Microneedles for gene and drug delivery in skin cancer therapy

The success of skin cancer treatment is severely limited in the route of administration because most genes and drugs cannot break through the excellent stratum corneum (SC) barrier of the skin, leading to their inability to reach the tumor tissues at therapeutic doses. As an excellent minimally invasive delivery method, microneedles (MNs) can bypass the SC and enter the skin microcirculation to achieve drug and gene delivery when used to puncture the skin. Compared with traditional administration approaches, MN-assisted gene and drug delivery have obvious advantages, in that they are simple, safe, painless, easily transport genes (such as DNA and siRNA (small interfering RNA)) and macromolecule drugs (including proteins and antibodies), and have good reproducibility. Besides, other treatment strategies including photothermal therapy (PTT) have been combined with MN arrays containing genes or drugs, which is expected to improve the therapeutic effect of skin cancer. Therefore, this review summarizes the latest developments in MNs for gene and/or drug delivery, with a focus on their performances as effective MNs for skin cancer treatment.