Cleavable, Covalently Linked, Affinity Coupling Immune Magnetic Nanoparticles for Specifically Depleting T Cells

Abstract

Hematopoietic stem cell (HSC) transplantation has become an accepted therapeutic modality for patients with hematopoietic disorders. However, transplant recipients are at high risk of a severe complication known as graft versus host disease (GvHD). To reduce the risk of GvHD, depletion of T cells in donor HSCs prior to transplantation is of vital importance. Magnetic-activated cell sorting (MACS) using immuno-magnetic nanoparticles to selectively deplete T cells presents a potential solution for HSC transplantation. In this study, we presented a complete protocol for the synthesis of immuno-magnetic nanoparticles and characterised their performance for the depletion of Jurkat T cells from cell culture and from a mixture of T cells and HSCs. First, the recombinant protein A/G, an Fc-specific antibody, and magnetic nanoparticles were covalently linked by amine groups on the surface of magnetic nanoparticles and the protein using 3-(2-pyridyldithio) propionic acid N-hydroxysuccinimide ester (SPDP). Then, the anti-Jurkat T antibodies were bound to protein A/G on magnetic nanoparticles via regio-oriented affinity binding. Approximately 85 μg of protein A/G and 25 μg of antibody were bound to 1 mg of magnetic beads. The immuno-magnetic nanoparticles were capable of depleting up to 73% of Jurkat T cells from culture medium and 72% of Jurkat T cells from the mixture. In addition, we showed that our depletion protocol was able to preserve the proliferation and differentiation characteristics of HSCs. In conclusion, our immuno-magnetic nanoparticles provide a potential solution for the depletion of T-cells prior to HSCs transplantation.