Table 2.
Methods for the delivery of RNAi triggers to cells and tissues
| Species/formulation | Packaging capacity | Applications and considerations | Refs* |
|---|---|---|---|
| Viral vector | |||
| Adenovirus | Up to ~35 kb, usually <10 kb | dsDNA vector with large packaging capacity, transient expression, highly immunogenic | 76,77 |
| Adeno-associated virus (AAV) | ~4.5 kb | ssDNA vector, small packaging capacity, mildly immunogenic, lasting expression in nondividing cells, capsid pseudotyping/engineering facilitates specific cell-targeting | 82,91,103,108 |
| Lentivirus | Up to 13.5 kb (larger inserts will decrease titre) | RNA vector, integration competent and incompetent forms available, less immunogenic than adenovirus or AAV, envelope pseudotyping facilitates cell targeting, clinical production more difficult than for adenovirus or AAV | 83,84,85,86,87,88,140,155 |
| Herpes simplex virus | 150kb | DNA vector, episomal, lasting expression, immunogenic | 119 |
| Bacterial vector species ‡ | |||
| Escherichia coli, S. Typhymurium§ | Delivery of short hairpin RNA or small interfering RNA to gut tissue | 73,74,75 | |
| Non-viral formulations || | |||
| Nanoparticle | Self-assembling, may target specific receptors, requires technical expertise to prepare | 59 | |
| Stable nucleic acid lipid particle (SNALP) | Stable for systemic delivery, broad cell-type delivery | 51 | |
| Aptamer | Targeting of specific receptors, requires sophisticated screening to develop | 53 | |
| Cholesterol | Stable for systemic delivery, broad cell-type delivery | 46 | |
| *Representative references. | |||
| ‡Bacterial minicells can carry plasmids, short interfering RNAs or drugs. | |||
| §Salmonella enterica subsp. enterica serovar Typhimurium. | |||
| ||The nucleic acids in non-viral carriers can be any size from small oligonucleotides to large artificial chromosomes. | |||