Maximize efficacy through Epidermal Vaccination
In the past few years, there has been a renewed interest in the exploitation of skin vaccination in pursuit of a more potent immune response considering that the skin but not the muscle contains large amounts of antigen-presenting cells (APCs). The epidermis is rich with APCs, the Langerhans cells (LCs), which detect the presence of foreign materials. Unstimulated LCs express low levels of major histocompatibility complex (MHC) and costimulatory molecules. The activation of LCs by antigens triggers a series of molecular events resulting in their migration from the epidermis to the draining lymph nodes, where they initiate adaptive primary immune responses. The majority of existing commercial vaccines are delivered to intramuscular or subcutaneous tissues by needle and syringe. These sites have far fewer resident dendritic cells than the epidermis. The epidermis also lacks vasculature and contains a low density of sensory nerve endings.
Additionally, epidermal immunization can avoid the bleeding and pain that are sometimes associated with needle and syringe immunization. These factors, combined with the abundance and superficial location of LCs, and their potent immune inductive activity, make the skin an attractive target for vaccine delivery.
The major challenge posed by targeting vaccines to the epidermis is to accurately and efficiently access the target tissue. Although the epidermis is superficially located and has a large surface area, access is restricted by the overlying stratum corneum, which forms a physical barrier to molecules > 500 Da molecular weight. Additionally, the epidermal layer is too thin to be reliably accessed by traditional needle and syringe injection.
Aquavit Pharmaceuticals is developing a single-use epidermal drug delivery device that aids in the method of self-administration of biologics, drugs, vaccines, etc. using a microchannel delivery apparatus. The needle features a patented screw thread design that allows the delivery of biologics and vaccines to the epidermis/papillary dermis. Unlike syringe needles and microneedles, the microchannel systems are painless, user-friendly and require a low learning curve. And it can be used by individuals during pandemic/endemic situations or at times when access to healthcare providers and institutions is restricted or limited. It can also be administered by registered physicians, nurses and affiliated doctors.