Targeted Integration in Stem Cells: Generating Genetically Engineered Cellular Drugs
Dr. Porteus started his talk with an introduction to “Living Drugs,” or cell and gene therapeutics, which he envisions as the future of medicine much akin to the role of small drug molecules. His group is interested in leveraging precisely targeted integration to engineering stem cells, such a human hematopoietic stem cells, to treat human disease. To this end, his lab relies on CRISPR/Cas9 and homologous recombination to precisely target genes for repair or to insert full gene sequences.
Stem cell gene editing is performed ex vivo using a CRISPR/Cas9 ribonucleotide complex and an AAV6 non-integrating virus for gene delivery. The combined use of CRISPR/Cas9 RNP and AAV6 in the Porteus lab is an efficient gene-editing system that has allowed them to modify various human primary cells successfully, including hematopoietic stem and progenitor cells (HSPCs), T-cells, and mesenchymal stem cells (MSCs).
Dr. Porteus shared how this system has allowed his team to introduce a variety of modifications into HSPCs, such as single-nucleotide changes (e.g., sickle cell disease), functional gene correction (e.g., SCIDX1), safe-harbor gene addition (e.g., Mucopolysaccharidosis type I), and transgene insertion (e.g., -thalassemia). He discussed how preclinical studies in his lab have translated to clinical studies to correct various human disease conditions. Overall, by modifying patient-derived stem cells, gene editing approaches allow autologous cell therapies and bypass immune mismatch complications associated with allogeneic cell transplantation. Therefore this approach represents a significant advancement in the treatment of human disease.