Transkingdom Nucleic Acid Delivery via Bacterial Intermediaries
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Solution Overview
Problem
Current nucleic acid delivery technologies face challenges such as rapid degradation, poor permeability across cell membranes, transient targeting effects, and safety concerns, limiting the clinical efficacy of RNAi-based therapies.
Innovation Solution
A transkingdom delivery platform engineered with dsRBDs like TRBP, RNase R knockout, and methyltransferase genes like HEN1 to enhance nucleic acid stability and invasive properties, using non-pathogenic bacteria to target specific epithelial tissues with improved stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If siRNA/shRNA is used for gene silencing, then gene expression inhibition is achieved, but the nucleic acid is rapidly degraded by ribonucleases reducing efficacy
Solution Approach 1:
The patent employs bacterial delivery vehicles as intermediary carriers to protect siRNA/shRNA from ribonuclease degradation. The bacterial cell wall and intracellular environment serve as a protective barrier, allowing the nucleic acids to reach target tissues without direct exposure to degrading enzymes in the extracellular milieu.
Solution Approach 2:
The patent modifies the biochemical parameters of the delivery system by using bacteria with altered RNase activity or RNase-deficient strains. This changes the enzymatic environment within the delivery vehicle, preventing nucleic acid degradation while maintaining the ability to deliver functional siRNA/shRNA to target cells.
2Reliability
If siRNA/shRNA is administered directly, then gene silencing is achieved, but permeability across cell membranes is poor resulting in low bioavailability
Solution Approach 1:
The patent uses bacterial vehicles as intermediaries to overcome the cell membrane barrier. The bacteria naturally possess mechanisms for membrane interaction and entry, which they exploit to deliver the nucleic acid payload directly into target cells, bypassing the permeability limitations of direct siRNA/shRNA administration.
Solution Approach 2:
The bacterial delivery system utilizes the bacteria's own natural invasion and entry mechanisms to deliver the therapeutic nucleic acids. The bacteria self-propel into target cells using their inherent motility and adhesion properties, eliminating the need for external permeation enhancers or complex delivery apparatus.
3Productivity
If viral vectors are used for delivery, then delivery efficiency is improved, but safety concerns arise including cell death, tumorigenesis, and hepatotoxicity
Solution Approach 1:
The patent employs non-pathogenic bacteria as disposable, transient delivery vehicles. These bacteria deliver their payload and are then eliminated by the host immune system or natural clearance mechanisms, avoiding the persistent integration and long-term safety concerns associated with viral vectors. The bacteria serve their delivery function and are discarded, leaving no permanent genetic footprint.
Solution Approach 2:
The patent extracts the delivery function from viral systems and transfers it to bacterial systems. By separating the delivery mechanism (bacterial invasion and entry) from the nucleic acid payload, the system achieves viral-level delivery efficiency without the inherent safety risks of viral replication and integration capabilities.
4Object-generated harmful factors
If synthetic carriers are used for delivery, then safety is improved compared to viral vectors, but delivery efficiency is low requiring large toxic doses
Solution Approach 1:
The patent creates a composite delivery system combining the safety advantages of synthetic carriers with the high delivery efficiency of biological invasion mechanisms. The bacterial vehicle integrates cellular components for active entry with controlled payload delivery systems, achieving both safety and efficiency that neither synthetic nor viral systems alone can provide.
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 platform achieves stable and persistent RNAi silencing, efficient intracellular delivery, and adaptable clinical administration, reducing the need for permeation enhancers and synthetic siRNA manufacturing, while providing a versatile platform for various therapeutic nucleic acids.
Implementation Method 1
dsRBPs such as TRBP bind dsRNAs with high affinity and provide protection against RNA degradation
Implementation Method 2
methylation of the 3′ terminal nucleotide, as provided by a methyltransferase such as HEN1, protects against 3′-5′ degradation and 3′ uridylation of siRNA
Data Source
AI summary
A transkingdom platform for the delivery of therapeutic nucleic acids to epithelial tissues where the nucleic acids are designed to have enhanced stability. The platform offers numerous improvements to prior delivery platforms including expression of the double-stranded RNA binding domain (dsRBD) domains of TAR RNA binding protein (TRBP), knockout of RNase R activity in the bacterial delivery vehicle, and expression of the methyltransferase gene, HEN1, for simultaneous packaging with a therapeutic nucleic acid delivery vehicle.