Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists design new delivery device for gene therapy

07.07.2010
Scientists have designed a nanoparticle that appears to effectively deliver genetic material into cells with minimal toxic effects.

In lab experiments, the researchers have found that this device, a vector, is able to deliver DNA deeply enough into a cell to allow genetic material to be activated – a critical step in gene therapy. This vector is between 2 ½ and 10 times more effective than other experimental materials, according to the research.

Biomedical researchers continue to pursue gene therapy as a treatment option for a variety of diseases known to be caused by a genetic defect. That pursuit includes efforts to ensure the safety of the therapy and find the most effective way to deliver the genes.

In many experiments, deactivated viruses that retain their ability to infect other cells are used as vectors to deliver normal genes intended to replace, or turn off, defective genes. But because some of the viruses can generate an immune response that complicates the treatment, scientists also are pursuing nonviral vector techniques for gene therapy.

In this case, Ohio State University scientists combined two ingredients – calcium phosphate and a lipid shell – to create a nanoparticle that protects DNA during its journey to the cell and then dissolves to allow for gene activation in the target cell. Nano refers to the tiny size of the particle in question – its general structure can be detected only by an atomic force microscope.

Calcium phosphate is a mineral found in bones and teeth. Lipids are fatty molecules that help maintain the structure of cell membranes. Alone, calcium phosphate is toxic and lipids get absorbed by cells. Together, they form a protective and inflexible structure that, thanks to complex chemical reactions, self-destructs once inside a cell.

“Our nanoparticle is a foreign body just like a viral vector is, but it has a self-destructive mechanism so it does not generate a strong response from the immune system,” said Chenguang Zhou, a graduate student in pharmaceutics at Ohio State and lead author of the study. “The material we use is also biocompatible. Calcium phosphate is in our bones and the lipids we use are synthetic, but can be biologically degraded. That’s why there is low toxicity.”

The research is published in a recent issue of the International Journal of Pharmaceutics.

Zhou noted that other researchers have tried to use liposomes – nanometer-sized bubbles made out of the same material as a cell membrane – to create nonviral vectors for gene delivery. While the material did a good job of protecting the DNA, it did not do a good job of releasing the gene into a cell.

“The liposome gets internalized into cells. It’s sort of like eating food that gets stuck in the stomach or intestines, but never gets to the rest of the body,” he said.

Similarly, calcium phosphate alone has been considered as a gene delivery vehicle. But because of its salty properties, it becomes unstable and expands in size, which makes it too big to penetrate some cell and vascular walls, and which can cause the immune system to reject it.

“So what we do is encapsulate a calcium phosphate core inside the liposome,” Zhou said. “And when this calcium phosphate gets inside a cell and that environment becomes acidic, it gets dissolved and then the gene can be very effectively released into the cytoplasm and transported to the nucleus. That is the theory.”

Zhou and colleagues have developed what they consider an easy method to manufacture this particle. They create a synthetic lipid and place it in a solution that contains calcium and phosphate, which becomes integrated with the lipid. As the acidic properties in the solution change, the calcium phosphate forms a core.

The scientists then mix a solution containing plasmid DNA with their newly formed particle, and all the materials become bundled together. Plasmid DNA is a circular DNA molecule that is able to turn on gene activity that starts a protein-building process without altering an entire genome, or the complete hereditary information of an organism.

Because this particular vector is intended for injection into the bloodstream as a cancer treatment, the particle is designed to protect the DNA from being digested by enzymes as it travels to target cells. A test that exposed this solution to serum, a component of blood, showed that the hybrid particle provided this protection, while unprotected DNA was digested by enzymes.

The researchers next applied this DNA-infused particle solution to mouse cells. The DNA contained the gene code for green fluorescent protein that would be turned on only after it entered the cell. They observed that the particle penetrated the cell membrane and, after a series of interactions occurred, the green fluorescent protein lit up inside the cell, indicating the DNA had reached its target.

For comparison, the group also monitored DNA movement on its own and in other types of vectors. Their hybrid vector was 24 times more effective at delivering genetic material to the cell than was DNA on its own, and 10 times more effective than calcium phosphate preparations.

“We know the particle gets to where it needs to go and what happens to the particle,” Zhou said. “Do we know that the DNA reaches the nucleus? That is something we still need to find out. But because we saw the green fluorescent protein expressed, we think it got to the nucleus or at least as far as the cytoplasm. What’s important is that the protein got inside the cell.”

The study also showed that this hybrid particle maintained its structure for at least 21 days and, when compared with a variety of other potential vector substances, did very little damage to cells, meaning it is not as toxic as most other materials.

With viral vectors, gene therapy is considered a one-time treatment because when the virus carrying new genes infects a cell, that interaction changes the recipient’s entire genome, effectively canceling the activity of the defective gene. Zhou said that with this nonviral vector, treatment would be designed as an intravenous injection on a regular basis until cells are “infected enough to make a change.”

The researchers next plan to test the particle’s ability to travel through the bloodstream and enter target cells in animals.

This work was supported by the National Science Foundation (NSF) and the National Institutes of Health. Zhou has a fellowship in Ohio State’s NSF Nanoscale Science and Engineering Center (NSEC) for Affordable Nanoengineering of Polymeric Biomedical Devices.

He completed the research with Ohio State co-authors Bo Yu and L. James Lee of the Department of Chemical and Biomolecular Engineering; Xiaojuan Yang and Robert Lee of the Division of Pharmaceutics; and Tianyao Huo and Rolf Barth of the Department of Pathology. Yu, Yang, L. James Lee and Robert Lee are also affiliated with the NSEC.

Contact: Chenguang Zhou, (614) 292-5870; zhou.213@osu.edu
Written by Emily Caldwell, (614) 292-8310; caldwell.151@osu.edu

Chenguang Zhou | EurekAlert!
Further information:
http://www.osu.edu

More articles from Life Sciences:

nachricht Warming ponds could accelerate climate change
21.02.2017 | University of Exeter

nachricht An alternative to opioids? Compound from marine snail is potent pain reliever
21.02.2017 | University of Utah

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>