Sachiko Hirobe

Transcutaneous immunization using a dissolving microneedle array protects against tetanus, diphtheria, malaria, and influenza.

Transcutaneous immunization (TCI) is an attractive alternative vaccination route compared to the commonly used injection systems. We previously developed a dissolving microneedle array for use as a TCI device, and reported that TCI with the dissolving microneedle array induced an immune response against model antigens. In the present study, we investigated the vaccination efficacy against tetanus and diphtheria, malaria, and influenza using this vaccination system. Our TCI system induced substantial increases in toxoid-specific IgG levels and toxin-neutralizing antibody titer and induced the production of anti-SE36 IgG, which could bind to malaria parasite. On influenza HA vaccination, robust antibody production was elicited in mice that provided complete protection against a subsequent influenza virus challenge. These findings demonstrate that TCI using a dissolving microneedle array can elicit large immune responses against infectious diseases. Based on these results, we are now preparing translational research for human clinical trials.

Development and Clinical Study of a Self-Dissolving Microneedle Patch for Transcutaneous Immunization Device

ABSTRACTPurposeWe previously reported the safety and efficacy in animal experiments of transcutaneous immunization (TCI) using a self-dissolving microneedle patch (MicroHyala; MH) made of hyaluronic acid and collagen. However, this MH was an unsuitable TCI device for the human skin, as collagen is suspected to induce inflammation. In this study, we developed an improved collagen-free MH (new-MH) and conducted clinical study to evaluate the fundamental properties and safety in human.MethodsMicroneedle dissolution, skin irritation, and antigen-specific antibody production about new-MH were measured in mice and/or rats. On the basis of the results, the clinical study was conducted in healthy volunteers to evaluate local and systemic adverse events caused by new-MH application.ResultsWe confirmed that the microneedles of new-MH, as well as those on our old-MH that contained collagen, could easily pierce stratum corneum without severe skin irritation, and that TCI using new-MH efficiently increased antibody titer with comparable to TCI using old-MH. Application of new-MH caused no severe adverse reactions in 20 healthy volunteers enrolled in a clinical study.ConclusionsThese results verified that new-MH is a safe TCI device in human, and greatly encouraged us to advance PI/PII clinical studies of antigen-loaded new-MH.

Frontiers of transcutaneous vaccination systems: Novel technologies and devices for vaccine delivery

Abstract Transcutaneous immunization (TCI) systems that use the skins immune function are promising needle-free, easy-to-use, and low-invasive vaccination alternative to conventional, injectable vaccination methods. To develop effective TCI systems, it is essential to establish fundamental techniques and technologies that deliver antigenic proteins to antigen-presenting cells in the epidermis and dermis while overcoming the barrier function of the stratum corneum. In this review, we provide an outline of recent trends in the development of techniques for the delivery of antigenic proteins and of the technologies used to enhance TCI systems. We also introduce basic and clinical research involving our TCI systems that incorporate several original devices.

Performance and characteristics evaluation of a sodium hyaluronate-based microneedle patch for a transcutaneous drug delivery system

The MicroHyala(®) microneedle (MN) patch was developed to provide a simple, safe, and effective drug delivery system. In this study, we examined the performance and characteristics of our fabricated MN patch to identify potential quality issues with future commercial application. Mechanical failure force analysis identified that the strength of the MN patch was affected by environmental humidity, because higher moisture levels weakened the strength of the MN. Incorporation of all-trans retinoic acid (ATRA) or ovalbumin (OVA) into the MN patch decreased the mechanical failure force by almost 50% of the strength of placebo (without drug) patches. ATRA-loaded MN patches displayed good stability after storage at 4 °C, with more than 90% and 85% of the drug remaining in the patch after 8 and 24 weeks of storage, respectively. Tetanus toxoid- and diphtheria toxoid-loaded MN patches stored for 12 months induced robust antigen-specific immune responses similar to the responses by freshly prepared MN patches. Fluorescence imaging findings suggested that prolonged antigen deposition was induced by MN-mediated fluorescein isothiocyanate-labeled (FITC)-OVA vaccination. Overall, although the strength of MN requires improvement, our developed MN patch appears to be an effective pharmaceutical product providing a simple, safe, and relatively painless approach.

Vaccine efficacy of transcutaneous immunization with amyloid β using a dissolving microneedle array in a mouse model of Alzheimer's disease

Vaccine therapy for Alzheimers disease (AD) based on the amyloid cascade hypothesis has recently attracted attention for treating AD. Injectable immunization using amyloid β peptide (Aβ) comprising 1-42 amino-acid residues (Aβ1-42) as antigens showed therapeutic efficacy in mice; however, the clinical trial of this injected Aβ1-42 vaccine was stopped due to the incidence of meningoencephalitis caused by excess activation of Th1 cells infiltrating the brain as a serious adverse reaction. Because recent studies have suggested that transcutaneous immunization (TCI) is likely to elicit Th2-dominant immune responses, TCI is expected to be effective in treating AD without inducing adverse reactions. Previously reported TCI procedures employed complicated and impractical vaccination procedures; therefore, a simple, easy-to-use, and novel TCI approach needs to be established. In this study, we investigated the vaccine efficacy of an Aβ1-42-containing TCI using our novel dissolving microneedle array (MicroHyala; MH) against AD. MH-based TCI induced anti-Aβ1-42 immune responses by simple and low-invasive application of Aβ1-42-containing MH to the skin. Unfortunately, this TCI system resulted in little significant improvement in cognitive function and Th2-dominant immune responses, suggesting the need for further modification.

Transcutaneous vaccines – current and emerging strategies

Introduction: Vaccination, which is the major fundamental prophylaxis against illness and death from infectious disease, has greatly contributed to the global improvement of human health. However, the disadvantages of conventional injection systems hamper the delivery of vaccination technologies to developing countries. The imminent practice of easy-to-use vaccination methods is expected to overcome certain issues associated with injectable vaccinations. One innovative method is the transcutaneous immunization (TCI) system. Areas covered: Two major strategies for TCI are discussed in this review. One is to promote antigen permeation of the skin barrier by patch systems or nanoparticles. The other is the delivery of antigens into the skin by electroporation and microneedles in order to physically overcome the skin barrier. Moreover, adjuvant development for TCI is discussed. Expert opinion: Many different approaches have been developed for TCI, which have the potential to be effective, easy-to-use and painless methods of vaccination. However, in practical terms, the guidelines concerning the manufacturing processes and clinical trial evaluation of the procedures have not kept pace with the development of these novel formulations. The accumulation of information regarding skin characteristics and the properties of TCI devices will help refine TCI system development guidelines and thus lead to the improvement of transcutaneous vaccination.

Clinical study of transcutaneous vaccination using a hydrogel patch for tetanus and diphtheria

Abstract Transcutaneous immunization (TCI) is a non-invasive and easy-to-use vaccination method. We demonstrated the efficacy and safety of a transcutaneous vaccine formulation using a hydrogel patch in animal experiments. In the present study, we performed a clinical study to apply our TCI formulation for vaccination against tetanus and diphtheria in human. The TCI device was a hydrogel patch (antigen-free) applied to the left brachial medial skin of 22 healthy volunteers for 48h. Next, the hydrogel patch, containing 2mg tetanus toxoid (TT) and 2mg diphtheria toxoid (DT) as the TCI formulation, was applied to 27 healthy volunteers for 24h and some volunteers were vaccinated again by TCI formulation. For safety assessment, the patch application site was observed to assess local adverse events, and systemic adverse events were determined by a blood test. The antigen-free hydrogel patch and TCI formulation containing TT and DT did not induce local or systemic severe adverse events. For vaccine efficacy estimation, toxoid-specific serum antibody titers were determined by ELISA and the toxin-neutralizing activity of the induced antibody was evaluated in a passive-challenge experiment. The anti-TT IgG titer and the anti-DT IgG titer increased, and a significant effect was detected by paired t-test. The antibody titers were maintained at higher level than that before vaccination for at least 1 year. Moreover, toxoid-specific antibodies were produced by the second vaccination in some subjects. Antibodies induced by application of the TCI formulation neutralized the toxin and prevented toxic death in mice. In addition, changes in the skin condition due to application of the TCI formulation were observed under in vivo confocal Raman spectroscopy. The amount of water and patch components in the stratum corneum increased after application of the TCI formulation, suggesting that the change in the skin condition was related to antigen penetration. These data indicate that this easy-to-use TCI system induces an immune response without severe adverse reactions in humans. This easy-to-use and safe TCI formulation enables mass treatment in an outbreak setting and increased vaccination rates in developing countries, and will greatly contribute to worldwide countermeasures against infectious diseases.

Development of a novel therapeutic approach using a retinoic acid-loaded microneedle patch for seborrheic keratosis treatment and safety study in humans

Seborrheic keratosis is one of the most common skin benign tumors in humans with a high occurrence rate of 80%-100% in people > 50 years of age; however, its pathogenesis is still unclear. The standard treatment includes cryotherapy and laser surgery for physically removing lesions. Drug therapy for this condition has not been well established. We aimed to evaluate the use of all-trans retinoic acid (ATRA)-loaded microneedle (MN) patches as a simple, alternative therapeutic option to traditional surgical treatments. This therapeutic strategy was designed to induce the proliferation of basal keratinocytes and accelerate stratum corneum turnover, leading to the lesion falling off the surface of the skin. The MN patch induced epidermal hyperplasia and marked expression of heparin-binding epidermal growth factor-like growth factor mRNA and protein corresponding to ATRA activity in the skin of HR-1 hairless mice. The acceleration of stratum corneum turnover was also observed by the dansyl chloride method. The skin irritation study in mice and safety study in humans support the safety findings of our study. Overall, MN patches can offer an effective and safe means of ATRA delivery into the skin, and the ATRA-loaded MN patch appears to be an effective pharmaceutical product providing a novel therapeutic option for seborrheic keratosis.

Clinical study of a retinoic acid-loaded microneedle patch for seborrheic keratosis or senile lentigo.

Aims: Pigmented lesions such as of seborrheic keratosis and senile lentigo, which are commonly seen on skin of people > 50 years of age, are considered unattractive and disfiguring because of their negative psychological impact. Drug therapy using all‐trans retinoic acid (ATRA) is an attractive option for self‐treatment at home. We have developed an ATRA‐loaded microneedle patch (ATRA‐MN) and confirmed the pharmacological effects of ATRA‐MN application in mice. Here, we describe a clinical study to evaluate the safety and efficacy of ATRA‐MN in subjects with seborrheic keratosis or senile lentigo. Main methods: ATRA‐MN was applied to the lesion site of each subject for 6 h once per week for 4 weeks. The skin irritation reaction was scored to assess adverse reactions and blood tests were performed to evaluate the presence of systemic adverse reactions. To assess the treatment effect using ATRA‐MN, the desquamation and whitening ability of the investigational skin was observed. Key findings: Desquamation of the stratum corneum was observed following four ATRA‐MN applications at 1‐week intervals, but ATRA‐MN applications did not induce severe local or systemic adverse effects. Significance: These results showed that ATRA‐MN treatment is promising as a safe and effective therapy for seborrheic keratosis and senile lentigo.

Analysis of transcutaneous antigenic protein delivery by a hydrogel patch formulation

We have developed a hydrogel patch, which could promote antigen penetration through stratum corneum (SC), and have demonstrated its safety and efficacy in animals and humans. For the availability improvement of our system, it is important to develop a device, which enhances antigen penetration through SC more efficiently. In this study, we have tried to collect the basic information involved in transcutaneous antigen delivery by investigating the immune event induced by our system and examining the effect of physical property of antigens or patch component on antigen penetration. A hydrogel patch delivered antigens through SC into skin, and some of Langerhans cells captured antigens, activated, and migrated to regional lymph nodes. We also showed that protein distribution into SC was regulated by various complexly-intertwined factors of proteins but not one particular parameter. Additionally, glycerin as the patch component contributed to the formation of SC hydration by patch application, which might be one of the factors of acceleration of protein penetration. On the basis of the present information, we are planning to modify the patch composition and establish the antigen modification technology for improvement in the efficacy of transcutaneous immunization.