In previous posts, I've briefly described our intention to develop novel characteristics in CHO cell lines using the enabling zinc finger nuclease (ZFN) technology to manipulate genes in these cells.
Our current plans will allow us to introduce a series of ZFNs and cell lines that should be of interest to the to biopharamceutical process development and production communities. Ultimately, our goal is to produce a cell line platform that contains "the optimal" stacking of engineered gene traits, coupled with media, feeds and processes to define a truly optimized production system in CHO. Our goal would not only be to increase characteristics like growth and productivity, but we would also wish to influence molecule efficacy and/or remove interfering factors to purification like HCP or viral elements. We could also conceivably extend bioreactor life by simultaneously manipulating anti-apoptotic genes and/or manipulating genes that regulate waste products (e.g ammonia build up).
As of this moment, our products and services built around zinc finger nucleases fall into two major areas with regard to clients interested in biopharmaceutical production. Clients can order custom ZFNs (about 8 week lead time) to manipulate (generally knock out) specific genes. Popular choices so far have been genes like dhfr and GS - for obvious reasons. However, the range of targets can be expected to expand as we place significant emphasis on identifying new targets of interest. And, as a client, you can bring your own unique targets to the table right now and contract to have a custom ZFN created for your specific gene of interest.
In addition to purchasing specific zinc finger nucleases, you may opt to have our scientists actually take those ZFNs and create the complete cell line for you. We have our own Custom Cell Engineering Services (CCES) group that is performing this service for a number of clients under contract. This is generally a 16-18 week process and we can do the work in one of our CHO lines or more commonly we're asked to make the appropriate manipulation in the customer's proprietary cell line. We can offer this service with full traceability and GMP controls - and we can create Master Cell Banks via our CMO services that are part of SAFC Pharma in Carlsbad, CA.
As this total program progresses over the next several months, many of these tools - specific ZFNs with wider market appeal - say dhfr and GS - will be available as catalog items that effectively can be purchased off the shelf with no lead time. Similarly, specific CHO cell lines that have been created with single or multiple trait knockouts using these same ZFNs will also become available as catalog items. The latter will also be banked in our best chemically defined CHO media and matched to chemically defined feeds for use in fed batch systems.
The medium development and feed program will continue to evolve in tandem with the cell line development program. We believe we can add a lot of value by matching the cell line platform development with the medium and feed development at each step of the way. In the end, we will end up with a system that is fully optimized for the given platform. We believe this is a more extensive approach than has really been undertaken in the indsutry up until now -- and for us is steeply enabled by our recent acquisition of the ZFN technology rights. The ability to rapidly manipulate genes in mammalian systems in a very targeted way, and to then match medium development to that process in real time through use of not only our existing expertise but scale down and automated models will allow us to make significant strides in this area in a short period of time. We think that is exciting for not only ourselves but for our customers.
Posted by Bruce Lehr Feb 28, 2010.
We frequently use RNAi to validate new targets prior to shifting to ZFNs. RNAi can knock down a gene's expression but won't totally eliminate it and is not permanent. Zinc finger nucleases are very specific enzymatic scissors that can be designed to very specifically remove a single gene (they could also allow you to make a modification in a gene or to insert a gene)and the change is permanent. So as we get into designing platform cell lines for use in production, we go to ZFNs to create a stably modified set of traits. You can read more at this link to Sigma-aldrich site, http://bit.ly/axlyYd
Posted by: Bruce Lehr | 03/01/2010 at 09:06 AM
Hi Bruce,
I'm not familiar with the ZFN paradigm. How does it compare to RNAi technologies?
Posted by: Pharma Conduct Guy | 02/28/2010 at 08:15 PM