Cell expansion in monolayer with and without growth factor cocktail (TFP: transforming growth factor beta 1, fibroblast growth factor 2, and platelet-derived growth factor bb) supplementation. Phase micrographs of cells. Day 1 is shown as an example of seeding density, which is 5000 cells/cm2 for all conditions. BSA, bovine serum albumin; FBS, fetal bovine serum; HS, human serum.