Transdermal delivery by smart tattoo

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Tattoos are already used in the clinic to mark where doctors will apply radiation treatments, to correct skin discoloration, to mark potential tumors or other pathologies in endoscopic surgery, and for applying permanent makeup.

Now, researchers in fields spanning from chemical engineering and dermatology to medical anthropology are investigating tattoos not only as therapeutic in nature, but also as a means for better drug delivery and as “smart tattoos” to monitor and diagnose diseases. Tattoos are more than skin deep.

Affectionately known as Ötzi, or the Iceman, the 5,300-year-old mummy has several tattoos decorating his body. Unlike the pictorial tattoos popular today, Ötzi’s tattoos consist of lines and crosses, and most are in locations that would have been covered by his clothes such as at the base of his spine, ankles, and around his knees. Because of this, researchers hypothesize that his tattoos were likely therapeutic in nature, and the fact that almost all of his tattoos line up with traditional acupuncture points to relieve pain supports this theory.

While some tattoo pigments elicit an allergic reaction, researchers wondered whether they could tip the immune scales in the opposite direction and use tattooing as a mode of vaccination. With the skin’s unique composition of immune cells, it is an excellent place to mount a multi-faceted immune response of antibodies and immune cells. Capitalizing on this, researchers have developed multiple methods to target immune cells in the skin, including a gene gun (which shoots DNA-coated gold particles and was originally developed to genetically modify plants), microneedles, a jet injector (a high-pressure stream of liquid containing vaccine components), and a tattoo machine.

Researchers have mostly investigated the potential of tattoo-based vaccination in the context of DNA vaccines because DNA vaccines delivered via the skin generally induce a stronger immune response than vaccines injected into the muscle. While there are multiple DNA vaccines in clinical trials for HIV, human papilloma virus (HPV), Zika fever, and cancer, the only DNA vaccine approved for human use so far is India’s ZyCoV-D DNA vaccine against SARS-CoV-2.

In a study comparing intramuscular vaccination to tattoo-based vaccination, researchers found that the tattoo delivery strategy led to a faster T cell response to HPV and protection against an influenza virus challenge. More T cells encountered the vaccine antigen via tattooing than when the same vaccine was given via a standard injection into the muscle.

As far as we know the cyclodextrin-based tattoos have not been studied yet.

Demarko, S. Tattoo therapeutics deliver medicine more than skin deep. DDN Oct. 12, 2022

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