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At least 343 records · Page 19Linked to original sources
PubMed1988

An in vitro model of Chlamydia trachomatis infection in the regenerative phase of the human endometrial cycle.

An in vitro model of the regenerative phase of the human endometrial cycle was developed in order to study the growth of Chlamydia trachomatis during the period following menses. Glandular epithelial fragments were prepared from curettings of endometria and explanted onto coated substrata. Epithelial cells migrated rapidly from the explant in a fashion which closely mimicked the regeneration of the surface epithelium after menses. The cultures were then experimentally infected with C. trachomatis serotype E at various times during formation of the outgrowth. Chlamydial inclusions developed both within the explants and in the outgrowing epithelial sheets. They were also found in isolated epithelial and non-epithelial cells. However, the most striking feature of chlamydial inclusion development within these cultures was the tendency for inclusions to be located in cells at the periphery of the epithelial sheets. This was partly due to the failure of the cells within the sheets to bind chlamydiae after centrifugation of the organisms onto the culture and partly due to a phenomenon similar to phagokinesis. During this process infectious chlamydial particles were cleared from the substratum by migrating cells with free motile edges, which occasionally led to internalization and inclusion development within these cells.

Cells, Cultured↗
PubMed2000

The affinity of MCF7 breast cancer cells to hyaluronan substrates of different molecular weight and concentrations in an in vitro model.

The affinity of MCF7 breast cancer cells to hyaluronan (HA) was investigated in an in vitro model. The cells form a tightly adhering monolayer on native HA with a concentration of 5 mg/ml. On native HA at higher concentrations the cells reduce their adhesion to the substrate in favor of increased intercellular bonds, resulting in a cluster-like aggregate that tends to detach from the substrate. Aggregate formation is accomplished after 12 h incubation. The phenomenon is independent of the CD44 receptor. Degradation of native HA by hyaluronidase abolishes aggregate formation even at high HA concentrations in favor of formation of a firmly adhering monolayer. This model may help to understand tumor spread on HA tissue structures and may explain therapy successes with hyaluronidase in tumor patients.

Adenocarcinoma↗
PubMedDate not supplied

Use of an in vitro model of tissue-engineered human skin to study keratinocyte attachment and migration in the process of reepithelialization.

To produce a stable epidermis, keratinocytes need to be firmly attached to the basement membrane. However, following wounding, keratinocytes are required to develop a migratory phenotype in order to reepithelialize the wound. To investigate some of the issues underlying reepithelialization, we have developed a three-dimensional in vitro model of tissue-engineered skin, comprising sterilized human dermis seeded with human keratinocytes and dermal fibroblasts. Using this model, we have shown that the inclusion of fibroblasts within the model increases the stability of keratinocyte attachment. We have also demonstrated that keratinocyte migration occurs most effectively in the absence of a basement membrane and following the inclusion of fibroblasts in the model. In addition, subjecting the keratinocyte layer to mechanical trauma induces a migratory phenotype. We conclude that this three-dimensional in vitro wound model can be used to increase our understanding of the factors that enhance keratinocyte migration and hence wound healing in vivo.

Animals↗
PubMed2007

Multilineage differentiation and characterization of the human fetal osteoblastic 1.19 cell line: a possible in vitro model of human mesenchymal progenitors.

The in vitro study of human bone marrow mesenchymal stromal cells (BMMSCs) has largely depended on the use of primary cultures. Although these are excellent model systems, their scarcity, heterogeneity, and limited lifespan restrict their usefulness. This has led researchers to look for other sources of MSCs, and recently, such a population of progenitor/stem cells has been found in mesodermal tissues, including bone. We therefore hypothesized that a well-studied and commercially available clonal human osteoprogenitor cell line, the fetal osteoblastic 1.19 cell line (hFOB), may have multilineage differentiation potential. We found that undifferentiated hFOB cells possess similar cell surface markers as BMMSCs and also express the embryonic stem cell-related pluripotency gene, Oct-4, as well as the neural progenitor marker nestin. hFOB cells can also undergo multilineage differentiation into the mesodermal lineages of chondrogenic and adipocytic cell types in addition to its predetermined pathway, the mature osteoblast. Moreover, as with BMMSCs, under neural-inducing conditions, hFOB cells acquire a neural-like phenotype. This human cell line has been a widely used model of normal osteoblast differentiation. Our data suggest that hFOB cells may provide for researchers an easily available, homogeneous, and consistent in vitro model for study of human mesenchymal progenitor cells.

Antigens, Polyomavirus Transforming↗
PubMed2000

An in vitro model of ischemic-like stress in retinal pigmented epithelium cells: protective effects of antioxidants.

We have developed a model of in vitro cell oxidative stress in bovine retinal pigment epithelium cells exposed to a ischemia-like condition obtained by interference with glucose utilization through both oxidative phosphorylation and glycolysis. This resulted in a statistically significant decrease of the intracellular ATP levels, which reflects a bioenergetic decline similar to that associated with mitochondrial damage or loss in normal post-mitotic cells aging in vivo. This new model of cellular oxygen stress seems adequate for investigation of the protective action of antioxidants, in agreement with our finding of a statistically significant increase in the ATP levels over the values of the non-treated samples in retinal pigment epithelium cells exposed to the above oxygen stress in medium supplemented with 300 microM vitamin C or 10 mM N-acetylcysteine.

Adenosine Triphosphate↗
PubMed1993

In vitro model of Haemophilus ducreyi adherence to and entry into eukaryotic cells of genital origin.

Electron microscopy was used to examine Haemophilus ducreyi adherence to and entry into eukaryotic cells of genital origin. A clinical H. ducreyi isolate (90-244) adhered in snake-like whorls to the surfaces of cervical carcinoma cells (HeLa 229), endometrial adenocarcinoma cells (HEC-1-B), and human neonatal foreskin fibroblast (HFF) cells. A prototype strain of H. ducreyi (CIP542) adhered in randomly organized clumps on the surfaces of HFF. Strain 90-244 entered HFF and HEC-1-B cells but did not enter HeLa cells. The H. ducreyi in the HFF cells at 2 h were partly surrounded by a membrane consistent with that of a phagocytic vacuole. At 2 h, strain CIP542 was found in interstitial spaces between the HFF cells and also in the cytoplasm of the cells. After 7 and 24 h, both strains of H. ducreyi were found in the large interstitial spaces between the HFF cells, in the cytoplasm, and extracellularly. This model of in vitro H. ducreyi infection of eukaryotic cells will allow for more specific study of factors that determine the virulence of H. ducreyi.

Adenocarcinoma↗
PubMed2001

Bone tissue cultures: an in vitro model for the evaluation of bone defect healing after L-arginine and L-lysine administration.

The development of new therapeutic strategies and innovative biomaterials for the muscoloskeletal system, stresses the need for researchers to have reliable, easy, less time-consuming and ethical experimental models. The aim of the present study was to characterise an in vitro model of cultured rat femora and test the possibility of using this model in dynamic studies on bone healing. 24 femurs were explanted after 12 rats were killed for other experimental protocols. A standard bone defect was created in the distal femoral condyles and femurs were cultured in GBJb medium. Arginine and lysine were administered daily in the Arg-Lys group. The other femurs were left untreated (Control group). At 1, 7, 14 and 21 days, alkaline phosphatase activity, nitric oxide and calcium were measured on the supernatant. At 21 days, femurs were embedded in polymethylmethacrylate for histomorphometry and microhardness evaluation of the newly formed bone. The current results showed that it was possible to study bone healing in vitro by using cultured bones from adult animals. A process for bone healing was observed also in untreated bones. Moreover, the structural analysis of the cultured bone showed that it had characteristics similar to those of the femurs, when they were embedded in resin immediately after animal sacrifice. The effect of Arg and Lys confirmed data of a previous study, where a faster healing of bone defect and fracture was observed in rabbits after Arg and Lys administration.

Alkaline Phosphatase↗
PubMed1991

Evaluation of tartar control dentifrices in in vitro models of dentin sensitivity.

The effects of anticalculus dentifrices were compared with other commercially available dentifrices in in vitro models of dentin sensitivity. Changes in the hydraulic conductance of dentin discs were measured with and without a smear layer before and after treatment and also after a post-treatment acid etch. The capacity of dentifrices to occlude open dentinal tubules in vitro was also assessed by scanning electron microscopy (SEM). There was good correlation (R = 0.98) between our test and values reported in the literature. Tartar control dentifrices gave reductions in fluid flow rates through the dentin discs comparable to those obtained with Promise, Sensodyne, Thermodent and Denquel. Additionally, tartar control dentifrices did not remove microcrystalline debris (smear layers) from the surfaces of dentin in vitro. These results were confirmed by SEM. Thus, according to the hydrodynamic theory of dentin sensitivity, these in vitro results suggest that pyrophosphate-containing dentifrices should reduce dentinal sensitivity.

Dental Calculus↗
PubMed1982

An in vitro model for the study of human parathyroid gland tissue: single cell suspensions and monolayer cultures.

An in vitro model for studies of parathyroid physiology is described using single cell suspensions and adherent monolayer cultures of human parathyroid tissue. The isolated cells were viable and maintained functional properties tested by calcium and magnesium sensitivity. Parathyroid hormone (PTH) secretion could be suppressed by rising calcium and magnesium concentrations. The secretory behaviour of the cells was not altered by cultivation or cryopreservation. The morphological integrity of the individual cells after mechanical and enzymatic preparation was confirmed by light and electron microscopy.

Adenoma↗
PubMed2004

The effect of 40 kHz ultrasound on tissue plasminogen activator-induced clot lysis in three in vitro models.

In a previous study, high-frequency ultrasound (US) (3 MHz) was shown to enhance in vitro fibrinolysis through enhanced supply of plasminogen to the clot surface. The application of high-frequency US is limited in vivo, however, due to tissue heating. We continued our research using low-frequency US with less tissue heating and improved penetration of the US. Three different in vitro models, internal plasma clot lysis and external lysis with compacted and noncompacted plasma clots, were used to determine the magnitude of the effect of low-frequency US (40 kHz; 0.5 W/cm(2)) on tissue plasminogen activator-induced lysis and to elucidate the mechanisms behind the effect. US enhanced lysis in all three models, with the largest effects (fourfold) being in the compacted plasminogen-poor clot model. Plasminogen supply to the clot surface was again shown to be an important contributor to US-enhanced lysis.

Combined Modality Therapy↗
PubMed1998

Inhibition of P-glycoprotein: rapid assessment of its implication in blood-brain barrier integrity and drug transport to the brain by an in vitro model of the blood-brain barrier.

PURPOSE: The objective of this work was to assess, in vitro, the passage of P-glycoprotein dependent drugs across brain capillary endothelial cells, when these drugs are associated with a reversing agent. METHODS: An in vitro model of the blood-brain barrier consisting of a coculture of brain capillary endothelial cells and astrocytes was used. RESULTS: We demonstrate that P-glycoprotein expression is upregulated by the presence of astrocytes. Uptake in the cells and transport across endothelial cell monolayers of vincristine, cyclosporin A and doxorubicin were studied. Using S9788 or verapamil as reversing agents, we found an increase in vincristine transport across the endothelial cell monolayers. On the other hand, the association of S9788 or verapamil with cyclosporin A failed to increase the transport of this drug. An increase in the transport of doxorubicin from luminal to abluminal compartment was also observed, due to endothelial cell monolayer breakdown. CONCLUSIONS: Using this model, it is possible to predict the passage of a P-glycoprotein dependent drug to the brain or its sequestration in brain capillary endothelial cells when this drug is associated with a reversing agent, or its toxicity on the blood-brain barrier integrity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

An in vitro model of the wound microenvironment: local phagocytic cell abnormalities associated with in situ complement activation.

An in vitro model was developed to investigate the inflammatory response to tissue damage. Human fibroblasts were heat killed and incubated with serum. Complement studies showed activation of the alternative pathway proportional to the number of dead cells; C3 was fixed on dead cells, and C5a was generated. Neutrophils (PMNLs) adhered to killed fibroblasts, a process requiring fresh serum. After adhering to killed fibroblasts in the presence of serum, PMNLs exhibited depressed chemotactic responsiveness to activated serum and reduced bactericidal activity against preopsonized Staphylococcus aureus. These data suggest that thermally killed cells activate and fix complement, a process generating cleavage products that, in turn, recruit PMNLs and bind them to the inflammatory site. Thus, in our model, dead tissue activates humoral mechanisms and inflammatory cells; this process results in depressed in situ host-defense function upon subsequent local challenge with microbes.

Blood Bactericidal Activity↗
PubMed1986

Thermodilution cardiac output--an in vitro model of low flow states.

The accuracy and reproducibility of thermodilution cardiac output measurements were examined in vitro at low flows, using the Edwards cardiac output computer. For each of 18 different volumetrically measured flows between 130 and 1035 ml/min, three cardiac outputs were determined for each of four different injectate volumes (1,2,3, and 5 ml) at two different temperatures (0 degrees C and room temperature). There was a significant (p less than .001) correlation between measured flow and cardiac output for all injectate volumes at both temperatures. The slopes of the regression lines ranged between 0.97 and 1.25, and the y-intercepts were all greater than 0. Although this thermodilution technique overestimated cardiac output, it was a reproducible means of measuring cardiac output in this low-flow in vitro model.

Cardiac Output↗
PubMed1987

An in vitro model for the study of acute release of von Willebrand factor from human endothelial cells.

An in vitro model is described which utilizes human umbilical vein endothelial cells cultured on plastic microcarrier spheres and perfused with serum-free medium. This model was used to study the acute release of von Willebrand factor following stimulation of the cells with putative agonists. Thrombin, plasmin and interleukin-1 were found to release von Willebrand factor. Adrenaline and bradykinin also stimulated release but only at high dosage. 1-desamino-8-D-arginine vasopressin (DDAVP) was inactive.

Bradykinin↗
PubMedDate not supplied

The cellular changes in primary and recurrent infection with herpes simplex virus type 2 in an in vitro model.

The cellular changes of primary and recurrent herpes simplex virus (HSV) infection were investigated in in vitro models. In the primary infection model, nuclear changes were characterized by clumping and margination of the nuclear chromatin, a homogeneous ground-glass nuclear appearance, multinucleation and the appearance of two different types of intranuclear inclusions. One of the two types of inclusions appeared as early as six hours postinfection, reached a maximum at nine hours postinfection and gradually decreased thereafter. This early inclusion, relatively small in size as compared to the other type of inclusion, gave a basophilic staining when the Papanicolaou staining method was used. The other type of inclusion was the typical Cowdry type A inclusion, which appeared as early as 12 hours postinfection. Both types of inclusions contained clear perinuclear halo. In the recurrent infection model, the appearance of all the nuclear changes was delayed, the appearance of early inclusions was infrequent, and the Cowdry type A inclusions were observed more frequently than in the primary infection model. These results may indicate that the early inclusion is a sign of rapid virus replication while the Cowdry type A inclusion is one form of the remains of an HSV infection.

Animals↗
PubMed1998

Primary culture of choroidal epithelial cells: characterization of an in vitro model of blood-CSF barrier.

A primary rat choroidal epithelial cell culture system was developed to investigate mechanisms of heavy metal toxicity on the blood-cerebrospinal fluid (CSF) barrier. Epithelial cells were dissociated from choroidal tissue by pronase digestion and cultured in standard DMEM culture media supplemented with 10% fetal bovine serum and 10 ng epithelial growth factor per ml. The procedure yielded 2-5 x 10(4) cells from pooled plexuses of three to four rats, and a viability of 77-85%. The cultures displayed a dominant polygonal type of epithelial cells, with a population doubling time of 2-3 d. The cultures were of distinct choroidal epithelial origins. For example, immunocytochemical studies using monospecific rabbit anti-rat TTR polyclonal antibody revealed a strong positive stain of transthyretin (TTR), a thyroxine transport protein exclusively produced by the choroidal epithelia. Also, reverse-transcriptase polymerase chain reaction (PCR) confirmed the presence of specific TTR mRNA in the cultures. The cultures were further adapted to grow on a freely permeable membrane sandwiched between two culture chambers. The formation of an impermeable confluent monolayer occurred within 5 d after seeding and was verified by the presence of a steady electrical resistance across the membrane (80 +/- 10 ohm per cm2). The epithelial barriers appeared to actively transport [125I]-thyroxine from the basal to apical chamber. These results suggest that this primary cell culture system possesses typical choroidal epithelial characteristics and appears to be a suitable model for in vitro mechanistic investigations of blood-CSF barrier.

Animals↗
PubMed1994

Development of an in vitro model for investigating the formation of the nuclear Ah receptor complex in mouse Hepa 1c1c7 cells.

An in vitro assay for investigating factors which modulate formation of the nuclear aryl hydrocarbon (Ah) receptor complex was developed using 9S cytosolic Ah receptor isolated from wild-type Hepa 1c1c7 cells treated with 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin (TCDD) at 4 degrees C and nuclei from Ah-responsive and -nonresponsive wild-type and mutant Hepa 1c1c7 cells. Incubation of the radiolabeled ([3H]TCDD) 9S cytosolic Ah receptor with nuclei from untreated wild-type Ah-responsive mouse Hepa 1c1c7 cells resulted in a time- and temperature-dependent formation of the nuclear Ah receptor complex as determined by either velocity sedimentation analysis or gel mobility shift assays using a consensus 32P-labeled dioxin-responsive element. Maximal levels of the nuclear Ah receptor formed within 30 min at 37 degrees C and significantly lower levels were observed after incubation at 4, 15, or 25 degrees C. Complementation studies using nuclei from untreated wild-type and Ah-nonresponsive class II mutant (translocation-deficient) cells and radiolabeled 9S cytosolic receptor (bound with [3H]TCDD) from both wild-type and mutant cell lines were also carried out. The results indicated that nuclear translocation was primarily inhibited using cytosol from mutant cells confirming the requirement for the aryl hydrocarbon receptor nuclear translocator protein for formation of the nuclear Ah receptor complex. The effects of a series of Ah receptor antagonists, ATP, vanadate apyrase, phosphatases, and lectin WGA, on formation of the nuclear Ah receptor complex were also investigated in the in vitro model using radiolabeled cytosolic Ah receptor and nuclei from untreated wild-type Hepa 1c1c7 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

An in vitro model of hepatitis C virus genotype 3a-associated triglycerides accumulation.

BACKGROUND/AIMS: The hepatitis C virus (HCV) induces lipid accumulation in vitro and in vivo. Although clinical observations are consistent with a direct effect of HCV genotype 3a on lipid metabolism, experimental systems have focused on the expression of HCV proteins of genotype 1. To extend these observations, we established an in vitro model expressing the HCV core of different genotypes. METHODS: The HCV core protein from patients with severe (genotype 3a) or no (genotypes 1b, 2a, 3h, 4h and 5a) liver steatosis was expressed in Huh7 cells. Core protein expression (by immunohistochemistry and immunoblot) and triglycerides accumulation (by Oil Red O stain and enzymatic measurement) were evaluated 48h after transfection. RESULTS: Although triglyceride accumulation occurred with genotypes 1b, 3a and 3h, the genotype 3a core protein expression resulted in the highest level of accumulation (i.e. about 3-fold with respect to 1b, and 2-fold with respect to 3h). This effect was not related to core protein expression levels and was abolished by culturing cells in lipid-free medium. CONCLUSIONS: Consistent with observations in chronic hepatitis C patients, the in vitro expression of HCV genotype 3a core protein is the ideal candidate model for studying the mechanisms of HCV-associated steatosis.

Adult↗