Nucleic acid aptamers against aggrecanases: a novel method for Degenerative Disc Disease Therapy

Abstract

Aptamers are short, single-stranded oligonucleotides, which bind to their targets through 3D conformational complementarity. Aptamers are frequently called 'chemical antibodies' because of their high specificity and affinity. More than 20 aptamers for the treatment of various diseases are evaluated in clinical trials. Role of intervertebral disc is to absorb shock and transmit load, allowing the spine to bend and move. Disc degeneration may cause serious low back pain and affect daily life. Aggrecanases ADAMTS-4 and -5 are critical proteins involved in the development of degenerative disc disease (DDD) and osteoarthritis. They have been used as targets for inhibitor selection against DDD in recent studies both in vitro and in silico. Small molecules targeted on catalytic domain of aggrecanases have been developed but have broad inhibitory activity which may cause serious side effects. Nucleic acid aptamers can potentially solve this problem. Recent studies on aggrecanases have also been restrained by the low expression level and low solubility of the catalytic domain. Our studies have developed new ways to express, refold and purify human ADAMTS-4 and ADAMTS-5. ADAMTS-4 and ADAMTS-5 catalytic domain incorporating with disintegrin domain and thrombospondin motif are expressed and purified from E. coli with high yield for the first time. Specific aptamers will then be tailor selected against each aggrecanase through a process called Systematic Evolution of Ligands by Exponential enrichment (SELEX). Selected aptamers will then be characterized and evaluated as a foundation for further DDD therapeutic development.