Research News & Highlights
DNA Aptamer-Mediated Cell Targeting
Cell-based therapy has shown great potential in treating diseases such as leukemia and osteoporosis. One important issue is the targeted delivery of cells in vivo, not only improving therapeutic efficacy, but also minimizing side effects. And several approaches in this field have already been studied.
A research team with members from University of Florida, Hunan University, and Xiamen University has developed diacyl phospholipid–DNA conjugates to modify cell surfaces for specific cell targeting.
DNA, the molecules carrying genetic information in all living things, is found to have the ability of being assembled into custom predesigned shapes, which can have high spatial addressability, and thus show great potential in various bionanotechnological applications.
Aptamers, synthetic ssDNA/RNA molecules, have also emerged as novel tools for the development of therapeutics, especially for targeted delivery, with several advantages, such as high stability, small size, ease of synthesis, easy chemical modifications, and low immunogenicity.
The research team writing this article developed diacyl phospholipid–DNA conjugates, and used this lipid–DNA probe to modify cell surfaces for specific cell targeting.
The team hypothesized that aptamers would induce cellular adhesion upon spontaneous receptor–ligand binding in a manner that mimics the natural process of cell–cell adhesion. They synthesized diacyl lipid–DNA aptamer conjugates, with the membrane-anchored aptamer divided into 3 distinct segments, an aptamer sequence called cell-SELEX, a PEG linker allowing DNA to extend out from the cell surface, and a synthetic diacyllipid tail with two stearic acids. Then, they designed a homotypic cell targeting experiment to confirm that membrane-anchored aptamers could induce cellular adhesion in a defined target-specific fashion. To further demonstrate aptamer specificity, experiments to show different types of cell assemblies were also designed to confirm the generality of this assembly strategy. In addition, the cell aggregation using flow cytometry was quantified, showing that the percentage of aggregation can be controlled by the aptamer concentration and the ratio of modified cells to target cells.
Further, the team used leukemia cell lines to demonstrate that aptamers anchored on the cell surface could act as targeting ligands that specifically recognize their target cells. They explored the potential of this probe in adoptive cell therapy using NK cells as a model, in which aptamer KK1B10 was involved. Immune-effector cells modified by the probe showed improved affinity, while remaining cytotoxic to target cancer cells.
A novel targeting ligand on cell membranes for specific cell targeting was successfully designed in this research, which demonstrated that the noncovalent modification is simple, yet effective, with no short-term effect on modified cells. Besides, the selective assembly of multiple types of cells by aptamer–protein recognition is rapid and target-specific. Immune effector cells modified with aptamers can recognize leukemia cells, thus leading to elevated cancer cell targeting and killing.
This research lays the foundation for further study on the metabolism of the synthetic lipid and in vivo cell trafficking, and revealed that the diversity of aptamer targets and the facile nature of the modification make this strategy attractive in cell-based delivery and therapy.
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