This is the first study to examine PER.C6TM cell glucose/energy and glutamine metabolism with fed-batch cultures at controlled low glutamine, low glucose, and simultaneous low glucose and low glutamine levels. PER.C6TM cell metabolism was investigated in serum-free suspension bioreactors at two-liter scale. Control of glucose and/or glutamine concentrations had a significant effect on cellular metabolism leading to an increased efficiency of nutrient utilization, altered byproduct synthesis, while having no effect on cell growth rate. Cultivating cells at a controlled glutamine concentration of 0.25 mM reduced qGln and q by approximately 30%, qAla 85%, and qNEAA 50%. The fed-batch control of glutamine also reduced the overall accumulation of ammonium ion by approximately 50% by minimizing the spontaneous chemical degradation of glutamine. No major impact upon glucose/energy metabolism was observed. Cultivating cells at a glucose concentration of 0.5 mM reduced qGlc about 50% and eliminated lactate accumulation. Cells exhibited a fully oxidative metabolism with Y of approximately 6 mol/mol. However, despite no increase in qGln, an increased ammonium ion accumulation and Y were also observed. Effective control of lactate and ammonium ion accumulation by PER.C6TM cells was achieved using fed-batch with simultaneously controlled glucose and glutamine. A fully oxidative glucose metabolism and a complete elimination of lactate production were obtained. The qGln value was again reduced and, despite an increased q compared with batch culture, ammonium ion levels were typically lower than corresponding ones in batch cultures, and the accumulation of non-essential amino acids (NEAA) was reduced about 50%. In conclusion, this study shows that PER.C6TM cell metabolism can be confined to a state with improved efficiencies of nutrient utilization by cultivating cells in fed-batch at millimolar controlled levels of glucose and glutamine. In addition, PER.C6TM cells fall into a minority category of mammalian cell lines for which glutamine plays a minor role in energy metabolism. © 2006 Wiley Periodicals, Inc.
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