Developing a High Throughput and Long Term Protein Expression Cho Cell Line( I )

Since 1987, the very first recombinant therapeutic protein, tissue-type plasminogen activator (tPA), approved by FDA, various recombinant therapeutic proteins continuously surfaced out on the market in the past two decades. Among more than two hundred recombinant proteins having been produced and serving for various purposes, 90% is classified as therapeutic proteins. If 10.94% CAGR is adopted to estimate the annual growth rate, the global market value of therapeutic proteins will be reaching 168 billion USD in 2017. Although there are various therapeutic protein production systems and platforms, the CHO cell system currently holds the main stream of therapeutic protein production regarding its quality, efficacy, and cost-efficiency. Besides that, previously approving cases by FDA as well as the successful CHO-produced therapeutics on market strongly encourage the production of therapeutic proteins in CHO. Currently, 70% of recombinant proteins were produced by CHO (Jayapal, et al., 2006). Hence, the exploit of novel high through-put CHO cell line is the future direction for elevating the scale of therapeutic protein production. Although several technologies focusing on recombinant protein production in CHO had been advanced in past twenty years, those improvements however only solved part of problems due to encountering complicate issues while engineering CHO cell. Those difficulties include as follows: (1) A time-consuming process to screen a highly productive rCHO line. (2) Adopting gene amplification strategy to increase protein production may cause the instability of host genome impeding long-term protein production. (3) Transgene silencing devastatingly reduces protein production. (4) A significant aforementioned effort is repeatedly required whenever newly generated clones will be serving to produce new therapeutic proteins. Accordingly, producing large amount of extrageneous gene product without de-stabilizing the host genome and silencing transgene will heavily rely on the transgene insertion locus. As the fact of successful examples on isolating those cost-efficient recombinant protein clones in current protein industry, I hereby hypothesized that “there exist the ideal transgene insertion loci within the CHO genome in which allows transgene insertion as well as different protein codings’ replacement to maintain the consistency on protein output”. Identifying such insertion positions in CHO shall provide a high throughput manufacture on CHO engineering for recombinant protein production. As such, the quantitation indicators for the success on current proposal will be as follows: (1) supporting long-term stable transgene expression; (2) holding host genome stability after transgene amplification; (3) allowing in-situ exchange different transgene cassettes at the same locus. Establishing such an optimized CHO cell line will be able to fit into the current scheme of industrial recombinant protein production and their infrastructures. In sum, the generated rCHO line from our novel system can be easily accepted and extensively adopted by industry for streamlining therapeutic protein production in today’s highly competitive market.

Project ID:PC10608-1858
External Project ID:MOST106-2633-B182-001