CHO expression platform (L-11266 / 11992 / 12273 / 12671)


Mammalian expression systems employing Chinese hamster ovary (CHO) cells are the workhorse of the biopharma industry, and were used to produce seven of the ten top selling biologics in 2011: Humira, Enbrel, Rituximab, Avastin, Herceptin, Avonex, and Rebif. CHO cells have also become the expression system of choice in a lab setting, enabling the rapid, large-scale production of hundreds of protein variants for high throughput screening.

Over the past 15 years, NRC-HHT has made crucial improvements in the vectors, cell lines, transfection vehicle and culture medium that comprise its proprietary CHO expression platform. These improvements in both stable and transient systems enable the fast, high yield, cost-effective production of most protein modalities. Our proprietary cumate switch enable users to turn the expression of a given gene on and off during production, a complementary feature that can be useful for production of toxic proteins or cell engineering.

Technology transfer

  • Non-exclusive R&D and/or commercial exploitation licence
  • R&D agreement for development of custom cell lines

Market applications

  • Transient expression of recombinant proteins for R&D purposes
  • Fully-scalable stable expression of recombinant proteins and lead candidates for R&D and commercial purposes

How it works

Transient expression

A stable CHO clone expressing a truncated but functional form of EBNA1 (CHO-3E7) was obtained and shown to enhance r-protein production when using pTT vectors. The control of the cytomegalovirus (CMV)-based expression cassette on an oriP-bearing pTT vector also increased productivity significantly. Further enhancement was achieved by co-expressing fibroblast growth factor 2 (FGF2) or using valproic acid in tandem with the co-expression of protein kinase B (AKT) followed by a temperature shift.

Stable expression

This platform generates CHO pools that stably express between 200 and 500 mg/L in under four weeks post-transfection: two weeks for clone selection, and two for production. The pools can be maintained for months in culture under selection pressure, and by doing so, productivity can be maintained at the 200 to 500 mg/L. Frozen/thawed cells retain their productivity.

The use of a novel Scaffold/Matrix Attachment Region (S/MAR) sequence in an expression vector can help increase the level of expression and prevent silencing of the transgene.


  • High yield, low cost protein production for research and biomanufacturing
  • Transient or stable expression
  • Family of validated pTT vectors
  • Choice of proprietary cell lines or custom cell line development to best suit your expression needs
  • Cumate switch allows you to turn the expression of a given gene on and off during production
  • Serum-free media enables easy recovery of recombinant proteins
  • Compatible with commercially available feeds; custom fed batch development


  • NRC file 11266 (vector/cassette): Patents granted in Canada, Europe, and Singapore, pending in the United States.
  • NRC file 11992 (CHO-3E7 cell line): Patents granted in Europe, pending in Canada and the US.
  • NRC file 12671 (CHO-BRI cell line): Transferred as a trade secret.
  • NRC file 12273 (S/MAR clones to increase stability): Patents pending in Canada, Europe and the United States.
  • NRC file 11225/11648 (Cumate switch): Patents granted in Canada, the United States, and Europe.


Daniel Desmarteaux, Client Relationship Leader
Telephone: 514-496-5300

April Luong, Client Relationship Leader
Telephone: 514-496-2745

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