Testing a Painless Treatment for Skin Diseases

Skin is the largest organ in the human body and there are a number of diseases, both hereditary and acquired, that affect it. Treating these diseases requires delivering medicines beneath the outermost protective layer of the skin, called the stratum corneum. The most common way to do this is through shots.

One potential treatment for many skin diseases is called RNA interference. RNA is a type of molecule in the body that contains the genetic code for translation into proteins, the building blocks of organs such as the skin. In patients with skin diseases, this genetic code may be damaged – causing genes to produce too many, or too few, proteins.

RNA interference involves using special double-stranded RNA (called siRNA) to regulate these genes. One of the two strands of RNA is activated by special proteins. This strand then finds a target gene within the body, allowing the proteins to destroy the targeted message. This therapy, though, would be painful for patients because it has to be delivered through a series of needle injections into the deep layers of the skin.

A recent publication in Molecular Therapy reports on an innovative, painless approach for penetrating the stratum corneum and delivering siRNAs to the epidermal and dermal layers of the skin. The investigators in this study developed a new polymer material that forms microneedle arrays that are long enough to reach the epidermis, but too short to prick the sensitive dermis. The approach is termed a Soluble Protrusion Array Device (PAD). These microneedle arrays are especially useful for treating skin diseases since they can be designed to deliver a uniform volume of siRNAs over a wide surface area.

The investigators further demonstrated that PADs applied to mouse foot pads successfully deposited the siRNA into the epidermal and dermal layers. The PAD-delivered siRNAs also inhibited expression of a targeted gene in the treated mice.

Overall, this study provides an exciting, nontoxic and painless approach for treatment of skin diseases using siRNAs. Expect to see this PAD approach in clinical trial in the not too distant future.