Cells are the basic unit of life and can be grown outside of the body in cell culture. There are two main types of cell lines: finite cell lines that divide a limited number of times and continuous cell lines that divide indefinitely. Cell lines can also be classified as primary or secondary based on whether they are derived directly from tissue or through sub-culturing. Some important cell lines used for research include HeLa cells from cervical cancer tissue, 293T kidney cells, A-549 lung carcinoma cells, and MCF-7 breast tumor cells. Cell lines provide a valuable model for studying cells outside of the body.

2. CELL
• It is the smallest unit of life.
• It is the basic structural, functional, and
biological unit of all known living
organisms.
• It is consisted of cytoplasm enclosed
within a membrane, which contains
many biomolecules such
as proteins and nucleic acids.
• First discovered by Robert Hooke in
1665.
• It has a dimensions between
1- 100 micrometres.

3. CELL LINE
• Cells of a multicellular organism.
• The cells are grown for prolonged periods in
vitro.
• First discovered by Dr. George Otto Gey in
1951.
• First discovered cell line, HeLa cell line.
• Some cell lines are known as immortalized
cell line.
• Cell lines are a very important tool for
research.

4. CLASSIFICATION
Cell Line
By Appearance
Finite Cell Line
Continuous Cell
Line
By Culture
Primary Cell Line
Secondary Cell
Line

5. BY APPEARANCE
Finite Cell Lines:
• Cell Lines where cell division
occurs for finite time period.
• Usually represents the losing
ability of proliferation of the
cultured cell.
• It is determined by genetic event
called “senescence”.
Continuous Cell Lines:
• Cell Lines where cell division occurs
indefinitely also known as
“immortalized cell line”.
• Cultured cells are usually spontaneously,
chemically or virally induced.
• Usually neoplastic.

6. BY CULTURE
Primary Cell Line:
• Derived directly from animal tissue
• May be normal or neoplastic.
• Cultured either as tissue explants
or single cells.
• Cultured in vitro.
• Retain differentiated phenotype.
• Mainly anchorage dependent.
• Exhibit contact inhibition.
• Not viable for long time.

7. SECONDARY CELL LINE:
• Done by sub-culturing of
primary cell line.
• Usually by transferring of cells
from one culture vessel to
another.
• Viable for long time.
• Anchorage independent.
• Consisting of proliferating cells.
• Cell line gets continuously
evolved and properly
established.

8. CELL CULTURE
• Cells are grown under controlled
conditions (in vitro).
• Cells isolated from living tissues.
• Carried out under controlled
conditions like essential nutrients,
growth factors, hormones, and
gases.
• Artificial substrate (adherent or
monolayer culture) or culture
medium (suspension culture) are
required for it.

9. CLASSIFICATION
Cell Culture
Primary Culture
Adherent Culture
Suspension
Culture
Secondary Culture

10. IN-VITRO CELL CULTURE
Animal Cell Culture:
• Used provide a good model
system for studying.
• Used in toxicity testing.
• Used to observe replication
of viruses in cell cultures .
Plant Cell Culture:
• Used to produce clones of a
plant.
• To quickly produce mature
plants.
• Mainly based on totipotency.
• Large scale production of
artificial seeds.

11. COMMON EXAMPLES
Cell Line Organism Origin Tissue
HeLa Human Cervical Cancer
293-T Human Kidney (Embryonic)
A-549 Human Lungs Carcinoma
ALC Mouse Bone Marrow
CHO Hamster Ovary
FM 3 Human Metastatic Lymph Node
Vero Monkey Kidney
Caco-2 Human Colo-rectal Carcinoma
MCF-7 Human Breast Tumor

12. HeLa Cells 293-T Cells A-549 Cells
ALC Cells CHO Cells
Vero Cells Caco-2 Cells MCF-7 Cells
FM-3 Cells

13. CELL LINE MAINTENANCE
• Creating master or working cell
banks.
• Before use, cells must be quickly
thawed to prevent crystallization.
• Transfer cells in tissue culture to
perform cell counting.
• Incubation in 370C with 5% CO2 in
10% FBS.
• For sub-culturing cells are
trypsinized.
• Storage in 10% DMSO and 10%
FBS at -200C for 1hr. and then at -
800C and then cryopreserved.