urine and the cells are highly expandable, and have self-renewal capacity and paracrine properties. As a novel cell source, urine-derived stem cells (USCs) provide advantages for cell therapy and tissue engineering applications in bladder tissue repair because they originate from the urinary tract system. Importantly, USCs can be obtained via a noninvasive, simple, and low-cost approach and induced with high efficiency to differentiate into bladder cells.

A fibrin/hyaluronic acid hydrogel for the delivery of mesenchymal stem cells and potential for articular cartilage repair

Background

Osteoarthritis (OA) is a degenerative joint disease affecting approximately 27 million Americans, and even more worldwide. OA is characterized by degeneration of subchondral bone and articular cartilage. In this study, a chondrogenic fibrin/hyaluronic acid (HA)-based hydrogel seeded with bone marrow-derived mesenchymal stem cells (BMSCs) was investigated as a method of regenerating these tissues for OA therapy. This chondrogenic hydrogel system can be delivered in a minimally invasive manner through a small gauge needle, forming a three-dimensional (3D) network structure in situ. However, an ongoing problem with fibrin/HA-based biomaterials is poor mechanical strength. This was addressed by modifying HA with methacrylic anhydride (MA) (HA-MA), which reinforces the fibrin gel, thereby improving mechanical properties. In this study, a range of fibrinogen (the fibrin precursor) and HA-MA concentrations were explored to determine optimal conditions for increased mechanical strength, BMSC proliferation, and chondrogenesis potential in vitro.

Results

Increased mechanical strength was achieved by HA-MA reinforcement within fibrin hydrogels, and was directly correlated with increasing HA-MA concentration. Live/dead staining and metabolic assays confirmed that the crosslinked fibrin/HA-MA hydrogels provided a suitable 3D environment for BMSC proliferation. Quantitative polymerase chain reaction (qPCR) of BMSCs incubated in the fibrin/HA-MA hydrogel confirmed decreased expression of collagen type 1 alpha 1 mRNA with an increase in Sox9 mRNA expression especially in the presence of a platelet lysate, suggesting early chondrogenesis.

Conclusion

Fibrin/HA-MA hydrogel may be a suitable delivery method for BMSCs, inducing BMSC differentiation into chondrocytes and potentially aiding in articular cartilage repair for OA therapy.

Transdifferentiation of autologous bone marrow cells on a collagen-poly(ε-caprolactone) scaffold for tissue engineering in complete lack of native urothelium

Urological reconstructive surgery is sometimes hampered by a lack of tissue. In some cases, autologous urothelial cells (UCs) are not available for cell expansion and ordinary tissue engineering. In these cases, we wanted to explore whether autologous mesenchymal stem cells (MSCs) from bone marrow could be used to create urological transplants. MSCs from human bone marrow were cultured in vitro with medium conditioned by normal human UCs or by indirect co-culturing in culture well inserts. Changes in gene expression, protein expression and cell morphology were studied after two weeks using western blot, RT-PCR and immune staining. Cells cultured in standard epithelial growth medium served as controls. Bone marrow MSCs changed their phenotype with respect to growth characteristics and cell morphology, as well as gene and protein expression, to a UC lineage in both culture methods, but not in controls. Urothelial differentiation was also accomplished in human bone marrow MSCs seeded on a three-dimensional poly(ε-caprolactone) (PCL)-collagen construct. Human MSCs could easily be harvested by bone marrow aspiration and expanded and differentiated into urothelium. Differentiation could take place on a three-dimensional hybrid PCL-reinforced collagen-based scaffold for creation of a tissue-engineered autologous transplant for urological reconstructive surgery.

The differentiation of human adipose-derived stem cells towards a urothelium-like phenotype in vitro and the dynamic temporal changes of related cytokines by both paracrine and autocrine signal regulation

Purpose

To investigate the differentiation ability of human adipose-derived stem cells (ASCs) towards urothelium-like cells in vitro and the dynamic changes of related cytokines and cytokine receptors in the culture medium.

Materials and Methods

The ASCs were induced using both conditioned media (CM) and the transwell co-culture system with an immortalized urothelium cell line (SV-HUC-1,HUC) for 21 days. Protein and mRNA expression of the mature urothelium specific markers uroplakin-IA (UP-1A) and uroplakin-II (UP-II) were detected by immunofluorescence and quantitative real-time PCR, respectively. Array detection was used to screen 41 cytokines and receptors in the upper medium of urothelium, non-induced ASCs and urothelium-induced ASCs at three time points, early (12 hours), intermediate (7 days) and late (21 days).

Results

After induction for 7 days, the ASCs grown in both CM and transwell co-culture system expressed uroplakin-IA (13.54±2.00%; 17.28±1.84%) and uroplakin-II (19.49±1.73%; 13.98±1.47%). After induction for 21 days, ASCs grown in co-culture had significantly increased expression of uroplakin-IA (48.03±1.25%; 49.57±2.85%) and uroplakin-II (45.38±2.50%; 46.58±1.95%). In the upper medium of urothelium, 28 cytokines and 8 cytokine receptors had significantly higher expression than the counterpart of non-induced ASCs. After 7 days induction, the expression of 22 cytokines and 8 cytokine receptors was significantly elevated in the upper medium of induced ASCs compared to non-induced ASCs. At the early and intermediate time points, ASCs secreted high levels of relative cytokines and soluble receptors, but their expressions decreased significantly at the late time point.

Conclusion

The adipose-derived stem cells have the potential to be differentiated into urothelium-like cells in vitro by both CM and transwell co-culture system with mature urothelium. Numerous cytokines and receptors were involved in the differentiation process with dynamic temporal changes by both paracrine and autocrine signal regulation. Further studies should be carried out to determine the detailed mechanism of cytokines and receptors and to enhance the urothelium differentiation efficiency of ASCs.

Evaluation of silk biomaterials in combination with extracellular matrix coatings for bladder tissue engineering with primary and pluripotent cells

Silk-based biomaterials in combination with extracellular matrix (ECM) coatings were assessed as templates for cell-seeded bladder tissue engineering approaches. Two structurally diverse groups of silk scaffolds were produced by a gel spinning process and consisted of either smooth, compact multi-laminates (Group 1) or rough, porous lamellar-like sheets (Group 2). Scaffolds alone or coated with collagen types I or IV or fibronectin were assessed independently for their ability to support attachment, proliferation, and differentiation of primary cell lines including human bladder smooth muscle cells (SMC) and urothelial cells as well as pluripotent cell populations, such as murine embryonic stem cells (ESC) and induced pluripotent stem (iPS) cells. AlamarBlue evaluations revealed that fibronectin-coated Group 2 scaffolds promoted the highest degree of primary SMC and urothelial cell attachment in comparison to uncoated Group 2 controls and all Group 1 scaffold variants. Real time RT-PCR and immunohistochemical (IHC) analyses demonstrated that both fibronectin-coated silk groups were permissive for SMC contractile differentiation as determined by significant upregulation of α-actin and SM22α mRNA and protein expression levels following TGFβ1 stimulation. Prominent expression of epithelial differentiation markers, cytokeratins, was observed in urothelial cells cultured on both control and fibronectin-coated groups following IHC analysis. Evaluation of silk matrices for ESC and iPS cell attachment by alamarBlue showed that fibronectin-coated Group 2 scaffolds promoted the highest levels in comparison to all other scaffold formulations. In addition, real time RT-PCR and IHC analyses showed that fibronectin-coated Group 2 scaffolds facilitated ESC and iPS cell differentiation toward both urothelial and smooth muscle lineages in response to all trans retinoic acid as assessed by induction of uroplakin and contractile gene and protein expression. These results demonstrate that silk scaffolds support primary and pluripotent cell responses pertinent to bladder tissue engineering and that scaffold morphology and fibronectin coatings influence these processes.

Hair follicle stem cells can be driven into a urothelial-like phenotype: an experimental study

The aim of this study was to show that conditioned medium might induce transdifferentiation of hair follicle stem cells into urothelial-like cells. Several conditioned media and culture conditions (skeletal muscle cell conditioned medium, smooth muscle cell conditioned medium, fibroblast conditioned medium, transforming growth factor-conditioned medium, urothelial cell conditioned medium, and co-culture of hair follicle stem cells and urothelial cells) were used. The hair follicle stem cells phenotype from rat whisker hair follicles was checked by using flow cytometry and immunofluorescence. Cytokeratins 7, 8, 15 and 18 were used as markers. Urothelial cell conditioned medium increased the expression of urothelial markers (cytokeratin 7, cytokeratin 8, cytokeratin 18), whereas it decreased a hair follicle stem cells marker (cytokeratin 15) after 2 weeks of culture. This process depended on the time of cultivation. This medium was able to sustain the epithelial phenotype of the culture. Other media including a co-culture system failed to induce similar changes. Smooth muscle conditioned medium resulted in a loss of cells in culture. Hair follicle stem cells are capable of differentiating into urothelial-like cells in vitro when exposed to a bladder-specific microenvironment.

Tissue engineering for the oncologic urinary bladder

Urinary diversion after radical cystectomy in patients with bladder cancer normally takes the form of an ileal conduit or neobladder. However, such diversions are associated with a number of complications including increased risk of infection. A plausible alternative is the construction of a neobladder (or bladder tissue) in vitro using autologous cells harvested from the patient. Biomaterials can be used as a scaffold for naturally occurring regenerative stem cells to latch onto to regrow the bladder smooth muscle and epithelium. Such engineered tissues show great promise in urologic tissue regeneration, but are faced with a number of challenges. For example, the differentiation mesenchymal stem cells from various sources can be difficult and the smooth muscle cells formed do not precisely mimic the natural cells.

Fluorescent magnetic nanoparticle-labeled mesenchymal stem cells for targeted imaging and hyperthermia therapy of in vivo gastric cancer

How to find early gastric cancer cells in vivo is a great challenge for the diagnosis and therapy of gastric cancer. This study is aimed at investigating the feasibility of using fluorescent magnetic nanoparticle (FMNP)-labeled mesenchymal stem cells (MSCs) to realize targeted imaging and hyperthermia therapy of in vivo gastric cancer. The primary cultured mouse marrow MSCs were labeled with amino-modified FMNPs then intravenously injected into mouse model with subcutaneous gastric tumor, and then, the in vivo distribution of FMNP-labeled MSCs was observed by using fluorescence imaging system and magnetic resonance imaging system. After FMNP-labeled MSCs arrived in local tumor tissues, subcutaneous tumor tissues in nude mice were treated under external alternating magnetic field. The possible mechanism of MSCs targeting gastric cancer was investigated by using a micro-multiwell chemotaxis chamber assay. Results show that MSCs were labeled with FMNPs efficiently and kept stable fluorescent signal and magnetic properties within 14 days, FMNP-labeled MSCs could target and image in vivo gastric cancer cells after being intravenously injected for 14 days, FMNP-labeled MSCs could significantly inhibit the growth of in vivo gastric cancer because of hyperthermia effects, and CCL19/CCR7 and CXCL12/CXCR4 axis loops may play key roles in the targeting of MSCs to in vivo gastric cancer. In conclusion, FMNP-labeled MSCs could target in vivo gastric cancer cells and have great potential in applications such as imaging, diagnosis, and hyperthermia therapy of early gastric cancer in the near future.

An oligodeoxynucleotide that induces differentiation of bone marrow mesenchymal stem cells to osteoblasts in vitro and reduces alveolar bone loss in rats with periodontitis

To investigate the effect of oligodeoxynucleotides (ODNs) on the differentiation of rat bone marrow mesenchymal stem cells (BMSCs) to osteoblasts, in order to find a candidate ODN with potential for the treatment of periodontitis, a series of ODNs were designed and selected to test their effect on the promotion of the differentiation of BMSCs to osteoblasts in vitro and on the repair of periodontal tissue in rats with periodontitis. It was found that MT01, one of the ODNs with the sequences of human mitochondrial DNA, stimulated the proliferation of BMSCs, the differentiation of BMSCs to osteoblasts and mRNA expression of bone-associated factors including Runx2, Osterix, OPG, RANKL and collagen I in vitro. In vivo study showed that MT01 prevented the loss of alveolar bone in the rats with periodontitis and induced the production of proteins of OPG and Osterix in the bone tissue. These results indicated that MT01 could induce differentiation of BMSCs to osteoblasts and inhibit the alveolar bone absorption in rats with periodontitis.