The isolation and characterization in vitro of normal epithelial cells, endothelial cells and fibroblasts from rat urinary bladder

MAPK4 silencing in gastric cancer drives liver metastasis by positive feedback between cancer cells and macrophages

Liver metastasis is a major cause of death in gastric cancer patients, but the underlying mechanisms are poorly understood. Through a combination of in vivo screening and transcriptome profiling followed by quantitative RT-PCR and tissue array analyses, we found that mitogen-activated protein kinase 4 (MAPK4) downregulation in gastric cancer tissues from patients is significantly associated with liver metastasis and poor prognosis. The knockdown of MAPK4 in gastric cancer cells promotes liver metastasis in orthotopic mouse models. MAPK4 depletion in gastric cancer cells induces the secretion of macrophage migration inhibitory factor (MIF) to polarize tumor-associated macrophages (TAMs) in orthotopic xenograft tumors. Moreover, TAMs activate epithelial-mesenchymal transition of gastric cancer cells to suppress MAPK4 expression, which further increases MIF secretion to polarize TAMs. Taken together, our results suggest a previously undescribed positive feedback loop between cancer cells and macrophages mediated by MAPK4 silencing that facilitates gastric cancer liver metastasis.

Exploring Interactions between Primary Hepatocytes and Non-Parenchymal Cells on Physiological and Pathological Liver Stiffness

Simple Summary

Chronic liver disease is characterized by progressive hepatic fibrosis leading to the formation of cirrhosis irrespective of the etiology with no effective treatment currently available. Liver stiffness (LS) is currently the best clinical predictor of this fibrosis progression irrespective of the cause of the disease. However, it is not well understood how does LS regulate the critical hepatocytes–non parenchymal cell interactions. We here present, to the best of our knowledge, the first analyses of the impact of physiological and pathological stiffness on hepatocytes–non parenchymal cell interaction. Our findings indicate the role of stiffness in regulating the hepatocytes interactions with NPCs necessary for maintenance of hepatocytes function.

Abstract

Chronic liver disease is characterized by progressive hepatic fibrosis leading to the formation of cirrhosis irrespective of the etiology with no effective treatment currently available. Liver stiffness (LS) is currently the best clinical predictor of this fibrosis progression irrespective of the etiology. LS and hepatocytes-nonparenchymal cells (NPC) interactions are two variables known to be important in regulating hepatic function during liver fibrosis, but little is known about the interplay of these cues. Here, we use polydimethyl siloxane (PDMS) based substrates with tunable mechanical properties to study how cell–cell interaction and stiffness regulates hepatocytes function. Specifically, primary rat hepatocytes were cocultured with NIH-3T3 fibroblasts on soft (2 kPa) and stiff substrates that recreates physiologic (2 kPa) and cirrhotic liver stiffness (55 kPa). Urea synthesis by primary hepatocytes depended on the presence of fibroblast and was independent of the substrate stiffness. However, albumin synthesis and Cytochrome P450 enzyme activity increased in hepatocytes on soft substrates and when in coculture with a fibroblast. Western blot analysis of hepatic markers, E-cadherin, confirmed that hepatocytes on soft substrates in coculture promoted better maintenance of the hepatic phenotype. These findings indicate the role of stiffness in regulating the hepatocytes interactions with NPCs necessary for maintenance of hepatocytes function.

Characterization and Standardization of Cultured Cardiac Fibroblasts for Ex Vivo Models of Heart Fibrosis and Heart Ischemia

A full understanding of cardiac fibroblast (cFB) biology is essential to study the adverse cardiac remodeling and recovery of myocardium infarction. However, compared to cardiac myocytes, cFBs are less well characterized. Important questions, including the variability introduced by cell age (neonatal vs. adult), culture conditions (passage, plate coating, and culture medium), and responses to stimuli (e.g., hypoxia and drug treatments), have not been well addressed and standardization of techniques is lacking. This variability invites inconsistency and the confounding of study conclusions. Thus, we here focus on characterizing cell responses and standardizing procedures for cFB isolation and culture conditions to provide reliable platforms to address important questions about cFB proliferation, activation, collagen matrix formation, and responses to relevant stimuli. Thirty litters of 1-3-day pups and 30 female (240-330 g) Sprague-Dawley rats were used to isolate neonatal and adult cFBs. We detail and validate procedures to isolate cFBs for the use of culture or direct analysis. We characterize the differences between neonatal and adult cFBs, define the changes of cFBs during serial passage, and identify the response of cFBs to different culture conditions. We have also established models for the functional screening of profibrotic and antifibrotic drugs based on cFB proliferation, myofibroblast activation, and pericellular collagen matrix formation, and models of hypoxia/reoxygenation with appropriate time course and media conditions to achieve consistent cell injury. Our standardized procedures will ensure consistency in assessing cFB function. This original contribution provides a valid platform for the ex vivo investigation of the role of cFBs in cardiac ischemia and fibrosis.

Anti-proliferative effects of polyphenols from pomegranate rind (Punica granatum L.) on EJ bladder cancer cells via regulation of p53/miR-34a axis

miRNAs and their validated miRNA targets appear as novel effectors in biological activities of plant polyphenols; however, limited information is available on miR-34a mediated cytotoxicity of pomegranate rind polyphenols in cancer cell lines. For this purpose, cell viability assay, Realtime quantitative PCR for mRNA quantification, western blot for essential protein expression, p53 silencing by shRNA and miR-34a knockdown were performed in the present study. EJ cell treatment with 100 µg (GAE)/mL PRE for 48 h evoked poor cell viability and caspase-dependent pro-apoptosis appearance. PRE also elevated p53 protein and triggered miR-34a expression. The c-Myc and CD44 were confirmed as direct targets of miR-34a in EJ cell apoptosis induced by PRE. Our results provide sufficient evidence that polyphenols in PRE can be potential molecular clusters to suppress bladder cancer cell EJ proliferation via p53/miR-34a axis.

Altered phenotype of cultured urothelial and other stratified epithelial cells: implications for wound healing

The differentiation of cultured stratified epithelial cells can deviate significantly from that of normal epithelium, leading to suggestions that cultured cells undergo abnormal differentiation, or a truncated differentiation. Thus cultured epidermal and corneal epithelial cells stop synthesizing their tissue-specific keratin pair K1/K10 and K3/K12, respectively. The replacement of these keratins in the suprabasal compartment by K6/K16 keratins that are made by all stratified squamous epithelia during hyperplasia rules out a truncated differentiation. Importantly, the keratin pattern of in vivo corneal epithelium undergoing wound repair mimics that of cultured rabbit corneal epithelial cells. Although cultured urothelial cells continue to synthesize uroplakins, which normally form two-dimensional crystalline urothelial plaques covering almost the entire apical urothelial surface, these proteins do not assemble into crystals in cultured cells. Cultured epithelial cells can, however, rapidly regain normal differentiation on the removal of mitogenic stimuli, the use of a suitable extracellular matrix, or the transplantation of the cells to an in vivo, nonmitogenic environment. These data suggest that cultured epithelial cells adopt altered differentiation patterns mimicking in vivo regenerating or hyperplastic epithelia. Blocking the synthesis of tissue-specific differentiation products, such as the K1 and K10 keratins designed to form extensive disulfide cross-links in cornified cells, or the assembly of uroplakin plaques allows epithelial cells to better migrate and proliferate, activities that are of overriding importance during wound repair. Cultured urothelial and other stratified epithelial cells provide excellent models for studying the regulation of the synthesis and assembly of differentiation products, a key cellular process during epithelial wound repair.

[Current status of tissue engineering in urology. Review of the literature]

In the eighties a new field of the medicine appears wich applies the principles of cellular cultivation to synthetic biodegradable polymers scaffolds with the purpose of creating autologous biological substitutes that could improve, maintain or restore the function of organs or damaged tissues. The Tissue Engineering constitutes a new discipline in full phase of development especially in USA, with multiple potential applications in several medical specialities. Our speciality can't remain indifferent to interest and encouraging future originated by this new science. In this work we have made a wide bibliographical revision in the Medline to know the antecedents, current state and the possible future applications of Tissue Engineering in Urology.

[Experimental study about viability of autologous free graft in vitro cultivated urinary epithelium]

OBJECTIVE

The purpose of this study is to apply the in vitro keratinocyte culture techniques and the tissue engineering principles to urothelium, to obtain a three-dimensional autologous tissue suitable for grafting. We also showed the viability of free graft cultured urothelium in an experimental model.

MATERIAL AND METHODS

An animal experimental model was designed to apply the techniques of cellular culture and tissue engineering. Biopsy specimens of bladder mucosa were obtained, in vitro cultured and posteriorly implanted in each animal. We established three groups based on different follow-up periods (7, 14 and 30 days), and made a final histomorphological study to demonstrate the viability of the graft at the end of its respective follow-up period.

RESULTS

A three-dimensional in vitro tissue was obtained, composed of a bio-artificial submucosa (fibrin gel and fibroblast) where the uroepithelial cells were seeding; a biodegradable polyglycolic acid mesh was used to facilitate the tissue manipulation and implantation. In the morphological study all the implants appeared viable, but the grafts with longer implantations periods were better conformed, showing a tisular structure with multiple cellular layers.

CONCLUSIONS

In vitro keratinocyte culture techniques could be applied to other epithelial tissues as the urothelium. We obtained a three-dimensional in vitro tissue suitable for grafting in a relatively short time. The histological study demonstrated that free autologous urothelial graft is totally viable, opening future clinics applications.

Cultured porcine urinary bladder epithelial cells as a screening model for genotoxic effects of aromatic amines: characterisation and application of the cell culture model

Isolated epithelial cells from porcine urinary bladders were maintained in dividing long-term monolayer cultures, and were used as a model system for the urinary bladder in toxicological studies in vitro. To examine the state of differentiation during the culture period, the culture system was characterised morphologically by light and transmission electron microscopy and by immune fluorescence labelling with antibodies against cytokeratins 7,13 and pan. The cultured cells were identified as urothelial epithelium by their polarised structure, and by their expression of several uroepithelial specific morphological features, such as fusiform vesicles, tight junctions and an asymmetric apical cell membrane. Additionally, the cells were labelled with anti-cytokeratin 7,13 and pan antibodies, and negatively with anti-vimentin antibodies. The maintenance of suitable culture conditions was shown by the stable enzyme activities of (gamma-glutamyltranspeptidase, alkaline phosphatase and acid phosphatase over a culture period of 4 weeks. A good viability of the cultured cells under the chosen culture conditions was shown by the presence of low amounts of lactate dehydrogenase (< of = 5%) in the culture medium. The activities of the chosen marker enzymes for cell differentiation (gamma-glutamyltranspeptidase), lysosomes (acid phosphatase) and luminal membranes (alkaline phosphatase) were relatively stable over the observed culture period. Enzyme activities involved in metabolism of xenobiotics were determined, to define the ability for metabolism in cultured cells compared with bladder tissue in situ. Several constitutive phase I and II enzyme activities were found to be stable during the culture period, indicating that the cultured cells should be able to metabolise xenobiotics in a comparable manner to the urothelium in vivo. The cytotoxic effects of xenobiotics were investigated and IC50 values were determined by means of lactate dehydrogenase leakage and inhibition of neutral red uptake. The induction of sister chromatid exchanges was used as a parameter for the genotoxic effects of several xenobiotics. This cell culture system was found to be a very good screening system for the testing of substances that affect the bladder, especially aromatic amines.

The long-term culture of porcine urothelial cells and induction of urothelial stratification

OBJECTIVE

To assess porcine urothelial cell cultures and the in vitro induction of urothelial stratification in long-term cultures, to study their morphological, functional and genetic behaviour, and thus provide potential autologous urothelium for tissue-engineered substitutes for demucosalized gastric or colonic tissue.

MATERIALS AND METHODS

Primary cultures of porcine urothelium were established and the cells passaged thereafter. Cell specificity was confirmed by cytokeratin analysis, cell membrane stability assessed using lactate dehydrogenase leakage, cell de-differentiation by gamma-glutamyl transferase activity and genomic stability by karyotype investigations. Histology and scanning electron microscopy were performed to study the cultured cells and the stratified constructs. Furthermore, collagen matrices were tested as cell scaffolds.

RESULTS

The cells were cultured for 180 days; 10 subcultures were established during this period. Stratification was induced in a culture flask and on a collagen matrix. Cytokeratins 7, 8, 17 and 18 were expressed in all cultures, and cell membranes were stable, with no evident de-differentiation. The cultures were stable in their genotype and no chromosomal aberrations were found. The histology and immunohistochemistry of the stratified porcine constructs, and cell membrane stability and cell de-differentiation, were compared with those in the human system.

CONCLUSION

Pig and human urothelial cells can be cultured over a long period with no signs of senescence. Urothelial stratification can be induced in vitro. The collagen matrix seems to be an excellent scaffold, allowing cell adherence and growth.

Long term growth and maintenance of stratified rat urothelium in vitro

Culture conditions that allow long term growth and maintenance of rat urothelium have been determined using short (3 to 8 days) and long (14 to 60 days) term measurements of cell density and tritiated thymidine incorporation as indices. The basal nutrient medium utilized was a mixture of 199 plus Ham's F 12 (1:1) supplemented with insulin (1 microgram/ml) and hydrocortisone (1 microgram/ml). Long term culture of urothelium seems to require porous collagen. Porous albumin, or plastic dishes thinly coated with albumin, collagen, fibronectin or mixtures thereof, did not support long term maintenance. Serum was required at a concentration of 5%, independent of other additives. Decreasing Ca++ levels below that normally found the basal medium (approximately 1 X 10(-3] to as low as 1 X 10(-4), resulted in increased short term proliferation, but decreased long term maintenance by causing a loss of stratification of the urothelium. Even a slight increase in Ca++ concentration from 1.0 to 1.5 X 10(-3) resulted in an inhibition of proliferation and an increase in the number of large flat cells which subsequently sloughed off in sheets. The deletion of either insulin, hydrocortisone or both, inhibited growth. The addition of epidermal growth factor (EGF) or its homologue, transforming growth factor (TGF-alpha), increased cell proliferation markedly and caused a variable increase in stratification. However, epithelium induced to rapid growth and proliferation with EGF, eventually exhausted its growth potential and died. TGF-beta 1, alone or in combination with either EGF or alpha-TGF, had no additional effect upon urothelial growth. Repeated transfers of urothelium by enzymatic dissociation led to decreased growth and maintenance potential. The data indicates that long term maintenance of stratified urothelium in culture requires a porous collagen substrate and fetal bovine serum together with hormonal requirements and concentrations of Ca++ that neither greatly stimulate nor inhibit growth.

An improved method for the preparation and culture of urothelial cells

Urothelial cells have been prepared by a new method involving collagenase treatment of the lumen of a ureter. These cells have been identified as epithelial and successfully subcultured. In addition, we have observed that growth rate is significantly increased by the inclusion of an extract of bovine hypothalamus in the growth medium. This system for cell preparation and culture should greatly facilitate studies involving urothelial cells.

In vitro adherence of Escherichia coli to endometrial epithelial cells of rats and influence of estradiol

The influence of ovarian hormones on the adhesion of Escherichia coli to endometrial epithelial cells was investigated in an in vitro system. Endometrial cells liberated by collagenase from rat uteri were used. Optimal test conditions were obtained when 5 X 10(8) E. coli bacteria were added to 10(5) epithelial cells and incubated for 60 min. The adhesion of the organisms was inhibited by the addition of either mannose or alpha-methyl-D-mannopyranoside. When epithelial cells collected from uteri of estradiol-treated rats were used, the number of E. coli adhering to the cells was markedly lower than that adhering to epithelial cells collected from control rats. These results suggest that E. coli adheres to endometrial epithelial cells with so-called type 1 pili and that estradiol alters the nature of the endometrial epithelium and prevents the adherence of the organisms to the cells.

Serial cultivation of normal rat bladder epithelial cells in vitro

Recent advances in culture techniques for human urothelial cells have led to the development of an improved method for growing primary rat bladder epithelial cells. We report here the conditions developed for large-scale in vitro growth and serial cultivation of normal diploid rat bladder epithelial cells. Primary cultures were initiated by attachment of bladder mucosal explants to type I collagen gels. A rapid outgrowth of epithelial cells from the explants occurred when cultured in a hormone-supplemented medium with epidermal growth factor. These primary outgrowths were passaged by nonenzymatic dispersion with 0.1 per cent ethylenediaminetetracetic acid and replating onto new gels. The capacity for routine serial passaging and maintenance of rat bladder epithelial cells required the presence of epidermal growth factor, a requirement not observed with human urothelial cells. The characteristics of the cultured rat bladder epithelial cells were similar to human urothelial cells in: ultrastructural and phase-contrast morphologic properties, showing junctional complexes, desmosomes, stratification and an apical glycocalyx; the absence of stromal cell contamination; and the ability to be serially passaged. Spontaneous cell-line formation was observed with the rat bladder epithelial cells, but has not been found with the human urothelial cells. With the method that we have developed, the number of rat bladder epithelial cells generated from a single bladder of a 4 to 6 week old rat was increased 100-fold from about 7 X 10(5) cells to 7 X 10(7) viable cells within 3 weeks of culture. The capability of culturing normal, primary rat bladder epithelial cells on this scale has not been reported previously and will facilitate comparative studies of the biological and molecular characteristics of the mammalian urothelium. Furthermore, this culture system will be useful for carcinogenesis studies, including metabolic activation of carcinogens and cellular transformation in vitro.

Growth and characterization of normal human urothelium in vitro

A method for initiating rapidly growing cultures of normal human transitional cells from ureter and embryonic bladder specimens has been developed and quantified. A new microdissection technique was used to nonenzymatically separate the urothelium. The use of enriched medium containing 10 micrograms/ml insulin, 5 micrograms/ml transferrin, and 1 microgram/ml hydrocortisone resulted in improved growth. The use of thin collagen gel substrates (0.6 ml/60 mm petri dish) resulted in 97% attachment of explants compared to 77% attachment on plastic. Explants grown on thicker collagen (2 ml/60 mm petri dish) showed, in addition to better attachment, enhanced growth of cells as determined both by measurements of colony size and cell density. Cultures of transitional cells that were initiated using explants could be passed three to five times using 0.1% EDTA for dispersion. Autoradiography of [3H]thymidine-labeled cells showed an initial phase of rapid cell division in primary explant cultures and restimulation of cell division in passaged cultures. Transmission electron microscopy showed that the cells growing out from the explants were continuous with the stratified urothelium maintained in the original explant. Stratification of transitional cells occurred in cultures of both ureter and embryonic bladder cells. Surface cells were joined near their apices by junctional complexes. Desmosomes and Golgi vesicles were present in all cells. Passage in culture did not alter the morphological characteristics of cells.

Fine structure of cultured epithelial cells derived from voided urine of normal adults

Cultures of epithelial cells can be initiated with the sediment of voided urine of normal adults. Tightly or loosely packed colonies were formed by cells of diverse morphologic configuration. Ultrastructural studies revealed that the proliferating cells formed abundant desmosomes, imperfectly formed tight junctions and lamina densa, all typical of epithelial cells. Some cells were lined by the characteristic asymmetric unit membrane, thus confirming the urothelial derivation of the cultures. Peculiar, apparently hitherto not described multivesicular bodies, seemingly of cytoplasmic origin, were observed near the surfaces of some cells. The urinary cell culture system is a potentially useful tool for diagnostic and research purposes.

Adhesion of Corynebacterium renale, Corynebacterium pilosum, and Corynebacterium cystitidis to bovine urinary bladder epithelial cells of various ages and levels of differentiation

The adhesion of Corynebacterium renale, Corynebacterium pilosum, and Corynebacterium cystitidis to various epithelial cell layers of bovine urinary bladders was examined. Adhesion was most efficient to the urinary sediment epithelial cells and the superficial cells immediately before shedding, followed by the remaining superficial cells and intermediate cells in this order, and least efficient to the deeper intermediate and basal cells. Incubation of the intermediate cells for 6 h increased the number of bacteria that adhered to these cells.

A simple method for preparing single cell suspensions of heart and smooth muscle for radioreceptor labeling studies

A simple method of preparing single cell suspensions for radioligand binding studies is described. The method involves incubating tissues in the presence of collagenase and elastase for 90 min in physiological solution with 1 mM calcium chloride and the mechanical disruption of the tissue by pipetting. The tissues examined were atria, ventricle, bladder, uterus, and taenia coli removed from mature guinea pigs. Viability of the cells by trypan blue exclusion showed 60-88% viable cells and receptor binding studies using (3H]-1-quinuclidinyl benzilate (QNB) yield KD values of approximately equal to 0.1 nM. The receptor numbers for each tissue were (receptors/cell): atria, 5700; ventricle, 11,000; uterus, 31,000; bladder, 44,000; taenia coli, 68,000.

The resistance of epithelia to vascularization: proteinase and endothelial cell growth inhibitory activities in urinary bladder epithelium

The avascularity of epithelia may be attributed to the presence of an extractable, low-molecular-weight factor. This factor contains potent inhibitors of proteolytic enzymes, as well as a growth inhibitory activity directed against endothelial cells in vitro. It is extracted from the epithelium of bovine urinary bladders by 1 M NaCl. The extract is ultrafiltered through an Amicon XM-50 membrane, then concentrated and dialyzed into a 0.9% NaCl solution, using a UM-2 membrane. This ultrafiltrate, called the UM-2 retentate (UM-2R), contains approximately 6 micrograms protein/g tissue. The UM-2R has a low content of uronic acid and is practically devoid of hydroxyproline. SDS-PAGE reveals that the UM-2R consists of six major proteins. The UM-2R contains a Trasylol-like proteinase inhibitor that expresses strong trypsin inhibitory activity. Comparisons between bladder and serum UM-2Rs and electrophoretic mobility assays indicate that this proteinase inhibitory activity is derived from the bladder epithelium and not from the serum. The UM-2R is cytotoxic to cultured endothelial cells. Cultures of other cell types (normal and neoplastic) are not affected. The bladder-derived proteinase and endothelial cell growth inhibitory activities may protect epithelia from vascular invasion.