What is the difference between primary cells and cell line?
Cell cultures may be derived from primary explants or dispersed
cell suspensions. Because cell proliferation is often found in
such cultures, a confluent monolayer or a dense cell suspension
is formed. According to the traditional definition, the first
harvesting and subculturing of this cell population is called
primary cells [Freshney, R.I. (1987). Culture of Animal Cells.
A Manual of Basic Technique. (New York, Alan R. Liss, Inc.)].
This type of cell has a finite lifespan, during which cells with
the highest growth capacity will predominate, resulting in a degree
of genotypic and phenotypic uniformity in the population.
A cell line is a population of cells that grow and replicate
continuously and has undergone a genetic transformation, resulting
in indefinite growth potential. Cell lines have been maintained
in vitro for medical and/or research purposes. In practice, continuous
cell lines can be cultured through a very high number of subcultures
and further genotypic/phenotypic changes may occur at very high
passage numbers.
It should note that the definitions of these terms can vary between
research groups. Many researchers do not use the term "cell line"
to refer to any cell population unless it has undergone a genetic
transformation. Go to top
What is the difference between population doubling and passage
number?
A population doubling is a two-fold increase in the total number
of cells in a culture, and is most commonly referred to during
the exponential, or "log", phase of growth. The term passage number
refers to the number of times that a cell population has been
removed from the culture vessel and undergone a subculture (passage)
process, in order to keep the cells at a sufficiently low density
to stimulate further growth. Go
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How should I handle cryopreserved cells upon receiving?
Upon receiving the package, immediately transfer the cryopreserved
cells from the dry ice shipping container to a liquid nitrogen
freezer. The interval between transfer from the shipping container
to the liquid nitrogen freezer should be as short as possible
to prevent warming. Do not store the cells at -80°C as this
causes irreversible damage to the cells. Go
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How much experience do I need for starting with normal human
cell cultures?
Experience working under sterile conditions with a laminar flow
hood is highly recommended, and it is of advantage to have experience
with other cell types. If you are a beginner in cell culture or
would like to establish a cell culture lab, we can assist you.
Please contact our Cell Culture Specialist. Go
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How do I establish a culture from cryopreserved cells?
1. Remove a vial of cells from liquid nitrogen freezer, taking
care to protect hands and eyes.
2. Loosen the cap on the vial 1/4 turn for 10 seconds to release
any liquid nitrogen that may be trapped in the threads, then re-tighten
the cap.
3. Place the vial in a 37°C waterbath, hold and rotate the
vial gently until the contents are completely thawed.
4. Remove the vial from the waterbath immediately, wipe it dry,
and transfer it to a sterile field.
5. Rinse the vial with 70% ethanol, and then wipe to remove excess.
6. Remove the cap, being careful not to touch the interior threads
with fingers. Using 1 ml eppendorf pipette gently resuspend the
contents of the vial.
7. Dispense the contents of the vial into the equilibrated, poly-L-lysine
coated culture vessels (a T-75 flask for most of cells). A seeding
density of 5,000 cells/cm2 for most cell type is recommended.
8. Replace the cap or cover, and gently rock the vessel to distribute
the cells evenly. Loosen caps if necessary to permit gas exchange.
9. Return the culture vessels to the incubator (37°C, 5% CO2/95%
air).
10. Change the growth medium 6 -16 hours after plating to remove
the residual DMSO and unattached dead cells. Go
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Do I need to spin the cells to remove DMSO when I first plate
cryopreserved cells?
It is not recommend to spin cells to remove DMSO residue when
you first plate the cryopreserved cells. The centrifugation procedure
can be more harmful to cells than the DMSO residue, particularly
if inappropriately high speeds are used. We experience that cells
do not suffer deleterious effects if the DMSO concentration is
sufficiently low. If you plate the whole cryovial (one ml) of
cells in a T-75 flask with the recommended 15 ml of medium, the
DMSO concentration will be less than 0.67% (v/v) and no adverse
effect were found. Practically, if you plate cells at 5000 - 10,000
cells/cm2, the concentration of DMSO is even lower. Go
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How often should I change the medium?
The medium should be changed every 2 - 3 days depends on how
vigorously the cells grow. Most cell culture laboratories routinely
feed cells every Monday, Wednesday, and Friday.
Note: After thawing and plating of cryopreserved cells, the first
medium change should be done within 6 - 16 hours to remove the
DMSO residual and dead cells. Go
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Can I expand and refreeze ScienCell's normal human cells?
It depends on which cell type. Some cell types such as neurons,
microglia and some slow growing epithelial cells are not recommended
for expansion and refreezing. Other cell types such as fibroblasts,
stellate cells, mesangial cells, astrocytes and so on are can
be expanded and refrozen. However, one should note that the refreezing
process may result in altered growth performance in the cells.
If you want to refreeze the cells, please consult our tech support
personal and use ScienCell SF-CFM, a defined serum-free freezing
medium, for the best result. Go
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Can I freeze ScienCell's growth media for long-term storage?
It is not recommend to freeze growth media. The freezing of high
nutrient medium will lead to irreversible precipitation of medium
components. Go to top
How much volume of medium should I add to the flasks?
It is recommend to add 5 ml of medium to a T-25 flask, 15 ml
of medium to a T-75 flask, and 30 ml of medium to a T-150 flask.
Go to top
Do I need additional medium supplements to work with your
specialty media?
ScienCell's growth medium is specially designed for each cell
type. After adding the associated components (growth supplement,
antibiotics, and fetal bovine serum) to the basal medium, you
have the complete growth medium. No further addition is required.
Go to top
What is the shelf-life time of supplemented complete growth
media?
After adding all the supplements to the basal medium, the medium
becomes a complete growth medium. If the complete growth medium
is stored at 4°C and the duration for which the medium is
kept at room temperature or 37°C is as short as possible for
each use, the shelf-life time for the complete growth medium is
6 weeks. Go to top
Can I use my own medium or other commercially available media
for culturing ScienCell's normal human cells?
ScienCell's normal human cells have been cultured and tested
in our complete growth medium and have adapted to this formula.
Using other media for culturing ScienCell's normal human cells
may yield unsatisfactory growth results due to the adaptation
process. We recommend the use of our special media for culturing
the normal human cells. Go
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How many passages can I perform with normal human cells?
ScienCell does not use the term "passage" for describing the
growth potential because each customer uses a different split
ratio. ScienCell Research Laboratories guarantees 15 population
doublings for normal human cells (unless otherwise indicated on
the cell specification sheet) when using ScienCell's cell culture
media and reagents for the culturing procedures. Go
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What is the recommended split ratio for normal human cells?
ScienCell does not recommend a split ratio for normal human cells
because the yield of cells after trypsinization varies. We recommend
counting the cells after trypsinization and seeding the cells
at 5,000 to 10,000 cells per cm² (find the recommended seeding
density on the corresponding product information sheet). Go
to top
Is it possible to subject normal human cells to an experimental
starvation?
Yes, it is possible to perform an experimental starvation phase
with ScienCll's normal human cells. Cells can be kept for some
time in basal medium without supplements, but the cells must be
in a good condition. After this period, the experiment should
be terminated because prolonged periods lead to cell death. It
is advisable to test prior to the experiment how long cells will
survive a starvation period; this duration will depend on many
factors. Go to top
Is it possible to transfect normal human cells with plasmid
DNA?
Yes, we have successfully transfect many cell types such as dermal
fibroblasts, lung fibroblasts, dermal microvascular endothelial
cells and others. Go to top
If your questions have not been answered by this list, please
contact our cell culture specialist.
ScienCell
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