Release Date: December 22, 2004
BUFFALO, N.Y. -- 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 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, Ph.D., executive director of the UB Institute for Lasers, Photonics and Biophotonics, SUNY Distinguished Professor in the Department of Chemistry in the University at Buffalo's 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, Ph.D., a co-author and postdoctoral researcher in the UB Department of Chemistry and UB's 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 non-viral 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 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.
"No gene-delivery vehicle -- either viral or non-viral -- has ever been tracked in the cell before," explained Tymish Y. Ohulchanskyy, Ph.D., the third co-author and post-doctoral 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 UB researchers now 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.