Cara Donahue

Dissolvable Microneedle Arrays for Intradermal Delivery of Biologics: Fabrication and Application

ABSTRACTPurposeDesign and evaluate a new micro-machining based approach for fabricating dissolvable microneedle arrays (MNAs) with diverse geometries and from different materials for dry delivery to skin microenvironments. The aims are to describe the new fabrication method, to evaluate geometric and material capability as well as reproducibility of the method, and to demonstrate the effectiveness of fabricated MNAs in delivering bioactive molecules.MethodsPrecise master molds were created using micromilling. Micromolding was used to create elastomer production molds from master molds. The dissolvable MNAs were then fabricated using the spin-casting method. Fabricated MNAs with different geometries were evaluated for reproducibility. MNAs from different materials were fabricated to show material capability. MNAs with embedded bioactive components were tested for functionality on human and mice skin.ResultsMNAs with different geometries and from carboxymethyl cellulose, polyvinyl pyrrolidone and maltodextrin were created reproducibly using our method. MNAs successfully pierce the skin, precisely deliver their bioactive cargo to skin and induce specific immunity in mice.ConclusionsWe demonstrated that the new fabrication approach enables creating dissolvable MNAs with diverse geometries and from different materials reproducibly. We also demonstrated the application of MNAs for precise and specific delivery of biomolecules to skin microenvironments in vitro and in vivo.

In vivo induction of regulatory T cells promotes allergen tolerance and suppresses allergic contact dermatitis

Abstract Allergic contact dermatitis (ACD) is a common T‐cell mediated inflammatory skin condition, characterized by an intensely pruritic rash at the site of contact with allergens like poison ivy or nickel. Current clinical treatments use topical corticosteroids, which broadly and transiently suppress inflammation and symptoms of ACD, but fail to address the underlying immune dysfunction. Here, we present an alternative therapeutic approach that teaches the immune system to tolerate contact allergens by expanding populations of naturally suppressive allergen‐specific regulatory T cells (Tregs). Specifically, biodegradable poly(ethylene glycol)‐poly(lactic‐co‐glycolic acid) (PEG‐PLGA) microparticles were engineered to release TGF‐&bgr;1, Rapamycin, and IL‐2, to locally sustain a microenvironment that promotes Treg differentiation. By expanding allergen‐specific Tregs and reducing pro‐inflammatory effector T cells, these microparticles inhibited destructive hypersensitivity responses to subsequent allergen exposure in an allergen‐specific manner, effectively preventing or reversing ACD in previously sensitized mice. Ultimately, this approach to in vivo Treg induction could also enable novel therapies for transplant rejection and autoimmune diseases. Graphical abstract Figure. No Caption available.

Skin Immunization Obviates Alcohol-Related Immune Dysfunction.

Alcoholics suffer from immune dysfunction that can impede vaccine efficacy. If ethanol (EtOH)-induced immune impairment is in part a result of direct exposure of immune cells to EtOH, then reduced levels of exposure could result in less immune dysfunction. As alcohol ingestion results in lower alcohol levels in skin than blood, we hypothesized that the skin immune network may be relatively preserved, enabling skin-targeted immunizations to obviate the immune inhibitory effects of alcohol consumption on conventional vaccines. We employed the two most common chronic EtOH mouse feeding models, the liver-damaging Lieber-DeCarli (LD) and liver-sparing Meadows-Cook (MC) diets, to examine the roles of EtOH and/or EtOH-induced liver dysfunction on alcohol related immunosuppression. Pair-fed mice were immunized against the model antigen ovalbumin (OVA) by DNA immunization or against flu by administering the protein-based influenza vaccine either systemically (IV, IM), directly to liver (hydrodynamic), or cutaneously (biolistic, ID). We measured resulting tissue EtOH levels, liver stress, regulatory T cell (Treg), and myeloid-derived suppressor cell (MDSC) populations. We compared immune responsiveness by measuring delayed-type hypersensitivity (DTH), antigen-specific cytotoxic T lymphocyte (CTL), and antibody induction as a function of delivery route and feeding model. We found that, as expected, and independent of the feeding model, EtOH ingestion inhibits DTH, CTL lysis, and antigen-specific total IgG induced by traditional systemic vaccines. On the other hand, skin-targeted vaccines were equally immunogenic in alcohol-exposed and non-exposed subjects, suggesting that cutaneous immunization may result in more efficacious vaccination in alcohol-ingesting subjects.