Home stretch | Useful new needles

Vaccinations are useful alright, but nobody really enjoys their administration. Microneedles are not only less frightening than the dreaded long hypodermic needle, Anne Römgens thinks they come with many other benefits. She examined this new technique as a PhD candidate at Biomedical Engineering.

“As microneedles do not invade the skin far, no nerves or hardly any are hit; hence it is much less painful than a big hypodermic needle”, Anne Römgens explains. She compares the feeling to a bit of Velcro that is pressed onto the skin. “Then again, I’m not afraid of big needles either, so maybe I am not the ideal subject”, she says with a smile.

The administration of a vaccine with a grid of microneedles (think of a plate the size of a fingertip, with flimsy needles sticking out - a sort of medical Ministeck) comes with a completely different advantage, though: it could also make vaccinations much cheaper. “It is no longer inevitable to administer the vaccine in a liquid form, for you can also apply it as a coating on the needles. In that case you can store the vaccine in a solid state, so that it keeps much longer and does not need to be stored while refrigerated.” This is favorable in particular for distant regions in developing countries, which is actually an important motivating factor for Römgens’ research.

Moreover, in the skin there are many cells that are involved in the immune system. This means that via the short needles - Römgens tested specimens only 0.3 mm long - the vaccine ends up precisely at the right spot, so that you need to administer less of it. “For influenza vaccines this has already been proved”, she says. It is even possible to use soluble needles, which stay in place in the skin and are fully absorbed by it within a minute. In that case there is no sharp waste to worry about either – which is always a potential source of contamination.

Römgens examined under the microscope how deep the needles permeate the skin and how much force this takes, depending on the thickness of the needles. For this purpose she was given residual skin from abdominoplasty procedures performed in the Catharina Hospital. She concluded that the tip of the needle should be less than fifteen micrometer in diameter.

The ideal distance between the needles depends inter alia on the way in which the vaccine is spread in the skin, and how the immune cells that are present there react to it. The PhD candidate described that process by means of a computer model. “Thereby we have shown that the dose per microneedle must be attuned to the distance between the microneedles”, she explains.

Despite all these fantastic benefits the needles will not be on the market for some time yet. This is due to the fact that for a long period it proved to be difficult to make needles with the required dimensions, as Römgens clarifies. And one should also take into account that the effectiveness and safety of medicinal products must naturally first be established without any doubt whatsoever. “Still, more and more people are involved in this now, while the interest from the business community is also increasing rapidly, as I have noticed.” So who knows how soon we may be able to face up to the flu jab without any fears.

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