Cell kinetics in stroma-free and stromal culture system. Lin⁻CD34⁻ cells were plated onto pre-established irradiated HESS-5 stromal cells or no stroma cells in medium containing 10% FCS and human cytokines: TPO, FL, SCF, G-CSF, IL-3, and IL-6. The cell number was determined on days 4 and 7.