Overcoming the stratum corneum barrier: microneedle delivery of macromolecules and vaccines [Abstract]

Microneedle patches are being developed as a method for painlessly and transiently disrupting the stratum corneum barrier to facilitate both the localised and systemic delivery of an extended range of drugs, macromolecules and vaccines. Despite an increasing body of evidence demonstrating the practical utility of this approach, a number of important challenges still require addressing before the technology can translate from a proven laboratory concept to a widely accepted clinical tool. Therefore, whilst academic groups and commercial ventures continue to improve microneedle design and extend the applications for the technology, our attention is now turning to the translatable aspects of the approach, i.e. ensuring that clinical microneedle use is intuitive, effective and reproducible. Our research projects aim to contribute to this goal through (i) Employing computational and imaging techniques to learn how microneedles perform in the real human skin environment and investigate microchannel injury and repair, (ii) Using freshly excised human skin as a relevant model to monitor the efficacy, reproducibility and safety of microneedle-assisted delivery of drugs, nanoparticles and nucleic acids, (iii) Demonstrating stimulation of immune response (and characterising the mechanism of such a response at the cellular and molecular level) in human tissue following microneedle vaccination with influenza and other vaccines, (iv) Developing and optimising the formulation of fastdissolving sugar glass microneedles, coated solid microneedles and liquid-loaded pocketed microneedles that retain the stability and facilitate the effective targeted delivery of model and therapeutic proteins, (v) Using public volunteer studies to inform device application procedures to ensure simple and reliable microneedle insertion, and (vi) Engaging with healthcare practitioners and the general public to capture the opinions, perceptions and concerns of potential end-users of microneedle technology. An update on our progress in each of these areas will be presented with grateful acknowledgement of the collaborative support of engineers, physicists, pharmacists, clinical dermatologists, immunologists and fellow pharmaceutical scientists