Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 151-165). / Immunization is a powerful approach for the prevention and control of infectious disease, however despite the successes of modem vaccine development, there remain several notable obstacles for the advancement of vaccine-mediated improvements in global healthcare. Many of the current limitations in vaccine availability and administration are the result of obligate needle-based delivery, which in addition to contributing to reduced speed, ease, and compliance in administration, has been shown to contribute to reduced overall safety due to needle re-use and needle-based injuries. Needle-based vaccine delivery to immunologically passive tissues such as muscle may limit efficacy, thus motivating the targeting of more inherently potent immune-competent sites. These inherent limitations of needle-based vaccination on global health have led to a strong impetus to develop needle-free vaccination strategies which have the potential to improve vaccine efficacy and availability, enhance the ease, speed, and safety of vaccine administration, and reduce vaccination associated costs world-wide. Here we present the design and preclinical testing of several parallel materials strategies for the noninvasive delivery of subunit vaccines to the skin. We have utilized laser ablative micro-molding of poly(dimethylsiloxane) to generate bio resorbable poly(lactide-co-glycolide) micro-structured skin patches bearing -100 micron-scale needles arrayed across their surface. Upon topical application, these 'microneedle arrays' are able to safely, and painlessly insert into the immune-competent epidermal skin layers to generate microscopic conduits through which otherwise impermeant vaccines and therapeutics are able to passage into the body. We have leveraged this approach in combination with layer-by-layer (LbL) directed assembly to generate vaccine-loaded conformal coatings on the surface of these microneedle arrays, which are then delivered into the skin through topical patch application. The construction of coatings containing antigen-expressing plasmid DNA (pDNA), together with immune-stimulatory RNA, and degradable cationic polymers provided tunable control over vaccine dosage, rapid and effective vaccine delivery in murine and primate skin models, and potent immunogenicity against a model HIV antigen in mice. In this case, DNA vaccine delivery was able to elicit strong functional CD8' T cell and humoral responses matching or exceeding the potency of in vivo electroporation, currently the most promising approach for clinical DNA delivery in humans. Further efforts have explored the use of LbL for encapsulation and delivery of soluble and particulate protein subunit vaccines, giving enhanced generation of diverse and potent humoral responses in mice. In other work, we have developed an approach enabling rapid delivery of micron-scale degradable polymer matrices or hydrogel depots using dissolvable composite microneedle structures for the delivery of vaccines with programmable kinetics. These efforts have demonstrated the potential of persistent vaccine release on tuning immune potency following non-invasive microneedle delivery, including induction of potent effector and memory CD8* T cell responses and more powerful and diverse antigen-specific humoral responses. Finally, we have developed an approach for simple loading and delivery of clinically advanced recombinant adenoviral vaccine vectors from sugar-glass coatings on bioresorbable microneedles. Formulation in microneedle coatings improved vaccine stability at room temperature and preclinical testing of these vaccine patches in mice and nonhuman primates demonstrated equivalent immunogenicity compared to parenteral injection, eliciting strong systemic and disseminated mucosal CD8' and CD4* T cell responses to a model HIV antigen. These cellular responses were correlated with a similarly potent systemic and mucosal humoral response, together suggesting the utility of this approach for non-invasive adenoviral immunization in a model close to humans. Together these results strongly demonstrate the potential of materials engineering strategies for the effective formulation, delivery, and release of recombinant vaccines by microneedle patches targeting the skin. In addition to the significant practical advantages enabled by microneedle delivery including improved safety, convenience, and storage, we have shown that advanced formulation strategies paired with controlled release are able to initiate humoral and cellular adaptive immunity more potently than possible through parenteral injection. Comprehensive tests in both mice and primates have suggested that these principles may be broadly applied to enhance various recombinant vaccination strategies potentially targeting numerous disease targets. Finally, initial tests performed in nonhuman primates have indicated the promise of engineered microneedle approaches for successful translation to humans. Overall, these findings provide a strong basis for the continued development of similar vaccination strategies for the comprehensive transformation of conventional vaccination enabling significant vaccine-mediated improvements in global health. / by Peter C. DeMuth. / Ph.D.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/81667 |
| Date | January 2013 |
| Creators | DeMuth, Peter C. (Peter Charles) |
| Contributors | Darrell J. Irvine and Paula T. Hammond., Massachusetts Institute of Technology. Department of Biological Engineering., Massachusetts Institute of Technology. Department of Biological Engineering. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 165 p., application/pdf |
| Rights | MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission., http://dspace.mit.edu/handle/1721.1/7582 |
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