Mini chamber system for long-term maintenance and observation of cultured cells

We constructed a mini chamber system that was able to maintain cell culture on a microscope for long periods. It is a modified closed system with medium perfusion and CO2 circulation. The closed CO2 circulation and ample air inside the chamber distinguish it from other closed systems. Using different cell lines, the system was shown to be able to support long-term, time-lapse recording. After 229 hours of time-lapse recording, A2058 cells (a melanoma cell line) became overconfluent but still multiplied. Many CAD cells (a murine neuron-like cell line) still moved their cell bodies and kept their neurite-like processes after 28 days of recording. The entire healing process of a scratch-wounded 124 (a bladder cancer cell line) monolayer can be monitored. Such a modified closed system should find many applications in developmental biology, cell biology, and cancer biology where long-term, time-lapse recording is required or when the health of cells is important.     

Development of an efficient transformation system for Catharanthus roseus cell cultures using particle bombardment

We have developed an efficient direct DNA transfer procedure for the facile engineering of Catharanthus roseus cell cultures. Particle bombardment of callus derived from leaf material permitted rapid selection and establishment of transgenic cell lines. Transgenic callus were recovered at a frequency of between 60–80% of total callus bombarded with a single plasmid. Bombardment using two separate plasmids resulted in a 25–60% frequency of transgenic callus recovered, up to 90% containing both input plasmids. Between 10–20 g FW of transgenic material was produced within 3 months of bombardment, providing sufficient material for molecular and biochemical analyses. We developed two complementary systems allowing selection on either hygromycin or kanamycin to permit re-transformation using plasmids carrying additional genes of interest. Use of leaf tissue as explant for transformation avoids time-consuming and labor intensive procedures involving suspension cultures. We provide molecular data on integration and expression of selected and non selected transgenes in a number of transgenic callus lines. Transgene integration events for co-transformed plasmids were relatively simple, occurring at one or two sites in the genome for most of the lines we analysed. Molecular analysis of callus resulting from co-transformation experiments using two different plasmids revealed that in nine of 10 putative transgenic lines we selected for analysis both plasmids had integrated into the genome. RNA gel-blot analysis and histochemical staining showed that an unselected transgene, gusA, was expressed in seven of the ten lines we analysed.     

An observation chamber for studying temperature-dependent and drug-induced events in live neurons using fluorescence microscopy

Live-cell imaging chambers are used in a wide range of cell biology research. Recently, chambers capable of taking high-resolution and time-lapse images of live cells have been developed and become commercially available. However, because most of these chambers are designed to maintain a thermally stable environment for the cells under study, it is usually very difficult to use them to study temperature-dependent cellular events. Here we report the development of a chamber that is able to be used for the continuous monitoring of live neurons under most commercially available upright epifluorescence and confocal microscopes and in which the temperature and composition of the medium surrounding the neurons can be changed rapidly and reversibly. This live-cell observation chamber has been used successfully with cultured rat hippocampal neurons to study temperature-dependent changes in the dynamics of the microtubule cytoskeleton using fluorescence recovery after photobleaching (FRAP) together with the localization of α-tubulin in the dendritic spines. The success of these observations demonstrates the usefulness and applicability of the live-cell observation chamber described here to a wide range of cell biology experiments.     

Development of a shaking bioreactor system for animal cell cultures

The feasibility of using shake flasks to culture animal cells was evaluated using various sizes of cylindrical shaped vessels as bioreactors. It was found that conditions can be optimized so that hybridoma, Chinese Hamster Ovary cells, and insect cells can be efficiently cultured in the shaking reactors to cell densities comparable to that obtained with stirred-jar bioreactors, and the system is scalable to larger volumes for the production of recombinant proteins or cell mass production in the laboratory.     

Development of assay system for immunoglobulin production regulatory factors using whole cell cultures of mouse splenocytes

We tried to establish an assay system for screening and assessment of immunoregulatory factors using whole cell cultures of mouse splenocytes and found that splenic adhesive cells markedly increased immunogobulin (Ig) production of splenocytes. In the absence of adhesive cells, lipopolysaccharides, pokeweed mitogen, and phytohemagglutinin stimulated the production of IgA, IgG, and IgM in a class-dependent manner. Adhesive cells increased more markedly Ig production of splenocytes stimulated with these mitogens. When mouse splenocytes were cultured with milk proteins in the absence of adhesive cells, lactoferrin, beta-lactoglobulin, alpha-casein, and beta-casein stimulated IgA and IgG production. Adhesive cells increased IgA production of splenocytes stimulated with milk proteins, especially. These results suggest that the assay system is useful for assessment of Ig production-regulating factors.     

A reversible multi-well chamber for incubation of cultured cells with small volumes: application to screening of hybridoma fusions using immunofluorescence microscopy

Immunofluorescence microscopy is a powerful technique for detecting the location of surface and intracellular antigens in individual cells. However, using standard methods, processing large numbers of samples for immunofluorescence is cumbersome and difficult. To simplify greatly this process, we have developed a chamber that reversibly creates multiple small wells in a large (150 mm) tissue culture dish. This device allows the rapid and convenient processing of hundreds of samples each of 100 microliters volume. Each sample is examined using a short working distance, high numerical aperture immersion objective for maximum sensitivity and resolution. This apparatus makes immunofluorescence a practical method for the primary screening of hybridoma clones.     

Hydrohalite spatial distribution in frozen cell cultures measured using confocal Raman microscopy

Hydrohalite, a crystalline rock salt hydrate, (NaCl·2H₂O), can form in cryopreservation samples under certain circumstances changing the local chemical environment of the preserved cells. Evidence of this crystalline phase was recently found by microspectroscopy measurements, and believed to form exclusively extracellular. We have studied the spatial distribution of hydrohalite in frozen mouse fibroblast cell samples by means of confocal Raman scanning microscopy (CRM). Hydrohalite has a unique Raman spectrum with several bands in the high frequency tail of the OH-stretching band which can be used for unambiguous identification. Hydrohalite can only form through eutectic crystallization in saline solutions without any cryoprotective agents and the spatial distribution thus gives a more detailed view on this crystallization process. This is important since eutectic crystallization has been empirically correlated to cell death, but the exact injury mechanism is unclear. By the means of colocalization of Raman bands we show that hydrohalite can indeed form intracellularly and is not a strictly extracellular phenomenon. We furthermore found that intracellular ice and intracellular hydrohalite very often coincide. Finally we show that the addition of 0.5 wt.% dimethyl sulfoxide (Me₂SO) inhibits formation of hydrohalite. This study shows how Raman microscopy and successive analysis can be employed non-invasively within cryobiology to give additional chemical and structural information compared to conventional imaging techniques.     

Determination of [3H]TdR-labelling indices of cultured cells grown on detachable chamber slides

The in vitro effects of xenobiotic agents on the incorporation of DNA precursors was determined using a detachable chamber slide assembly. The technique presented allows for the comparative assessment of several agents, even when a limited number of cells is available. The use of a glass slide also potentiates the use of higher magnifications with a greater resultant resolution than that achievable with past methods.     

Demonstration of the oncogenic activity of cell cultures using antithymocytic serum]

The authors examined 10 cell strains of different origin as to their effect on mice by means of antithymocytic (ATC) serum. In dependence on the strain used the tumors developed in different number and with different growth tendency. In control animals not treated by the ATC serum, small ganglions developed in some cases which, however, disappeared in 2--3 days. Both strains of diploide cells WI 38 and LEP and primary cultures of chicken fibroblast from embryos of SPF chickens did not develop any tumors. The antithymocytic serums from calfs were found to be less toxic for mice than the rabbit sera.     

Method of total staining of monolayer cell cultures using vanadium hematoxylin]

Original method of cytological staining for monolayer cell cultures and outgrowth zone of tissue explants with vanadium hematoxylin is described. This staining method is simple, universal, reproducible and give opportunity to stain rapidly practically all cellular elements of cultivated monolayer with high degree of cytological resolution of intracellular structures (nucleus, cytoplasmic organelles etc.).     

Relationship between antibody formation in cultures of lymphoid cells and incubation temperature]

An increase of the plaque-forming cells (PFC) and of the 3H-thymidine incorporation in the spleen cell cultures of immunized and nonimmunized C57BL/6 mice were studied in increase of the incubation temperature from 2 to 37 degrees C. An exponential rise of the PFC cells with the elevation of temperature and the presence of the "breaking" temperature, above which the rate of increase of the PFC cells displayed a sharp elevation, was demonstrated. The curves of intensification of the 3H-thymidine incorporation with the temperature elevation failed to follow the pattern of the PFC growth curve in a number of cases. Cultivation of immune cells at low temperatures led to the accumulation in the medium of some factors simulating the AFC formation.     

Development and utilization of crustacean long-term primary cell cultures: Ecdysteroid effects in vitro

Summary

Long-term maintenance of lobster, Homarus americanus and crayfish, Pacifasticus leniusculus primary cell cultures of testicular and hematopoietic tissues, for 11 and 3 months, respectively, succeeded in a modified Medium 199 supplemented with 10% fetal bovine serum (pH 7.5, 200°C). In addition, NaC1 was used to adjust the lobster culture medium to 1000 mOsm and the crayfish medium to 400 mOsm. Proline concentration was also elevated. Testes were dissociated with 200 U/ml type II collagenase 2–3 days prior to culture.

Lobster hemocytes reacted to 10^?7 M 20-hydroxyecdysone (20-HE) by reducing contact inhibition and increasing invasive behavior one week after hormonal exposure. The presence of 10^?7 M 20-HE caused mesodermal cell death and spermatogonial proliferation in lobster testicular cell cultures within one week. Crayfish testicular mesodermal cells formed vacuoles 5 days after exposure to 10^?8 M 20-HE. These results are discussed in relation to the cellular events that occur in vivo during premolt.     

Open-dish incubator for live cell imaging with an inverted microscope

Here we describe the design and fabrication of an inexpensive cell culture incubator for the stage of an inverted light microscope for use in live cell imaging. This device maintains the temperature of the cell culture at 37 degrees C with great stability and, after reaching equilibrium, provides focal stability of an image for 20-25 min with oil-immersion lenses. We describe two versions of the incubator: one for use with standard 60-mm plastic culture dishes, and the other version for imaging of cells on glass coverslips. Either can be made for less than $400. Most components are widely available commercially, and it requires only simple wiring and 3 h to assemble. Although the device is generally useful for live cell imaging on an inverted microscope, it is particularly suitable for work in which instruments are introduced into the culture, such as electrophysiology or micromanipulation. The design is based on the principle that control performance is limited by the lag time between detection and response. The key element of the design is a heated, temperature-controlled aluminum ring serving as a mini-incubator surrounding the culture vessel. For this reason, we call our design a "ringcubator."