title: Closed loop control of lactate concentration in mammalian cell culture by Raman spectroscopy leads to improved cell density, viability, and biopharmaceutical protein production.
abstract: Accumulation of lactate in mammalian cell culture often negatively impacts culture performance, impeding production of therapeutic proteins. Many efforts have been made to limit the accumulation of lactate in cell culture. Here, we describe a closed loop control scheme based on online spectroscopic measurements of glucose and lactate concentrations. A Raman spectroscopy probe was used to monitor a fed-batch mammalian cell culture and predict glucose and lactate concentrations via multivariate calibration using partial least squares regression (PLS). The PLS models had a root mean squared error of prediction (RMSEP) of 0.27 g/L for glucose and 0.20 g/L for lactate. All glucose feeding was controlled by the Raman PLS model predictions. Glucose was automatically fed when lactate levels were beneath a setpoint (either 4.0 or 2.5 g/L) and glucose was below its own setpoint (0.5 g/L). This control scheme was successful in maintaining lactate levels at an arbitrary setpoint throughout the culture, as compared to the eventual accumulate of lactate to 8.0 g/L in the historical process. Automated control of lactate by restricted glucose feeding led to improvements in culture duration, viability, productivity, and robustness. Culture duration was extended from 11 to 13 days, and harvest titer increased 85% over the historical process. Biotechnol. Bioeng. 2016;113: 2416-2424. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Cell Culture Development, Biogen, Inc., 5000 Davis Drive, Research Triangle Park, 27709, North Carolina. thomas.matthews@biogen.com.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Matthews
authors.affiliation: Cell Culture Development, Biogen, Inc., Cambridge, Massachusetts.
authors.forename: Brandon N
authors.initials: BN
authors.lastname: Berry
authors.affiliation: Cell Culture Development, Biogen, Inc., 5000 Davis Drive, Research Triangle Park, 27709, North Carolina.
authors.forename: John
authors.initials: J
authors.lastname: Smelko
authors.affiliation: Cell Culture Development, Biogen, Inc., 5000 Davis Drive, Research Triangle Park, 27709, North Carolina.
authors.forename: Justin
authors.initials: J
authors.lastname: Moretto
authors.affiliation: Cell Culture Development, Biogen, Inc., 5000 Davis Drive, Research Triangle Park, 27709, North Carolina.
authors.forename: Brandon
authors.initials: B
authors.lastname: Moore
authors.affiliation: Manufacturing, Biogen Inc., Research Triangle Park, North Carolina.
authors.forename: Kelly
authors.initials: K
authors.lastname: Wiltberger
mesh_terms: D061249:Batch Cell Culture Techniques / Q000379:methods*; D002452:Cell Count; D049109:Cell Proliferation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D025461:Feedback, Physiological / Q000502:physiology*; D005947:Glucose / Q000032:analysis / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D011994:Recombinant Proteins; D019344:Lactic Acid; D005947:Glucose
keywords: Raman; advanced process control; cell culture; chemometrics; multivariate calibration; process analytical technology