Transfection in vivo
Transfection in vitro can be mediated by the non-viral reagents (such as liposome, polymer, nano-particle) or viral vectors (such as lentiviruses, adenovirus and AAV).
Non-viral methods
Formulations of liposome, polymer and nano-particle have been optimized for in vivo delivery, especially with the use of transfection enhancer and secondary injection. What’s more, the three non-viral methods can also be combined together (Figure 1). As shown in Figure 1, multifunctional envelope-type nano-devices (MEND) are designed to promote the delivery of DNA and RNA. In MEND, PEG is used to extend nucleic acids’ half-life in systemic circulation, ligands are for specific targeting, peptides, including a protein-transduction domain, are intend to increase intracellular availability, while membrane fusogenic lipids were utilized to enhance endosomal escape and protect the degradation of nucleic acids [10,15].
Over the last several years, many progresses have been made in the field of gene transfection with polymer, cationic liposome and nanoparticle. Parameters, such as charge density, and hydrophilic and hydrophobic content, are optimized to improve polymer characteristics (such as the strength of the polyplex–cell membrane interaction, serum stability, DNA release, endosomal escape and nuclear localization) [16]. Biocompatible, nontoxic and effective novel artificial liposomal systems are used in liposome-mediated gene transfection [17]. Magnetic nano-particles and implantable magnets are designed to deliver therapeutic gene to its target tissues, showing great advantages in clinic [18].
Viral vector
Lentiviruses can integrate a significant amount of viral cDNA into the host genome, mediate stable and long-term transgene expression, and efficiently infect dividing cells and nondividing cells in vivo [19]. You could find a lot of information and protocol about lentivirus on this website: https://www.genemedi.com/i/lentivirus-packaging.
With no integration ability, recombinant adenovirus can’t be integrated into host genome, have large cargo capacity (~8kb), and are easily manipulated with recombinant DNA techniques [20]. Genemedi got a rich experience in adenovirus packaging and purification, you could find more information on https://www.genemedi.com/i/aav-packaging.
With mild immunogenicity, adeno-associated viruses (AAV) have superior biosafety rating and broad range of infectivity and mediate long-term and stable expression of target gene in vivo [21]. Genemedi is good at lentivirus production, please find more information on this website: https://www.genemedi.com/i/aav-packaging.
Comparison | Retrovirus | Lentivirus | Adenovirus | AAV |
Genome | ss RNA | ss RNA | ds DNA | ss DNA |
Integration | Yes | Yes | No | No |
Packaging Capacity | 3kb | 4kb | 5.5kb | 2kb |
Time to peak expression | 72h | 72h | 36h-72h | Cell: 7 days; Animals: 2 weeks |
Sustainable time | About 3 weeks | Stable expression | Transient expression | > 6 months |
Cell Type | Most Dividing | Most Dividing/Non-Dividing Cells | Most Dividing/Non-Dividing Cells | Most Dividing/Non-Dividing Cells |
Titer | 10^7 TU/ml | 10^8 TU/ml | 10^11 PFU/ml | 10^12 vg/ml |
Animal experiment | Suitable | Low efficiency | Lowest efficiency | Most suitable |
Immune Response | High | Medium | Medium | Ultra-low |
Lentivirus, adenovirus and AAV all can mediate gene in vivo transfection. To date, lentiviral vector-based gene delivery in vivo has been proved to be effective in treatment of several diseases [22], including β-thalassemia [23], X-linked adrenoleukodystrophy (ALD) [24], metachromatic leukodystrophy [25,26], and Wiskott-Aldrich Syndrome [27]; adenovirus has been applied in treatment of several cancers, including prostate cancer [28], chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) [29], non-small cell lung cancer (NSCLC) [30], melanoma [31], renal cell carcinoma [32]; while AAV vectors have achieved promising gene therapy outcomes in a great number of diseases, including lipoprotein lipase deficiency (LPLD) [33], spinal muscular atrophy (SMA) [34], retinal dystrophy [35,36], cystic fibrosis [37,38], Duchenne Muscular Dystrophy [39], Hemophilia [40], congestive heart failure [41], Parkinson’s disease [42] and Rheumatoid Arthritis [43,44].