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Abstract

Since 1969 much attention has been devoted to the useof spinfilter systems for retention of mammalian cellsin continuous perfusion cultivations. Previousinvestigations dealt with hydrodynamic conditions,fouling processes and upscaling. But hydrodynamicconditions and fouling processes seem to have asecondary importance in spinfilter performance duringauthentic perfusion cultivations. Obviously,alterations in culture condition are more relevantespecially during long-term processes. Therefore, ourpratical approach focussed on the performance qualityof a commercially available 20 mum spinfilterduring a perfusion cultivation of a recombinant CHOcell line in pilot scale regarding the followingissues: 1) retention of viable cells in thebioreactor; 2) removal of dead cells and cell debrisfrom the bioreactor; 3) alterations in culturecondition; and 4) changes in perfusion mode.Furthermore, we tested the performance of 20 mumspinfilters in 2 and 100 l pilot scale using solidmodel particles instead of cells. Our investigationsshowed that retention of viable cells in pilot scalewas independent of spinfilter rotation velocity andperfusion rate; the retention increased from 75 to 95%corresponding to operation time, enlarging celldiameter and enhanced formation of aggregates in theculture during the perfusion cultivation. By means ofthe Cell Counter and Analyzer System (CASY) anoperation cut off of 13 mum was determined forthis spinfilter. Using solid model particles in 2 lscale, optimal retention was achieved at a tip speedof 0.43 m s(-1) (141 rpm) - furtherenhancement of spinfilter rotation velocity up to0.56 m s(-1) (185 rpm) decreased the retentionrapidly. In pilot scale best retention performance wasobtained with tip speeds of 0.37 m s(-1)(35 rpm) and 1.26 m s(-1) (120 rpm). Hence,significant retention in pilot scale could already beachieved with low agitation. Therefore, the additionof shear force protectives could be avoided so thatthe purification of the target protein from thesupernatant would be facilitated.

Cell Technology for Cell Products

“…Wen et al (2000) obtained a separation efficiency of 88% using two sequential settlers. Iding et al (2000), studying perfusion cultures of CHO cells using a spin-filter, obtained efficiencies in the range of 75-95%. Apparent viability drops (trypan blue exclusion) of 2.9%, 5.7%, and 5.8% were observed for HC 3020, 3015 and 2010, respectively, while greater losses were observed for HC 2015 and 2020 (17.8% and 14.4%, respectively).…”

Bioreactor systems for the production of biopharmaceuticals from animal cells

“…The steric effect of the rotating screen allows cells to be retained when the screens have pore sizes larger than the average cell [28]. Spin filters typically are made of 316L stainless steel and have pore sizes that range from 10 to 25 μm [29–31], although larger pore sizes of 50 μm and even 120 μm have been successfully used to retain cell aggregates [32] and microcarrier cultures [33]. In addition to allowing cell separation from product in perfusion cultures, the use of a spin filter has been proven to reduce hydrodynamic damage to cells; consequently, cell viability and productivity are improved when compared with cultures performed in the absence of a spin filter [34].…”

“…The performance of a spin filter can be enhanced by optimizing the culture conditions and perfusion parameters. Spin filter rotation speed and perfusion rate do not affect the retention of viable cells; however, enlarging cell diameters and the formation of aggregates during operation of a perfusion culture increase cell-retention rates from 75 to 95 % [30]. Additionally, the cell retention performance of a spin filter has been shown to be comparable with that of an ultrasonic filter.…”