This question is part of the following Ask The Expert session:
Perfusion cultures can be run using Cellbag bioreactors with integrated filter for cell retention. Harvest can be withdrawn directly through the filter, using a harvest line that ends in a luer connector at the bag wall. The filter has a nominal pore size of 7 µm and floats on top of the culture liquid. The lateral movement during the rocking of the bioreactor delays cell attachment thus, improving filter lifetime. In WAVE 25 an improved perfusion control is available, which allows continuous harvest and has an auto-calibration function to accurately maintain the perfusion rate. The fact that no recirculation loop is required makes this option quick and simple to set up. The integrated cell retention filter is available for culture volumes from 1 to 25 L.
Such a setup has been tested for insect cells, resulting in very high cell concentrations and recombinant protein production. Details can be found in: Wang L. et al. 2012 Mol. Biotechnol. 52(2):170-179
For an option that allows an exchange of the filter during the perfusion process, an external hollow fiber cartridge can be used to retain the cells. A study on the use of this cell retention can be found in: Clincke M. et al. 2013 Biotechnol. Prog. 29(3):754-767.