An integrated cell culture-protein purification system for the automated production

Medicilon's protein scientists have been working on protein expression and purification for many years. We can start your project even you have nothing in hand but the name of your protein. In Medicilon's laboratories, protein purification is performed in scales from micrograms and milligrams. All Protein Purification Services start with the analysis of physico-chemical and biological properties of a target protein resulting in the development of tailored procedures for its extraction, purification and characterization.Email:marketing@medicilon.com.cn Web:www.medicilon.com

An integrated cell culture protein purification system has been developed for the continuous, automated production of pure cell culture protein products. The instrument comprises a bioreactor subunit (2) having a hollow fiber bioreactor to culture and maintain cells which secrete the desired product into the cell culture medium. The culture medium is circulated through a purification cartridge (4) which adsorbs the desired product. The system is capable of continuously removing the product from the culture medium by immunoaffinity adsorption and pure product is then recovered. The product can also be recovered automatically in a discontinuous operation from the spent culture medium by either affinity, ion exchange, or hydrophobic purification techniques. The integrated system allows continuous production of high-quality pure proteins from cell culture.

Complex proteins are increasingly used in research, diagnostics and therapeutics. Many of these proteins can only be produced in appropriate eiicaryotic cells. With the advent of hybridoma technology and other progress in genetic engineering of eucar otic cells, mammalian or yeast cell lines are becoming , the method of choice for producing complex proteins on a large scale.

The secreted product needs to be purified from the cell culture medium. Most lnnminalian cells require serum which contains a diverse mixture of proteins, many of which are present at high concentrations. Even in serum-free media systems, numerous other proteins are secreted from the cells. For most of the applications the final product has to meet high levels of purity and activity.

The successful prod uction of these proteins depends largely on the development of fast and efficient methods of purification. Typically, the purification constitu tes the major cost (up to 80% of the total cost) in these processes. Thp large scale use of these protein products is hindered because of the high os t.

There is an urgent need for processes to produce proteins in a simple .and economical way. Significant cost reduction in the production of protein biologies could be realized if the purification would be integrated with cell cultu re into a fully automated system. In addition, the product quality is also expected to improve because the secreted protein is continuously removed from the culture medium in which the product is exposed to catabolic enzymes. Protein identity is an important issue for protein biotherapeutics, i.e. the final product should be free of degraded or other aberrant protein molecules. The integration requires that the presence of the purification unit in the cell culture system would not affect the conditions of cell culture. Therefore, highly-specific purification methods like affinity/immunoaffinity.T.TUTE SHEET chromatography is needed to make the integration of cell culture and pu rification feasible for the continuous purification of secreted product.

Progress in cell culture technology has led to the development of membrane hior^actors for growing eucaryotic, such as mammalian cells within well-defined compart ments. Cells grown inside low nonspecific adsorption flat sheet or hollow fiher membranes in thin (200-400 u ) layers are continuously perfused wit h nutrients and grow to cell densities previously unattainable by the stationary, stirred tank or airlift-type fermentors. Nutrient deprivation or shea sensitivity issues are minimized by this technology. This allows high cell viability in the bioreactor and minimize DNA contamination of the product. The microfiltration membrane eliminates the opportunity of bacterial con lamination of the bioreactor. The cells are grown at tissue density with h igh production rates surpassing the production capacity of conventional bioreact.ors. After populating the available compartment space, the cells reach n growth-arrested state in which most of their energy is directed towards prod uction. This configuration allows the highest production capacity per unit volume of bioreactor space.

Another important aspect of the integration is the availability of appropriate protein separation technologies. Current protein purification technologies require significant improvement in order to realize the potentials of the integration concept. A major obstacle is that the interaction of the cell culture medium with the protein separation material (chromatography resin) may change the composition of the medium which can be detrimental to the cells in culture. Chromatography media like ion exchange or hydrophobic matrices can drast ically change the culture medium composition and thus are unsuitable for an integrated instrument if continuous removal of the product is desired. Riospocific, affinity separation is the only method offering the least interference with cell culture. However, current affinity technologies have serious shortcomings which have prevented them from being incoporated into an integrated system.