Permanent Human Cell Line for Transient Protein Expression
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Solution Overview
Problem
Current methods for transient expression of recombinant proteins in mammalian cells face challenges such as low expression levels and the lack of a human cell system suitable for both transient and stable production, leading to differences in post-translational modifications that can impact product quality and safety.
Innovation Solution
A method involving the use of permanent human cell lines transfected with nucleic acid sequences for adenoviral gene functions E1A and E1B, and the large T antigen or EBV Nuclear Antigen-1, which allows for transient expression by episomal replication of expression plasmids, enhancing protein yields and authenticity of human post-translational modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stable production cell lines are used for transient expression, then expression levels improve, but the time required for cell line development increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-immortalizing human amniocytes with adenoviral E1A and E1B gene functions before transient transfection. This creates a permanent cell line that is already optimized for high-level expression, eliminating the need for time-consuming stable cell line development while maintaining high productivity. The cell line is prepared in advance with the necessary viral gene functions that enable subsequent episomal replication and high expression levels.
Solution Approach 2:
The patent changes the cellular state parameter by transforming primary human amniocytes into immortalized cells through introduction of adenoviral E1A and E1B genes. This parameter change enables the cells to proliferate indefinitely and support high-level transient expression without requiring stable integration of expression cassettes, thus reducing development time while maintaining high expression levels.
2Productivity
If non-human mammalian cell lines are used for transient expression, then expression levels improve, but product quality decreases due to non-authentic post-translational modifications
Solution Approach 1:
The patent uses human amniocytes as the base cell line, ensuring homogeneity in species origin. This guarantees that all post-translational modifications (glycosylation, phosphorylation, etc.) are authentically human, matching the target protein's native characteristics. The immortalized cell line maintains this human cellular identity while acquiring enhanced expression capabilities.
Solution Approach 2:
The patent creates a universal human cell line that can serve multiple purposes: it maintains authentic human post-translational modification capabilities like primary human cells, while also gaining immortalized proliferation characteristics and high transient expression capacity. This multi-functional cell line eliminates the need to switch between different cell systems for different development phases.
3Productivity
If episomal replication is enabled in permanent human cell lines, then protein yields increase, but the complexity of the cell line increases
Solution Approach 1:
The patent segments the functional requirements by separating the immortalization function (adenoviral E1A and E1B genes) from the episomal replication function (SV40 origin of replication). The E1A and E1B genes are stably integrated to provide immortalization, while the SV40 origin remains on transiently introduced plasmids that replicate episomally. This segmentation allows each function to operate independently, simplifying the overall system.
Solution Approach 2:
The patent uses the SV40 large T antigen as an intermediary that bridges the immortalized human cell line and the episomal plasmids. The large T antigen recognizes the SV40 origin of replication on transient plasmids and initiates their replication, enabling high-level transient expression without requiring stable integration of the expression cassettes into the human genome.
Data Source
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AI summary
The present invention relates to a permanent human cell line comprising the nucleic acid sequences for the adenoviral gene functions E1A and E1B and the nucleic acid sequence for the large T antigen of SV40 or the Epstein-Barr virus (EBV) nuclear antigen-1 (EBNA-1). The present invention further relates to a method for the transient expression of recombinant polypeptides and proteins in the permanent human cell line.