Downstream processing is the initial step of a biomanufacturing process to harvest cell culture containing highly-expressed active pharmaceutical ingredients. This is then purified and concentrated for final product formulation and commercialization.
The entire phase requires cGMP compliance to ensure that these living organisms are maintained under safe and sterile conditions. The equipment to be used in isolation, purification, and filtration can be enclosed in a cell therapy aseptic isolator during the whole process. This technology will prevent occupational contamination and unwanted air particles to mix with the isolates.
• Process filtration
Filtration is used at several stages in the downstream processing of the bioreactor harvest, as well as for the preparation of purified water and other processing fluids (buffers, sanitizing agents, etc.). Several filtration steps are integral to the Capture, Intermediate purification and Polishing stages; these types of filtration fall into one of three general types:
Filtration is a crucial step in the downstream processing of any harvest cells since it is also integral to the capture, intermediate purification, and polishing stages. Moreover, filtration is utilized for the preparation of purified water and other liquids for buffering and sanitizing purposes. Below are the different types of filtration process:
A flat membrane disk is the simplest arrangement of the filter. However, as membrane surface area requirements increase, a pleated sheet either with or without a secondary supporting layer is formed. The combined filtration layer is then wrapped around a perforated collecting core. An advanced version of this type fits an even greater membrane area into the same cartridge volume by folding the pleats over, allowing a greater length of membrane along each fold.
In the typical pleated membrane DFF cartridge, flow is directed from the inlet (through the media in a perpendicular or direct path across the membrane) to the outer surface of the media. The flow the collects in the core and exits the holder to the device’s downstream port.
TFF is rapid and efficient method for separating and purifying process flow. It can be used to recover and purify solutions from small volumes (10 mL) up to thousands of liters. With TFF the feed flows tangentially over the surface of the membrane, where a portion flows through the membrane as permeate.
Liquid chromatography is purification method employing a packed resin bed, through which a solution containing a mixture of solutes is flowed; specific solutes are differentially bound or slowed as they contact the bed, while others pass through without interacting with the packed resin. The large majority of chromatography steps used in the purification of mAbs and other protein-based biotherapeutics are those in which some constituents bind or interact with a ligand of the stationary phases (packed resin) absolutely, while others pass through with no interaction. The bound components are then removed or eluted by the gradual or step-wise change of the composition of the mobile phase run through the packed resin bed, such that bound feed constituents are ideally eluted separately from the product of interest. In bind-elute methods the product is what binds, while in flow-through methods the product passes through while other unwanted elements of the feed are temporarily bound.