Hello Nimra Laraib,

There is no such thing as good passage number. Even though cancer cell lines are immortal, cell health will decrease as passage number increases. At a certain point, you will have to discard higher passage cells because as the passage number increases their phenotype and genotype can change. Cell lines at high passage number experience alterations in morphology, growth rates, their response to stimuli may change, protein expression and transfection efficiency may be altered, compared to lower passage cells. So, you use cancer cell lines at low passage number preferably below passage 30.

There are a number of cell banks available that provide information about cancer cell lines with respect to morphology, growth media, subculture information, seeding density, freezing conditions, etc.

They include:

1. The American Type Culture Collection (ATCC).

https://www.ncbi.nlm.nih.gov/books/NBK209072/

2. DSMZ- German Collection of Microorganisma and Cell Cultures.

https://www.dsmz.de/collection/catalogue/details/culture/ACC-57

3. European Collection of Cell Cultures (ECACC).

https://bioinformatics.hsanmartino.it/cldb/descat5.html

4. Japanese Collection of Research Bioresources Cell Bank (JCRB Cell Bank).

https://cellbank.nibiohn.go.jp/english

5. Cell Bank Australia.

https://www.cellbankaustralia.com/resources/Cellbank_Flyer_Why_Deposit.pdf

So, if you go through the above links, you may obtain all the necessary information about the cancer cell line you are interested including the seeding density.

Good Luck!