Nucleic acid guided molecular tool for in-vivo theranostic applications

Abstract

Aptamers generated de novo by iterative process of in-vitro selection called Systemic Evolution of Ligand by EXponential enrichment (SELEX) which mimics Darwinian evolution process. SELEX is a powerful and yet simple technique that has been used to isolate DNA or RNA sequences with a function of interest (e.g. ligand-binding or catalysis) from a pool of random-sequence oligonucleotides based on their ability to bind to various types of different targets. Aptamers also known as chemicalbodies because of nature of selection and similarity in their action to antibodies. Aptamers have become attractive molecules in diagnostics and therapeutics rivaling and, in some cases, and extends many features of other molecular probes such as antibodies because of their nanomolar affinities and high specificities toward target molecule, amenable to various modifications, non-immunogenic nature and flexible structure properties. Recently, an increasing number of aptamers have been developed against various biomarkers expressed at the surface of mammalian cells or pathogenic microrganisms. This class of targets (mostly proteins) is associated with several pathologies including cancer, inflammation and infection diseases. Several of these aptamers were tested in-vivo as drugs or as targeting agents for site specific drug delivery, siRNA, microRNA or molecular imaging and may prove useful in the treatment of a wide variety of human maladies, including infectious diseases, cancer, and cardiovascular diseases. In this book chapter, we review the observations that expedited the development of this emerging class of therapeutics and speculate on the efficacy in the clinical studies.