INTRODUCTION Characterization of cell lines is necessary to identify linage of the cells, to the genetic stability, phenotypic variation and to check cross contamination. Techniques used for chacterization- karyotying, estimation of DNA content, DNA hybridiztion.
CHARCTERISTIC OF CULTUREDCELLS Cell to cell interaction is very low Cannot perform differentiated and specialized functions Hormonal and nutritional influence on the cultured cells differs from that on the invivo cells
3-D architecture of the invivo cells is notfound in cultured cells.The environment of the cultured cellsfavours proliferation and spreading ofunspecialized cells.
1)CELL-CELL INTERACTION Cell–cell interaction-direct interactions between cells that play a role in the development and function of multicellular organisms. Cell adhesion occurs through cell surface receptors for the molecules in the extra cellular matrix. That cells secrete matrix proteins which spread on the substrate. Then the cells bind to matrix through receptors.
CELL ADHENSION MOLECULE It occur between homologus cells. Two types: Calcium dependent CAMs Calcium independent CAMs E.g: Proteoglycans Low affinity transmembrane and it can bind to matrix molecules such as collagen and growth factors. It attached to the cytoskeletons of the cultured cells.
2)MEASUREMENT OF GROWTH PARAMETERSOF CULTURED CELLSPOPULATION DOUBLING TIME (PDT) The time interval for the cell population to double at the middle of the logarithmic phase.CONFLUENCE Denotes the cultured stages wherein all the available substrate (growth area) is utilized, and the cells are in the close contact with each other.
CELL CYCLE TIME (OR) GENERATION TIME The interval from one point in the cell division to the same point in the cycle, on division later. Thus the cell cycle time is measured from one point in the cell cycle until the same point is reached again.CELL DENSITY The number of cells per ml of the medium
CONTACT INHIBITION Inhibition of cell motility and plasma membrane ruffling when the cells are in complete contact with adjacent cells. This mostly occurs at confluence state and results in the ceasation of the cell proliferation. SATURATION DENSITY The density of the cells (cell/ml² surface area) in the plateau phase.
3)TISSUE TYPINGMORPHOLOGY OF CELLS The composition of the cultured medium and the alteration of the substrate inflence the cellular morphology. E.g: In tissue culture lab, the terms fibroblastic and epithelial are used to describe the appearance of the cells rather than their orgin.
SPECIES OF ORGIN OF CELLS It can be done by, Chromosomal analysis Electrophoresis of isoenzyme A combination of both these methods
IDENTIFICATION OF TISSUE OF ORGIN Based on two characteristics it was identified: The lineage to which the cells belong The status of the cells i.e., stem cells, precursor cells.
TISSUE MARKERS FOR CELL LINEIDENTIFICATION Differentiated product as cell markers-E.g: Albumin for hepatocytes. Enzymes as tissue markers-E.g: Alkaline phosphate for enterocytes. Filament protein as tissue marker-E.g: Desmin for muscle cells.
TRANFORMED CELLS TRANFORMATION- change in phenotype due to the acquirement of new genetic material. It exhibit alteration in may characters Growth rate mode of growth longevity Tumorigenicity Specialized product formation
IDENTIFICATION OF SPECIFIC CELL LINES Chromosome analysis DNA detection RNA and protein analysis Enzyme activities
CONCLUSION Biology and characterization of cultured cells or cell lines is important for dissemination of cell lines through call banks, and to establish contacts between research lab and commercial companies.