Vaccine tattooing proves effective

Key Points

National Report - Skin-tattooing devices may be associated more with vanity than vaccines, but in the hands of researchers in Germany and England, the devices are indeed showing promise as valuable delivery vehicles for important vaccines or pharmaceutical medicines.

In a study looking at skin tattooing as a means of delivering DNA to stimulate an immune response and help prevent diseases including cancer, researchers found the tattoo injection of molecular DNA fragments to be far more effective than the alternative of intramuscular injection, which has so far been shown to have only limited efficacy.

The murine study looked at the injection of the major capsid protein L1 - a protein fragment of human papillomavirus type 16 - via intradermal tattoo versus intramuscular injection.

The tattoo injections induced the higher immune responses compared with intramuscular injection, even though adjuvants improved the intramuscular injection response, but not the tattoo response.

"Three doses of DNA delivered by tattoo induced at least 16 times higher levels of anti-L1 antibodies than three intramuscular DNA immunizations applied after (molecular adjuvant) cardiotoxin pre-treatment or GM-CSF DNA co-delivery," the researchers report.

In addition, among mice treated with the tattoo device, the lymphocytes proliferated more strongly after mitogen stimulation, indicating an inflammatory response following the tattooing.

"The tattoo delivery of DNA is a cost-effective method that may be used in laboratory conditions when more rapid and more robust immune responses are required," the researchers concluded (Genetic Vaccines and Therapy. 2008, 6:4).

Regeneration and stimulation

Tattoo devices use a solid vibrating needle that repeatedly punctures the skin, wounding the epidermis and the dermis.

According to Martin Mueller, Ph.D., a study author, the injury to the skin is preceded by hemorrhage, necrosis, inflammation and ultimately a regeneration that stimulates the immune system.

"The tattoo injection causes some local tissue damage and inflammation, which attracts what are probably just the right immune cells," says Dr. Mueller, of the German Cancer Research Centre in Heidelberg.

"Sometimes a new antigen may not be enough to trigger a strong enough response from the immune system, but the danger signals generated by dead cells or necrosis on the microscopic level could be the sufficient signal that is needed."

While the specific cellular process triggered by the tattoo injection may be somewhat complex, the tattoo device, itself, was decidedly low-tech, Dr. Mueller tells Dermatology Times.

"We simply used a tattoo device that we purchased from a tattoo supply store - the same type meant to be used on humans. It wasn't customized at all," he says.

Since no ink was used in the injections, no permanent mark was left behind on the skin after the injections.

Even without ink, however, recipients of any type of tattoo injections may have a long-lasting memory of the notorious pain associated with the process.

But in the context of treating the serious diseases that DNA tattoo therapy would be used for, the pain would likely be more acceptable, Dr. Mueller says.

"The normal decorative tattooing process can involve sitting for more than an hour and enduring the pain.

"This, on the other hand, would be just a short 15 or 20 seconds," he says.

Meanwhile, new tattoo injection technology being developed in England - also for medical purposes - could help to further ease some of the pain in the process.

Researchers with the Surrey-based Imprint Pharma are developing a painless tattoo machine that could be used to deliver drugs to the skin.

Peter Crocker, the company's director, says the device's tattoo needles were designed to work in a manner that causes less damage to the skin.

"The needle makes a tiny cut and stretches the skin, rather than making a bigger cut, and it delivers a very fast injection compared to a normal tattooing machine.