Cell lines / cell culture in your methods sections

Required details;

General

  • Media formulations and suppliers information including all supplements
  • Seeding densities for specific experimental procedures (cells per flask or dish size)
  • Times from seeding to experiment
  • Plasticware supplier
  • Description of any substrate treatment – coating protein name, conc, supplier, coating approach
  • Independent experimental unit level (see * below) – how many “biological repeats” how many “technical repeats” per experiment.

In addition;

Immortalised/permanent lines;

  • Line name, species, origin tissue, type.
  • Supplier (commercial source details or collaborator)
  • Reference(s) for first description/characterisation
  • How you validated them;  genetic fingerprinting? blotting/immunofluorescence/flow etc (usually the data associated with validation goes in supplementary figures)
  • Passage number, feeding schedule, etc
  • Immortalisation technique (SV40T, E6/E7, hTert etc)

Primary isolated cells

  • Source tissue / supplier
  • Number of donors and donor characteristics (age, sex, disease status etc)
  • Ethics
  • Mycoplasma screening approach (kit, primer and PCR details)
  • Validation – images/blots/flow data etc. References to support these choices. See also the antibodies section for information associated with any antibody based validation

Note; for PhD thesis/dissertations – the isolation/establishment of a new primary cells or immortalised line might be quite an involved process that is integral to your data and so could end up as figures in your main results rather than as supplemental.

*Stats comment – Identifying the independent experimental unit

Hopefully by the time you are writing a methods section someone has had a proper chat/lesson about experimental design…!

Basically, cell culture experiments often get described as “technical replicates” or “biological repeats” however, what is what, and what is appropriate for your studies is something that you have decided during your experimental design and analysis. It is not obvious to the reader! So that means you should tell them.

Simply the “biological repeats” generate the numbers you actually use in your analysis. The number of biological repeats you have is your n number. Depending on the experiment, this is usually 1 donor = 1 biological repeat for primary cells and either 1 independently thawed population of immortalised cells or one separately passage flask of cells – this decision depends on your viewpoint and where you think non-independence comes in.

Technical replicates are the multiple points that you gained from within your experiment; these are used to generate the value for the biological repeat. Eg if you have 3 wells of control cells and 3 wells of drug treated cells that you ran together in a single experiment, your “biological repeat” would be 1, your technical replicates would be 3.

 

Go back to methods tips pages (+ links to examples of other sections)

Go back to the full methods guide (+ links to examples of other sections)

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