title: Effect of conditioned medium factors on productivity and cell physiology in Trichoplusia ni insect cell cultures.
abstract: The influence of conditioned medium (CM) on cell physiology and recombinant protein production in Trichoplusia ni insect cells (T. ni, BTI-Tn-5B1-4) has been investigated. Cell cycle analysis showed that a high proportion of the cell population (80-90%) was in G1 during the whole culture, indicating that the S and G2/M phases are short relative to the G1 phase. Directly after inoculation, a rapid decrease of the S-phase population occurred, which could be observed as a lag-phase. The following increase in the number of cells in S occurred after 7 h of culture for cells in fresh medium, whereas for cells with the addition of CM it occurred at an earlier time point (5 h) and these cells had therefore a shorter lag-phase. The initial changes in the S-phase population were also affected by the inoculum cell density, as higher seeding cell densities resulted in a more rapid increase in the S-phase population after inoculation. These changes in cell cycle distribution were reflected in the cell size, and the CM-cells were smaller than the cells in fresh medium. Recombinant protein production in T. ni cells was improved by the addition of CM. The specific productivity was increased by 30% compared to cells in fresh medium. This beneficial effect was seen between 20 and 72 h of culture. In contrast, the highest specific productivity was obtained already at 7 h for the cells in fresh medium and then decreased rapidly. The total product concentration was around 30% higher in the culture with CM compared to the culture in fresh medium, and the maximum product concentration was obtained on day 2 compared to day 3 for the cells in fresh medium. Our results indicate that the positive effect on productivity by CM is related to its growth-promoting effect, suggesting that the proliferation potential of the culture determines the productivity.
authors.affiliation: Karo Bio AB, Huddinge, SE-141 57 Huddinge, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Calles
authors.forename: Ulrika
authors.initials: U
authors.lastname: Eriksson
authors.forename: Lena
authors.initials: L
authors.lastname: Häggström
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D019476:Insect Proteins / Q000096:biosynthesis* / Q000187:drug effects; D009036:Moths / Q000166:cytology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000187:drug effects; D013997:Time Factors
chemical_list: D017077:Culture Media, Conditioned; D019476:Insect Proteins; D011994:Recombinant Proteins