Cell culture

About: Cell culture is a research topic. Over the lifetime, 133361 publications have been published within this topic receiving 5364150 citations. The topic is also known as: cell culture techniques.

The relationship between in vitro cellular aging and in vivo human age.

Abstract: Differences between early and late passage cell cultures on the organelle and macromolecular levels have been attributed to cellular "aging". However, concern has been expressed over whether changes in diploid cell populations after serial passage in vitro accurately reflect human cellular aging in vivo. Studies were therefore undertaken to determine if significant differences would be observed in the in vitro lifespans of skin fibroblast cultures from old and young normal, non-hospitalized volunteers and to examine if parameters that change with in vitro "aging" are altered as a function of age in vivo. Statistically signigificant (P less than 0.05) decreases were found in the rate of fibroblast migration, onset of cell culture senescence, in vitro lifespan, cell population replication rate, and cell number at confluency of fibroblast cultures derived from the old donor group when compared to parallel cultures from young donors. No significant differences were observed in modal cell volumes and cellular macromolecular contents. The differences observed in cell cultures from old and young donors were quantitatively and qualitatively distinct from those cellular alterations observed in early and late passage WI-38 cells (in vitro "aging"). Therefore, although early and late passage cultures of human diploid cells may provide an important cell system for examining loss of replicative potential, fibroblast cultures derived from old and young human donors may be a more appropriate model system for studying human cellular aging.

High-level expression of a recombinant antibody from myeloma cells using a glutamine synthetase gene as an amplifiable selectable marker.

Abstract: We report a method for introducing a glutamine synthetase (GS) selectable marker into myeloma cells in which transfectants are selected by growth in a glutamine-free medium. Vector amplification can subsequently be selected using the specific inhibitor of GS, methionine sulphoximine (MSX). Using this system, DNA sequences encoding a chimeric B72.3 IgG4 antibody were expressed from hCMV-MIE promoters in NSO myeloma cells. A cell line was isolated after a single round of selection for vector amplification which contains approximately 4 copies of the vector, secretes 10-15 pg/cell/day cB72.3 antibody during exponential growth and can accumulate 560 mg/l antibody in a fed-batch air-lift fermentation system. Productivity is stable in the absence of MSX selection.

Inducible expression of human hepatitis B virus (HBV) in stably transfected hepatoblastoma cells: a novel system for screening potential inhibitors of HBV replication.

Abstract: We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.

Identification and characterization of subpopulations in undifferentiated ES cell culture.

Abstract: Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass (ICM) and the epiblast, and have been suggested to be a homogeneous population with characteristics intermediate between them. These cells express Oct3/4 and Rex1 genes, which have been used as markers to indicate the undifferentiated state of ES cells. Whereas Oct3/4 is expressed in totipotent and pluripotent cells in the mouse life cycle, Rex1 expression is restricted to the ICM, and is downregulated in pluripotent cell populations in the later stages, i.e. the epiblast and primitive ectoderm (PrE). To address whether ES cells comprise a homogeneous population equivalent to a certain developmental stage of pluripotent cells or a heterogeneous population composed of cells corresponding to various stages of differentiation, we established knock-in ES cell lines in which genes for fluorescent proteins were inserted into the Rex1 and Oct3/4 gene loci to visualize the expression of these genes. We found that undifferentiated ES cells included at least two different populations, Rex1+ / Oct3/4+ cells and Rex1- / Oct3/4+ cells. The Rex1- / Oct3/4+ and Rex1+ / Oct3/4+ populations could convert into each other in the presence of LIF. In accordance with our assumption that Rex1+ / Oct3/4+ cells and Rex1- / Oct3/4+ cells have characteristics similar to those of ICM and early-PrE cells, Rex1+ / Oct3/4+ cells predominantly differentiated into primitive ectoderm and contributed to chimera formation, whereas Rex1- / Oct3/4+ cells differentiated into cells of the somatic lineage more efficiently than non-fractionated ES cells in vitro and showed poor ability to contribute to chimera formation. These results confirmed that undifferentiated ES cell culture contains subpopulations corresponding to ICM, epiblast and PrE.

In vitro expansion and genetic modification of gastrointestinal stem cells in spheroid culture

Abstract: It is useful to be able to grow enriched populations of stem cells in vitro. Growth of stem cells as tissue spheroids is a key methodology permitting sustainable culture of adult epithelial cells. Gastrointestinal stem cells can be propagated by using conditioned medium from a supportive cell line (L-WRN). This protocol describes how to prepare conditioned medium and how to culture stem cell-enriched epithelial spheroids from the mouse gastrointestine. These spheroids are also amenable to genetic modification with recombinant lentiviruses. This system enables many types of cell biological assays that have been performed with immortalized cell lines to be applied to spheroids. Isolation of epithelial cell units from mice takes up to 2 h, and stem cell-enriched gastrointestinal spheroids are obtained within 3 d. Genetically modified spheroids with lentiviruses can be obtained in 2 weeks.