Rapid and label-free isolation of human peripheral blood monocytes using a reversible CD36-binding aptamer for cell capture

Monocytes are mononuclear phagocytes crucial for tissue repair, pathogen clearance, and immune surveillance. Comprising 2-10% of all human blood peripheral leukocytes, monocytes are precursors to macrophages and dendritic cells and can be leveraged for diagnostics and treatment of various diseases, such as cancer and autoimmune conditions. Current methods of monocyte isolation for these applications, such as plastic adhesion, magnetic-activated antibody-based selection, and counterflow centrifugal elutriation are limited by either low purity and viability or costly equipment and reagents. Here, we develop and optimize an aptamer-based method for traceless isolation of monocytes from peripheral blood mononuclear cells at low cost with high purity and yield, and with minimal activation and immunogenic risks. We identify and use CD36 as a novel selection marker for monocyte isolation and confirm that monocytes isolated using our CD36-binding aptamer possess similar phenotypes to monocytes isolated from anti-CD14 and anti-CD36 antibodies with higher, unperturbed CD14 and CD36 expression.