Development of Aptamer Technologies for Immune Cell Isolations

Abstract

Aptamers are short, single-stranded nucleic acid molecules that bind to target molecules with high affinity and specificity. Due to their cheap synthesis, long-term stability, and homogeneity, aptamers have emerged as an attractive affinity reagent for cell separations. Aptamers are discovered through a process called Systematic Evolution of Ligands by Exponential Enrichment (SELEX). However, traditional SELEX strategies are labor-intensive and lead to many nonspecific binders, limiting the translational application of aptamers. Chapter 1 introduces aptamers, the SELEX method, and the application of aptamers as affinity ligands for protein and cell separations. In Chapter 2, we develop a novel method to discover new aptamers for applications in immunotherapy using a protease-cleavable membrane protein expressed in mammalian cells. In Chapter 3, we employ a CD36-binding aptamer to isolate monocytes from peripheral blood mononuclear cells (PBMCs) on a magnetic column with high purity and yield. In Chapter 4, we adapt aptamers to a scaled-up, resin-based isolation system for high-throughput depletion of monocytes and selection of CD8+ T cells from PBMCs. Chapter 5 highlights the advantages of cleave-SELEX in aptamer discovery and the use of aptamers in immune cell isolations and presents future work for cleave-SELEX and the CD36 aptamer.