Most (cancer) cell lines are sufficient in factors that normal cells are not (nutrients, growth factors, recalcitrance to death signals, all sorts of things). T

Most (cancer) cell lines are sufficient in factors that normal cells are not (nutrients, growth factors, recalcitrance to death signals, all sorts of things). Thus, they are much more robust and some cell lines can grow in 3D structures, in suspension, and in monolayers in flasks. While we do routinely culture primary cell explants, they are much more finicky. In part because their environment changes dramatically. Eventually they succumb to cell death (either apoptotic or not) or they senesce.