CRISPR-Cas9 Delivery via Single AAV Vector for HSC Genome Editing
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Solution Overview
Problem
Current genome-editing techniques are limited in their ability to efficiently and safely target multiple positions within the eukaryotic genome, requiring new technologies that are affordable, easy to set up, and scalable for therapeutic applications, especially for diseases with strong genetic contributions.
Innovation Solution
The use of the CRISPR-Cas system, specifically optimizing components like SaCas9 and dual guide RNA molecules, for precise genome engineering, including delivery via viral vectors like AAV to modify endogenous genome sequences in mammalian cells, reducing the number of viral vectors required and improving targeting specificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional genome-editing techniques (ZFN, TALEs, meganucleases) are used, then targeted genome perturbations can be achieved, but the system complexity and cost increase significantly
Solution Approach 1:
The CRISPR system divides genome editing into separate functional modules: a portable Cas9 enzyme and separate guide RNAs for each target site. This segmentation allows independent optimization of each component and simplifies the overall system compared to monolithic ZFN or TALE constructs.
Solution Approach 2:
The CRISPR-Cas9 system provides universal targeting capability through programmable guide RNAs that can be designed to match any genomic sequence with a PAM motif. A single Cas9 enzyme can perform multiple editing functions at different genomic locations by simply changing the guide RNA, eliminating the need for multiple specialized enzymes.
2Adaptability or versatility
If multiple viral vectors are used to deliver CRISPR components, then comprehensive genome editing can be achieved, but the number of vectors and delivery complexity increases
Solution Approach 1:
The patent combines multiple CRISPR components (Cas9 enzyme, guide RNAs, and editing templates) into a single AAV vector payload. This merging reduces the number of separate viral vectors needed from multiple to one, simplifying delivery while maintaining comprehensive genome editing capability through multiplexed guide RNA expression.
Solution Approach 2:
The single AAV vector is designed to perform multiple functions simultaneously: delivering Cas9, expressing multiple guide RNAs for different target sites, and providing homology-directed repair templates. This multi-functional design eliminates the need for separate vectors for each function.
3Productivity
If standard CRISPR systems are used, then genome editing can be performed, but off-target effects and lack of specificity reduce therapeutic safety
Solution Approach 1:
The system employs localized quality control through PAM motif requirements and guide RNA design algorithms that specifically scan for off-target sites with high stringency. Each guide RNA is optimized for its specific target location, and the PAM requirement ensures precise localization of Cas9 activity only at intended sites with correct contextual sequences.
Solution Approach 2:
The patent incorporates feedback mechanisms through in vitro validation of guide RNAs before use, off-target prediction algorithms that scan genomes for potential mismatch sites, and designs that incorporate mismatch tolerance testing. These feedback loops identify and eliminate potential off-target effects before therapeutic application.
4Measurement precision
If complex delivery systems are used to achieve precise targeting, then targeting specificity improves, but ease of operation and scalability decrease
Solution Approach 1:
The system uses synthetic guide RNA molecules that are chemically synthesized and pre-designed to match target sequences. These copied guide RNAs can be rapidly produced through standard DNA synthesis technologies, avoiding the need for complex in vivo generation systems and enabling quick adaptation to different target genes through simple sequence changes.
Solution Approach 2:
The system achieves high targeting specificity through parameter optimization in guide RNA design (20-24 nucleotide length, specific PAM requirements, mismatch tolerance parameters) rather than through complex delivery mechanisms. By adjusting these parameters, the system maintains high precision while keeping the delivery approach simple and scalable.
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
This approach simplifies genome editing, enhances targeting specificity, and reduces off-target effects, enabling effective therapeutic interventions by modifying nucleic acids in disease-affected cells and tissues, thus addressing the need for robust systems in treating genetic diseases.
Implementation Method 1
a guide sequence hybridized to a target sequence within the target polynucleotide
Implementation Method 2
a CRISPR enzyme complexed with a guide sequence hybridized to a target sequence within the target polynucleotide
Data Source
AI summary
The invention provides for delivery, engineering and optimization of systems, methods, and compositions for manipulation of sequences and/or activities of target sequences. Provided are delivery systems and tissues or organ which are targeted as sites for delivery. Also provided are vectors and vector systems some of which encode one or more components of a CRISPR complex, as well as methods for the design and use of such vectors. Also provided are methods of directing CRISPR complex formation in eukaryotic cells to ensure enhanced specificity for target recognition and avoidance of toxicity and to edit or modify a target site in a genomic locus of interest to alter or improve the status of a disease or a condition.