Cancer cell culture

MDA-MB-231 breast cancer cells were ordered from ATCC (Manassas, VA) and cultured in Dulbecco’s Modified Eagle’s Medium (Life Technologies, Carlsbad, CA) supplemented with fetal bovine serum (Corning, Corning, NY) and gentamicin (Life Technologies, Carlsbad, CA), at 37 °C and 5% CO₂. Culture media was changed every other day as needed. Cells were cultured to 80% confluence prior to being trypsinized and embedded inside of 3D collagen I matrices at a seeding density of 50,000 cells per gel. Cell laden gels were cultured for a week to observe long-term phenotypic differences, with media changes every other day.