Cell-Specific Aptamer-Functionalized RNAi: A New Prospect for Targeted siRNA Delivery - Nanotechnology for the Delivery of Therapeutic Nucleic Acids - page 120

or immune activation. Among these issues, efficient delivery remains
the primary challenge. Therefore, delivery formulations must be
developed to overcome this key hurdle before RNAi-based therapies
can be realized as a general approach for the treatment of human
diseases.
The power of aptamers as siRNA and drug delivery vehicles
is prompting the widespread development of multifunctional
formulation for targeted RNAi therapeutics. Advantages of a cell type
specific, aptamer-functionalized nanocarrier system are as follows:
(1) a nanoscale size that not only allows preferential accumulation
in the tumor tissue/organ in the passive targeting mode but also
improves circulation time and biodistribution; (2) cell type-specific
aptamers facilitate selective internalization in target cells; (3) a
combinatorial therapy format that simultaneously administers
two or more therapeutic agents to achieve synergistic therapeutic
efficacy; (4) fluorescent labeling allows real-time tracking of
drugs for monitoring therapeutic responses. Despite some of the
successful examples reviewed in this chapter, continued efforts are
still required to further refine these formulations for their clinical
translation. It is still important to explore the molecular events
associated with RNAi and aptamer-mediated target recognition,
thereby accelerating the development of aptamer-siRNAs as

diagnostic and therapeutic agents.

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