The rationale for using sterile equipment for transfection protocols (whether transfecting siRNA into HUVEC cells or otherwise) is to prevent contamination of your cell line. I would have a hard time believing any results in which I suspected that the data were gathered using methods that did not reasonably preclude contamination. It makes your data far less reproducible, which degrades its value. How you can say for sure that your cells are the same as mine, if they're treated under different conditions (one using sterile, never-used products, and the other using questionably sterile products)? I suppose that you'd have to be able to show that your "old requirements" are equivalent to the "new requirements." I could see someone building an argument based off of the use of a validated sterilizing protocol, as well as by testing and quantifying their media for contamination (or degree of contamination) between both methods.

What exactly do you mean saying you use "old requirements"? Do you use pipet tips and tubes many times!? I think Joseph is right, you should always cultivate and treat cells under sterile conditions to avoid contaminations which can influence your work. Pipet tips, tubes and other consumables should always be discarded after use and other instruments should be sterilized!

Dear Joseph Cusimano,

Thank you very much for your answer

What a helpful information!

I appreciate you again