We describe herein the development of a high affinity and specific
DNA aptamer as a new
ligand for use in liposomal nanoparticles to target cultured mouse
tumor endothelial cells (mTECs). Active targeted nanotechnology based drug delivery systems are currently of great interest, due to their potential for reducing side effects and facilitating the delivery of cytotoxic drugs or genes in a site specific manner. In this study, we report on a promising aptamer candidate AraHH036 that shows selective binding towards mTECs. The aptamer does not bind to normal cells, normal endothelial cells or
tumor cells. Therefore, we synthesized an aptamer-
polyethylene glycol (PEG)
lipid conjugate and prepared aptamer based
liposomes (ALPs) by the standard
lipid hydration method. First, we quantified the higher capacity of ALPs to internalize into mTECs by incubating ALPs containing 1 mol%, 5 mol% and 10 mol% aptamer of total
lipids and compared the results to those for unmodified PEGylated
liposomes (PLPs). A confocal
laser scanning microscope (CLSM) uptake study indicated that the ALPs were taken up more efficiently than PLPs. The measured Kd value of the ALPs was 142 nM. An intracellular trafficking study confirmed that most of the
rhodamine labeled ALPs were taken up and co-localized with the green
lysotracker, thus confirming that they were located in lysosomes. Finally, using an aptamer based proteomics approach, the molecular target
protein of the aptamer was identified as
heat shock protein 70 (HSP70). The results suggest that these ALPs offer promise as a new carrier molecule for delivering anti-angiogenesis drugs to
tumor vasculature.