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PubMed2007

Formation of spheroids composed of Henle layer cells and fat droplet in the cultures of rat hair follicles.

The aim of the study was to elucidate the structure of dark-looking spheroids, which appeared in the cultures of hair follicles isolated from rat dermis. These spheroids were particularly numerous when if a keratinocyte growth medium with a reduced amount of supplements was used. Light microscopic observations disclosed that these spheroids consisted of fat droplets covered by cells reacting with the antitrichohyalin AE 15 monoclonal antibody. These fat droplets originated from subcutaneous adipocytes damaged during isolation and remained in cultures. The morphological appearance of cells covering fat droplets studied at the EM level corresponded with that of the cells in the Henle layer of the intact hair follicles in the dermis. EM observations further suggested that in cultures the Henle layer detached from the Huxley layer and that the fat droplets penetrated under the Henle layer resulting in formation of a spheroid. Since from 2 cm2 of rat skin more than 400 spheroids were regularly obtained, it seems conceivable that they could be exploited for isolation of the Henle layer cells.

Animals↗
PubMed2005

Viable head and neck tumor spheroids stimulate in vitro autologous monocyte MCP-1 secretion through soluble substances and CD14/lectin-like receptors.

Biopsies from carcinoma tissue and benign control mucosa from head and neck squamous cell carcinoma (HNSCC) patients were used to establish fragment (F)-spheroids in vitro. We have previously shown that autologous monocytes co-cultured with F-spheroids in vitro augment their secretion of monocyte chemotactic protein-1 (MCP-1). Presently, the aims of the present work were to study whether the metabolic activity, secreted products and/or specific receptor/ligand on the surface of the F-spheroids and monocytes are necessary for stimulation of the monocyte MCP-1 secretion upon F-spheroid co-culture. Actinomycin D (1 mug/ml for 24 h) pre-treatment of the F-spheroids abolished the monocyte MCP-1 co-culture response. Co-culture of monocytes and F-spheroids separated by a semi-permeable membrane showed a decreased, but still present, monocyte MCP-1 co-culture response. Conditioned medium from F-spheroids stimulated allogenous monocytes to secrete MCP-1. The addition of glucose or galactose, but not mannose, to co-cultures partially inhibited the monocyte MCP-1 co-culture response. The addition of anti-CD14 antibody diminished the MCP-1 co-culture response. In conclusion, the monocyte MCP-1 co-culture response is dependent on metabolically active spheroids, secreted stimuli, and is augmented by direct contact with F-spheroids, possibly via lectin-like receptors and the CD14 receptor.

Autoantibodies↗
PubMed2004

Preservation of the characteristics of the cultured human type II alveolar epithelial cells.

The human type II alveolar epithelial cells lost their specific characteristics during cultivation. We examined the ultrastructural and biochemical nature of the human type II cells cultured by two culture systems. To make a physiological alveoli model, the epithelial cells were seeded onto the cell culture insert and allowed contact with the air directly. The cells exposed to the air expressed polarity and immature lamellar bodies in their cytoplasm. Separately, the alveolar epithelial cells were cultured as spheroids to construct the three-dimensional condition. These cells expressed mature morphological characteristics as epithelial cells and lamellar bodies. The expression of the surfactant apoprotein-A (SP-A) and -C (SP-C) mRNA was compared in the cells cultured as a monolayer, the air exposed and the spheroids. SP-A mRNA was detected in all the cultured epithelial cells, but SP-C mRNA, a specific protein for the type II cells, was expressed only in the cells forming spheroids. The expression of uPA, one of the fibrinolytic enzymes, its receptor (uPAR) and its inhibitor-1 (PAI-1) were also examined. The epithelial cells exposed to the air and formed spheroids expressed a larger amount of uPA mRNA than the monolayer, although the amount of uPAR mRNA were comparable in these cells. The amount of PAI-1 mRNA significantly increased when the epithelial cells were exposed to the air. These results indicate that the type II alveolar epithelial cells induced and preserved their specific characteristics by taking the physiological three-dimensional structure, and these characteristics were partially restored by exposure to the air. Those findings suggest that the alveolar epithelial cells should be cultivated in three-dimensional form with contact to the air to regenerate an appropriate alveolar tissue.

Apoproteins↗
PubMed2000

A model for xenogenic immune response.

PURPOSE: To develop a model for analyzing the immune response after xenogenic human fetal retinal pigment epithelium (HFRPE) transplantation. MATERIALS AND METHODS: Pure sheets of HFRPE cells were isolated and attached to poly (DL-lactide-co-glycolide) polymer films and HFRPE spheroids were formed. The spheroids were transplanted into the subretinal space of New Zealand albino rabbits and were observed for 5 months. Bare polymer films were transplanted into the subretinal space of Dutch Belted pigmented rabbits, serving as control. RESULTS: The polymer film was biodegraded within 3 weeks in the subretinal space. No signs of inflammation in the retina or choroid were observed. The HFRPE spheroids were easily transplanted into the subretinal space. The immune response was followed with ophthalmoscopy. Light microscopy indicated a localized immune response in the transplanted area in which the retina and the choroid were infiltrated with immune cells. This infiltration was denser in the choroid. CONCLUSIONS: HFRPE spheroid transplantation may be utilized as a model for studying the xenogenic immune response after HFRPE transplantation. This model may also have applications in evaluating the role of immune suppressive agents in preventing rejection after HFRPE transplantation.

Absorbable Implants↗
PubMed2000

Resistance of L132 lung cell clusters to glyoxal-induced apoptosis.

Glyoxal is a highly reactive glycating agent involved in the formation of advanced glycation end products (AGEs) and known to induce apoptosis. AGE-mediated apoptosis may be an important mechanism of alveolar epithelial remodelling in pulmonary fibrosis. In this study, we investigated the cytotoxic effect of glyoxal on the fetal human epithelial lung cell line L132 under serum-free conditions. This type of culture, which forces the cells to grow as spheroids, also excludes effects of preformed AGEs by the reaction of glyoxal with fetal calf serum proteins. Our results showed that in cells treated with 200 microM glyoxal, the intercellular contacts in spheroids were disrupted, i.e. cells became totally dissociated. Immunocytochemical analysis revealed a dose-dependent accumulation of the AGE product epsilonN-(carboxymethyl)lysine (CML) in cells detached from cell clusters. The loss of cell attachment was associated with decreased expression of beta1-integrins and CD44 as revealed by laser scanning cytometry (LSC). Increasing concentrations of glyoxal induced an increase in the number of apoptotic cells which were identified by the immunoreactivity for active caspase-3. Remaining cell clusters showed resistance to both CML formation and apoptosis. The present findings demonstrate that cells treated with glyoxal undergo possibly anoikis, a specific mode of apoptosis caused by loss of cell adhesion.

Anoikis↗
PubMed2005

Water permeability in human airway epithelium.

Osmotic water permeability (P(f)) was studied in spheroid-shaped human airway epithelia explants derived from nasal polyps by the use of a new improved tissue collection and isolation procedure. The fluid-filled spheroids were lined with a single cell layer with the ciliated apical cell membrane facing the outside. They were capable of surviving hours of experiment involving continuous superfusion of the bathing medium and changes of osmolarity. A new image analysis technique was developed for measuring the spheroid diameters, giving high time and measurement resolutions. The transepithelial P(f), determined by the changes of the apical solution osmolarity, was not influenced by the presence of glucose, Na(+), or Na(+)/glucose-cotransport inhibitors in the bath, but was sensitive to the aquaporin (AQP) inhibitor HgCl(2). The measured P(f) levels and the values of activation energy were in the range of those seen in AQP-associated water transport. Together, these results indicate the presence of an AQP in the apical membrane of the spheroids. Notably, identical values for P(f) were found in CF and non-CF airway preparations, as was the case also for the calculated spontaneous fluid absorption rates.

Absorption↗
PubMed2006

Stimulation of aquaporin-5 and transepithelial water permeability in human airway epithelium by hyperosmotic stress.

Osmotic water permeability (P(f )) was measured in spheroid-shaped human nasal airway epithelial explants pre-exposed to increasing levels of hyperosmotic stress. The fluid-filled spheroids, derived from nasal polyps, were lined by a single cell layer with the ciliated apical cell membrane facing the outside. The P(f ) was determined from diameter changes of the spheroids in response to changes in bathing medium osmolarity forth and back between 300 and 225 mOsm x l(-1). Continuous diameter measurements also allowed determination of spontaneous fluid absorption. Hyperosmotic pretreatment (increase from 300 up to 600 mOsm x l(-1)) caused a time- and osmolarity-dependent increase (up to approximately 1.5 times) in epithelial P(f ) which was of similar magnitude in cystic fibrosis (CF) and non-CF spheroids. The effect saturated at approximately 450 mOsm x l(-1) and at approximately 24 h. Expression of aquaporin-5 (AQP5), studied by immunofluorescence and confocal microscopy, showed an increase in parallel with the increase in P(f ) following hyperosmotic stress. The AQP5 was localized both in cytoplasmic vesicles and in apical cell membranes. Spontaneous fluid absorption rates were equal in CF and non-CF spheroids and were not significantly influenced by hyperosmotic stress. The results suggest that hyperosmotic stress is an important activator of AQP-5 in human airway epithelium, leading to significantly increased transepithelial water permeability.

Aquaporin 5↗
PubMed2001

Vascular endothelial growth factor expression, angiogenesis, and necrosis in renal cell carcinomas.

Rapidly growing tumors often develop necrosis. In the present study the expression of vascular endothelial growth factor (VEGF) was investigated and compared to microvessel density and necrosis of renal cell carcinomas. In the tumor-host interface the microvessel density was significantly increased compared to central tumor areas. Tumor necrosis was associated with a decrease of microvessel density and an increase of the VEGF protein expression within the perinecrotic rim. VEGF protein was focally upregulated in vital tumor tissue. An increase of the apoptotic rate of endothelia and vital tumor tissue in tumors with necrosis could not be detected. VEGF(121,165) mRNA was decreased in proliferatively active carcinomas compared to less proliferative tumors. Multicellular renal cell cancer spheroids as a model of chronic hypoxia developed central apoptosis but no necrosis. VEGF was upregulated in the spheroid. Tumor microvessels expressed matrix metalloproteinase -2 and -9 and an incomplete pericyte covering in comparison to tumor-free tissue indicating immature active angiogenesis. We conclude that highly proliferative renal cell carcinomas outgrow their vascular supply and develop chronic hypoxia inducing a decrease of proliferation and an increase of VEGF expression. However, chronic hypoxia does not cause significant necrosis or apoptosis. Tumor necrosis is more likely induced by acute hypoxia due to immature microvessels. Furthermore, VEGF expression associated with concomitant tumor necrosis may help identify renal cell carcinomas susceptible to antiangiogenic therapy.

Antigens, Nuclear↗
PubMed2002

Brain tumor invasion model system using organotypic brain-slice culture as an alternative to in vivo model.

PURPOSE: The primary cause of local recurrence and therapeutic failure in the treatment of malignant gliomas is the invasion of tumor cells into the surrounding normal brain. While it is known that malignant gliomas infiltrate diffusely into regions of normal brain, it is frequently very difficult to unequivocally identify the solitary invading glioma cell in histopathological preparations, or in experimental glioma models. We have developed an experimental invasion assay system, which allows us to track the solitary invasive glioma cell, using human brain tissue obtained from routine craniotomies for seizures or trauma. METHODS: This tissue is cut into 1-mm thick slices and cultured in the upper chamber of Transwell culture dishes on top of a 0.4- micro m pore size polyester membrane, which is fed on medium provided in the lower chamber. Glioma cells are stably transfected with vectors containing a green fluorescent protein (GFP) cDNA. Stable, high-level expression GFP transfectants were selected by direct visualization under fluorescence microscope. In addition, various tumor spheroids are stained with vital dye, DiI, to track the invading cells. GFP-expressing glioma cells or stained spheroids were then implanted on the center of the brain slice, and the degree of brain tumor invasion into the brain tissue was evaluated at different time points by optical sectioning using a confocal microscope. RESULTS: We observed that GFP-expressing glioma cells or stained spheroids could be readily tracked and followed with this model system. Individual tumor cells that exhibited green or red fluorescence could be identified and their migration path through the brain slices unequivocally followed. CONCLUSION: This experimental invasion system may be of considerable utility in studying the process of brain tumor invasion and in evaluating its invasiveness in individual brain tumor because it not only provides a better representation of extracellular matrix molecules normally encountered by invading glioma cells, but also provides the fluorescent tag applied to the tumor cells.

Astrocytoma↗
PubMed2003

Enhancement of effects of irradiation by gemcitabine in a glioblastoma cell line and cell line spheroids.

BACKGROUND AND PURPOSE: To determine the cytotoxicity of, and radioenhancement by, gemcitabine on a glioma cell line grown as a monolayer and as spheroid cultures. MATERIAL AND METHODS: We used a human glioma cell line, Gli-6, which originated from a biopsy specimen of a patient with a glioblastoma multiforme. Spheroids of Gli-6 were prepared by seeding a single cell suspension on agarose-coated Petri dishes. Clonogenic and growth delay assays were used to determine radio-chemosensitivity of monolayer cultures. The growth delay assay was used to determine that of Gli-6 spheroid cultures. RESULTS: Spheroid cultures were found to be more resistant to irradiation with/or without gemcitabine than monolayer cultures. Whereas gemcitabine significantly enhances the radiation effect of exponentially growing Gli-6 monolayer cultures at minimal cytotoxic concentrations (10 nM, 24 h), no enhancement was seen in confluent monolayer cultures and in large spheroids at the same concentration. In small spheroids no enhancement was observed at a low-dose gemcitabine (10 nM for 24 h), but an enhancement was observed at higher concentrations (100 nM for 24 h). CONCLUSION: Gemcitabine can lead to enhancement of the effects of X-irradiation in both monolayer as spheroid glioblastoma cultures. The lack of enhancement in confluent monolayer cultures supports the view that cell cycle distribution of cells is important in radiosensitisation by gemcitabine

Antimetabolites, Antineoplastic↗
PubMed2005

Effects of irradiation and cisplatin on human glioma spheroids: inhibition of cell proliferation and cell migration.

PURPOSE: Investigation of cell migration and proliferation of human glioma cell line spheroids (CLS) and evaluation of morphology, apoptosis, and immunohistochemical expression of MIB-1, p53, and p21 of organotypic muticellular spheroids (OMS) following cisplatin (CDDP) and irradiation (RT). MATERIAL AND METHODS: Spheroids of the GaMg glioma cell line and OMS prepared from biopsy tissue of six glioblastoma patients were used. Radiochemosensitvity (5 microg/ml CDDP followed by RT) was determined using migration and proliferation assays on CLS. In OMS, histology and immunohistochemical studies of MIB-1, p53, and p21 expression were examined 24 and 48 h following treatment. RESULTS: Combination treatment led to a migration inhibition of 38% (CDDP 13%; RT 27%) and specific growth delay of 2.6 (CDDP 1.3; RT 2.1) in CLS. Cell cycle analysis after combination treatment showed an accumulation of cells in the G2/M phase. In OMS, apoptosis increased, cell proliferation decreased, and p53/p21 expression increased more pronounced following CDDP+RT. No morphological damage was observed. CONCLUSION: CDDP can lead to enhancement of the RT effect in spheroids of both human glioma cell line spheroids and biopsy spheroids from glioblastoma specimens. The exerted effect is additive rather than synergistic.

Antineoplastic Agents↗
PubMed2005

Effect of the cyclin-dependent kinases inhibitor p27 on resistance of ovarian cancer multicellular spheroids to anticancer chemotherapy.

PURPOSE: A low proliferating fraction in solid tumors limits the effectiveness of cell-cycle-dependent chemotherapeutic agents. To understand the molecular basis of such resistance, we examined the expression of the cyclin-dependent kinases inhibitor p27, and relationship with drug resistance and P-gp expression in ovarian cancer multicellular spheroids. METHODS: We cultured ovarian cancer cells (A2780 and CAOV3) as multicellular spheroids and examined the expression of p27 and P-glycoprotein (P-gp) by western blot, flow cytometry and confocal. We also analyzed the cell-cycle distribution by flow cytometry. In addition, trypan blue exclusion testing and cell apoptosis analysis were used to detect the sensitivity to Taxol. RESULTS: When transferred from monolayer to three-dimensional culture, a consistent upregulation of p27 protein and P-gp protein was observed in ovarian cancer cell lines. Compared with monolayer cells, there was a significant increase of G0-G1 phase cells and decrease of S and G2-M phase cells in spheroid cells. Aggregates of cells showed higher cell viability than monolayer cells. Antisense oligodeoxynucleotide (ASON) -mediated downregulation of p27 reduced intercellular adhesion, increased cell proliferation, downregulated P-gp expression and sensitized cells to Taxol. CONCLUSIONS: Our results implicate that p27 serves as a regulator of drug resistance in ovarian tumors. ASON-mediated alteration of p27 reverses resistance of ovarian cancer to anticancer agents that are associated with increased sensitivity of ovarian cancer cells to chemotherapeutic agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Short exposure to millimolar concentrations of ethanol induces apoptotic cell death in multicellular HepG2 spheroids.

PURPOSE: We have shown previously that 1 mM ethanol reduces cell proliferation and increases apoptosis in monolayers of human hepatocellular carcinoma (HepG2) cells. However, in vivo liver tumors are usually three-dimensional and multicellular. The purpose of this study was therefore to determine the effect of ethanol in multicellular tumor spheroids (MCTS) as a model system in vitro. METHODS: After the application of 1 mM ethanol for 24 h and 48 h, viable, apoptotic and necrotic cells within MCTS were stained with specific fluorescent dyes, and their amount and distribution within the MCTS were assessed by confocal laser scanning microscopy. To evaluate the effect on HepG2 cell migration and cell proliferation, the outgrowth potential after 1 week in culture was evaluated. RESULTS: As assessed by YO-PRO-1 staining, ethanol increased the number of apoptotic cells from 21.5 units (U) in control spheroids to 364 U and 482.2 U after 24 h and 48 h in ethanol-treated spheroids, respectively (P < 0.001). Merocyanine staining fluorescence increased from 10.7 U in the control to 122 U after 24 h and 293.2 U after 48 h (P < 0.001). Cell viability, as determined by staining with the acetoxymethyl ester of calcein, decreased from 578.5 U in the control to 236 U and 73.4 U after 24 h and 48 h of ethanol exposure respectively (P < 0.001). Necrosis showed an increase from 2 U in control to 24.9 after 24 h and 54 U after 48 h. MCTS treated with ethanol showed almost complete inhibition of outgrowth potential after 1 week in culture, compared to controls (P < 0.005). CONCLUSIONS: Small concentrations of ethanol (1 mM) induced apoptosis in HepG2 MCTS with a concomitant inhibition on outgrowth potential, accompanied with a low degree of necrosis. These findings suggest that low concentrations of ethanol may already be sufficient for the treatment of hepatocellular carcinoma.

Antineoplastic Agents↗
PubMed2005

How to induce non-polarized cells of hepatic origin to express typical hepatocyte polarity: generation of new highly polarized cell models with developed and functional bile canaliculi.

Few in vitro models expressing complex hepatocyte polarity are available. We used the unpolarized rat Fao cell line to isolate the polarized WIF-B line. These complex rat-human hybrid cells form functional simple bile canaliculi. To obtain Fao-derived polarized models with a simpler chromosome content and developed bile canaliculi, we employed two approaches. Partial success was achieved with monochromosomal hybrids. As shown by the immunolocalization of apical, basolateral, and tight-junctional proteins, monochromosomal hybrid 11-3 cells were polarized. They formed simple functional bile canaliculi and transiently expressed the typical polarity of simple epithelial cells. One subclone blocked in this polarity state was isolated. A more robust approach was provided by spheroid culture, a three-dimensional system that strengthens cell-cell contacts. Transient spheroid culture induced irreversible polarization of Fao cells. This induction occurred in most spheroids (approximately 1% of the cells). From populations enriched in stably polarized cells, we generated new polarized cell models, designated Can. Can 3-1 cells formed simple functional bile canaliculi when plated at high density. Regardless of plating density, Can 9 and Can 10 cells formed long tubular branched canaliculi competent for vectorial transport of organic anions and bile acids, and involving several dozen adjacent cells. Thus, we have generated new cell models stably expressing typical hepatocyte polarity. Among these models, Can 9 and Can 10 are the first capable of forming functional, highly developed bile canaliculi similar to those formed in vivo.

Animals↗
PubMed2006

Simulated weightlessness changes the cytoskeleton and extracellular matrix proteins in papillary thyroid carcinoma cells.

Studies of astronauts, experimental animals, and cells have shown that, after spaceflights, the function of the thyroid is altered by low-gravity conditions. The objective of this study was to investigate the cytoskeleton and extracellular matrix (ECM) protein synthesis of papillary thyroid cancer cells grown under zero g. We investigated alterations of ONCO-DG 1 cells exposed to simulated microgravity on a three-dimensional random-positioning machine (clinostat) for 30 min, 24 h, 48 h, 72 h, and 120 h (n=6, each group). ONCO-DG 1 cells grown under microgravity exhibited early alterations of the cytoskeleton and formed multicellular spheroids. The cytoskeleton was disintegrated, and nuclei showed morphological signs of apoptosis after 30 min. At this time, vimentin was increased. Vimentin and cytokeratin were highly disorganized, and microtubules (alpha-tubulin) did not display their typical radial array. After 48 h, the cytoskeletal changes were nearly reversed. The formation of multicellular spheroids continued. In parallel, the accumulation of ECM components, such as collagen types I and III, fibronectin, chondroitin sulfate, osteopontin, and CD44, increased. The levels of both transforming growth factor beta-1 (TGF-beta(1)) and TGF-beta receptor type II proteins were elevated from 24 h until 120 h clinorotation. Gene expression of TGF-beta(1) was clearly enhanced during culture under zero g. The amount of E-cadherin was enhanced time-dependently. We suggest that simulated weightlessness rapidly affects the cytoskeleton of papillary thyroid carcinoma cells and increases the amount of ECM proteins in a time-dependent manner.

Carcinoma, Papillary↗
PubMed2006

Dynamic analysis of hepatoma spheroid formation: roles of E-cadherin and beta1-integrin.

A spheroid is an in vitro multicellular aggregate that provides a microenvironment resembling that of normal tissue in vivo. Although cell adhesion molecules such as integrins and cadherins have been implicated in participating in the process of spheroid formation, little is known about the timing of their action. In this study, we have employed an image-based quantitative method to investigate the compactness of cell aggregates during hepatoma spheroid formation in a dynamic fashion. By modulating beta1-integrin and E-cadherin activity with specific blocking antibodies, ion chelators, and RGD-sequence-containing peptides, we show that these cell adhesion molecules mediate the formation of spheroids through the establishment of complex cell-cell and cell-extracellular matrix (ECM) interactions. The dynamics of spheroid formation can be separated into three stages. In the first stage, ECM fibers act as a long-chain linker for the attachment of dispersed single-cells to form loose aggregations through the binding of integrins. This is followed by a delay period in which cell aggregates pause in compaction, presumably because of the accumulation of sufficient amounts of E-cadherins. In the third stage, strong homophilic interaction of E-cadherins is a major factor for the morphological transition from loose cell aggregates to compact spheroids. These findings thus provide comprehensive information on the molecular mechanisms and dynamics of hepatoma spheroid formation.

Cadherins↗
PubMed2003

Evolution of the brain tumour spheroid model: transcending current model limitations.

Tumour recurrence and the high mortality and morbidity associated with malignant brain tumours may be attributed to the failure of current therapeutic modalities (surgery, radiation and chemotherapy) to control the invasion of malignant brain tumour cells into healthy brain tissue. Several in vitro and in vivo models have been developed and used to study brain tumour invasion and cell motility. Here, we review some of the traditional in vitro models of brain tumour invasion and the latest adaptations to the widely used spheroid model. Several research groups studying the mechanisms mediating brain tumour invasion have made important contributions to the field by improving in vitro models of tumour migration and invasion. Sharing these advances will hopefully accelerate experimental discovery and the development of novel anti-invasion brain tumour therapies.

Brain Neoplasms↗
PubMed2002

Photodynamic therapy with photofrin reduces invasiveness of malignant human glioma cells.

In this study we investigated the influence of Photofrin-based photodynamic therapy (PDT) on the migration of two human glioma cell lines in vitro. U87 and U25ln tumour cells were treated with Photofrin at various doses and subjected to a fixed optical (632 nm) dose of 100 mJ/cm(2). Photofrin cytotoxicity was determined using MTT and colony forming assays. Using a matrigel artificial basement membrane migration assay, we demonstrated that low doses of subcytotoxic PDT treatment, such as PDT with 2.5 micro g/ml Photofrin on U87 cells and 1 micro g/ml on U25ln cells, significantly ( p<0.001) inhibited in vitro migration of both cell lines. Furthermore, in a qualitative spheroid confrontation assay, subcytotoxic PDT of co-cultures between tumour spheroids and brain aggregates resulted in an absence of progressive tumour invasion and destruction of the brain aggregate. In conclusion, our data indicate that low-dose subcytotoxic PDT with Photofrin significantly inhibits invasiveness of U87 and U25ln cells.

Animals↗