Novel aptamer development for cell isolation and targeted drug delivery

Abstract

Aptamers are oligonucleotides that can bind to their targets with high affinity. These “chemical antibodies” provides numerous advantages over their biological counter parts. It is discussed in chapter 1 that aptamers are attractive alternatives to antibodies when used in cell sorting technologies and drug delivery systems due to their reversable binding mechanisms, stability, chemical modification flexibility, low cost, and other properties. In our group, we discovered a couple of novel DNA aptamers using cell-SELEX (Systemic Evolution of Ligands by EXponential enrichment) technique. We presented a transferrin receptor 1 (TfR1, CD71) binding aptamer discovery process and application in chapter 2. This aptamer was used in a cell sorting system to separate cancerous B cells from healthy white blood cells designated for downstream adoptive cell therapy production. In chapter 3, we modified this CD71 aptamer for reversable cell targeting. The new version of CD71 aptamer was paired with a CD8 binding aptamer in a multiplexed traceless cell isolation method. In chapter 4, we sought to identify a CD4 binding aptamer in order to tracelessly isolate both CD4+ and CD8+ T cells from PBMCs (peripheral blood mononuclear cells) for CAR (chimeric antigen receptor) T cell manufacturing. In chapter 5, we present one of the aptamers developed in this discovery process that has high binding to cancerous T cells. We modified this newly discovered aptamer for into different targeted drug delivery systems to treat acute lymphoblastic leukemia T cells. Lastly, the major discoveries on characterizing the CD71 aptamer and optimizing the dual selection method were summarized in chapter 6, along with recommended future work.