Two-compartment technology      Efficient cell cultivation relies on maintaining an optimal supply of oxygen and nutrients, as well as on removing inhibiting metabolic waste products efficiently. These factors limit the maximum cell density obtainable from standard, homogeneous cell culture techniques which are consequently poor at achieving high expression levels of proteins.            The Two-Compartment Bioreactor CELLine is designed to overcome such limitations. The innovative CELLine technology separates the bioreactor into a medium and cell compartment by means of a 10 kDa semi-permeable membrane. This membrane allows a continuous diffusion of nutrients into the cell compartment with a concurrent removal of any inhibitory waste product. The individual accessibility of the compartments allows to supply cells with fresh medium without mechanically interfering with the culture.            Efficient gas transfer is ensured by a silicone membrane which forms the cell compartment base. This membrane provides an optimal oxygen supply and control of carbon dioxide levels by providing a short diffusion pathway to the cell compartment. All together, the technology built into CELLine allows simulating quasi in vivo cultivation conditions leading to high cell densities.            Easy Operation      Due to its uncomplicated design working with the CELLine bioreactor is as simple as with any standard tissue culture flask. For a straightforward control of the growth process, microscopic observation of the cells is made possible by the transparent design of the CELLine classic bioreactor. The system operates independently of any complicated control technology and works without any pump systems or agitation devices. Easily and securely stackable, CELLine flasks occupy a minimum of space in any standard CO2 incubator.            A specific adaptation of the cell culture techniques or media composition is generally not necessary when starting to work with CELLine and both, serum-supplemented or serum free media are suitable.            Cost efficiency      CELLine has been designed to bring substantial cost savings to cell cultivation. Labour costs are considerably reduced, because fewer disposable flasks need to be handled compared to other culture techniques in order to produce milligram amounts of protein.            Also the expenses for media supplements are significantly reduced, since the addition of serum or other synthetic additives can be limited to the cell compartment. Furthermore, the high production yield and quality obtained in the relatively small culture volume of CELLine contribute to reduce costs and labour time in the subsequent downstream processing steps of the product.            Animal welfare      CELLine is a disposable bioreactor that is competitive in costs and performance to the production of monoclonal antibodies using mice ascites. As an added benefit, when expressing monoclonal antibodies in hybridomas using CELLine, the antibody preparation is free of any contamination from mouse immunoglobulins.            Over recent years, CELLine technology has been successfully adopted worldwide for the production of monoclonal antibodies and thereby has contributed diminishing the use of laboratory mice.