Modified AAV Capsids for Muscle-Targeted Gene Delivery
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Solution Overview
Problem
Existing AAV vectors for systemic gene delivery to muscle cells face inefficiencies due to a natural propensity to infect liver cells, leading to significant vector loss in the liver and reduced therapeutic efficacy in muscle tissues, necessitating high doses to achieve therapeutic levels.
Innovation Solution
Modification of AAVrh74 capsids with specific amino acid substitutions or insertions, such as isoleucine at position 502, tryptophan to arginine at position 505, and the YIGSR peptide at position 591, enhances muscle-specific targeting and reduces liver infection, increasing transduction efficiency up to 56-fold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AAV vectors are used for systemic delivery to muscle cells, then gene delivery to muscle tissues is achieved, but significant vector loss occurs in the liver reducing therapeutic efficacy
Solution Approach 1:
The capsid proteins are modified with specific amino acid substitutions (e.g., VP1: N502I, W505R) and peptide insertions (YIGSR at position 591) to create localized binding affinity for muscle-specific receptors such as α7β1 integrin and CD31, while eliminating affinity for liver cells. This local quality modification enables selective targeting of muscle tissues over liver, resolving the contradiction between achieving muscle delivery and avoiding liver sequestration
Solution Approach 2:
The invention changes the biochemical parameters of the capsid proteins by introducing specific amino acid mutations and peptide insertions that alter the surface properties and receptor binding characteristics. These parameter changes in capsid protein sequence and structure result in shifted tropism from liver-preferential to muscle-preferential binding, thereby reducing vector loss in the liver while maintaining muscle delivery efficacy
2Reliability
If high doses of AAV vectors are administered to achieve therapeutic levels in muscle, then therapeutic efficacy is improved, but manufacturing costs and immune responses increase
Solution Approach 1:
By modifying capsid parameters (amino acid sequence, peptide insertions) to enhance muscle-specific binding affinity and reduce liver uptake, the invention increases transduction efficiency per unit dose. This parameter change allows achieving therapeutic efficacy at lower overall doses, thereby reducing manufacturing costs and minimizing immune responses while maintaining therapeutic effectiveness
Data Source
AI summary
Modified capsid proteins, isolated polynucleotides, methods for the preparation of modified capsid proteins, recombinant viral particles, recombinant expression systems for the generation of modified viral particles, and methods of gene editing and regulation are provided herein.