Iontophoretic transdermal delivery using chitosan-coated PLGA nanoparticles for transcutaneous immunization

Abstract

Transdermal administration of poly(dl-lactide-co-glycolide) (PLGA) nanoparticles using iontophoresis (IP) is useful for efficient drug delivery to hair follicles. In this study, we investigated the possibility of using it in allergen immunotherapy. Hen egg-white lysozyme (HEL) was used as a model antigen. We successfully prepared PLGA nanoparticles with a mean volume diameter of 98.4 ± 36.8 nm using an antisolvent diffusion method. The PLGA nanoparticles were coated with chitosan hydroxypropyltrimonium chloride to shield the PLGA-derived negative charge. The surface charge number density was calculated to be 1.28 × 10−2 M, confirming that the particles had positive charges. An uptake test into dendritic cells was performed using fluorescently labeled HEL. The results of FACS measurement showed that the usage of the nanoparticle carrier increased the mean fluorescence intensity by 5.6 times. An ex vivo skin accumulation study was carried out using abdominal mouse skin and a Franz-type diffusion cell with and without IP. When IP was applied to the nanoparticles, the HEL concentration in mouse skin was 9.6 times higher than that without IP and 2.1 times higher than that of the HEL solution. Images of skin sections confirmed that HEL was efficiently delivered to hair follicles using IP and nanoparticle carriers. HEL-specific IgG1 and IgG2a titers were determined in an in vivo percutaneous immunoreactivity study. Ten weeks after the initiation of the test using IP and the nanoparticle carrier, HEL-specific IgG1 and IgG2a titers were 7.4 × 104 and 6.6 × 102, respectively. Both values were higher than those obtained by subcutaneous injection of HEL solution, indicating the effectiveness of the combined use of IP and nanoparticle carriers.