Nucleic Acid Delivery

In 1987, Felgner et al. published on the use of cationic lipids for gene delivery in cells. This revolutionary finding ushered in a new age of advances in synthetic gene delivery methodologies. MTI-GlobalStem scientists have played an important role in the development of novel, highly successful transfection reagents, beginning with their development of Lipofectamine® and Lipofectamine® 2000 during their tenure at BRL/Life Technologies.

MTI-GlobalStem specializes in developing proprietary nanoparticles described as Nucleic Acid Transporters.  A Nucleic Acid Transporter System is made up of three distinct components that can be used in combination to deliver nucleic acids into cells. The three components are Cell Surface Ligands, Lysis Agents, and Nuclear Ligands (see below). These three components, separately or together, are covalently attached to nucleic acid binding moieties in order to bind non-covalently to nucleic acids.  Generally, when two or three components are combined with nucleic acids, they mimic how viruses attach to the cell, release from the endosome and enter in to the cytoplasm, and then optionally have their nucleic acid transported to the nuclei. Our goal is to create synthetic nanoparticles that have the molecular delivery efficiency of viruses.

Nucleic Acid Transporter Components  

  • Surface Ligand - a chemical compound or structure that binds to molecules on the cell surface. These cell surface molecules include any protein, glycoprotein, and glycolipids found at the surface of the cell. Cell surface ligands include anything that enters into the cell through cytosis, via endocytosis, potocytosis, or pinocytosis.   Examples of cell surface ligands include virus proteins or peptides that bind the cell surface components, antibodies or peptide fragments of antibodies, phage display peptides that bind to receptors, glycoproteins, carbohydrates, or lipids on the surface of the cell.  
  • Lysis Agent - a molecule or compound, which include lipids, proteins or peptides that are capable of breaking down the endosomal membrane and freeing the Nucleic Acid Transporter into the cell. Lysis agents include replication deficient viruses, peptides from viruses and bacteria that can cause lysis of membranes or fusion of membranes or both.
  • Nuclear Ligand - a ligand that binds a nuclear receptor. Generally these are nuclear localization sequences (NLS) derived from viruses or nuclear proteins.  The nuclear localization sequence from the SV40 Large T antigen is a common example. 

Cationic peptides, spermine and spermine derivatives, spermidines, histones, polylysines and polyamines, are examples of nucleic acid binding moieties. Once a surface ligand, lysis agent, or nuclear ligand attaches to a nucleic acid binding moiety it is capable of non-covalently binding and condensing nucleic acids into nanoparticles capable of delivering nucleic acids to the cell.  

These nanoparticles can then be used separately or in combination with liposomes and other polymers to efficiently target and deliver nucleic acid to the cells. Because of the variety of cell surface ligands and endosomal release agents (Lysis agents) that can be used in combination with nuclear localization sequences, MTI can design nucleic acid transporters for any specific cell type for a given type of nucleic acid, i.e. DNA, mRNA, or siRNA.


References

  • Felgner, P. L., Gadek, T. R., Holm, M., Roman, R., Chan, H. W., Wenz, M., & Danielsen, M. (1987). Lipofection: a highly efficient, lipid-mediated DNA-transfection procedure. Proceedings of the National Academy of Sciences,84(21), 7413-7417.
  • Hawley-Nelson, P., Ciccarone, V., Gebeyehu, G., Jessee, J., & Felgner, P. L. (1993). Lipofectamine reagent: a new, higher efficiency polycationic liposome transfection reagent. Focus, 15(3), 73-79.



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