A cell culturing system comprising: a bioreactor configured for growing cells on microcarriers within a fluid medium; and a filter assembly (106, 600) for separating the microcarriers from the fluid medium and the cells, the filter assembly comprising: a container comprising a flexible bag bounding a sterile compartment adapted to hold a fluid; an inlet port (151, 604) through which fluid flows into the compartment; an inlet tube coupled to the bioreactor and to the inlet port (151, 604) so that the microcarriers, the cells, and fluid medium can be transferred from the bioreactor to the compartment of the container; an outlet port through which fluid flows out of the compartment; and a filter (170, 602) disposed within the compartment, the filter dividing the compartment into an inlet chamber that is fluidly coupled with the inlet port and an outlet chamber that is fluidly coupled with the outlet port, characterized in that the filter allows the fluid medium and the cells to pass therethrough but prevents the microcarriers disposed in the fluid medium from passing therethrough, the filter comprising a porous bag or sock coupled with the inlet port. a bioreactor configured for growing cells on microcarriers within a fluid medium; and a filter assembly (106, 600) for separating the microcarriers from the fluid medium and the cells, the filter assembly comprising: a container comprising a flexible bag bounding a sterile compartment adapted to hold a fluid; an inlet port (151, 604) through which fluid flows into the compartment; an inlet tube coupled to the bioreactor and to the inlet port (151, 604) so that the microcarriers, the cells, and fluid medium can be transferred from the bioreactor to the compartment of the container; an outlet port through which fluid flows out of the compartment; and a filter (170, 602) disposed within the compartment, the filter dividing the compartment into an inlet chamber that is fluidly coupled with the inlet port and an outlet chamber that is fluidly coupled with the outlet port, characterized in that the filter allows the fluid medium and the cells to pass therethrough but prevents the microcarriers disposed in the fluid medium from passing therethrough, the filter comprising a porous bag or sock coupled with the inlet port. a container comprising a flexible bag bounding a sterile compartment adapted to hold a fluid; an inlet port (151, 604) through which fluid flows into the compartment; an inlet tube coupled to the bioreactor and to the inlet port (151, 604) so that the microcarriers, the cells, and fluid medium can be transferred from the bioreactor to the compartment of the container; an outlet port through which fluid flows out of the compartment; and a filter (170, 602) disposed within the compartment, the filter dividing the compartment into an inlet chamber that is fluidly coupled with the inlet port and an outlet chamber that is fluidly coupled with the outlet port, characterized in that the filter allows the fluid medium and the cells to pass therethrough but prevents the microcarriers disposed in the fluid medium from passing therethrough, the filter comprising a porous bag or sock coupled with the inlet port.