Summary
UCLA researchers in the Department of Medicine have developed a novel method to conjugate targeting ligands on lentiviral vectors. The method allows for selective transduction of mammalian cells types avoiding non-target organs.
Background
Gene therapy is a promising method to treat genetic disorders. Lentiviral vectors are used as a gene transduction tool in both experimental and clinical settings that require long-term transgene expression. Their ability to integrate their transgenes into host chromosomes enables their transgenes to be expressed for a long period of time providing clinicians with a valuable tool to tackle otherwise untreatable diseases. Despite the advantage of long-term transgene expression, lentiviral vectors can also cause insertional mutagenesis (destruction of host genes and their regulatory elements), so it is important to restrict the integration of the vectors only to the specific target cells to avoid dentrimental side-effects. Systemic administration of commonly used lentiviral vectors results in non-specific transduction of wide varieties of cells, due to the broad tropism of the envelope proteins used to pseudotype lentiviral vectors. Trapping of the vectors by the liver and spleen decreases the numbers of vectors available to reach other target organs, and transduction of the cells in the liver and spleen increases unnecessary insertional mutagenesis of these cells by vector integration. There remains a need for efficient delivery of transgenes to target cells and tissues that avoids unnecessary transduction of non-target cells. Conjugating certain types of lentiviral vectors with targeting ligands can redirect the vectors to specifically transduce desired cell types. However, extensive genetic and/or biochemical manipulations are required for conjugation, which hinders applications for targeting lentiviral vectors for broader research fields.
Innovation
UCLA researchers have developed vectors that escape trapping in non-target organs, and specifically bind and transduce the target cell types. These lentiviral vectors pseudotyped with the novel envelope proteins can be conjugated with biotinylated targeting ligands. The conjugated ligands mediate specific binding and transduction of the target cell types. This lentiviral transduction system can be used to selectively deliver transgenes into specific cell types in vivo, which increases the numbers of vectors reaching the targeted cells and tissues and decreases adverse effects in non-targeted cells and tissues. The targeting construct can be prepared by simply mixing the novel envelop proteins of pseudotyped vectors with biotinylated targeting ligands. The heterologous gene to be delivered can be a therapeutic gene, a corrective gene, a wild type gene, a cytotoxic gene, a marker gene, or other gene employed for therapeutic purposes, investigative purposes, and/or for detection. This simple method of ligand conjugation and ease of obtaining various types of biotinylated ligands will make targeted lentiviral transduction easily applicable to broad fields of research as well as gene therapy. This gene delivery system can be also used for protein delivery by incorporating proteins of interest inside lentiviral vectors. This gene delivery system can be also used for protein delivery by incorporating proteins of interest inside lentiviral vectors.
Applications
▶ Gene therapy
▶ Gene transduction
▶ Selective biologics delivery
▶ Gene detection
Advantages
▶ Cell-type specific transduction
▶ Facile construction
▶ Stable targeting ligand-lentiviral vector conjugate
▶ Variety of targeting ligands available
State Of Development
The efficacy of this method of gene delivery has been tested in mammalian cells.