A Summary of Non-Viral Gene Therapy Approaches—Booknotes from a Review Paper
Gene therapy involves the manipulation of gene expression pathways in cells utilized in the treatment of both genetic and pathological diseases. The delivery of genetic-based material, such as RNA or DNA, to cells modifies their expression patterns.¹ The gene delivery process is driven by a carrier vector, most commonly viral vectors. The delivery mechanism is a critical part of the process, as it influences the type, duration, and outcome of the specific treatment, and successful delivery requires successful uptake and translocation to active sites.
Non-viral alternatives to viral vectors have gained significant attention because of their flexible design, low cytotoxicity and immunogenicity, and gene delivery efficacy. Some limitations of viral vectors include their complex formulation, storage-related difficulties, and off-target effects.¹
Biologically-derived Vectors
Bacterial vectors have demonstrated great ability to deliver diverse genetic cargo, such as plasmid DNA, RNA-based constructs, and larger genetic elements.² They additionally have the potential to incorporate powerful genomic integration technologies due to specific bacterial properties, like ideal sizing for uptake into antigen presenting cells (ACPs) and their ability to deliver both protein and genetic cargo.¹ However, concerns over the biosafety of bacterial vectors have limited their widespread clinical use.
Gene delivery vectors comprised of biomaterials can be divided into two classes: polymers and lipids. Both of these types of vectors can be readily synthesized and tailored to address application-specific problems. Following cellular uptake, endosomal escape is a key step in ensuring gene expression. However, sub-biological endosomal escape and gene transfer efficacy are potential limitations of this class of vectors.³
These technologies can be combined to create hybrid vectors. For example, the authors developed a “class of hybrid bio-synthetic gene delivery vectors” comprised of an E. coli inner-core and a cationic polymer outer-core, which improved APC cellular outcomes significantly, compared to commercially available and individual-component vectors.¹
Another delivery strategy that has gained momentum is the application of bacterial outer membrane vesicles (OMVs); these are vectors generated from the natural or induced budding of proteoliposomes from Gram-negative bacteria.⁴
Nontraditional Biomaterial Vectors
A contemporary biomaterial approach is the class of delivery vectors called biomimetic vectors. These vectors adopt and employ properties displayed by living organisms and mimic biophysical properties, such as size, shape, immunogenic signals, and surface antigens.⁵,⁶
Another method utilized in the development of nontraditional biomaterials vectors is the layer-by-layer (LBL) formation approach. This approach involves loading microneedles with releasable polymer films containing alternating layers of pDNA, polymer, and adjuvants.⁷
Purilogics develops ion exchange and HIC membrane adsorbers which can help with non-viral gene therapy nanocarrier purification. Purilogics can also develop a custom affinity membrane to fit your needs.
Send an email to bd@purilogics.com to learn more!
Check out our previous posts to read more about our membrane adsorbers:
References
1. Jones, C. H., Hill, A., Chen, M., & Pfeifer, B. A. (2015). Contemporary approaches for nonviral gene therapy. Discovery Medicine, 19(107), 447-454.2. JLarsen, M. D. B., Griesenbach, U., Goussard, S., Gruenert, D. C., Geddes, D. M., Scheule, R. A., ... & Alton, E. W. F. W. (2008). Bactofection of lung epithelial cells in vitro and in vivo using a genetically modified Escherichia coli. Gene therapy, 15(6), 434-442.3. JJones, C. H., Chen, C. K., Ravikrishnan, A., Rane, S., & Pfeifer, B. A. (2013). Overcoming nonviral gene delivery barriers: perspective and future. Molecular pharmaceutics, 10(11), 4082-4098.4. JÜnal, C. M., Schaar, V., & Riesbeck, K. (2011). Bacterial outer membrane vesicles in disease and preventive medicine. Seminars in immunopathology 33(5), 395-408.5. JHe, Y., Nie, Y., Cheng, G., Xie, L., Shen, Y., & Gu, Z. (2014). Viral mimicking ternary polyplexes: a reduction‐controlled hierarchical unpacking vector for gene delivery. Advanced Materials, 26(10), 1534-1540.6. JKang, S., Lu, K., Leelawattanachai, J., Hu, X., Park, S., Park, T., & Jin, M. M. (2013). Virus-mimetic polyplex particles for systemic and inflammation-specific targeted delivery of large genetic contents. Gene therapy, 20(11), 1042-1052.7. JBechler, S. L., & Lynn, D. M. (2012). Characterization of degradable polyelectrolyte multilayers fabricated using DNA and a fluorescently-labeled poly (β-amino ester): Shedding light on the role of the cationic polymer in promoting surface-mediated gene delivery. Biomacromolecules, 13(2), 542-552.