Characterisation of mammalian cell culture processes with NIR spectroscopy

Sammanfattning: The importance of recombinant proteins produced by mammaliancell culture has increased dramatically due to the discoveriesin the field of recombinant biotechnology. Therefore,optimising and gaining process knowledge about cell culture hasalso gained in interest. However, the lack of real-time,in-process monitoring devices for mammalian cell cultureslimits the possibility to monitor and control these processes.In this thesis the use of NIR spectroscopy to monitor mammaliancell culture on-line and in real time is investigated. NIRspectroscopy is suggested as a process development tool to gainimportant information about cell culture properties and as anon-line and real time monitoring device in production.The first study concerned the implementation of NIRequipment into the reactor and the required calibrationstrategies for certain cell culture parameters, viz. glucose-,lactate-, ammonia- and cell content and viability. The resultsshow that it is possible to continuously and on-line monitorthese cell culture parameters in a bioreactor using NIRspectroscopy.The second study investigated the use of multivariatelymodelled NIR spectra from mammalian cell cultures toinvestigate process phenomena. The spectra were visualisedusing score plots. The results show that key process phenomenaand unexpected alternations could be tracked by using scoreplots.The third paper is a discussion concerning the potential ofusing NIR spectroscopy for monitoring and controllingbioprocesses. The paper discusses available analysis methodsfor bioprocesses and the problems associated with samplecollection. Also the development of NIR process equipment anddata treatment for NIR spectroscopy is discussed. The main partof the article focuses on the potential use of NIR spectroscopyduring manufacturing of biopharmaceuticals. Issues such ascalibration, regulatory demands and equipment costs are alsodiscussed.In conclusion this thesis shows that NIR spectroscopy can beused for quantitative and qualitative on-line monitoring ofmammalian cell cultures.Keywords:near-infrared (NIR) spectroscopy, cellculture, mammalian cell culture, characterisation, glucose,lactate, ammonia, cell content, viability, multivariateanalysis, principal component analysis (PCA), partial leastsquares regression (PLS), score plots.