Non-integrating S/MAR Vectors for Stable Transgene Expression
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Solution Overview
Problem
Current gene therapy methods using S/MAR-based vectors face limitations such as suboptimal expression levels, gene silencing, and low establishment rates, primarily due to the risks associated with integrating transgenes into the host cell genome.
Innovation Solution
The development of self-replicating non-integrative episomal S/MAR expression vectors, specifically designed with a bacterial replication-selection region, a transcription unit for vertebrate cell expression, and an S/MAR insert flanked by 5\' splice donor and 3\' splice acceptor sites within the 3\' UTR, to enhance expression and establishment efficiency while avoiding antibiotic resistance marker gene transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If viral retroviral and lentiviral vectors are used for stable modification, then stable modification is achieved, but the risk of inducing deleterious mutations and cancer increases
Solution Approach 1:
The patent extracts the transgene from the integrating viral vector system and maintains it as a separate episomal element. The S/MAR element enables the transgene to be maintained extrachromosomally without integration into the host genome, thereby eliminating the risk of insertional mutagenesis while preserving stable expression.
Solution Approach 2:
The S/MAR element acts as an intermediary between the transgene and the host genome. Instead of direct integration, the transgene is maintained as an episome that interacts with the nuclear matrix through the S/MAR element, providing stable maintenance without the harmful effects of genomic integration.
2Object-affected harmful factors
If S/MAR based vectors are used for stable maintenance, then integration risk is reduced, but expression level is suboptimal
Solution Approach 1:
The patent merges multiple functional elements into a single vector construct: the S/MAR element for stable episomal maintenance, the bacterial origin of replication for plasmid replication, the eukaryotic promoter for transcription, and the polyadenylation signal for proper RNA processing. This combination achieves both stable maintenance and high expression levels.
Solution Approach 2:
The patent optimizes various parameters of the vector system including the choice of S/MAR element, promoter strength, origin of replication, and polyadenylation signals to maximize expression levels while maintaining episomal stability. The bacterial origin enables high copy number maintenance which directly increases expression levels.
3Object-affected harmful factors
If S/MAR based vectors are used, then integration risk is reduced, but establishment rate is low
Solution Approach 1:
The vector is designed with universal functionality across different cell types and applications. The bacterial origin of replication ensures efficient plasmid replication and maintenance in diverse mammalian cells, while the S/MAR element provides broad compatibility for episomal maintenance. This multi-functionality increases the establishment rate across different cell types.
4Reliability
If antibiotic resistance marker genes are included in vectors, then selection is enabled, but antibiotic resistance marker gene transfer occurs
Solution Approach 1:
The patent uses a transient antibiotic resistance marker that is present only during the selection phase and is subsequently eliminated. The marker gene is designed to be lost after selection, providing temporary selection capability without long-term propagation of resistance genes. This approach maintains selection reliability while eliminating the harmful effect of persistent antibiotic resistance marker transfer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified S/MAR vectors demonstrate improved transgene expression and vector establishment efficiency compared to traditional S/MAR vectors, reducing the risk of gene silencing and maintaining stable episomal maintenance without integration into the host genome.
Implementation Method 1
Scaffold/matrix attachment regions (S/MARs), which are also known as scaffold-attachment regions (SARs) or matrix-associated regions (MARs) are known as sequences in the genome of eukaryotic organisms mediating attachment of the nuclear matrix
Implementation Method 2
a bacterial replication-selection region comprising a bacterial origin of replication and a selectable marker
Implementation Method 3
a transcription unit for expression of a transgene in a vertebrate cell, comprising a promoter, a 5′ UTR, a transgene, and a 3′ UTR
Data Source
AI summary
The present invention relates to a polynucleotide comprising at least one promoter and an S/MAR element, wherein the S/MAR element is located downstream of the promoter in the 3′ UTR of the transcription unit and wherein the S/MAR element is flanked by a 5′ splice donor site and a 3′ splice acceptor site; the present invention further relates to a composition comprising the polynucleotide, and to the polynucleotide for use in medicine and for use in treating genetic disease.