Feeder/Feeder—Free Culture

Feeder Culture

The first step in using a feeder culture is growing the feeder cells or using a prepared formula available from a variety of suppliers. Feeder cells—often mouse (mitotically inactive primary mouse embryonic fibroblasts) or human fibroblasts—are used in culture protocols to keep the stem cells from differentiating. The feeder cells provide secreted factors (many of which have not been identified), extracellular matrix, and cellular contact to keep the stem cells from differentiating and to maintain the normal karyotype. Researchers plate embryonic stem cells onto feeder layers. A limitation of working with feeder cells is cell overcrowding between the feeder cells and the embryonic stem cell colonies. An additional key factor in using feeder cells is to ensure that the density of the feeder cell is sufficient for the delivery of the right amount of factors to maintain the cells in an undifferentiated state without depleting nutrients in the coculture environment, and therefore diminishing the capacity of growth of stem cell colonies.

A Japanese patent has been filed for the use of an immobilized notch ligand protein as a feeder for culturing stem cells. The Notch pathway plays an important role in in vivo stem cell niches of the hematopoietic system, gut, mammary gland, and muscles. The patent calls for using a notch ligand protein on a human cell membrane to maintain the stem cells in an undifferentiated state. The hope is that using this type of feeder will allow the stem cells to be used for cell transplantation and genetic therapy. Other possible feeders to be used for stem cell culturing include human fetal muscle and skin, adult fallopian tube epithelium, and human fibroblasts from foreskin, skin, endometrial, embryo and placenta, and breast parenchyma cells.

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