Methods and Models for the Investigation of the Uptake of Nanoparticles into Hair Follicles

The document discussed the development of in vitro skin models and methods to investigate the uptake of nanoparticles (NPs) into hair follicles, with a focus on their potential for transfollicular vaccination. A method was created to quantify NP deposition in hair follicles, showing a strong correlation between in vitro pig ear models and in vivo human forearm results. Surface modifications, such as phospholipid coatings on poly(lactide-co-glycolide) (PLGA) NPs, were found to affect penetration levels, although massage increased penetration depth but not the amount of NPs in follicles. A proof of concept study demonstrated that PLGA and chitosan-PLGA NPs loaded with ovalbumin stimulated CD4+ and CD8+ T-cells more effectively than ovalbumin in solution, and transfollicular vaccination was possible in mice without prior skin treatment.