Ending reliance on toxic viruses

A gene therapy method that does not rely on potentially toxic viruses as vectors may be growing closer as the result of in vitro research results reported by University at Buffalo (N.Y.) scientists. The study, which describes the successful uptake of a fluorescent gene by cells using novel nanoparticles 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 scientists optically tracked--in real time--the process known as transfection, including the delivery of genes into cells, the uptake of genes by the nucleus and their expression. "We have 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," explains Paras N. Prasad, executive director of the Institute for Lasers, Photonics and Biophonics. "When the fluorescent protein was produced in the cell, we knew transfection had occurred."

The work is important in light of the difficulties that have plagued human gene-therapy 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' says Dhruba J. Bharali, a postdoctoral researcher in the Department of Chemistry. 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 nonviral vectors are safer, it is much more difficult to get them into cells and subsequently to achieve the release of DNA once they have succeeded at penetration. The advantage of the UB team's approach is that, unlike most other nonviral vectors, the DNA-nanoparticle complex releases its DNA before it can be destroyed by the cell's defense system, boosting transfection significantly.

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