Origin and ultrastructure of cells in vitro

Tissue culture of epithelium derived from Barrett's oesophagus

Barrett's oesophagus is a preneoplastic condition in which the squamous mucosa of the oesophagus is replaced by columnar epithelium. Epithelial cells of Barrett's oesophagus were isolated from resected oesophagus specimens by two methods not previously applied to the culture of Barrett's oesophagus cells. These techniques included trypsinisation of small fragments of mucosa, followed by plating in tissue culture dishes, and a direct tissue explant technique. A modified MCDB-153 growth medium was used. Primary trypsin technique cultures were plated on uncoated plastic, or plastic coated with type I collagen, type IV collagen, or fibronectin. Growth on type IV collagen and fibronectin plates was slower but produced less contamination from fibroblasts. By 20-40 days most cultures formed confluent monolayers made up of cells with epithelial morphology. The cells were cytokeratin positive, vimentin negative, and contained alcian blue positive vacuoles, confirming their epithelial origin and suggesting their derivation from Barrett's oesophagus. Electron microscopy showed tonofilaments, microvilli, and desmosomes. Cells proliferated through up to eight subcultures before growth slowed and cells showed senescent changes. This study shows that epithelial cells from Barrett's oesophagus can be grown by comparatively simple tissue culture techniques. These methods can provide sufficient material for a variety of molecular biology and biochemical studies of epithelial cells from Barrett's oesophagus.

Spontaneous immortalization of mouse embryo cells: strain differences and changes in gene expression with particular reference to retroviral gag-pol genes

We have studied the kinetics with which cultures of primary mouse embryo cells pass through the crisis period, escape their terminal differentiation (cellular senescence), and give rise to an immortal cell line. The process is strain-dependent, with cells from the outbred Swiss CD-1 mouse being considerably more adept at forming an immortal 3T3 line than cells from the inbred SWR line; Balb/c cells appeared intermediate in their behavior. The continued presence of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate or the poly(ADPribose)polymerase inhibitor 3-aminobenzamide affected the kinetics but did not seem to alter the outcome. Changes in expression of various genes, including those encoding mitogen-regulated protein (proliferin), endogenous gag-pol retrovirus sequences, insulin-like growth factor II, and a variety of protooncogenes, were monitored during the process of immortalization, and although certain changes were reproducibly characteristic of cells from a given mouse strain passed according to a specific regimen, none of the observed changes were reproducibly characteristic under all conditions of immortalization. In particular, our data indicate the absence of a strict correlation between cellular immortalization and the activation of endogenous gag-pol expression. We conclude from our observations that the establishment of permanent lines from primary mouse embryo cells in serum-containing medium reflects the selection of a variant subpopulation of cells that did not preexist but rather arose in response to the specific culture conditions by a process resembling differentiation. Multiple and complex changes in gene expression occur that are affected by the culture conditions and the strain (genotype) of the mouse.

Kidney glomerular explants in serum-free media. Sequential morphologic and quantitative analysis of cell outgrowths

Guinea pig glomeruli were grown in vitro for 22 days in a serum-free medium composed of Waymouth's MB 752/1 supplemented with sodium pyruvate, nonessential amino acids, antibiotics, insulin, transferrin, selenium, triiodothyronine, and fibronectin (FN), and sequential morphologic and quantitative studies of cell outgrowth were performed. Glomeruli grown in serum-free medium showed preservation of glomerular visceral epithelial cells but extensive necrosis of endocapillary cells (endothelial and mesangial cells). Morphologic analysis demonstrated progressive morphologic changes in cultured glomerular cells; however, most cell types observed in culture appeared to grow from the epithelial side of the glomerular basement membrane. Mitosis was a prominent component of glomerular cell outgrowth in vitro, and total DNA increased slightly during glomerular culture. FN was required for glomerular cell outgrowth, and studies using FN fragments demonstrated that the carboxy-terminal portion of FN was required for whole glomerular attachment. These results are used to develop a model for glomerular cell outgrowth in vitro.

Selective suppression of metastasis but not tumorigenicity of a mouse lung carcinoma by cell hybridization

Somatic cell hybrids were produced by polyethylene glycol-induced cell fusion between metastatic CMT 167 (HGPRT-/OUAR) C57BL/Icrfat mouse lung carcinoma cells and 2 non-metastatic cell lines: C3H/He mouse L-M(TK-) cells of mesenchymal origin and EJ (OUAS) human bladder carcinoma cells. Fusion of 2 different CMT167 (HGPRT-) clones with L-M(TK-) cells followed by selection in HMT medium gave rise to 14 intraspecific hybrids, which were shown to express H-2 antigens specific for both the C57 and C3H mouse strains. Three interspecific hybrids arising from fusion of EJ(OUAS) and CMT167(HGPRT-/OUAR) cells were selected in HMT/ouabain medium and characterized by human isozyme analysis. All the hybrids produced large tumours after subcutaneous inoculation of 5 X 10(5) cells into adult athymic nu/nu mice. The intraspecific hybrid tumours were predominantly sarcomatous (mesenchymal) in structure but a few contained epithelial acini. Metastatic ability (as assessed by production of lung metastases) was completely suppressed in 13 of the 14 mouse/mouse hybrid cell clones. These results suggest that tumorigenicity, tumour structure and the ability to metastasize are expressed independently. The interspecific hybrids, which had not retained a full human chromosome complement, produced metastatic tumours that remained epithelial in structure.

In vitro senescence of Syrian hamster mesenchymal cells of fetal to aged adult origin. Inverse relationship between in vivo donor age and in vitro proliferative capacity

Normal diploid Syrian hamster dermal mesenchymal cell strains, regardless of the age of the tissue of origin, exhibit in vitro cellular senescence. The frequency of spontaneous escape from senescence and conversion to a permanent cell line is less than 5% among replicate flasks. The overall pattern of senescence of cells of fetal, neonatal, young adult (6 months) and aged adult (24 months) origin is similar in terms of the morphological changes and proliferative changes indicated by the reduction of saturation density, cloning efficiency and [3H]thymidine labeling index and by the increase in population doubling time and cell volume. However, the average maximum cumulative population doubling level is characteristic for each cell type: 13-day gestation fetal cells, 28.6; neonatal cells, 18.7; young adult cells, 13.8; aged adult cells, 11.1. Thus, the in vitro proliferative capacity of Syrian hamster mesenchymal cells is inversely related to the in vivo age of the donor.

Surface markers of human gingival fibroblasts in vitro. Characterization and modulation by enzymes and bacterial products

Surface markers of human gingival fibroblasts in vitro were investigated using monoclonal and heterologous antisera against a range of cell surface antigens, together with rosetting techniques to characterize surface receptors for IgG and C3. WI-38 fibroblasts and human peripheral blood monocytes were used as control cells. Human gingival fibroblasts exhibited complement receptors and beta2-microglobulin, as did WI-38 cells. Ten per cent of the human gingival fibroblasts were positive for HLA-DR antigens and additionally exhibited a granulocyte antigen not apparent on WI-38 cells. Monolayers of the gingival fibroblasts were further exposed for short periods to varying concentrations of enzymes (trypsin, collagenase and neuraminidase), bacterial extracts (lipopolysaccharide and lipoteichoic acid) and crude supra- and subgingival plaque sonicates. Surface-marker analysis was then carried out. The most noticeable effects were obtained with Vibrio cholerae neuraminidase which enhanced C3 receptor and surface antigen expression, and supragingival plaque sonicate which depressed the expression of HLA-DR and granulocyte antigens while not affecting beta2-microglobulin expression. Trypsin reduced antigen expression to a degree, but its effects were mainly on cell adherence.

The ability of normal mouse cells to reduce the malignant potential of transformed mouse bladder epithelial cells depends on their somatic origin

Somatic cell hybrids have been made between a transformed mouse bladder carcinoma cell line and normal mouse bladder epithelium and mesenchyme. In the epithelial tumour/mesenchyme hybrids the malignant phenotype was expressed dominantly whereas in the carcinoma/normal epithelium hybrids the malignant potential was greatly reduced. In both cases the dominant in vitro and in vivo phenotype was that of the normal parental cells. All hybrid tumours were first palpable after 4-7 days, demonstrating that the tumours had not arisen as a result of in vivo selection of a sub-population of tumorigenic cells. Chromosome analysis showed that the carcinoma/normal epithelium hybrids were all in the hypertetraploid range but the large variation in the karyotypic profile of each hybrid made it impossible to implicate any specific chromosomes in the control of expression of the malignant phenotype. During normal development in bladder epithelium, terminal differentiation is associated with tetraploid formation by cell fusion. The reduction in malignancy of the carcinoma/normal epithelium hybrids may perhaps be due to the expression of genes associated with normal terminal differentiation after cell fusion and tetraploid formation. This is also supported by the more differentiated phenotype of the hybrid tumours. Of the 10 mesenchyme/epithelium hybrids analysed cytogenetically , four were in the hypertetraploid range from which little meaningful data could be obtained about specific chromosome losses. Chromosome analysis of the cells from the near-tetraploid hybrids showed only minor differences from what might have been expected from the input of the two parents; these differences appeared to be due to random chromosome loss. The maximum number of chromosomes lost from any of the hybrids was five, although one, two or three was more usual. The only consistent chromosome loss was of a single copy of chromosome 4, which in two of the hybrids represented the only chromosome change. The possibility that this loss might facilitate re-expression of the malignant phenotype is discussed.

Cellular heterogeneity in a tissue culture cell line derived from a human bladder carcinoma

To study heterogeneity in a cell line derived from a human bladder carcinoma (EJ), 7 clones were isolated at low passage and examined for differences in culture behaviour, ability to grow in agar and tumorigenicity in nude mice. The parent EJ line had several distinct chromosome populations (both diploid and tetraploid), grew in agar and produced tumours in nude mice. Three of the clones had pseudodiploid modes and 4 had either hypo- or hypertetraploid modes. The 7 clones had 5 marker chromosomes in common but the combination of other marker chromosomes made each clone unique. No significant difference was found between the clones in the in vitro growth rate although analysis of in vitro culture behaviour showed heterogeneity in the pattern of cell movement on plastic substratum. Three clones were composed of static cells, one clone had very mobile cells; the other clones had rates of movement intermediate between the two. Differences were also found in the packing density of the cloned cells and in the cell size. All 7 clones grew in agar but heterogeneity was seen between the clones as shown by widely varying colony-forming efficiencies (0.5-13%). One clone had a high colony-forming ability in agar but failed to produce tumours in nude mice. The other clones were tumorigenic regardless of colony-forming efficiency in agar. Specific chromosome abnormalities were found to be associated with growth in agar and tumorigenicity but not with the growth pattern or the rate of movement of the cloned cells in culture.

Microtubules and microfilaments in ageing hamster embryo fibroblasts in vitro

Microtubules and microfilaments were investigated in hamster lung fibroblasts, during their in vitro life-span. These cells show a senescence process characterized by a drastic phenotypic change, resulting in two phenotypes: the type 1 cells, characteristic of young cultures and the type 2 cells appearing progressively with culture passages. Microtubules and microfilaments were observed at the TEM and also visualized by the unlabelled peroxidase-anti-peroxidase method. Moreover, the susceptibility of microtubules to nocodazole was tested in type 1 and 2 cells. We could not provide evidence for a different susceptibility to the drug. However the depolymerization wave occurred centripetally in type 1 cells whilst centrifugally in type 2 cells. These observations are discussed in relationship with the early arrest of division growth of the type 2 differentiated cells.

Ageing of hamster embryo fibroblasts as the result of both differentiation and stochastic mechanisms

Fibroblasts from hamster embryos were serially cultivated in vitro and their evolution followed from a morphological, physiological and biochemical point of view. After an exponential growth for about 20 passages, cells entered the ageing phase which ended up after 29-34 passages. From our observations, it seems that the arrest of growth results from two different phenomena: first, the typically fibroblastic cells may undergo a stochastic ageing process; second, some of these cells evolve into a terminal differentiation process, characterized by a different non-fibroblastic phenotype.

The wound fibroblast and macrophage. I: Wound cell population changes observed in tissue culture

The number and type of cells which migrated from sequential explants of wounded fascia in rats reflected the dense and changing cell populations observed in healing wounds. Macrophages appeared in large numbers from explants taken in the 5 days following injury, thereafter fibroblast-like cells predominated. The results support the hypothesis that the fibroblast-like cell of tissue culture is the same as the wound fibroblast. The technique can be used to obtain wound cells and provides a useful bridge between in vivo and in vitro means of investigating wound repair.

The macrophage in Hodgkin's disease

Methods used to separate macrophages from human lympho-medullary tissue samples have been applied to involved and uninvolved spleens and lymph nodes from 44 patients with Hodgkin's disease. The tumour samples yielded a population of ultrastructurally atypical cells with the anatomical and functional attributes of macrophages. The findings suggest that the macrophage was the neoplastic element in the cases of Hodgkin's disease studied. A feature of samples of uninvolved tissue from Hodgkin's disease patients was that there were fewer macrophages identifiable in the samples than in the normal control tissues. These findings suggest that they may be a deficiency of normal macrophages as well as macrophage neoplasia in this disease. Both abnormalities would contribute to the defective cell-mediated immunity which is a characteristic of Hodgkin's disease.

The differentiation of follicular-like cells from the epithelium of Rathke's pouch grown in vitro

The epithelial rudiment of 4 day-old quail embryo adenohypophysis, cultivated in vitro under conditions allowing glandular differentiation, displays peripheral cells that progressively acquire follicular cell features. They elongate, develop numerous microvilli, junctional complexes, interlocking membranes and bundles of microfilaments. These follicular-like cells derive from peripheral epithelial cells that, in situ, become glandular. These results show that follicular cells can develop from undifferentiated cells. They undergo this pathway of development, in all likelihood, as a result of perturbations in their microenvironment.

Cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines: effects of methotrexate treatment

The cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines were determined by autoradiography (PLM method) as follows: DT-5: generation time (TC), 15.2 h; pre-synthetic gap phase (TG1), 3.2 h; DNA-synthetic phase (TS), 8.2 h; post-synthetic gap ph se (TG2), 3.3 h; visible mitotic phase (TM), 0.5 h. 11028: TC, 13.6 h; TG1, 1.9 h; TS, 7.7 h; TG2, 3.4 h; TM, 0.6 h. 11028+FeLV (11028 productively infected with feline leukemia virus): TC, 11.2 h; TG1, 0.2 h; TS, 8.3 h; TG2, 2.1 h; TM, 0.6 h. Exposure of the lymphoma cell lines to methotrexate (MTX) in vitro produces dose-related increases in cellular volume, associated with reductions in cellular proliferation. The relative sensitivities of these cell lines to MTX, measured by the ID50 MTX concentrations for DT-5, 11028, and 11028+FeLV are 118 nM, 122 nM, and 28 nM respectively. The cell kinetic effects of the ID50 MTX concentrations added to cultures of lymphoma cells pulse-labeled with tritiated thymidine are an approximately 2-h prolongation of TC, attributable to a lengthening of TS, with other cell cycle phases not significantly altered. These cell lines are highly tumorigenic when transplanted into the cheek pouches of immunosuppressed hamsters, with inocula of 10(4) cells producing rapidly growing, well vascularized tumors.

In vitro studies on the self-differentiating capacities of quail adenohypophysis epithelium

Isolated epithelial rudiments of 3--4 days quail embryo adenohypophysis were cultivated in vitro. Differentiation of glandular cells occurred when culture conditions allowed the formation of explants characterized by the presence of a fibroblastic sheet and of an epithelial roof surrounding a central cavity. Differentiation did not occur when culture conditions did not allow the fibroblastic sheet to be established or resulted in the absence of a cavity. The importance of the explant structure in differentiation is also indicated by the location of glandular cells. In vitro they differentiate near the cavity derived from Rathke's pouch lumen while in situ they first appear at the periphery of the rudiment, near the basement membrane. The results of this study show that the adenohypophyseal primordium can differentiate without any mesenchymal influence. The observed differentiation seems to be correlated with fibroblast-secreted material, and this hypothesis is discussed.

Hepatocyte suspensions and cultures as tools in experimental carcinogenesis

Isolation of preneoplastic cell populations would greatly facilitate analysis of the development of liver carcinogenesis. Suspensions of intact single cells can be prepared in an almost quantitative yield by two-step perfusion of the isolated liver. In the first step the liver is perfused with a Ca2+-free buffer (or with EGTA) in order to irreversibly cleave the desmosomes; in the second step perfusion with Ca2+-activated collagenase dissolves the collagenous extracellular matrix. The resulting single-cell suspension will be a mixture of intact normal and preneoplastic hepatocytes, other liver cell types (mostly Kupffer and endothelial cells), damaged cells, and subcellular debris. Intact hepatocytes can be purified--e.g., by differential centrifugation--but separation of preneoplastic from normal cells has not yet been achieved. Density gradient separation or selection in culture on the basis of the unique properties of preneoplastic hepatocytes (e.g., drug resistance) may prove useful. The use of hepatocyte cultures and liver-derived epithelial cell lines as test systems and models for chemical carcinogenesis in vitro is briefly reviewed.

Ultrastructural features of cultured human glia and glioma cells

The fine structure of three lines of human normal glial cells and eight established lines of malignant glioma cells are described. The glial cell lines were ultrastructurally very similar whereas the glioma cell lines differed greatly from one another. In sparse proliferating cultures there were no consistent findings which distinguished the glioma cell lines as a group from the normal glial cells. Only in post-confluent cultures could the consistently irregular cell surfaces and ruffling, both at the cell periphery and centrally on the upper cell surface, with associated pinocytosis, distinguish the glioma from the post-confluent glial cultures, which did not possess these properties. The common attributes of post-confluent glioma cells reflect the cells' continued proliferation. The glioma lines did display individual ultrastructural characteristics which appear to be stable, the glioma lines having retained these during a number of years of continual passage.

Properties of epithelial cells cultured from human carcinomas and nonmalignant tissues

Human epithelial cell cultures were examined for expression of plasminogen activator and fibronectin matrix. All of the cells examined showed ultrastructural evidence suggesting their epithelial origin, including microvilli and specialized junctions. The nonmalignant cells were also negative for endothelial cell markers (ie. they lacked factor VIII antigen, a nonthrombogenic surface and Weibel-Palade bodies). The nonmalignant lines all produced large amounts of plasminogen activator, whereas the tumor-derived lines showed a gradation of activities, ranging from lines having as much activity as the nonmalignant lines to lines having little or no activity above background. For both normal and malignant cells, addition of dexamethesone only slightly decreased the levels of plasminogen activator. By immunofluorescence microscopy, normal bladder and fetal intestine epithelial cells showed fibronectin in a globular and fibrillar matrix. In contrast, normal mammary epithelial cells had a much diminished amount of fibronectin with a punctate distribution.

The ultrastructure of functional mouse adrenal cortical tumor cells in vitro

Cells derived from a transplantable mouse adrenal cortical tumor maintain their differentiated function in vitro and secrete steroids in response to ACTH and other stimulatory agents. The cell line has been widely employed for various biochemical investigations but there have been few attempts to correlate this work with morphologic data. This communication describes the electron microscopic appearance of the tumor transplant in vivo and primary cultures derived from it at various intervals after the cells are placed in culture. Tumor cells in vivo bear considerable resemblance to normal adult mouse adrenal cortical cells. Organelles generally considered to be directly involved in steroid biosynthesis (mitochondria, smooth endoplasmic reticulum and lipid droplets) are not drastically altered. Certain modifications of the vasculature and cell membrane, seemingly related to steroidogenesis, are present in both the tumor and normal adrenal cortex. Within 2 days after the tumor cells are introduced to culture, their cytoplasm assumes a more simplified appearance. Smooth endoplasmic reticulum is less conspicuous and free ribosomes and polysomes are very abundant. Mitchondrial inner membranes are reorganized from a saccular arrangement in the cells in vivo into distinct lamellar cristae. The tumor cells now resemble undifferentiated embryonic adrenal cells, or cultured adrenal cells from various mammalian sources which have dedifferentiated in the absence of ACTH. In their morphologically unspecialized state, the normal cells are incapable of functional responses to ACTH. In contrast, the cultured, dedifferentiated tumor cells respond within minutes to this hormone and can demonstrate 5-20 fold increases in their basal steroid output. These data suggest that substantial steroidogenic activity can occur although the characteristic appearance of adrenal mitochondria is absent.

Normal human endometrium in cell culture. I. Separation and characterization of epithelial and stromal components in vitro

Separation of human endometrium into its epithelial and stromal components has been achieved through collagenase digestion and has permitted a study of these two cell populations under specific experimental culture conditions. The stromal cell populations showed a progesterone response, were easily handled in culture, and displayed a limited in vitro life span typical of human diploid fibroblasts. In contrast, epithelium only survived in short-term primary culture and showed no clear hormone response. High-density epithelial cultures remained viable for longer periods in culture. Comparisons between resurfacing endometrial epithelial cells in vivo and epithelial cells migrating from explants in vitro suggested that this initial epithelial migration in vitro was the counterpart of the repair response in vivo.

Ultrastructure and biological markers of neoplastic change in adult mouse epithelial cells transformed in vitro

The ultrastructure and in vitro growth properties of 5 tumorigenic mouse submandibular-gland epithelial cell lines were studied. In all lines, in vitro acinus formation occurred, and well differentiated epithelial cells showing epithelial microvilli and desmosomes and cytoplasmic tonofilaments were present. None of the cells showed specific ultratructural features of the normal differentiated submandibular-gland ducts. All the lines formed colonies in semi-solid agar and on confluent monolayers of BALB/c 3T3 cells, and all lacked density-dependent inhibition of growth, as demonstrated by a random distribution of [3H]TdR labelling throughout growing colonies. These 3 growth properties appear to be reliable in vitro markers for epithelial neoplastic transformation in this system, but colony-forming efficiency in agar is lower than that reported for many transformed mesenchymal cells.

A cell line from an induced carcinoma of mouse rectum

A tissue culture cell line has been established from one out of seven induced carcinomas of mouse large intestine. The cells have an epithelial morphology and form tumour acini in vitro. Electron microscopy shows that the cells have retained some differentiated characters, including junctional complexes and microvilli with attached glycoprotein strands both in the acini and at the free margins of the cell sheets.