Patent ID: 7374937

Claim:
A method of inducing proliferation of isolated human marrow stromal cells in vitro by plating and replating said cells at an initial density of 50 cells or less per square centimeter of growth surface wherein the method generates enhanced expandability of marrow stromal cells relative to results in a greater total number of cells to be obtained compared to the total number of cells obtained from plating and replating at an initial density of more than 50 cells or less per square centimeter of growth surface, the method comprising: (1) providing the isolated human marrow stromal cells and a growth medium comprising a mammalian serum to a growth surface such that the initial density of the isolated human marrow stromal cells is 50 cells or less per square centimeter of growth surface, (2) incubating the growth surface of step (1) under growth-promoting conditions, whereby the human marrow stromal cells proliferate, and (3) replating the proliferated marrow stromal cells and a growth medium comprising a mammalian serum to a second growth surface at least one time such that the initial density of the replated isolated human marrow stromal cells is 50 cells or less per square centimeter of growth surface, wherein the replating allows the cells to expand by a factor of at least 10-fold.