Targeted Delivery of Nucleic Acid and Protein Cargos into Primary Human Hematopoietic Stem Cells Using Bacteriophage T4

Here, we report, for the first time, delivery of mRNA and/or protein payloads into primary adult human hematopoietic stem cells (HSCs) using a bacteriophage-derived nanoparticle vector. We have been developing a new category of bacteriophage T4-engineered nanoparticles, termed "artificial viral vectors" (AVVs), for delivering therapeutic nucleic acid and protein complexes into human cells. Using a defined <i>in vitro</i> assembly-line platform, we decorated the capsid surface with mRNA and protein complexes through two outer capsid proteins, Hoc (highly antigenic outer capsid protein) and Soc (small outer capsid protein). First, we displayed a Hoc-protein G fusion protein to which HSC-targeted monoclonal antibodies (mAbs) are attached. Then we decorated the nanoparticle with the Soc-fused HIV-TAT molecule to create a positively charged capsid surface with cell penetrating function. Reporter mRNA molecules are then displayed on the capsid surface and the nanoparticle is coated with lipids. Such T4-AVVs transduced HSCs and delivered GFP and Luciferase reporter mRNAs at levels as high as 20% efficiency and exhibited targeted Ab-dependent phenotypes. Furthermore, we demonstrate simultaneous delivery of both protein and mRNA payloads, by decorating the capsid with mRNA and ∼507 kDa tetrameric β-galactosidase. The AVV-transduced HSCs maintain viability, and once optimized, the T4-AVV platform will provide enormous versatility to target various types of human cells and deliver next generation therapies for cancer and genetic diseases.