Chimeric Aptamer-Targeted Liposomal Delivery for CNS Transport
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Solution Overview
Problem
Current methods for targeting therapeutics to specific cells, such as cancer cells, face challenges due to the non-specific accumulation of drugs in normal cells, leading to undesirable side effects, and existing aptamers are susceptible to degradation in the serum, limiting their utility in targeted drug delivery.
Innovation Solution
Development of engineered ribonucleic acid (RNA) aptamers that specifically bind to the human transferrin receptor without competing with natural transferrin, allowing for targeted delivery of molecular entities to receptor-expressing cells, including cancer cells and cells in the central nervous system, using compositions like aptamer-conjugated liposomes or nanoparticles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural transferrin or existing aptamers are used for targeting, then targeted delivery to transferrin receptor-expressing cells is achieved, but the aptamers are susceptible to degradation by serum nucleases
Solution Approach 1:
The patent creates chimeric aptamers by combining DNA and RNA sequences to form a hybrid molecule that exhibits enhanced stability in serum while retaining binding affinity to the transferrin receptor. The DNA portion provides nuclease resistance while the RNA portion maintains structural integrity and binding capability, resolving the contradiction between stability and susceptibility to degradation.
Solution Approach 2:
The patent modifies the chemical composition parameters of the aptamer by incorporating 2'-fluoro modifications and other chemical alterations to the nucleotide structure. These parameter changes enhance resistance to nuclease degradation while preserving the aptamer's ability to bind the transferrin receptor, thereby improving reliability in serum environments.
2Productivity
If chemotherapeutic agents are administered systemically, then therapeutic effect is achieved, but non-specific accumulation in normal cells causes toxic side effects
Solution Approach 1:
The patent segments the therapeutic system into a targeting component (aptamer) and a therapeutic payload (chemotherapeutic agent or siRNA). The aptamer specifically binds to transferrin receptors overexpressed on cancer cells, directing the therapeutic payload selectively to the target cells while minimizing exposure to normal cells, thus resolving the contradiction between therapeutic efficacy and toxicity.
Solution Approach 2:
The aptamer acts as an intermediary molecule that mediates the selective delivery of chemotherapeutic agents to cancer cells. By binding specifically to the transferrin receptor on cancer cell surfaces, the aptamer facilitates targeted internalization of the therapeutic payload, reducing non-specific accumulation in normal tissues and thereby reducing toxic side effects while maintaining therapeutic efficacy.
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 aptamers effectively deliver molecular entities, such as siRNA, to targeted cells, enhancing drug delivery across the blood-brain barrier and into the central nervous system while avoiding non-specific binding and degradation, thereby reducing side effects and improving therapeutic efficacy.
Implementation Method 1
an isolated ribonucleic acid aptamer of 60 bases or less which binds a human transferrin receptor
Implementation Method 2
enhancing drug delivery across the blood-brain barrier and into the central nervous system
Data Source
AI summary
Aptamers targeted to a human transferrin receptor which do not compete with transferrin for binding are provided. Compositions and methods for aptamer-targeted liposomal drug delivery are also provided.