Nonviral gene delivery found

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Nonviral gene delivery found

By ELLEN GOLDBAUM

Contributing Editor

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 UB 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 nanoparticles developed as DNA carriers at

UB, 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 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, " explained Paras N. Prasad,

executive director of the UB Institute for Lasers, Photonics and

Biophotonics, SUNY Distinguished Professor in the Department of

Chemistry in the College of Arts and Sciences, and a co-author of

the paper.

" When the fluorescent protein was produced in the cell, we knew

transfection had occurred, " he said.

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, " explained

Dhruba J. Bharali, a coauthor and postdoctoral researcher in the

Department of Chemistry and the Institute for Lasers, Photonics and

Biophotonics, where the work was done.

" 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, " he said.

While nonviral vectors are safer, he noted that 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, he explained, 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.

The 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.

" No gene-delivery vehicle—either viral or nonviral—has ever been

tracked in the cell before, " explained Tymish Y. Ohulchanskyy, the

third coauthor and postdoctoral research scholar at the

institute. " By using our photonics approach, we can track gene

delivery step by step to optimize efficiency, " he said.

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, " said Prasad.

The researchers are 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.

This research was supported by the U.S. Air Force through its

Defense University Research Initiative on Nanotechnology (DURINT)

grant.

http://www.buffalo.edu/reporter/vol36/vol36n16/articles/Prasad.html