Hello, I need to generate tumors in nude mice with the cell lines SK MEL 28 (melanoma) and MDA MB 231 (breast cancer), both human tumoral cell lines. How many cells do i have to inject intradermically?
There is not a defined number of cells for generating tumors and it varies in a range and depends largely on route of injection. Different labs use different number of cells for development of tumor in mice. To be specific, You can use 2 × 10^6 MDA-MB-231 cells to inject into animal (8-10 wks old) and you can observe animal weekly. You can observe the development of tumors fr 5-9 weeks. Many people use different cell number and some has even generated tumors from 10^5 MDA-MB-231 amd MDA-MB-435 cells. But most of the time these cells are injected into mammary fat pads as intradermal injection are not preferred much. For SK MEL 28 cells, 2.5× 10^5 cells can be used for generating successful melanoma model (but in below cited reference they were injected via tail vein, you must take care that while injecting intradermally the cells can be trapped in portal circulation and so a greater number can be injected)
Please have a look on the following links and these can be really helpful for you in design of your study.
I agree with Ajay Kumar. There is no specific guideline about number of cells. In one study I injected 5 million MDA-231 cells in to flank of nu/nu (4-6 weeks old) mice subcutaneously for xenograft model. I think 4-6 weeks old mice would be better than 8-10 weeks old. Subcutaneous inoculation is preferred for primary tumor studies. Tail vein or intracardiac (required less cells like 10^5) is for metastatic tumor model. Sometimes mammary fat pad injection is difficult. In stead you can go for subcutaneous injection for primary tumor study. Use always lower passage number cells and should be confluent in flask. Hope this helps.