DNA tattoo patches

Scientists seem fascinated with tattoos these days (my Dec. 4, 2012 posting, my Nov. 9, 2012 posting, March 20, 2012 posting amongst others). The latest work comes from the Massachusetts Institute of Technology (MIT) according to this Jan. 29, 2013 news item,

In a paper appearing in the Jan. 27 [2013] online issue of Nature Materials (“Polymer multilayer tattooing for enhanced DNA vaccination”), MIT researchers describe a new type of vaccine-delivery film that holds promise for improving the effectiveness of DNA vaccines. If such vaccines could be successfully delivered to humans, they could overcome not only the safety risks of using viruses to vaccinate against diseases such as HIV, but they would also be more stable, making it possible to ship and store them at room temperature.

The Jan. 29, 2013 MIT news release by Anne Trafton, which originated the news item, explains the interest in DNA vaccines and this proposed delivery system,

Vaccines usually consist of inactivated viruses that prompt the immune system to remember the invader and launch a strong defense if it later encounters the real thing. However, this approach can be too risky with certain viruses, including HIV.

In recent years, many scientists have been exploring DNA as a potential alternative vaccine. About 20 years ago, DNA coding for viral proteins was found to induce strong immune responses in rodents, but so far, tests in humans have failed to duplicate that success.

This type of vaccine delivery would also eliminate the need to inject vaccines by syringe, says Darrell Irvine, an MIT professor of biological engineering and materials science and engineering. “You just apply the patch for a few minutes, take it off and it leaves behind these thin polymer films embedded in the skin,” he says.

Scientists have had some recent success delivering DNA vaccines to human patients using a technique called electroporation. This method requires first injecting the DNA under the skin, then using electrodes to create an electric field that opens small pores in the membranes of cells in the skin, allowing DNA to get inside. However, the process can be painful and give varying results, Irvine says.

“It’s showing some promise but it’s certainly not ideal and it’s not something you could imagine in a global prophylactic vaccine setting, especially in resource-poor countries,” he says.

Irvine and Hammond took a different approach to delivering DNA to the skin, creating a patch made of many layers of polymers embedded with the DNA vaccine. These polymer films are implanted under the skin using microneedles that penetrate about half a millimeter into the skin — deep enough to deliver the DNA to immune cells in the epidermis, but not deep enough to cause pain in the nerve endings of the dermis.

Once under the skin, the films degrade as they come in contact with water, releasing the vaccine over days or weeks. As the film breaks apart, the DNA strands become tangled up with pieces of the polymer, which protect the DNA and help it get inside cells.

The researchers can control how much DNA gets delivered by tuning the number of polymer layers. They can also control the rate of delivery by altering how hydrophobic (water-fearing) the film is. DNA injected on its own is usually broken down very quickly, before the immune system can generate a memory response. When the DNA is released over time, the immune system has more time to interact with it, boosting the vaccine’s effectiveness.

The polymer film also includes an adjuvant — a molecule that helps to boost the immune response. In this case, the adjuvant consists of strands of RNA that resemble viral RNA, which provokes inflammation and recruits immune cells to the area.

The ability to provoke inflammation is one of the key advantages of the new delivery system, says Michele Kutzler, an assistant professor at Drexel University College of Medicine. Other benefits include targeting the wealth of immune cells in the skin, the use of a biodegradable delivery material, and the possibility of pain-free vaccine delivery, she says.

Here’s a citation and link to the paper,

Polymer multilayer tattooing for enhanced DNA vaccination by Peter C. DeMuth, Younjin Min, Bonnie Huang, Joshua A. Kramer, Andrew D. Miller, Dan H. Barouch, Paula T. Hammond, & Darrell J. Irvine. Nature Materials (2013) doi:10.1038/nmat3550 Published online 27 January 2013

The article is behind a paywall. And, for those who find images help to better understand,

Graphic: Christine Daniloff/MIT [downloaded from http://web.mit.edu/newsoffice/2013/vaccine-film-delivery-hiv-0127.html]

Graphic: Christine Daniloff/MIT [downloaded from http://web.mit.edu/newsoffice/2013/vaccine-film-delivery-hiv-0127.html]

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