How do cultured cells differ from those growing within a body?
In general, cells grown in culture are removed from their normal organization in the tissue that they came from. Most cultured cells grow at most to a single layer (they don’t usually grow in three dimensions), at which point they sense each other and become “contact inhibited” and no longer grow. Although many cell lines are derived from tumors and are cancer cells that grow essentially “forever”, many others are not transformed. Cultured cells are also removed from any circulating molecules put out by other tissues (for example, one organ puts out a hormone that can be recognized and change the action of an organ elsewhere in the body).
