A bank of suspension adapted HEK293 cells grows fine out of thaw in shake flasks but slows to a stop when transitioned to 3L bioreactors. This same bank has successfully grown in the same reactors previously. It seems as though the banks keep going bad, but there is no indication of temperature fluctuations in the LN2 storage
The cells begin to grow in the reactors, but slowly stop proliferating. Viability remains greater than 97% but aggregation decreases as growth decreases. Eventually after several days growth stops entirely. Doubling time for this bank is usually under 24hrs.
Offline and online readings for pH and DO from the bioreactors are equivalent.
Hi Michael. Why do not try with a bioreactor without shear stress. I would like to suggest an Air-lift. A gentle pneumatic agitation with good kLa values.
If these cells grew in this bioreactor before, then something has changed either in the cells or the bioreactor. Controlled experiments should be able to identify the problem.
Dear Michael,
First of all, what type of bioractor are you using ?
I have experimenting a very similar situation for the last 6 weeks. I am studying with Monascus purpureus strain; when I try shake flasks, they grew rapidly and produced the secondary metabolite I was looking for but when I put them in a 2L bioreactor, everything changes, they grow slowly and produces very low metabolites undesirably.
So, I could not figure it out yet but I think that it might be the shear stress(mixing speed, rpm) and aeration(vvm) combined effect. If I'll find a suitable solution, I'll let you know.
Best Regards,
Selim
The point that seems to be getting missed is that these same lines previously grew just fine in this same bioreactor. For that reason, I doubt that shear suddenly has become the problem.
Dear Ron,
In my situation, it is not.
The mycelium never grew and produced the secondary metabolite that I wanted in the bioreactor. So it can be the issue in my experiments.
Best Regards,
I based my response on what Michael originally posted.
...suspension adapted HEK293 cells...This same bank has successfully grown in the same reactors previously.
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