Modular Layer-by-LayerNanoparticle Platform for HematopoieticProgenitor and Stem Cell Targeting

Effective delivery of drug and gene cargos to hematopoietic stem and progenitor cells (HSPCs) is a major challenge. Current therapeutic strategies in genetic disorders or hematological malignancies are hindered by high costs, low accessibility, and high off-target toxicities. Layer-by-layer nanoparticles (LbL NPs) are modular systems with tunable surface properties to enable highly specific targeting. In this work, we developed LbL NPs that target HSPCs via antibody functionalization with reduced off-target uptake by circulating myeloid cells. NPs layered with poly(acrylic acid), a bioinert polymer, provided more stealth properties <i>in vivo</i> than other tested bioactive polyanions. The additional conjugation of anti-cKit and anti-CD90 antibodies improved NP uptake by 2- to 3-fold in nondifferentiated bone marrow cells <i>in vitro</i>. By contrast, anti-CD105 functionalized NPs showed the highest association to HSPCs <i>in vivo</i>, ranging from 3.0 to 8.5% in progenitor subpopulations. This LbL NP platform was then adapted to target human HSPC receptors, with similar targeting trends in healthy CD34+ human cells. By contrast, anti-CXCR4 functionalization demonstrated the greatest targeting to human B-cell lymphoma and leukemia cells. Taken together, these results underscore the therapeutic potential of this modular LbL NP platform with the capacity to target HSPCs in a disease-dependent context.