ATP is released from the bladder mucosa in response to stretch, but the cell types responsible are unclear. Our aim was to isolate and characterize individual populations of urothelial, myofibroblast, and detrusor muscle cells in culture, and to examine agonist-stimulated ATP release. Using female pig bladders, urothelial cells were isolated from bladder mucosa following trypsin-digestion of the luminal surface. The underlying myofibroblast layer was dissected, minced, digested, and cultured until confluent (10–14 days). A similar protocol was used for muscle cells. Cultures were used for immunocytochemical staining and/or ATP release investigations. In urothelial cultures, immunoreactivity was present for the cytokeratin marker AE1/AE3 but not the contractile protein α-smooth muscle actin (α-SMA) or the cytoskeletal filament vimentin. Neither myofibroblast nor muscle cell cultures stained for AE1/AE3. Myofibroblast cultures partially stained for α-SMA, whereas muscle cultures were 100% stained. Both myofibroblast and muscle stained for vimentin, however, they were morphologically distinct. Ultrastructural studies verified that the suburothelial layer of pig bladder contained abundant myofibroblasts, characterized by high densities of rough endoplasmic reticulum. Baseline ATP release was higher in urothelial and myofibroblast cultures, compared with muscle. ATP release was significantly stimulated by stretch in all three cell populations. Only urothelial cells released ATP in response to acid, and only muscle cells were stimulated by capsaicin. Tachykinins had no effect on ATP release. In conclusion, we have established a method for culture of three cell populations from porcine bladder, a well-known human bladder model, and shown that these are distinct morphologically, immunologically, and pharmacologically.
ATP; porcine; bladder; urothelium; myofibroblast; detrusor; ultrastructure
Normal urothelium is characterised by terminally differentiated superficial cells, which express cytokeratin 20 in the cytoplasm. In contrast, cultured human stratified urothelium, which does not undergo complete terminal differentiation of its superficial cells, does not express cytokeratin 20. If spinal cord injury (SCI) affects urothelial differentiation or induces squamous or other metaplastic change undetected by histological analysis, the superficial urothelial cells of the neuropathic bladder might be expected to show absence of immunostaining for cytokeratin 20.
Patients and Methods
We studied immunostaining for cytokeratin 20 in bladder biopsies taken from 63 consecutive SCI patients. Immunostaining was performed on paraffin-embedded tissue using a mouse monoclonal antibody (clone: Ks20.8).
Of 63 biopsies, the epithelium was scarce in two. Eight biopsies showed squamous metaplasia and immunostaining for cytokeratin 20 was absent in all the eight biopsies. Of the remaining 53 cases, in which the umbrella cell layer of the urothelium was intact, immunostaining for cytokeratin 20 was seen only in ten biopsies.
Superficial cells in the transitional epithelium showed immunostaining for cytokeratin 20 in 10 of 53 bladder biopsies taken from SCI patients. The reasons for this could be either that there is an underlying metaplasia or that changes in the neuropathic bladder affect urothelial differentiation. Taken with evidence from other systems, such as loss of cytokeratin 20 expression from static organ cultures of urothelial tissue, this might suggest that other factors, such as impairment of voluntary voiding in SCI patients, could affect expression of markers such as cytokeratin 20.
Urothelial cells, myofibroblasts, and smooth muscle cells are important cell types contributing to bladder function. Multiple receptors including muscarinic (M3/M5), tachykinin (NK1/NK2), and purinergic (P2X1/P2Y6) receptors are involved in bladder motor and sensory actions. Using female pig bladder, our aim was to differentiate between various cell types in bladder by genetic markers. We compared the molecular expression pattern between the fresh tissue layers and their cultured cell counterparts. We also examined responses to agonists for these receptors in cultured cells. Urothelial, suburothelial (myofibroblasts), and smooth muscle cells isolated from pig bladder were cultured (10–14 days) and identified by marker antibodies. Gene (mRNA) expression level was demonstrated by real-time PCR. The receptor expression pattern was very similar between suburothelium and detrusor, and higher than urothelium. The gene expression of all receptors decreased in culture compared with the fresh tissue, although the reduction in cultured urothelial cells appeared less significant compared to suburothelial and detrusor cells. Cultured myofibroblasts and detrusor cells did not contract in response to the agonists acetylcholine, neurokinin A, and β,γ-MeATP, up to concentrations of 0.1 and 1 mM. The significant reduction of M3, NK2, and P2X1 receptors under culture conditions may be associated with the unresponsiveness of cultured suburothelial and detrusor cells to their respective agonists. These results suggest that under culture conditions, bladder cells lose the receptors that are involved in contraction, as this function is no longer required. The study provides further evidence that cultured cells do not necessarily mimic the actions exerted by intact tissues.
smooth muscle; urothelium; suburothelium; myofibroblasts; muscarinic receptors; tachykinin receptors; purinergic receptors; cell culture
Primary culture and animal and cell-line models of prostate and bladder development have limitations in describing human biology, and novel strategies that describe the full spectrum of differentiation from foetal through to ageing tissue are required. Recent advances in biology demonstrate that direct reprogramming of somatic cells into pluripotent embryonic stem cell (ESC)-like cells is possible. These cells, termed induced pluripotent stem cells (iPSCs), could theoretically generate adult prostate and bladder tissue, providing an alternative strategy to study differentiation.
To generate human iPSCs derived from normal, ageing, human prostate (Pro-iPSC), and urinary tract (UT-iPSC) tissue and to assess their capacity for lineage-directed differentiation.
Design, setting, and participants
Prostate and urinary tract stroma were transduced with POU class 5 homeobox 1 (POU5F1; formerly OCT4), SRY (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (gut) (KLF4), and v-myc myelocytomatosis viral oncogene homolog (avian) (MYC, formerly C-MYC) genes to generate iPSCs.
Outcome measurements and statistical analysis
The potential for differentiation into prostate and bladder lineages was compared with classical skin-derived iPSCs. The student t test was used.
Results and limitations
Successful reprogramming of prostate tissue into Pro-iPSCs and bladder and ureter into UT-iPSCs was demonstrated by characteristic ESC morphology, marker expression, and functional pluripotency in generating all three germ-layer lineages. In contrast to conventional skin-derived iPSCs, Pro-iPSCs showed a vastly increased ability to generate prostate epithelial-specific differentiation, as characterised by androgen receptor and prostate-specific antigen induction. Similarly, UT-iPSCs were shown to be more efficient than skin-derived iPSCs in undergoing bladder differentiation as demonstrated by expression of urothelial-specific markers: uroplakins, claudins, and cytokeratin; and stromal smooth muscle markers: α-smooth-muscle actin, calponin, and desmin. These disparities are likely to represent epigenetic differences between individual iPSC lines and highlight the importance of organ-specific iPSCs for tissue-specific studies.
IPSCs provide an exciting new model to characterise mechanisms regulating prostate and bladder differentiation and to develop novel approaches to disease modelling. Regeneration of bladder cells also provides an exceptional opportunity for translational tissue engineering.
Take Home Message
Induced pluripotent stem cells derived from human prostate and urinary tract cells can differentiate back into prostate and bladder cells. These cells provide a convenient ready-to-access model that offers enormous potential in clinical regenerative medicine and disease modelling.
Prostate; Bladder; Differentiation; Pluripotent; Stem cells; Tissue engineering; Ureter; Urothelium; Androgen receptor; POU5F1 (formerly OCT4); SOX2; KLF4; MYC (formerly cMYC); NANOG
Children with complex urogenital anomalies often require bladder reconstruction. Gastrointestinal tissues used in bladder augmentations exhibit a greatly increased risk of malignancy, and the bladder microenvironment may play a role in this carcinogenesis. Investigating the influences of the bladder microenvironment on gastrointestinal and urothelial cell cycle checkpoint activation and DNA damage response has been limited by the lack of an appropriate well-differentiated urothelial cell line system.
To meet this need, we have developed a well-differentiated conditionally immortalized urothelial cell line by isolating it from the H-2Kb-tsA58 transgenic mouse. These cells express a thermosensitive SV40 large T antigen that can be deactivated by adjustment of cell culture conditions, allowing the cell line to regain normal control of the cell cycle. The isolated urothelial cell line demonstrates a polygonal, dome-shaped morphology, expresses cytokeratin 18, and exhibits well-developed tight junctions. Adaptation of the urothelial cell line to hyperosmolal culture conditions induces expression of both cytokeratin 20 and uroplakin II, markers of a superficial urothelial cell or “umbrella cell.” This cell line can be maintained indefinitely in culture under permissive conditions but when cultured under non-permissive conditions, large T antigen expression is reduced substantially, leading to increased p53 activity and reduced cellular proliferation.
This new model of urothelial cells, along with gastrointestinal cell lines previously derived from the H-2Kb-tsA58 transgenic mouse, will be useful for studying the potential mechanisms of carcinogenesis of the augmented bladder.
The control and regulation of the lower urinary tract (LUT) is partly mediated by purinergic signaling. This study investigated the distribution and function of P2Y receptors in the rat urinary bladder. Application of P2Y agonists to rat urothelial cells evoked increases in intracellular calcium; the rank order of agonist potency (pEC50 ± S.E.M.) was ATP (5.10 ± 0.07)>UTP (4.91 ± 0.14)>UTPγS (4.61 ± 0.16) = ATPγS (4.70 ± 0.05) > 2MeSADP = NECA = ADP (<3.5). The rank order potency for these agonists indicates that urothelial cells functionally express P2Y2/P2Y4 receptors, with a relative lack of contribution from other P2Y or adenosine receptors. Real-time PCR, western blotting and immunocytochemistry, confirmed the expression of P2Y2, and to a lesser extent P2Y4 in the urothelium. Immunocytochemical studies revealed expression of P2Y2 staining in all layers of the urothelium, with relative absence of P2Y4. P2Y2 staining was also present in sub-urothelial nerve bundles and underlying detrusor smooth muscle. Addition of UTP and UTPγS was found to evoke ATP release from cultured rat urothelial cells. These findings indicate that cultured rat urothelial cells functionally express P2Y2/P2Y4 receptors. Activation of these receptors could have a role in autocrine and paracrine signaling throughout the urothelium. This could lead to the release of bioactive mediators such as additional ATP, nitric oxide and acetylcholine, which can modulate the micturition reflex by acting on sub-urothelial myofibroblasts and/or pelvic afferent fibers.
Purinergic receptors; urinary bladder; epithelium; lower urinary tract
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.
The goal of this study was to explore the feasibility of utilizing human umbilical mesenchymal stem cells (HUMSCs)-seeded Bladder acellular matrix graft (BAMG) for bladder reconstruction in a canine model.
HUMSCs were isolated from newborn umbilical cords and identified by flow cytometry. Partial cystectomy was performed in the experimental and control group. Bladder defects were repaired with HUMSCs-BAMG in the experimental group and repaired with unseeded-BAMG in control group. The implanted grafts were harvested after surgery. H&E and immunohistochemistry staining were performed to evaluate the regeneration of the bladder defect. Primary cultured HUMSCs displayed typical fibroblast morphology with spindle-shaped. Flow cytometry indicated that these cells were positive for CD105 (97.3%) and CD44 (99%), but negative for CD34 (2.8%), CD31 (2.1%), and CD45 (1.7%). Immunohistochemistry staining showed that a multilayered urothelium and well-developed smooth muscle were observed at 12 weeks in experiment group. In contrast, multilayered urothelial tissues were also observed at 12 weeks in group B, but well-developed smooth muscle bundles were observed.
Our preliminary results demonstrate that UMSC-seeded BAMGs are superior to unseeded BAMGs to promote the regeneration of bladder defects. Our findings indicated that HUMSCs may be a potential cell source for bladder tissue engineering.
Different clinical conditions can compromise the urinary bladder function and structure. Routine regenerative practices in urology for bladder augmentation have been associated with diverse side effects. The internal lining of the bladder, the urothelium, plays an integral role in normal bladder function. Tissue engineering has provided novel therapeutic strategies through scaffolding and cell transplantation. Nano-scale surface features of scaffolds are valuable parameters for enhancement of cell behavior and function.
Material and methods
We fabricated a new hybrid scaffold of poly ɛ-caprolactone (PCL) and poly-L-lactide acid (PLLA) using an electrospinning system to exploit each polymer's advantages at nano-scale in the same scaffold. Dog urothelial cells were isolated, characterized by immunocytochemistry, and expanded for loading on the scaffold. Cell viability and proliferation on the scaffold surface were assessed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, cytoarchitecture, distribution and detailed morphology of cells, and expression of cell specific markers were examined using hematoxylin and eosin (H + E) staining, scanning electron microscopy (SEM), and immunohistochemistry, respectively.
According to MTT results, the scaffold did not exert any cytotoxic effect, and also supported cell proliferation and viability for 14 days of culture, which led to a significant increase in the number of cells. Scanning electron microscopy images revealed evenly distributed and normal appearing colonies of urothelial cells. A well-defined layer of cells was observed using H + E staining, which preserved their markers (pan-cytokeratin and uroplakin III) while growing on the scaffold.
Our findings confirmed favorable properties of PCL/PLLA regarding biocompatibility and applicability for upcoming new methods of bladder augmentation and engineering.
urothelial cells; poly ɛ-caprolactone/poly-L-lactide acid; hybrid scaffold; tissue engineering
FGF10 is required for embryonic epidermal morphogenesis including brain development, lung morphogenesis, and initiation of limb bud formation. In this study, we investigated the role of FGF10 as a lead induction factor for stem cell differentiation toward urothelial cell. To this end, human multi-potent stem cell in vitro system was employed. Human amniotic fluid stem cells were co-cultured with immortalized bladder cancer lines to induce directed differentiation into urothelial cells. Urothelial markers, uroplakin II, III and cytokeratin 8, were monitored by RT-PCR, immunocytochemistry and western blot analysis. Co-cultured stem cells began to express uroplakin II, III and cytokeratin 8. Targeted FGF10 gene knock down from bladder cancer cells abolished the directed differentiation. In addition, when FGF10 downstream signaling was blocked with the mek inhibitor, the co-culture system lost the capacity to induce urothelial differentiation. Exogenous addition of recombinant FGF10 protein promoted stem cell differentiation into urothelium cell lineage. Together, this report suggests that paracrine FGF10 signaling stimulates the differentiation of human stem cell into urothelial cells. Current study provides insight into the potential role of FGF10 as a lead growth factor for bladder regeneration and its therapeutic application for bladder transplantation.
Human amniotic fluid stem cell; Fibroblast growth factor 10; Urothelium; Co-culture; Bladder cancer cells
Although urothelial progenitor-like cells have been described in the human urinary tract, the existence of stem cells remains to be proven. Using a culture system that favors clonogenic epithelial cell growth, we evaluated and characterized clonal human urothelial cells. We isolated human urothelial cells that were clonogenic, capable of self-renewal and could develop into fully differentiated urothelium once re-implanted into the subcapsular space of nude mice. In addition to final urothelial cell differentiation, spontaneous formation of bladder-like microstructures was observed. By examining an epithelial stem cell signature marker, we found p63 to correlate with the self-renewal capacity of the isolated human urothelial clonal populations. Since a clinically relevant, long-term model for functional reconstitution of human cells does not exist, we sought to establish a culture method for porcine urothelial cells in a clinically relevant porcine model. We isolated cells from porcine ureter, urethra and bladder that were clonogenic and capable of self-renewal and differentiation into fully mature urothelium. In conclusion, we could isolate human and porcine cell populations, behaving as urothelial stem cells and showing clonogenicity, self-renewal and, once re-implanted, morphological differentiation.
The upper (suburothelial) lamina propria (ULP) is a distinct region in the human bladder with dense populations of interstitial cells (IC), fine vascular networks and variable development of muscularis mucosae (MM). It is more and more obvious that the ULP plays an important role in bladder physiology and bladder disease, and in the present study we have quantified changes in the cellular key players of the ULP in bladders from patients with carcinoma in situ (CIS), multiple sclerosis (MS) and bladder pain syndrome (BPS). Tissue samples for the different patient groups were obtained from radical cystectomy-specimens. Standardized immunohistochemistry with a panel of specific cell markers was used to characterise the ULP cellular structures, followed by digitalised morphometry and quantitative staining analysis. Alterations in the ULP area were most pronounced in MS bladders, but also present in BPS and CIS bladders. We observed an increased thickness and increased variability in thickness of the ULP IC area in MS and BPS bladders; a significantly increased development of MM in MS bladders; a changed organization of vascular plexuses in the lamina propria in most pathologic bladders and a changed phenotype of ULP IC: a significantly decreased expression of progesterone receptor in MS bladders and a trend towards decreased expression of alpha-smooth muscle actin in BPS bladders. We show here for the first time the presence of disease-specific changes in organisation and/or phenotype of the different key players of the ULP area in human bladder. The present findings further support the hypothesis that the ULP area is involved and altered in different bladder diseases.
P2X receptors mediate the effects of ATP in micturition and nociception. During postnatal maturation, a spinobulbospinal reflex and voluntary voiding replace primitive voiding reflexes. This may involve changes in neuroactive compounds and receptors in bladder reflex pathways. We examined P2X2 and P2X3 receptors in bladder and spinal cord from postnatal (P0-P36) and adult Wistar rats. Western blot of whole bladders for P2X2 and P2X3 expression was performed. Immunostaining for P2X2 and P2X3 receptors in urothelium and detrusor smooth muscle whole-mounts and spinal cord sections was examined. Western blot demonstrated an age-dependent decrease (R2= 0.96, p ≤ 0.005) in P2X2 receptor expression in bladder whereas P2X3 receptor expression in bladder peaked (p ≤ 0.005) from P14-P21. P2X2-immunoreactivity (IR) was present in urothelial cells, suburothelial plexus, detrusor smooth muscle and serosa at birth with staining in urothelial cells and serosa being most predominant. With increasing postnatal age, the intensity of P2X2-IR decreased in urothelial cells but increased in suburothelial plexus. P2X3-IR increased in urothelial cells and suburothelial plexus with postnatal age whereas staining in detrusor and serosa remained relatively constant. At birth, P2X3-IR was present in the dorsal horn (DH), lateral collateral pathway (LCP), and dorsal commissure. With increasing age, P2X3-IR was restricted to superficial DH and LCP. P2X2-IR was present in ependyme cells (S-100-IR) of the central canal as early as P2. These studies demonstrate plastic expression of P2X2 and P2X3 receptors in bladder and spinal cord during early postnatal development at times coincident with appearance of mature voiding patterns.
postnatal development; micturition reflexes; sacral parasympathetic nucleus; dorsal commissure; dorsal horn
The mammalian ureter contains a water-tight epithelium surrounded by smooth muscle. Key molecules have been defined which regulate ureteric bud initiation and drive the differentiation of ureteric mesenchyme into peristaltic smooth muscle. Less is known about mechanisms underlying the developmental patterning of the multilayered epithelium characterising the mature ureter. In skin, which also contains a multilayered epithelium, cytokeratin 15 (CK15), an acidic intermediate filament protein, marks cells whose progeny contribute to epidermal regeneration following wounding. Moreover, CK15+ precursor cells in skin can give rise to basal cell carcinomas. In the current study, using transcriptome microarrays of embryonic wild type mouse ureters, Krt15, coding for CK15, was detected. Quantitative polymerase chain reaction analyses confirmed the initial finding and demonstrated that Krt15 levels increased during the fetal period when the ureteric epithelium becomes multilayered. CK15 protein was undetectable in the ureteric bud, the rudiment from which the ureter grows. Nevertheless, later in fetal development, CK15 was immunodetected in a subset of basal urothelial cells in the ureteric stalk. Superficial epithelial cells, including those positive for the differentiation marker uroplakin III, were CK15-. Transformation-related protein 63 (P63) has been implicated in epithelial differentiation in murine fetal urinary bladders. In wild type fetal ureters, CK15+ cells were positive for P63, and p63 homozygous null mutant ureters lacked CK15+ cells. In these mutant ureters, sections of the urothelium were monolayered versus the uniform multilayering found in wild type littermates. Human urothelial cell carcinomas account for considerable morbidity and mortality. CK15 was upregulated in a subset of invasive ureteric and urinary bladder cancers. Thus, in ureter development, the absence of CK15 is associated with a structurally simplified urothelium whereas, postnatally, increased CK15 levels feature in malignant urothelial overgrowth. CK15 may be a novel marker for urinary tract epithelial precursor cells.
Radical changes in both expression and glycosylation pattern of transmembrane mucins have been observed in various malignancies. We and others have shown that MUC1 and MUC4, two transmembrane mucins, play a sentinel role in cell signaling events that drive several epithelial malignancies. In the present study, we investigated the expression profile of MUC1 and MUC4 in the non-neoplastic bladder urothelium, in various malignant neoplasms of bladder and in bladder carcinoma cell lines.
Material and Methods
Immunohistochemistry was performed on tissue sections from the urinary bladder biopsies, resection samples and tissue microarrays (TMAs) with monoclonal antibodies specific for MUC1 and MUC4. We also investigated their expression in bladder carcinoma cell lines by RT-PCR and immunoblotting.
MUC1 is expressed on the apical surface or in umbrella cells of the normal non-neoplastic bladder urothelium. Strong expression of MUC1 was also observed in urothelial carcinoma (UC). MUC1 staining increased from normal urothelium (n = 27, 0.35±0.12) to urothelial carcinoma (UC, n = 323, H-score, 2.4±0.22, p≤0.0001). In contrast to MUC1, MUC4 was expressed in all the layers of non-neoplastic bladder urothelium (n = 14, 2.5±0.28), both in the cell membrane and cytoplasm. In comparison to non-neoplastic urothelium, the loss of MUC4 expression was observed during urothelial carcinoma (n = 211, 0.56±0.06). However, re-expression of MUC4 was observed in a subset of metastatic cases of urothelial carcinoma (mean H-score 0.734±0.9).
The expression of MUC1 is increased while that of MUC4 decreased in UC compared to the normal non-neoplastic urothelium. Expression of both MUC1 and MUC4, however, are significantly higher in urothelial carcinoma metastatic cases compared to localized UC. These results suggest differential expression of MUC1 and MUC4 during development and progression of bladder carcinoma.
Bladder cancer is a significant health problem in rural areas of Africa and the Middle East where Schistosoma haematobium is prevalent, supporting an association between malignant transformation and infection by this blood fluke. Nevertheless, the molecular mechanisms linking these events are poorly understood. Bladder cancers in infected populations are generally diagnosed at a late stage since there is a lack of non-invasive diagnostic tools, hence enforcing the need for early carcinogenesis markers.
Forty-three formalin-fixed paraffin-embedded bladder biopsies of S. haematobium-infected patients, consisting of bladder tumours, tumour adjacent mucosa and pre-malignant/malignant urothelial lesions, were screened for bladder cancer biomarkers. These included the oncoprotein p53, the tumour proliferation rate (Ki-67>17%), cell-surface cancer-associated glycan sialyl-Tn (sTn) and sialyl-Lewisa/x (sLea/sLex), involved in immune escape and metastasis. Bladder tumours of non-S. haematobium etiology and normal urothelium were used as controls. S. haematobium-associated benign/pre-malignant lesions present alterations in p53 and sLex that were also found in bladder tumors. Similar results were observed in non-S. haematobium associated tumours, irrespectively of their histological nature, denoting some common molecular pathways. In addition, most benign/pre-malignant lesions also expressed sLea. However, proliferative phenotypes were more prevalent in lesions adjacent to bladder tumors while sLea was characteristic of sole benign/pre-malignant lesions, suggesting it may be a biomarker of early carcionogenesis associated with the parasite. A correlation was observed between the frequency of the biomarkers in the tumor and adjacent mucosa, with the exception of Ki-67. Most S. haematobium eggs embedded in the urothelium were also positive for sLea and sLex. Reinforcing the pathologic nature of the studied biomarkers, none was observed in the healthy urothelium.
This preliminary study suggests that p53 and sialylated glycans are surrogate biomarkers of bladder cancerization associated with S. haematobium, highlighting a missing link between infection and cancer development. Eggs of S. haematobium express sLea and sLex antigens in mimicry of human leukocytes glycosylation, which may play a role in the colonization and disease dissemination. These observations may help the early identification of infected patients at a higher risk of developing bladder cancer and guide the future development of non-invasive diagnostic tests.
Epidemiological studies associate infection with S. haematobium, an endemic parasitic flatworm in Africa and the Middle East, with the development of bladder cancer. Nevertheless, little molecular evidence exists supporting this association. This work draws attention to the common molecular pathways underlying these two events, highlighting a potentially unreported link between infection and cancer development. It has been demonstrated that a panel of biomarkers commonly associated with aggressive forms of bladder cancer is also present in non-malignant tissues infected with the parasite. This may offer a means of early identification of people with this parasitic infection who are at risk of developing of bladder cancer, and may guide the establishment of non-invasive diagnostic tests. Furthermore, we observed that parasite eggs mimic the molecular nature of human cells, providing a possible mechanism of immune escape and persistent infection. Such knowledge is considered pivotal to develop novel therapeutic strategies.
The urothelium is a newly recognized sensory structure that detects bladder fullness. Pivotal to this sensory role is the release of ATP from the urothelium. However, the routes for urothelial ATP release, its modulation by receptor-mediated pathways, and the autocrine/paracrine role of ATP are poorly understood, especially in native tissue. We examined the action of key neurotransmitters: purinergic and muscarinic agonists on ATP release and its paracrine effect. Guinea pig and human urothelial mucosa were mounted in a perfusion trough; superfusate ATP was measured using a luciferin-luciferase assay, and tissue contractions were recorded with a tension transducer. Intracellular Ca2+ was measured in isolated urothelial cells with fura-2. The P2Y agonist UTP but not the P2X agonist α,β-methylene-ATP generated ATP release. The muscarinic agonist carbachol and the M2-preferential agonist oxotremorine also generated ATP release, which was antagonized by the M2-specific agent methoctramine. Agonist-evoked ATP release was accompanied by mucosal contractions. Urothelial ATP release was differentially mediated by intracellular Ca2+ release, cAMP, exocytosis, or connexins. Urothelium-attached smooth muscle exhibited spontaneous contractions that were augmented by subthreshold concentrations of carbachol, which had little direct effect on smooth muscle. This activity was attenuated by desensitizing P2X receptors on smooth muscle. Urothelial ATP release was increased in aging bladders. Purinergic and muscarinic agents produced similar effects in human urothelial tissue. This is the first demonstration of specific modulation of urothelial ATP release in native tissue by purinergic and muscarinic neurotransmitters via distinct mechanisms. Released ATP produces paracrine effects on underlying tissues. This process is altered during aging and has relevance to human bladder pathologies.
Urothelium; ATP release; paracrine effect; purinergic; muscarinic; neurotransmitters; sensory
The epidermal growth factor receptor (HER1) has been implicated in regenerative growth and proliferative diseases of the human bladder epithelium (urothelium), however a cognate HER1 ligand that can act as a growth factor for normal human urothelial cells (HUC) has not been identified. Here we show that heparin-binding EGF-like growth factor (HB-EGF), an activating HER1 ligand, is an autocrine regulator of HUC growth. This conclusion is based on demonstration of HB-EGF synthesis and secretion by primary culture HUC, identification of HER1 as an activatable HB-EGF receptor on HUC surfaces, stimulation of HUC clonal growth by HB-EGF, inhibition of HB-EGF-stimulated growth by heparin and of log-phase growth by CRM 197, a specific inhibitor of HB-EGF/HER1 interaction, and identification of human urothelium as a site of HB-EGF precursor (proHB-EGF) synthesis in vivo. ProHB-EGF expression was also detected in the vascular and detrusor smooth muscle of the human bladder. These data suggest a physiologic role for HB-EGF in the regulation of urothelial proliferation and regeneration subsequent to mucosal injury. Expression of proHB-EGF is also a feature of differentiated vascular and detrusor smooth muscle in the bladder. Because proHB-EGF is known to be the high affinity diphtheria toxin (DT) receptor in human cells, synthesis of the HB-EGF precursor by human urothelium also suggests the possibility of using the DT-binding sites of proHB-EGF as an in vivo target for the intraluminal treatment of urothelial diseases.
Urinary bladder voiding is a complex mechanism depending upon interplay among detrusor, urothelium, sensory and motor neurons and connective tissue cells. The identity of some of the latter cells is still controversial. We presently attempted to clarify their phenotype(s) in the human urinary bladder by transmission electron microscopy (TEM) and immunohistochemistry. At this latter aim, we used CD34, PDGFRα, αSMA, c-Kit and calreticulin antibodies. Both, TEM and immunohistochemistry, showed cells that, sharing several telocyte (TC) characteristics, we identified as TC; these cells, however, differed from each other in some ultrastructural features and immunolabelling according to their location. PDGFRα/calret-positive, CD34/c-Kit-negative TC were located in the sub-urothelium and distinct in two subtypes whether, similarly to myofibroblasts, they were αSMA-positive and had attachment plaques. The sub-urothelial TC formed a mixed network with myofibroblasts and were close to numerous nerve endings, many of which nNOS-positive. A third TC subtype, PDGFRα/αSMA/c-Kit-negative, CD34/calret-positive, ultrastructurally typical, was located in the submucosa and detrusor. Briefly, in the human bladder, we found three TC subtypes. Each subtype likely forms a network building a 3-D scaffold able to follow the bladder wall distension and relaxation and avoiding anomalous wall deformation. The TC located in the sub-urothelium, a region considered a sort of sensory system for the micturition reflex, as forming a network with myofibroblasts, possessing specialized junctions with extracellular matrix and being close to nerve endings, might have a role in bladder reflexes. In conclusions, the urinary bladder contains peculiar TC able to adapt their morphology to the organ activity.
lamina propria; sub-urothelium and submucosa; detrusor; mast cells; myofibroblasts; CD34; PDGFRα; c-Kit; αSMA; calreticulin
These findings clearly demonstrate that substratum nanotopography inhibits TGFβ-induced corneal myofibroblast differentiation and suggests that structural features of this scale help to stabilize the keratocyte and fibroblast phenotypes in vivo.
The transition of corneal fibroblasts to the myofibroblast phenotype is known to be important in wound healing. The purpose of this study was to determine the effect of topographic cues on TGFβ-induced myofibroblast transformation of corneal cells.
Rabbit corneal fibroblasts were cultured on nanopatterned surfaces having topographic features of varying sizes. Cells were cultured in media containing TGFβ at concentrations ranging from 0 to 10 ng/mL. RNA and protein were collected from cells cultured on topographically patterned and planar substrates and analyzed for the myofibroblast marker α-smooth muscle actin (αSMA) and Smad7 expression by quantitative real time PCR. Western blot and immunocytochemistry analysis for αSMA were also performed.
Cells grown on patterned surfaces demonstrated significantly reduced levels of αSMA (P < 0.002) compared with planar surfaces when exposed to TGFβ; the greatest reduction was seen on the 1400 nm surface. Smad7 mRNA expression was significantly greater on all patterned surfaces exposed to TGFβ (P < 0.002), whereas cells grown on planar surfaces showed equal or reduced levels of Smad7. Western blot analysis and αSMA immunocytochemical staining demonstrated reduced transition to the myofibroblast phenotype on the 1400 nm surface when compared with cells on a planar surface.
These data demonstrate that nanoscale topographic features modulate TGFβ-induced myofibroblast differentiation and αSMA expression, possibly through upregulation of Smad7. It is therefore proposed that in the wound environment, native nanotopographic cues assist in stabilizing the keratocyte/fibroblast phenotype while pathologic microenvironmental alterations may be permissive for increased myofibroblast differentiation and the development of fibrosis and corneal haze.
We reported previously that both subtypes of estrogen receptors, ERα and ERβ, are expressed by human urothelial cells and mediate estrogen-induced cell proliferation in these cells. The aim of this study was to determine the extent to which each ER subtype contributes to urothelial cell proliferation and their possible involvement in the regulation of the cell cycle. We compared the expression of ERα and ERβ mRNAs and protein quantitatively in primarily cultured human bladder urothelial cells obtained from six individuals with three immortalized urothelial (E6, E7, and UROtsa) and two bladder cancer cell lines (HTB-9 and T24). We found that all these cells express similar levels of ERβ, but immortalized and cancer cells express much higher amounts of ERα than primary cells. Higher levels of ERα mRNA were also observed in the biopsies of bladder transitional cell carcinoma compared with sample from the same bladder unaffected by tumor. Using the ERα-selective agonist PPT, the ERβ-selective agonist DPN, and specific small interfering RNA against ERα or ERβ, we found that ERβ predominantly mediates estrogen-induced G1/S transition and cell proliferation in the primary urothelial cells. By contrast, ERα predominantly mediates estrogen-induced G1/S transition and cell proliferation in bladder cancer cell lines. Furthermore, we found that 17β-estradiol (E2) rapidly induces phosphorylation of extracellular signal-regulated kinases, but U0126, a mitogen-activated protein kinase kinase (MEK) inhibitor, does not affect E2-induced urothelial cell proliferation. E2 up-regulated cyclin D1 and cyclin E expression in both the primary and bladder cancer cells, and the cancer cells have higher cyclin D1 and cyclin E expression during G0/G1 phases. Our data suggest that estrogen exerts its effects through different ER subtypes in urothelial cells. Increased expression of ERα may contribute to early induction of cyclin D1 and cyclin E during the cell cycle in bladder cancer cells.
The pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS) is multifactorial, but likely involves urothelial cell dysfunction and mast cell accumulation in the bladder wall. Activated mast cells in the bladder wall release several inflammatory mediators, including histamine and tryptase. We determined whether mitogen-activated protein (MAP) kinases are activated in response to tryptase stimulation of urothelial cells derived from human normal and IC/PBS bladders. Tryptase stimulation of normal urothelial cells resulted in a 2.5-fold increase in extracellular signal regulated kinase 1/2 (ERK 1/2). A 5.5-fold increase in ERK 1/2 activity was observed in urothelial cells isolated from IC/PBS bladders. No significant change in p38 MAP kinase was observed in tryptase-stimulated normal urothelial cells but a 2.5-fold increase was observed in cells isolated from IC/PBS bladders. Inhibition of ERK 1/2 with PD98059 or inhibition of p38 MAP kinase with SB203580 did not block tryptase-stimulated iPLA2 activation. Incubation with the membrane phospholipid-derived PLA2 hydrolysis product lysoplasmenylcholine increased ERK 1/2 activity, suggesting the iPLA2 activation is upstream of ERK 1/2. Real time measurements of impedance to evaluate wound healing of cell cultures indicated increased healing rates in normal and IC/PBS urothelial cells in the presence of tryptase, with inhibition of ERK 1/2 significantly decreasing the wound healing rate of IC/PBS urothelium. We conclude that activation of ERK 1/2 in response to tryptase stimulation may facilitate wound healing or cell motility in areas of inflammation in the bladder associated with IC/PBS.
The occurrence of clear cell tumors in the bladder is not uncommon. Clear cell dysplasia is well-described and characterized by focal replacement of transitional mucosa by cells with abundant clear cytoplasm, nuclear enlargement, and a granular chromatin pattern. Clear cells can also be seen in clear cell adenocarcinoma, which is rare, comprising 0.5% to 2.0% of the reported bladder carcinomas. Other clear cell tumors found in the bladder to be considered in the differential diagnosis are tumors of Müllerian origin and metastatic lesions, such as renal cell carcinoma, clear cell sarcoma, and malignant melanoma. Clear cell urothelial carcinoma is exceedingly rare, with only nine clinical cases described in the literature.
We report the case of a 75-year-old Caucasian man who presented with intermittent hematuria, in whom a bladder tumor was identified. A final histopathology examination of a cystoprostatectomy specimen revealed a pT3b, G3 urothelial carcinoma of clear cell type (>90% clear cells) and a prostatic adenocarcinoma of Gleason grade 3+3 (score=6). The bladder tumor consisted of sheets of malignant cells with severe nuclear atypia and abundant clear cytoplasm; no glandular or tubular structures were identified. Tumor cells were periodic acid-Schiff positive and negative after diastase treatment; additional mucicarmine and oil red O stains were negative. Immunohistochemical stains showed the tumor cells positive for cytokeratin 7 (CK7), p63 (>80% nuclei), p53 (about 30% nuclei), vimentin, E-cadherin, cluster of differentiation (CD10), and Ki-67 (>70% nuclei). Stains for cell adhesion molecule 5.2 (CAM 5.2), CD117, cytokeratin 20 (CK20), human melanoma black 45 (HMB-45), paired box protein (PAX 8), placental alkaline phosphatase (PLAP), prostate specific antigen (PSA), renal cell carcinoma (RCC), cancer antigen 25 (CA25), leukocyte common antigen (LC), S-100 protein, and uroplakin III were all negative.
The tumor marker profile was consistent with clear cell type carcinoma of urothelial origin. Within the differential diagnoses, we ruled out other possible tumor types such as urothelial carcinoma with focal clear cell differentiation, clear cell adenocarcinoma, Müllerian tumors, and metastatic disease.
Clear cell; Cancer; Urinary bladder; Urothelial carcinoma
The Cajal–like intestitial cells (ICCs) act as a pacemaker and are responsible for generating smooth muscle activity in the gastrointestinal tract (GI). Interstitial cells that resemble ICCs in the GI have been identified in the urinary bladder.
Materials and methods
This review is based on a systemic literature research. The medline/pubmed, scopus, embase, and Web of Science databases were browsed in order to identify original and review articles, as well as editorials relating to cajal–like cells, urinary bladder, detrusor overactivity, overactive bladder, glivec, etc. The controlled vocabulary of the Medical Subject Headings (MeSH) database was used to ensure the sensitivity of the searches. 40 papers met the criteria and were used for this review.
Cajal cells lie in close proximity to the muscle cells, autonomic nerve endings, and urothelial cells. There is increasing evidence that ICCs play role in urinary tract dysfunction development (e.g. detrusor overactivity, primary obstructive megaureter, congenital ureteropelvic junction obstruction, etc.). ICCs may be responsible for generating electrical potentials and induction of detrusor muscle contractions. Novel pathomechanisms of detrusor overactivity development have been postulated, as follows: 1) the disturbance of spontaneous contractility caused by altered signal transduction of ICCs between nerves and detrusor muscle cells, and 2). the alteration in signal transduction between urothelium and afferent nerve endings via suburothelial ICCs. The c–kit receptor is not only a detection marker of these cells, but may also play a crucial role in the control of bladder function.
Cajal cells in urinary bladder suggest that the c–kit receptor may provide a novel target for treating detrusor overactivity. The review presents the current knowledge of ICCs, its role in urinary bladder function, and potential novel therapeutic strategy.
cajal cells; overactive bladder; treatment; glivec
Induction of smooth muscle differentiation from bladder mesenchyme depends on signals that originate from the urothelium. We hypothesize Sonic hedgehog (Shh) is the urothelial signal that promotes bladder mesenchymal proliferation and induces bladder smooth muscle differentiation.
Pregnant FVB mice were euthanized on embryonic day (E) 12.5 and fetal bladders were harvested. Two experimental protocols were utilized:
Bladder mesenchyme (BLM) was isolated by incubating intact bladders (IB) in 0.02 M EDTA and then removing the urothelium by microdissection. IB and BLM were cultured in Shh-deficient media or BLM was cultured in Shh-supplemented (480 nM) media for 72 h.IB were cultured for 72 h in media containing different concentrations of Shh (0, 48, and 480 nM).
Specimens were sized by serial sectioning. Cell counts were performed after trypsin digestion. Immunohistochemistry was performed to detect smooth muscle-specific protein expression. α-Actin expression was quantified using Western blot.
All specimens were viable at 72 h. BLM cultured without Shh survived but did not grow or undergo smooth muscle differentiation. IB cultured without Shh and BLM cultured with Shh grew and expressed smooth muscle proteins at 72 h. IB cultured with Shh were larger and contained more cells than IB cultured without Shh (all p <0.05). Increasing Shh concentration from 48 to 480 nM did not change bladder size, cell counts, or the level of α-actin expression. Prior to culture, IB did not express α-actin. After culture of IB in Shh-deficient media, α-actin was detected throughout the mesenchyme except in the submucosal layer. The IB submucosa was thinner after culture with 48 nM Shh and smooth muscle completely obliterated the submucosa after culture with 480 nM Shh.
In fetal mouse bladders, urothelium-derived Shh is necessary for mesenchymal proliferation and smooth muscle differentiation. Shh concentration affects mesenchymal proliferation and patterning of bladder smooth muscle.
Bladder; Urothelium; Sonic hedgehog; Smooth muscle differentiation