Cationic lipids (CL) are the most promising candidates for efficient and safe gene-delivery vectors for gene therapy. Compared with viral capsids, CLs do not induce a response from the immune system. Moreover, while viral capsids have a maximum DNA-carrying capacity of about 40 kbp, CLs, which form self-assemblies with distinct lamellar LαC and inverted hexagonal HIIC, or HIC nanostructures when complexed with DNA, place no limit on the size of the DNA.
Despite all these promises, transfection efficiency (TE; a measure of the expression of an exogenous gene that is transferred into cells) remains low, and only a substantial increase in the knowledge of relative interactions between CLs, DNA and cell’s components can lead to the design of optimal CL-DNA complexes for gene therapy.
Here we propose to design and study novel surface-functionalised PEG-CL-DNA complexes with a RGD and SV 40 peptide sequences. The use of PEG is required to avoid opsin complexation (hence, removal from the organism), while the RGD sequence is expected to induce endocytosis, allowing entrance of the complexes into cells. The SV 40 (a nuclear localisation sequence – NLS) is expected to lead to transport of the smaller sized complexes into the nucleus, permitting the usage of CLs as vectors in slowly or non-dividing cells.
To test these hypotheses, transfection studies and confocal microscopy will be carried out in cells, whereas the structures and interactions of the complexes will be characterised with synchrotron x-ray diffraction. The interactions between CLs, DNA and cell components (mainly cytoskeleton filaments and cytoskeletal proteins) will be studied in-vitro with synchrotron x-ray diffraction, confocal microscopy and cryo-transmission electron microscopy.
The whole of these studies will permit the rationalisation of the crucial parameters affecting TE, based on the structures of CL-DNA complexes and their interactions with the cytoskeleton.
Fields of science
- medical and health sciencesmedical biotechnologygenetic engineeringgene therapy
- natural sciencesbiological sciencesgeneticsDNA
- natural sciencesphysical sciencesopticsmicroscopyelectron microscopy
- natural sciencesphysical sciencesopticsmicroscopyconfocal microscopy
- natural scienceschemical sciencesorganic chemistryaliphatic compounds
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