SEARCH · Search PubMed

Results for “Spheroids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMedDate not supplied

Cultured human nasal epithelial multicellular spheroids: polar cyst-like model tissues.

We report here a new readily cultured nonadherent hollow spheroidal epithelial tissue model: human nasal epithelial multicellular spheroids, prepared from brushings of human nasal epithelium in vivo. Although cultured cyst-like epithelial models developed from embryonic, transformed, or polypoid tissues have been reported previously, human nasal epithelial multicellular spheroids are derived from normal mature nontransformed human airway epithelial cells. In our studies, spheroids ranged in size from 50 to 700 microns diameter (averaging approximately 250 microns). Cells of the spheroid displayed morphological polarity and formed junctional complexes. Transcellular electrolyte transport may underlie the increase in spheroid size which occurred in culture. The ease and simplicity of the brushing and culture procedures reported here render normal and diseased human cell populations more readily accessible to investigation. We believe human nasal epithelial multicellular spheroids may have important applications in the study of electrolyte and fluid transport processes, ciliary motility, epithelial polarity, cellular metabolism, and drug cytotoxicity in normal and pathophysiological states of the human respiratory tract (e.g., cystic fibrosis).

Biological Transport, Active↗

PubMed1999

Fluid absorption related to ion transport in human airway epithelial spheroids.

Airway epithelium explants from cystic fibrosis (CF) patients and non-CF subjects formed monolayered spheres, with the apical ciliated cell membrane facing the bath and the basolateral cell membrane pointing toward a fluid-filled lumen. With the use of two microelectrodes, transepithelial potential difference and changes in potential difference in response to passage of current pulses were recorded, and epithelial resistance and the equivalent short-circuit current were calculated. Non-CF control potential difference and short-circuit current values were significantly lower than the CF values, and amiloride inhibited both values. Fluid transport rates were calculated from repeated measurements of spheroid diameters. The results showed that 1) non-CF and CF spheroids absorbed fluid at identical rates (4.4 microl x cm(-2) x h(-1)), 2) amiloride inhibited fluid absorption to a lower residual level in non-CF than in CF spheroids, 3) Cl(-)-channel inhibitors increased fluid absorption in amiloride-treated non-CF spheroids to a level equal to that of amiloride-treated CF spheroids, 4) hydrochlorothiazide reduced the amiloride-insensitive fluid absorption in both non-CF and CF spheroids, and 5) osmotic water permeabilities were equal in non-CF and CF spheroids ( approximately 27 x 10(-7) cm x s(-1) x atm(-1)).

Amiloride↗

PubMed2005

Changes in P-glycoprotein activity are mediated by the growth of a tumour cell line as multicellular spheroids.

BACKGROUND: Expression of P-glycoprotein (P-gp), the multidrug resistance (MDR) 1 gene product, can lead to multidrug resistance in tumours. However, the physiological role of P-gp in tumours growing as multicellular spheroids is not well understood. Recent evidence suggests that P-gp activity may be modulated by cellular components such as membrane proteins, membrane-anchoring proteins or membrane-lipid composition. Since, multicellular spheroids studies have evidenced alterations in numerous cellular components, including those related to the plasma membrane function, result plausible that some of these changes might modulate P-gp function and be responsible for the acquisition of multicellular drug resistance. In the present study, we asked if a human lung cancer cell line (INER-51) grown as multicellular spheroids can modify the P-gp activity to decrease the levels of doxorubicin (DXR) retained and increase their drug resistance. RESULTS: Our results showed that INER-51 spheroids retain 3-folds lower doxorubicin than the same cells as monolayers however; differences in retention were not observed when the P-gp substrate Rho-123 was used. Interestingly, neither the use of the P-gp-modulating agent cyclosporin-A (Cs-A) nor a decrease in ATP-pools were able to increase DXR retention in the multicellular spheroids. Only the lack of P-gp expression throughout the pharmacological selection of a P-gp negative (P-gpneg) mutant clone (PSC-1) derived from INER-51 cells, allow increase of DXR retention in spheroids. CONCLUSION: Thus, multicellular arrangement appears to alter the P-gp activity to maintain lower levels of DXR. However, the non expression of P-gp by cells forming multicellular spheroids has only a minor impact in the resistance to chemotherapeutic agents.

Journal Article↗

PubMed1992

Morphological and immuno-cytochemical characterization of a hetero-spheroid composed of fibroblasts and hepatocytes.

A novel method for the preparation of spheroids containing two types of cells (hetero-spheroid) has been successfully developed by utilizing a collagen-conjugated thermo-responsive polymer, poly-N-isopropyl acrylamide (PNIPAAm), as a cell substratum. PNIPAAm solidifies above its lower critical solution temperature (LCST, about 30 degrees C), and instantly dissolves into the culture medium below its LCST. We firstly seeded and cultured human dermal fibroblasts on the substratum up to a confluent state and then seeded rat primary hepatocytes onto the fibroblast monolayer. The heterospheroid was prepared by detaching the hepatocyte-attached fibroblast monolayer at a temperature below LCST and culturing it on the non-adhesive substratum. The surface area of the substratum and the seeding population ratio of each cell precisely and reproducibly regulated the size and the cell composition of the resulting hetero-spheroid, respectively. Histological and immuno-cytochemical observations of spheroids revealed characteristic organizations of fibroblasts and hepatocytes within a spheroid because the latter cells expressed albumin for up to at least 3 weeks. TEM study of the hetero-spheroid showed the presence of structures morphologically similar to the Disse's space and the bile canaliculus, which are features characteristic of liver. These findings suggest that the method described above is useful for making a hetero-spheroid that morphologically and functionally resembles tissues or organs in vivo, i.e. an organoid.

Animals↗

PubMed2007

Expansion of an arbitrarily oriented, located, and shaped beam in spheroidal coordinates.

Within the framework of the generalized Lorenz-Mie theory (GLMT), the incident shaped beam of an arbitrary orientation and location is expanded in terms of the spheroidal vector wave functions in given spheroidal coordinates. The beam shape coefficients (BSCs) in spheroidal coordinates are computed by the quadrature method. The classical localization approximation method for BSC evaluation is found to be inapplicable when the Cartesian coordinates of the beam and the particle are not parallel to each other. Once they are parallel, all the symmetry relationships existing for the BSCs in spherical coordinates (spherical BSCs) [J. Opt. Soc. Am. A11, 1812 (1994)] still pertain to the BSCs in spheroidal coordinates (spheroidal BSCs). In addition, the spheroidal BSCs computed by our method are verified by comparing them with those evaluated by Asano and Yamamoto for plane wave incidence [Appl. Opt.14, 29 (1975)]. Furthermore, formulas are given for field reconstruction from the spheroidal BSCs, and consistency is found between the original incident fields and the reconstructed ones.

Journal Article↗

PubMed1995

Gene expression of liver-specific proteins in hepatocyte spheroids in primary culture.

Adult rat hepatocytes assemble to form multicellular spheroids under non-adherent environments such as immobilized chondroitin sulfate-proteoglycan in primary culture. Previously, we demonstrated that hepatocyte spheroids exhibited various differentiated structures as observed in the liver tissue. It was also shown that hepatocyte growth was highly suppressed and several differentiated functions, including albumin production and gluconeogenesis, were well preserved in spheroids. To investigate the differentiated functions of cultured hepatocytes in relation to cell morphology, we compared the expression of the albumin and transferrin genes in spheroids with those in monolayers by Northern blot analysis. Production of these proteins in the culture medium was simultaneously examined by ELISA. Gene expression and protein production of both albumin and transferrin were better preserved in spheroids. We also examined changes in the expression of liver-specific genes in response to IL-6. Reduced mRNA levels of both albumin and transferrin was only found in spheroids and no change was observed in monolayers. These results suggest that the regulation of tissue-specific gene expression is better preserved in spheroids, in which hepatocytes are in close contact with each other.

Albumins↗

PubMed2002

Cytoskeletal inhibitors, anti-adhesion molecule antibodies, and lectins inhibit hepatocyte spheroid formation.

We investigated the role of cytoskeletons, adhesion molecules, membrane-glycosylations, and proteoglycans in forming the shape of adult rat hepatocyte spheroids. Isolated hepatocytes were cultured on dishes coated with chondroitin sulfate phosphatidyl ethanolamine (CS-PE). Spheroid-forming ability was observed after adding cytoskeletal inhibitors (cytochalasin D, colchicine, okadaic acid, mycalolide B), anti-adhesion molecule antibodies (anti-E-cadherin, anti-connexin 32, anti-zo-1), a glycosphingolipid synthetic inhibitor (N-butyldeoxynojirimycin), a proteoglycan synthetic inhibitor (p-nitrophenyl-beta-D-xylopyranoside), and several lectins. Localization of actin was studied using confocal microscopy after rhodamine-phalloidin staining. Adding cytoskeletal inhibitors on the initial day resulted in weakly clustered cell aggregates rather than smoothly formed spheroids. These effects disappeared at lower reagent concentrations. When reagents were added on day 3, after the formation of spheroids, only mycalolide B was associated with an irregular spheroid surface; the others had no effect. Adding the anti-E-cadherin, anti-connexin 32 on the initial day showed inhibition of spheroid formation, but anti-zo-1 and proteoglycan synthetic inhibitor had no effects. Among the several lectins, only Wheat Germ Agglutinin (WGA), Ricinus communis Agglutinin I (RCA-I), and Concanavalin A (ConA) showed inhibition. These results suggest that cytoskeletal conformation and some adhesion molecules are necessary to form spheroids. Based on the interactions between lectins and hepatocytes in the present study, hepatocytes appear to contain an N-linked complex or N-linked hybrid glycosylated chains.

Animals↗

PubMed1995

Interaction between ionizing radiation, estrogens and antiestrogens in the modification of tumor microenvironment in estrogen dependent multicellular spheroids.

MCF7 human breast cancer cells growing as multicellular spheroids were examined as a model of three-dimensional cellular organization. Estrogen-free medium inhibited spheroid formation. In medium containing estrogens, the antiestrogen hydroxytamoxifen decreased the spheroid growth rate. Analyses with the recursion formula after Gompertz fitting showed that the rate of exponential decrease in growth rate (alpha) was alpha 0.099 +/- 0.013 d-1, and the decrease in alpha' was 0.061 +/- 0.015 d-1 for 0.1 microM hydroxytamoxifen and control spheroids respectively. MCF7 cells which had been growth arrested in an estrogen-free medium showed a significant decrease in radiosensitivity (surviving fraction at 2 Gy, SF2 = 63%) when compared with 0.1 nM 17 beta-estradiol-treated cells (SF2 = 38%). No differences in radiosensitivity were seen in MCF7 spheroids in estrogen-supplemented medium (radiation dose necessary to control 50% of spheroids (SCD50) was 5.51 Gy; derived alpha, beta and SF2 were 0.301 +/- 0.110 Gy-1, 0.018 +/- 0.005 Gy-2, and 51% respectively) when compared with monolayer cultures in the same medium (alpha = 0.316 +/- 0.059 Gy-1, beta = 0.023 +/- 0.006 Gy-2 and SF2 = 50%). In the spheroid model, manipulating the cellular environment, i.e., with estrogen treatment, modulates sensitivity to ionizing radiation.

Breast Neoplasms↗

PubMed2000

Primary porcine hepatocytes with portal vein serum cultured on microcarriers or in spheroidal aggregates.

AIM:To develop a culture mode providing durable biomaterials with high yields and activities used in bioartificial liver.METHODS:Hepatocytes were isolated from a whole pig liver by Seglen s method of orthotopic perfusion with collagenase. In culture on microcarriers, primary porcine hepatocytes were inoculated at a concentration of 5center dot10(7)/mL into the static culture systems containing 2g/L Cytodex-3, then supplemented with 100mL/L fetal calf serum (FCS) or 100mL/L porcine portal vein serum (PPVS) respectively. In spheroidal aggregate culture hepatocytes were inoculated into 100mL siliconized flasks at a concentration of 5.0center dot10(6)/mL.RESULTS:In culture on microcarriers hepatocytes tended to aggregate on Cytodex-3 obviously after being inoculated. Typical multi-cellular aggregated spheroids could be found in the two systems 24h-48h after hepatocytes were cultured. The morphological charact-eristics and synthetic functions were maintained for 5wk in FCS culture system and 8wk in PPVS culture system. In spheroidal aggregate culture about 80%-90% isolated hepatocytes became aggregated spheroids 24h after cultured in suspension and mean diameter of the spheroids was 100&mgr;m. The relationship among the hepatocytes resembled that in the liver in vivo. Synthetic functions of albumin and urea of the spheroids were twice those of hepatocytes cultured on monolayers.CONCLUSION:As high-yields and high-activity modes of culture on microcarriers or in spheroidal aggregate culture with portal vein serum are promising to provide biomaterials for bioartificial liver (BAL) efficiently.

Journal Article↗

PubMedDate not supplied

Differential expression of adhesion molecules (CD44, ICAM-1 and LFA-3) in cancer cells grown in monolayer or as multicellular spheroids.

Multicellular tumor spheroids have been used to examine numerous aspects of tumor biology since they often recreate the in vivo tumor environment much more closely than other models. Since the three-dimensional organization of cancer cells into spheroids is based upon cell-cell interactions which appear dramatically different in spheroids with respect to monolayer cultures, it can be hypothesized that a modulation in the expression of the molecules which are directly responsible for cell-cell and cell-matrix interactions, particularly the cell adhesion molecules (CAMs), may be involved. In order to test this postulate, the expression of three important CAMs involved in tumor processes (CD44, ICAM-1 and LFA-3) in the human cancer cell lines HT29 (colon adenocarcinoma), A431 (squamous epidermal carcinoma) and A2780 (ovarian carcinoma) grown in monolayer or as multicellular spheroids was compared. The results demonstrate that only two of the lines (HT29 and A431) formed spheroids after six days of gyratory culture while A2780 cells did not form such structures after up to 8 days of culture. In the two cell lines which did form early phase multicellular spheroids, flow cytometric analysis revealed that important differences exist between the same cells grown in monolayer and as spheroids in the quantity of expression of CAMs.

Adenocarcinoma↗

PubMed1992

Rhabdomyosarcoma spheroids with central proliferation and differentiation.

A novel type of multicellular spheroids was established and characterized with regard to growth behavior, proliferation, and differentiation. The spheroids were grown from clonal rat rhabdomyosarcoma cells using the spinner flask technique. The cell aggregates showed several unique properties that were different from those observed in most of the spheroids investigated to date. These properties include a non-Gompertzian volume growth; the coexistence of undifferentiated mononuclear cells and of differentiated, myotube-like giant cells with numerous nuclei; a relatively homogeneous intraspheroidal distribution of proliferating mononuclear cells with thymidine labeling even in the center of spheroids greater than 1 mm; the absence of necrosis in such large spheroids, and the accumulation of myotube-like cells in the center of these spheroids instead. There was a decrease in the overall proliferative activity of the mononuclear cells with increasing proportion of giant cells in the rhabdomyosarcoma spheroids.

Animals↗

PubMedDate not supplied

Effects of 5-fluorouracil and leucovorin in spheroids: a model for solid tumours.

We determined the cytotoxcity of 5FU alone or with leucovorin in MGH-U1 cells growing as monolayers or spheroids. The 5FU IC50 in spheroid and monolayers was 100 microM in both culture systems. The IC50 of 5FU and 5FU and 100 microM leucovorin in spheroids and monolayers was 100 microM and 50 microM, respectively. [H3]5 FU reached cells at all depths of the spheroid viable rim. Cells isolated from increasing depths of the spheroid viable rim demonstrated increasing resistance to 5FU. 5FU cytotoxicity is increased by leucovorin in monolayer but not spheroids, penetration is not limiting in 5FU cytotoxicity in spheroids and there is increasing resistance to 5FU in the viable rim.

Cell Division↗

PubMed1988

Mathematical model of simultaneous diffusion and binding of antitumor antibodies in multicellular human tumor spheroids.

Multicellular tumor spheroids are widely used as in vitro models of poorly vascularized tumor nodules in vivo. The uptake kinetics of tumor-associated antibodies in multicellular tumor spheroids is assumed to be governed by passive diffusion and irreversible binding of the antibodies with binding sites on the cell surface. By further assuming that the spheroids are homogeneous with respect to diffusion and binding, a mathematical model has been developed which permits the extraction of the macroscopic diffusion constant D and the macroscopic binding rate k from empirical studies. The model was applied to uptake kinetics data obtained (a) with a melanoma-associated monoclonal antibody 96.5 (isotype IgG2a)-human multicellular melanoma spheroid system exhibiting strong antibody to cell binding and (b) with the same monoclonal antibody-human multicellular colon adenocarcinoma HT29 spheroid system exhibiting nonspecific binding. The spheroids had approximately 300 microns diameter. The constants D and k were estimated to be 0.45 micron2 s-1 and 2.0 x 10(-3) s-1, respectively, for the system with specific binding. Saturation of binding sites occurred. In the nonspecific binding system, D and k were found to be 0.10 micron2 s-1 and 1.0 x 10(-5) s-1. No saturation of binding sites occurred. D and k were also estimated to be, respectively, 0.52 micron2 s-1 and 6.4 x 10(-5) s-1 for another melanoma-associated monoclonal antibody 140.240 (same isotype as 96.5) in the melanoma spheroid system exhibiting moderate cell binding with the antibody. The mathematical model describes well the system exhibiting nonspecific binding, but requires modifications and further development for the systems exhibiting moderate to strong binding.

Adenocarcinoma↗

PubMedDate not supplied

A comparative study of the effects of anthracycline derivatives on a human adenocarcinoma cell line (LoVo) grown as a monolayer and as spheroids.

The cytotoxicity of doxorubicin (DX), 4'-O-methyl-DX (MET-DX), 4'-deoxy DX (DEO-DX), 4'-deoxy-4'-iodo-DX (IODO-DX), daunorubicin (DNR)and 4-demethoxy-DNR (DM-DNR) on LoVo cells cultured as a monolayer (in exponential and stationary phases of growth) and as spheroids, are evaluated following 1-h exposure to the drugs. All compounds were more cytotoxic than DX in both systems. A comparison of the ID50 values for cell survival of monolayer cells and of the inhibition of relative growth of individual spheroids indicated that MET-DX and DNR, like DX, were less cytotoxic on spheroids than on monolayer cells in both growth conditions; DEO-DX, IODO-DX and DM-DNR showed an activity on spheroids that was intermediate between that observed on monolayer cells in exponential and stationary phases of growth. This observation indicated that the different pattern of activity of these anthracyclines on a spheroids system is not only related to the presence of cells at different cell cycle phases, but presumably also depends on factors related to the 3-dimensional structure of spheroid cells. Indeed DEO-DX, IODO-DX and DM-DNR, more lipophilic than the other compounds, might penetrate more deeply into spheroids, thus improving the cytotoxic response in this experimental system.

Adenocarcinoma↗

PubMed1987

The radiation response of a human colon adenocarcinoma grown in monolayer, as spheroids, and in nude mice.

A human colon adenocarcinoma cell line, WiDr, has been grown in monolayer, as multicellular spheroids, and as xenografted tumors in immune-deprived mice. The growth and radiation responses of the cells under these different growth conditions were compared. The mean doubling time of monolayer cultures was 0.8 day and the initial volume doubling times of spheroids and xenografts averaged 1.2 and 6 days, respectively. The mean total viable cell plating efficiencies were 82, 63, and 7% for cells from monolayers, spheroids, and xenografted tumors, respectively. The radiation responses of single cell suspensions prepared from WiDr tumors (8-10 mm in diameter), exponentially growing monolayer cultures (5 days growth), and spheroids (1200 microns in diameter) irradiated in air at 4 degrees C were similar. Values for D0 were 1.5 Gy and for n between 3 and 5. Nitrogen curves were characterized by a D0 of 5 Gy and n between 3 and 6. Oxygen enhancement ratios were approximately 3.3. Both spheroids and tumors had radioresistant components to the 37 degrees C/air-breathing survival curves with estimated hypoxic fractions of 8 and 12%, respectively. The final portion of the survival curves for irradiations in nitrogen and under normal growth conditions were parallel for both tumors and spheroids. Thus WiDr spheroids appear to model accurately the radiation sensitivity of WiDr tumors.

Adenocarcinoma↗

PubMed1986

[Radiation-induced differential responses of uterine adeno- and squamous cell carcinoma spheroids in dose-survival relationships].

Radiation-induced dose-survival relationships of human uterine adeno and squamous carcinoma cells grown as spheroid were studied, comparing them with monolayer cells. HEC-59 and SKG-3a cell lines were used. The spheroids were produced by Yuhas's method. In monolayer culture, D0,Dq and n values in the Hit-theory were as follows: HEC-59 (D0 = 1.6Gy, Dq = 0.6Gy, n = 1.5) and SKG-3a(D0 = 1.3Gy, Dq = 0.4Gy, n = 1.4). Survival curves of both cell lines as spheroids demonstrated biphasic curves after acute irradiation. HEC-59 cells grown as spheroids 300 microns in diameter did not have a great second component. SKG-3a cell, however, did apparently have a large amount of the second component when a 6Gy dose was exceeded. The shoulder in the dose-survival curves of both cells grown as spheroids became greater than monolayer cells up to 3Gy dose. It was therefore proven that spheroids possess similar characteristics to solid tumors. This suggests that spheroids are useful in studying radiation-induced effects in solid tumors.

Adenocarcinoma↗

PubMed1984

Lethal effect of bleomycin and peplomycin on HeLa cells in multicell tumor spheroids.

The lethal effects of bleomycin and its derivative, peplomycin, were determined for HeLa S3 cells grown in multicell spheroids cocultured with human diploid fibroblasts. Both drugs were less effective for cells in spheroids than for cells grown exponentially in monolayers. However, HeLa cells from spheroids exposed to the drugs in single-cell suspension were more sensitive to the drugs than were cells in monolayers. Sequential trypsinization of spheroids after exposure to both drugs showed that the surviving fraction increased sharply with increasing depth of cell layers in the spheroids. The presence of 0.5 mM misonidazole, a hypoxic radiosensitizer, enhanced the lethal effect of peplomycin only for the cells in the deeper layer. These findings suggest that the drug resistance of cells in spheroids was due, at least in part, to the microenvironment of the deeper layers. When spheroids were incubated in fresh medium following exposure to both drugs, the cells recovered from the potentially lethal damage within 1 hr. The extent of the recovery from a fixed drug concentration was higher in cells of the superficial layers than in cells of the deeper layers. It is suggested that the limitation of the lethal effects of bleomycin and peplomycin in solid tumors may be overcome by improving the state of oxygenation of hypoxic cells and by combining either drug with one which inhibits recovery from potentially lethal damage.

Antibiotics, Antineoplastic↗

PubMed1981

Flow cytometry studies of intracellular adriamycin in multicell spheroids in vitro.

A marked gradient of Adriamycin uptake in cells of tissue-like multicell spheroids in vitro has been demonstrated by fluorescence photomicroscopy and flow microfluorimetry techniques. As expected, this gradient led to an increased net survival for cells from Adriamycin-treated spheroids relative to monolayers and markedly greater clonogenicity of central spheroid cells than external cells selected by fluorescence-activated cell sorting. Growth of cells as spheroids seemed to impart an additional degree of drug resistance relative to cells grown as monolayers, in that equal toxicity required greater intracellular fluorescence (and thus more Adriamycin) for the spheroid cells. The flow cytometry techniques thus provide a mechanism for quantification of Adriamycin penetration into spheroids and provide a method for selection of cells from various depths within the spheroid.

Animals↗