Non-viral vectors deliver genes

A gene therapy method that doesn't rely on potentially toxic viruses as vectors may be growing closer as the result of in vitro research results reported by University at Buffalo scientists in the current online issue of the Proceedings of the National Academy of Sciences.

The paper, which describes the successful uptake of a fluorescent gene by cells using novel nano-particles developed as DNA carriers, demonstrates that the nanoparticles ultimately may prove an efficient and desirable alternative vector to viruses.

Using confocal microscopy and fluorescent spectroscopy, the UB scientists tracked optically in real time the transfection process, including the delivery of genes into cells, the uptake of genes by the nucleus and their expression.

UB has shown that using photonics, the gene-therapy transfer can be monitored, tracking how the nanoparticle penetrates the cell and releases its DNA in the nucleus. The production of the fluorescent protein in the cell indicated that transfection had occurred.

The work is important in light of the difficulties that have plagued gene-therapy human trials in recent years, including some fatalities that may have resulted from the use of viral vectors.

Efficient delivery of the desired gene and substantial release inside the cell is the major hurdle in gene therapy. Viruses have been used as efficient delivery vectors due to their ability to penetrate cells, but there is the chance they can revert back to 'wild' type. While non-viral vectors are safer it is much more difficult to get them into cells and then to achieve the release of DNA once they do penetrate cells.

The advantage of the UB team's approach is that unlike most other non-viral vectors, the DNA-nanoparticle complex releases its DNA before it can be destroyed by the cell's defence system, boosting transfection significantly.

The UB scientists also were able to use photonic methods to provide an unprecedented look at how transfection occurs, from the efficient uptake of nanoparticles in the cytoplasm to their delivery of DNA to the nucleus.

The research team makes its nanoparticles from a new class of materials: hybrid, organically modified silicas (ORMOSIL). The structure and composition of these hybrid ORMOSILs yield the flexibility to build an extensive library of tailored nanoparticles for efficiently targeting gene therapy into different tissues and cell types.

The UB researchers are now collaborating on in vivo studies with colleagues from the UB School of Medicine and Biomedical Sciences to use their novel nanoparticles to transfect neuronal cells in the brains of mice.