Frequently Asked Questions
The Cellca CHO host cell line used for all client projects is the CHO DG44 cell line directly obtained by its inventor, Dr. Lawrence Chasin, US. Cellca scientists have adapted this cell line to suspension cell growth in animal component free, chemically defined media, and it is, therefore, GMP compliant. All lots of serum utilized in the initial development phase of the cell line, to the point where it was adapted to chemically defined cell culture medium, have been fully documented, including source information and all certificates of analysis. Cellca has the full cell line history for the parental CHO DG44 cell line. All current Cellca cell line development programs are initiated from the parental host cell line. A full biological safety testing package is available as part of the cell line history.
Are there any industry concerns about using the DHFR/MTXR expression platform to make stable cell lines?
Genetic stability of CHO cells, in general, is a potential concern. Thus, in Cellca’s normal cell line development program a stability study is integrated to prove the stability of created cell lines. Around 90% of all clones generated using the Cellca platform are stable.
Cellca utilizes the CASY, (Omni Life Science) or the Vi-Cell (Beckman Coulter) for cell counts and viability measurements.
Cellca measures protein titer using an Octet instrument by Forte Bio (Pall) or Protein A HPLC.
Cellca uses a FACS-based single cell sorting method (FACS, BD) to place individual cells into 384 well plates. The Cellavista (Synentec Bio) platform is then used for single cell imaging to prove monoclonality of the clones. The single cell cloning approach using FACS combined with imaging is validated. The probability of monoclonality is > 99.9 %.
At least 1500 clones are sorted during single cell cloning using a FACSAria Fusion cell sorter (BD). After further expansion of the cells, the top 24 clones are selected based on growth, productivity, and monoclonality data. The top 24 clones are evaluated in a fed-batch process using ambr® 15. The ambr® platform allows us to run multiple experiments simultaneously in bioreactor similar mode. The comparability between the performance in the ambr® 15 and a stirred tank bioreactor was tested and approved at Sartorius Stedim Cellca. Due to the good correlation between the performance of the clones in ambr® 15 and bioreactor fed-batch processes the results of the ambr® 15 can easily be used to select the top 4 clones. For the top 4 clones, RCB will be prepared.