Tips for Culturing Human Melanoma Cell Lines
Rockland has partnered with The Wistar Institute to produce, validate and distribute a diverse panel of human melanoma cell lines.
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Growth Temperature for Cell Survival
The melanoma cells grow best at temperatures slightly less than 37°C, so 36.5°C is better. They’ll grow at 37°C, but not at temperatures higher than 37°C. Lower is better.
Depending on the melanoma cells, some will die off if the temperature is greater than 37°C, and some will just slow their growth. You can usually recover them; split them, and transfer the viable cells into a smaller dish, and increase the amount of serum. It is possible to recover them.
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Use of CO2
Melanoma cells grow best at 5% CO2, and that has to do with buffering the PH. The pH of the media should be slightly basic at 7.6, and if you keep the CO2< at 5%, that works the best.
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Brown Media
Melanoma cells are derived from melanocytes which produce melanin. Some of the melanoma cells retain this capability, and they produce melanin which will change the pigment color or the color of the media to a brownish color. In some of the melanoma cells, the pigment remains in packages. So if you look under the microscope you’ll see a lot of brown specs among your cells—this is perfectly normal.
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Cell Culture Media
Our melanoma cells grow best in tumor 2% media because that is what they were derived in. Also, calcium is very important.
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Seeding Density
The melanoma cell lines are all very unique. Some of them grow fast and you can split them 1:16, giving you a confluent flask in a week. There are other melanoma cells that you want to keep at a high density; otherwise, they start to senescence. They would need to be split maybe 1:2, or 1:3 and would take a good two to three weeks before they’re confluent again. Since they are all very unique, there are no general recommendations for all of the melanoma cells that would hold.
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Special Care
There are some melanoma cell lines that require special care. A couple of cell lines will require insulin, and there are some that are BRAF inhibitor-resistant, and thus need to be cultured with the BRAF inhibitor. If the BRAF inhibitor is removed, they will revert to a sensitive phenotype.
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Recovery when Transferring Cells
When you’re thawing the melanoma cells, each melanoma line has different viability. We've found that the more pigmented a cell line is, the worse the viability. They take a while to recover. Most of the cells are dead, so you want to plate them in a small flask to start. Be certain to change the media the following day and watch them. You need to cut back, split them into a smaller flask because you have a lot of cell death. Those lines are sometimes more difficult to get started. Once they’re growing, they grow great. But they do not like the thawing process.
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Verifying Integrity
If your cells are no longer responding in an experiment the way they have before, the first thing I would check is mycoplasma. That will alter a cell's response in an experiment. The second thing to check is to see if you are working with the same melanoma cell line as you thought you were, and that would be by performing DNA fingerprinting. The DNA fingerprint profiles are available online; you can compare the original results with the ones that you receive.
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Available Pairs
The melanoma cell line repertoire that we have has everything in it. We have cell lines that match the patient’s primary metastasis, we have in some patients several metastasis stages. We’ve been producing melanoma cell lines for 40 years, so we don’t have extensive clinical data on some of these. In some cases, we don’t know whether the metastasis is a secondary occurrence from the same site, or if it’s from another spot on the body. But you can still use those to look at heterogeneity.