INCREASED PRODUCTION OF RECOMBINANT HIGFBP-1 IN PEG INDUCED AUTOFUSION OF CHINESE-HAMSTER OVARY (CHO) CELLS

A recombinant Chinese hamster ovary (CHO) cell clone, Si, stably expre ssing human insulin-like growth factor binding protein-1 (hIGFBP-1), w as treated with polyethylene glycol (PEG), resulting in cell fusion, i n order to further enhance the protein expression by increasing the ge ne copy number and/or the amount of organelles important to the protei n expression/-secretion. Both the fused cell line, Peg1, and its mothe r cell line, S1, were adapted to serum-free growth in suspension and w ere characterised with respect to growth and productivity. Peg1 was ea sier to adapt to the serum-free suspension conditions and had a higher viability during the adaptation period than Si. Furthermore, Peg1 sho wed a stable productivity of hIGFBP-1 that was twice as high as that f or Si under both adherent and suspension conditions. A considerable di fference in the specific productivity (up to 3-4 times) was noticed du ring the growth phase. PEG fusion experiments have earlier been studie d in our laboratory with CHO cells producing recombinant factor VIII a nd our results correlates very well with the results obtained with the factor VIII producing cells. Surprisingly, it was possible to obtain high producing recombinant cell lines, which were stable for more than 4 months.