Fibroblasts are mesenchymal cells derived from the embryonic mesoderm. Mammary fibroblasts (MF) synthesize components of the stromal extracellular matrix of the mammary gland. More importantly, such stromal extracellular matrix regulates the proliferation and differentiation of mammary epithelial cells by influencing their gene expression. In addition, previous studies have shown that mammary fibroblasts play a role in recruiting macrophages for immune surveillance which, in concert with extracellular matrix turnover and angiogenesis, is associated with a supportive mammary microenvironment for tumor cell progression. These results suggest that MF play a stimulatory functional role in breast cancer development and invasion. HMF from ScienCell Research Laboratories are isolated from human breast. HMF are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HMF are characterized by immunofluorescence with antibodies specific to fibronectin. HMF are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast, and fungi. HMF are guaranteed to further expand for 15 population doublings under the conditions provided by ScienCell Research Laboratories. Recommended Medium It is recommended to use Fibroblast Medium (FM, Cat. #2301) for culturing HMF in vitro.