Cationic Lipid/Polynucleotide Condensates for in Vitro and in Vivo Polynucleotide Delivery - the Cytofectins

Non-Viral Delivery Systems to Transport Nucleic Acids for Inherited Retinal Disorders

Inherited retinal disorders (IRDs) represent a group of challenging genetic conditions that often lead to severe visual impairment or blindness. The complexity of these disorders, arising from their diverse genetic causes and the unique structural and functional aspects of retinal cells, has made developing effective treatments particularly challenging. Recent advancements in gene therapy, especially non-viral nucleic acid delivery systems like liposomes, solid lipid nanoparticles, dendrimers, and polymersomes, offer promising solutions. These systems provide advantages over viral vectors, including reduced immunogenicity and enhanced targeting capabilities. This review delves into introduction of common IRDs such as Leber congenital amaurosis, retinitis pigmentosa, Usher syndrome, macular dystrophies, and choroideremia and critically assesses current treatments including neuroprotective agents, cellular therapy, and gene therapy along with their limitations. The focus is on the emerging role of non-viral delivery systems, which promise to address the current limitations of specificity, untoward effects, and immunogenicity in existing gene therapies. Additionally, this review covers recent clinical trial developments in gene therapy for retinal disorders.

Evaluation of cationic liposome suitable for gene transfer into pregnant animals

Cationic liposome-mediated in vivo gene transfer represents a promising approach for somatic gene therapy. To assess the most suitable liposome for gene delivery into a wide range of organs and fetuses in mice, we have explored several types of cationic liposomes conjugated with plasmid DNA carrying the beta-galactosidase gene through intravenous injection into pregnant animals. Transduction efficiency was assessed by Southern blot analysis and expression of the transferred gene was evaluated by enzymatic demonstration of beta-galactosidase activity. Through the analysis of several types of recently synthesized cationic liposome/lipid formulations, DMRIE-C reagent, a liposome formulation of the cationic lipid DMRIE (1, 2-dimyristyloxypropyl-3-dimethyl-hydroxy ethyl ammonium bromide) and cholesterol in membrane-filtered water met our requirements. When the plasmid DNA/DMRIE-C complexes were administered intravenously into pregnant mice at day 11.5 post coitus (p.c.), transferred genes were observed in several organs in dams and were expressed. Furthermore, although the copy numbers transferred into embryos were low, we observed reporter gene expression in the progeny.

5'-linked lipid-oligodeoxyridonucleotide derivatives as inhibitors of human immunodeficiency virus replication

The covalent attachment of a phospholipid moiety, bound to the 5'-ends of phosphodiester and phosphorothioate oligonucleotides (L-ODNs and LS-ODNs), was achieved using H-phosphonate chemistry, and the lipid-oligonucleotides were assayed for the inhibition of virus replication in HIV-1 infected MT-4 cells. In the anti-HIV activity test, lipid-phosphorothioate oligonucleotides showed higher anti-HIV activities than non-lipid-phosphorothioate oligonucleotides, at the low concentration of 0.04 microM. LS-ODNs can inhibit HIV-1 reverse transcriptase activity through interactions with the enzyme. We found that the covalent attachment of a phospholipid group to the 5'-end of the phosphorothioate oligonucleotide enhances its nonsequence specific anti-HIV activity.

Transfer of genes to humans: early lessons and obstacles to success

Enough information has been gained from clinical trials to allow the conclusion that human gene transfer is feasible, can evoke biologic responses that are relevant to human disease, and can provide important insights into human biology. Adverse events have been uncommon and have been related to the gene delivery strategies, not to the genetic material being transferred. Human gene transfer still faces significant hurdles before it becomes an established therapeutic strategy. However, its accomplishments to date are impressive, and the logic of the potential usefulness of this clinical paradigm continues to be compelling.