Such standardization is possible because biopharmaceutical
products are usually secreted by cells into the cell culture
broth, allowing capture without cell disruption. This strategy can also be
applied to plants and efforts have been made to develop plant cell
suspension cultures that secrete proteins into the medium, and
even whole-plant systems in which the roots or leaves secrete proteins
into hydroponic medium or in which proteins are removed from the
plants by applying a vacuum.