plant and mammalian tissue culture culture systems and aseptic technique
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Plant and Mammalian Tissue Culture
Culture Systems and Aseptic Technique
Culture Vessels
Mammalian cells can be grown in a variety of containers.
The choice of container is typically dependent upon cell growth characteristics and the number of cells required.
Culture Vessels
Most tissue culture container are disposable, made of polystyrene, and have been radiation-sterilized.
Untreated plastic is usually fine for suspension cells
Most adherent cells grow better on treated plastic.
Culture Vessels
Treated PlasticPermanent modification to the polystyrene surface
Causes a net charge on the surface of the plastic
Modifier used include:• Proteins• Plasma• Amino Acids
Culture Vessels
Some cells types require a specific attachment substrate be added to the culture dish.
Common examples are extracellular matrix proteins CollagenFibronectinLaminin
Adherent Cells
Flasks are commonly used to carry and expand cells.
Either vented or non-vented tops.
Adherent Cells
Dishes commonly used for specific experiments Scraping cells for SDS-
PAGE and Western Blotting
Fixing and staining cells for protein localization and interactions.
Adherent Cells
Multi-well plates6, 12, 24, 96, 384 wells
Allow for multiple replicates of experiments effectively
Different Growth Areas for each size
Adherent Cells
Adherent Cells
Chamber Slides
Used to prepare cells for microscope studies.
Suspension Cells
Suspension cultures are usually grown either:In magnetically rotated spinner flasks or
shaken Erlenmeyer flasks• This actively keeps cells suspended in medium
In stationary culture vessels such at T-flasks and bottles
• Don’t need to agitate because they are unable to attach firmly to the surface
Suspension Cells
Spinner FlasksRequire special
variable speed magnetic stir plate.
Erlenmeyer FlasksRequire platform
shaker
Types of Cells
Cultured cells are usually described based upon their morphology.Epithelial-like cells
• Attached to substrate and flattened in shape
Lymphoblast-like cells• Cells that do not attach to a substrate and have a
spherical shape
Fibroblast-like cells• Cells that are attached to a substrate and appear
elongated and bipolar frequently forming swirls in heavy culture
Handling Cell Cultures
Adherence to good laboratory practice when working with cell cultures is essential for two reasons:
reduce the risk of exposure of the worker to any potentially infectious agent(s) in the cell culture
to prevent contamination of the cell culture with microbial or other animal cells
Aseptic Technique
Aseptic Technique Refers to a procedure that is performed
under sterile conditions. This includes medical and laboratory
techniques, such as with microbiological cultures.
Aseptic Technique
For Cell and Tissue culture this is the execution procedures without the introduction of contaminating microorganisms
Aseptic Technique
Work with cells in a biological safety cabinet laminar flow hoodprevent airborne
organisms from entering your cultures
always use ETOH to clean hood before and after use
Laminar Flow Hood
A typical laminar flow hood Filtered air enters the
work space from the from above
Do not block vents!
UV lights can be turned on after the work is finished to sterilize surfaces.
Aseptic Technique
Always use separate sterile pipettes for each manipulation
Never cough, sneeze, or yawn directly in your culture
Work rapidly but carefully
Incubator
Cell Culture Incubator
Internal temperature is controlled.
CO2 incubators contain a continuous flow of carbon dioxide containing air.
Visualizing Cells
Inverted Microscope
Large stage so plates and flasks can be used.
Magnification; 4X, 10X, 20X, 40X
Contamination
The presence of microorganisms can inhibit cell growth, kill cells, and lead to inconsistent results.
It is not a question of if, but when, your cells become contaminated.
Contamination is both observed under microscope and only by other tests.
Contamination
Cultures can be infected through:
Poor handling
From contaminated media, reagents, and equipment (e.g., pipets)
From microorganisms present in incubators, refrigerators, and laminar flow hoods
From skin of the worker and in cultures coming from other laboratories
Contamination
Bacteria, yeasts, fungi, molds, mycoplasmas, and other cell cultures are common contaminants in animal cell culture.
Cloudiness (due to large cells in suspension) or filaments from mold are obvious signs
Microbial Contamination
The presence of an infectious agent sometimes can be detected by turbidity and a sharp change in the pH of the medium (usually indicated by a change in the color of the medium), and/or cell culture death.
pH 7.2
pH 6.5
pH 8.0
Contamination
Mycoplasma – grow slowly and do not kill cells but will likely alter their behavior. Mostly tested by PCR for specific mycoplasma genes or using kits based on staining of growth in cytoplasm of cells
Some labs will test every 6 months for this kind of contamination
Contamination
Cross-culture contamination: multiple cells growing together – based on doubling rate, one cell may take over the other as the dominant population
Up to 60% of cultured lines are contaminated (NIH 2009)
Contamination
How to get rid of contamination?AVOID at all costs: sterile techniques, clean and
properly maintained hood and incubator, clean room.Laziness or familiarity are most common causes.Antibiotics may help reduce contamination but may
also alter cell functionsClearing contamination – only for novel cell lines,
can be done with some agents.• Wash cells to reduce contaminant burden• Use sub-lethal doses of fungacide or antibiotic