Performance and usability evaluation of novel intradermal injection device Immucise™ and reanalysis of intradermal administration trials of influenza vaccine for the elderly

A Hollow Microneedle Equipped with a Micropillar for Improved Needle Insertion and Injection of Drug Solution

PURPOSE

Hollow-type microneedles (hMNs) are a promising device for the effective administration of drugs into intradermal sites. Complete insertion of the needle into the skin and administration of the drug solution without leakage must be achieved to obtain bioavailability or a constant effect. In the present study, several types of hMN with or without a rounded blunt tip micropillar, which suppresses skin deformation, around a hollow needle, and the effect on successful needle insertion and administration of a drug solution was investigated. Six different types of hMNs with needle lengths of 1000, 1300, and 1500 µm with or without a micropillar were used.

METHODS

Needle insertion and the disposition of a drug in rat skin were investigated. In addition, the displacement-force profile during application of hMNs was also investigated using a texture analyzer with an artificial membrane to examine needle factors affecting successful insertion and administration of a drug solution by comparing with in vivo results.

RESULTS

According to the results with the drug distribution of iodine, hMN1300 with a micropillar was able to successfully inject drug solution into an intradermal site with a high success rate. In addition, the results of displacement-force profiles with an artificial membrane showed that a micropillar can be effective for depth control of the injected solution as well as the prevention of contact between the hMN pedestal and the deformed membrane.

CONCLUSION

In the present study, hMN1300S showed effective solution delivery into an intradermal site. In particular, a micropillar can be effective for depth control of the injected solution as well as preventing contact between the hMN pedestal and the deformed membrane. The obtained results will help in the design and development of hMNs that ensure successful injection of an administered drug.

Microneedle-Mediated Cell Therapy

Microneedles have emerged as a promising platform for transdermal drug delivery with prominent advantages, such as enhanced permeability, mitigated pain, and improved patient adherence. While microneedles have primarily been employed for delivering small molecules, nucleic acids, peptides, and proteins, recent researches have demonstrated their prospect in combination with cell therapy. Cell therapy involving administration or transplantation of living cells (e.g. T cells, stem cells, and pancreatic cells) has gained significant attention in preclinical and clinical applications for various disease treatments. However, the effectiveness of systemic cell delivery may be restricted in localized conditions like solid tumors and skin disorders due to limited penetration and accumulation into the lesions. In this perspective, an overview of recent advances in microneedle-assisted cell delivery for immunotherapy, tissue regeneration, and hormone modulation, with respect to their mechanical property, cell loading capacity, as well as viability and bioactivity of the loaded cells is provided. Potential challenges and future perspectives with microneedle-mediated cell therapy are also discussed.

mRNA vaccine designs for optimal adjuvanticity and delivery

Adjuvanticity and delivery are crucial facets of mRNA vaccine design. In modern mRNA vaccines, adjuvant functions are integrated into mRNA vaccine nanoparticles, allowing the co-delivery of antigen mRNA and adjuvants in a unified, all-in-one formulation. In this formulation, many mRNA vaccines utilize the immunostimulating properties of mRNA and vaccine carrier components, including lipids and polymers, as adjuvants. However, careful design is necessary, as excessive adjuvanticity and activation of improper innate immune signalling can conversely hinder vaccination efficacy and trigger adverse effects. mRNA vaccines also require delivery systems to achieve antigen expression in antigen-presenting cells (APCs) within lymphoid organs. Some vaccines directly target APCs in the lymphoid organs, while others rely on APCs migration to the draining lymph nodes after taking up mRNA vaccines. This review explores the current mechanistic understanding of these processes and the ongoing efforts to improve vaccine safety and efficacy based on this understanding.

Efficient drug delivery to lymph nodes by intradermal administration and enhancement of anti-tumor effects of immune checkpoint inhibitors

Immune checkpoint inhibitors are novel immunotherapy drugs that have improved cancer treatments. Yet only a small percentage of patients experience durable responses to immune checkpoint inhibitors. Recently, it has been suggested that lymph nodes are important for the efficacy of immunotherapy. However, it is still unclear whether the efficient anti-PD-L1 antibody delivery to tumor-draining lymph nodes improves drug efficacy. In this study, we first characterized lymphatic drug delivery by intradermal administration compared with conventional subcutaneous and systemic administration in rodents and non-human primates. The results confirmed that intradermal administration of immune checkpoint inhibitors is suitable for efficient delivery to the tumor-draining lymph node. In FM3A and EMT6 tumor mice models with different PD-L1 expressions in tumor, efficient delivery of anti-PD-L1 antibody to tumor-draining lymph node by intradermal administration resulted in efficient inhibition of tumor growth in both models. The intradermal administration of low-dose anti-PD-L1 antibody also significantly suppressed tumor growth compared to intraperitoneal administration. It also suppressed tumor growth regardless of PD-L1 expression in tumors, suggesting the importance of blocking PD-L1 in tumor-draining lymph nodes. Hence, efficient delivery by intradermal administration of anti-PD-L1 antibody to tumor-draining lymph node might to be helpful to enhance drug efficacy and potentially reduce adverse events.

Dose-sparing effect of Sabin-derived inactivated polio vaccine produced in Japan by intradermal injection device for rats

The live-attenuated oral polio vaccine has long been used as the standard for polio prevention, but in order to minimize the emergence of pathogenic revertants, the inactivated polio vaccine (IPV), which is administered intramuscularly or subcutaneously, is being increasingly demanded worldwide. However, there is a global shortage of IPV, and its cost is an obstacle in developing countries. Therefore, dose-sparing with intradermal administration of IPV has been investigated. In this study, rats were immunized by intradermal (ID) and intramuscular (IM) administration of Sabin-derived inactivated polio vaccine (sIPV) produced in Japan, and the immune responses were evaluated. The results showed that one-fifth (1/5)-dose of ID administration yielded neutralizing antibody titers comparable to the full-dose IM administration, whereas 1/5-dose of IM administration was less effective than the full dose. Furthermore, a vertical puncture-type ID injection device (Immucise) that was originally developed for humans was modified for rats, resulting in successful and stable ID administration into the thin skin of rats. Based on these results, the ID administration of sIPV using Immucise in clinical use is expected to offer benefits such as reduced amounts of vaccine per dose, cost-effectiveness, and thereby the feasibility of vaccination for more people.

Enhancing Immunogenicity of Influenza Vaccine in the Elderly through Intradermal Vaccination: A Literature Analysis

BACKGROUND

Aging and immunosenescence lead to a gradual decline in immune responses in the elderly and the immunogenicity of influenza vaccines in this age group is sub-optimal. Several approaches have been explored to enhance the immunogenicity of influenza vaccines in the elderly, including incorporating vaccine adjuvant, increasing antigen dosage, and changing the route of vaccine administration.

METHOD

We systematically compared the immunogenicity and safety of influenza vaccines administered by intradermal (ID) route and either intramuscular (IM) or subcutaneous (SC) routes in older adults aged ≥ 65.

RESULTS

Of 17 studies included in this analysis, 3 studies compared the immunogenicity of ID vaccination to that of SC vaccination and 14 studies compared ID and IM vaccinations. ID vaccination was typically more immunogenic than both IM and SC routes at the same dosage. Importantly, a minimum of 3 µg of hemagglutinin antigen could be formulated in an ID influenza vaccine without a significant loss of immunogenicity. ID administration of standard-dose, unadjuvanted influenza vaccine was as immunogenic as IM injection of adjuvanted influenza vaccine. Waning of influenza-specific immunity was significant after 6 months, but there was no difference in waning immunity between vaccinations in ID, IM, or SC routes. While ID vaccination elicited local adverse reactions more frequently than other routes, these reactions were mild and lasted for no more than 3 days.

CONCLUSIONS

We conclude that ID vaccination is superior to IM or SC routes and may be a suitable approach to compensate for the reduced immunogenicity observed in elderly adults. We also conclude that the main benefit of ID influenza vaccine lies in its dose-sparing effect. Additional research is still needed to further develop a more immunogenic ID influenza vaccine.

Does an Intradermal Vaccination for Monkeypox Make Sense?

Mankind has recently had to deal a series of virus-mediated pandemics, resulting in extensive morbidity and mortality rates that have severely strained healthcare systems. While dealing with viral infections as a healthcare concern is not new, our exceptionally mobile society has added to the critical challenge of limiting pathogen spread of a highly transmissible virus prior to the generation, testing, and distribution of safe and effective vaccines. The tremendous global effort put forth to address the recent pandemic induced by SARS-CoV-2 infection has highlighted many of the strengths and weaknesses of how vaccines are identified, tested, and used to provide protection. These uncertainties are exacerbated by the lack of clear and consistent messaging that can occur when the processes of research, development, and clinical testing that normally requires years of study and consideration are compressed into a few months. In this commentary, I will provide some background on the intramuscular (IM), subcutaneous (SC), and intradermal (ID) administration routes used for injectable vaccines and some information on potential immunological outcomes. With this background, I will address the recent FDA decision to allow an approved vaccine against monkeypox virus to be administered by ID, as well as its initial approval route via SC, injection as a dose-sparing strategy to maximize immunization numbers using current stockpiles.

Controllable self-replicating RNA vaccine delivered intradermally elicits predominantly cellular immunity

Intradermal delivery of self-replicating RNA (srRNA) is a promising vaccine platform. Considering that human skin temperature is around 33°C, lower than core body temperature of 37°C, we have developed an srRNA that functions optimally at skin temperature and is inactivated at or above 37°C as a safety switch. This temperature- c ontrollable srRNA (c-srRNA), when tested as an intradermal vaccine against SARS-CoV-2, functions when injected naked without lipid nanoparticles. Unlike most currently available vaccines, c-srRNA vaccines predominantly elicit cellular immunity with little or no antibody production. Interestingly, c-srRNA-vaccinated mice produced antigen-specific antibodies upon subsequent stimulation with antigen protein. Antigen-specific antibodies were also produced when B-cell stimulation using antigen protein was followed by c-srRNA booster vaccination. Using c-srRNA, we have designed a pan-coronavirus booster vaccine that incorporates both spike receptor binding domains as viral surface proteins and evolutionarily conserved nucleoproteins as viral non-surface proteins, from both SARS-CoV-2 and MERS-CoV. It can thereby potentially immunize against SARS-CoV-2, SARS-CoV, MERS-CoV, and their variants. c-srRNA may provide a route to activate cellular immunity against a wide variety of pathogens.