A rising star in breaking the blood-brain barrier: how can nucleic acid aptamers revolutionize the treatment of central nervous system diseases?
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Nucleic acid aptamers are very short, single-stranded DNA or RNA oligonucleotides (typically containing 20 to 100 nucleotides). They possess the unique ability to fold into stable three-dimensional (3D) structures (such as hairpin structures, G-tetramers, etc.), allowing them to bind to specific target molecules with extremely high affinity and specificity, much like a key and lock. Compared to traditional protein antibodies, nucleic acid aptamers offer advantages such as easier synthesis and modification, lower cost, and easier entry into biological tissues.
Nucleic acid aptamers primarily cross the blood-brain barrier via receptor-mediated transcytosis (RMT). The surface of brain endothelial cells contains numerous receptors responsible for nutrient transport, such as transferrin receptor (TfR) and low-density lipoprotein receptor-associated protein 1 (LRP1). Scientists have designed nucleic acid aptamers that can precisely target these receptors. Once they bind to the receptors, they initiate intracellular transport mechanisms, safely delivering the nucleic acid aptamer and its carried therapeutic cargo (such as genes or drugs) across the endothelial cells and ultimately releasing it into the brain parenchyma.
Compared to existing CNS drug delivery systems, nucleic acid aptamers offer the following significant advantages:
Low immunogenicity and safety: Due to their small size and lack of exogenous protein epitopes, nucleic acid aptamers are less likely to trigger a strong immune response in the human body, making them suitable for neurodegenerative diseases requiring long-term treatment.
High precision: They can bind to targets with extremely high affinity at the nanomolar (nM) or even picomolar (pM) level, significantly reducing off-target toxicity to surrounding tissues.
Flexible chemical modification: Their stability in the blood can be easily increased and their circulating half-life extended through chemical modifications such as PEGylation.
High cost-effectiveness: Utilizing chemical synthesis, mass production costs are far lower than recombinant antibody technology (large-scale synthesis costs approximately US$0.01 per nucleotide).
Although nucleic acid aptamers still face challenges before entering human clinical trials, such as the easy degradation of RNA by nucleases and differences in receptor performance among different species, their powerful technological potential is undeniable. Combining AI predictive design with nanotechnology, nucleic acid aptamers are not only expected to become "super couriers" for future neuropharmaceuticals and gene therapies, but also to achieve the goal of "therapeutic," ushering in a new era of personalized precision treatment for patients suffering from brain diseases.
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