ABSTRACT

This chapter focuses on the different approaches for separating mammalian cells from cell culture medium containing recombinant proteins of therapeutic interest and their further primary isolation. Today the most common products from mammalian cells are secreted proteins. The isolation of the target protein requires in most cases the initial removal of particles of different physical and chemical properties such as cells and cell debris (1,2). This clarification step describes the transition from product generation to product isolation (3). The unit operation has to perform a proper solid-liquid phase separation of the cell suspension in order to enable further product purification, as the subsequent steps in general require feed streams with low particle occurrence. Upon the removal of larger particles such as cells and debris the clarified cell supernatant undergoes a primary purification step. The main objective of this unit operation is to remove proteins and other molecules with very different physical and chemical character and capture the target protein in a preferably significant reduced liquid volume. If both objectives, capture and volume reduction, cannot be accomplished in one step, an ultra-or diafiltration is performed upon initial capture in order to reduce the liquid volume and transfer the target protein into appropriate buffer conditions for the subsequent fine purification process step. The following paragraphs will give an overview of different methods and established techniques used for the removal of cells and cell debris and the subsequent primary purification of the target protein. Special emphasis is put on techniques developed and applied to clinical and commercial manufacturing of recombinant proteins and patents related to those operations.