A Promising Needle-Free Pyro-Drive Jet Injector for Augmentation of Immunity by Intradermal Injection as a Physical Adjuvant.

Current worldwide mRNA vaccination against SARS-CoV-2 by intramuscular injection using a needled syringe has greatly protected numerous people from COVID-19. An intramuscular injection is generally well tolerated, safer and easier to perform on a large scale, whereas the skin has the benefit of the presence of numerous immune cells, such as professional antigen-presenting dendritic cells. Therefore, intradermal injection is considered superior to intramuscular injection for the induction of protective immunity, but more proficiency is required for the injection. To improve these issues, several different types of more versatile jet injectors have been developed to deliver DNAs, proteins or drugs by high jet velocity through the skin without a needle. Among them, a new needle-free pyro-drive jet injector has a unique characteristic that utilizes gunpower as a mechanical driving force, in particular, bi-phasic pyrotechnics to provoke high jet velocity and consequently the wide dispersion of the injected DNA solution in the skin. A significant amount of evidence has revealed that it is highly effective as a vaccinating tool to induce potent protective cellular and humoral immunity against cancers and infectious diseases. This is presumably explained by the fact that shear stress generated by the high jet velocity facilitates the uptake of DNA in the cells and, consequently, its protein expression. The shear stress also possibly elicits danger signals which, together with the plasmid DNA, subsequently induces the activation of innate immunity including dendritic cell maturation, leading to the establishment of adaptive immunity. This review summarizes the recent advances in needle-free jet injectors to augment the cellular and humoral immunity by intradermal injection and the possible mechanism of action.

Induction of potent antitumor immunity by intradermal DNA injection using a novel needle-free pyro-drive jet injector.

The current success of mRNA vaccines against COVID-19 has highlighted the effectiveness of mRNA and DNA vaccinations. Recently, we demonstrated that a novel needle-free pyro-drive jet injector (PJI) effectively delivers plasmid DNA into the skin, resulting in protein expression higher than that achieved with a needle syringe. Here, we used ovalbumin (OVA) as a model antigen to investigate the potential of the PJI for vaccination against cancers. Intradermal injection of OVA-expression plasmid DNA into mice using the PJI, but not a needle syringe, rapidly and greatly augmented OVA-specific CD8+ T-cell expansion in lymph node cells. Increased mRNA expression of both interferon-γ and interleukin-4 and an enhanced proliferative response of OVA-specific CD8+ T cells, with fewer CD4+ T cells, were also observed. OVA-specific in vivo killing of the target cells and OVA-specific antibody production of both the IgG2a and IgG1 antibody subclasses were greatly augmented. Intradermal injection of OVA-expression plasmid DNA using the PJI showed stronger prophylactic and therapeutic effects against the progression of transplantable OVA-expressing E.G7-OVA tumor cells. Even compared with the most frequently used adjuvants, complete Freund's adjuvant and aluminum hydroxide with OVA protein, intradermal injection of OVA-expression plasmid DNA using the PJI showed a stronger CTL-dependent prophylactic effect. These results suggest that the novel needle-free PJI is a promising tool for DNA vaccination, inducing both a prophylactic and a therapeutic effect against cancers, because of prompt and strong generation of OVA-specific CTLs and subsequently enhanced production of both the IgG2a and IgG1 antibody subclasses.

Effect of mRNA Delivery Modality and Formulation on Cutaneous mRNA Distribution and Downstream eGFP Expression.

In vitro transcribed messenger ribonucleic acid (mRNA) constitutes an emerging therapeutic class with several clinical applications. This study presents a systematic comparison of different technologies-intradermal injection, microneedle injection, jet injection, and fractional laser ablation-for the topical cutaneous delivery of mRNA. Delivery of Cy5 labeled mRNA and non-labeled enhanced green fluorescent protein (eGFP) expressing mRNA was investigated in a viable ex vivo porcine skin model and monitored for 48 h. Forty 10 µm-thick horizontal sections were prepared from each skin sample and Cy5 labeled mRNA or eGFP expression visualized as a function of depth by confocal laser scanning microscopy and immunohistochemistry. A pixel-based method was used to create a semi-quantitative biodistribution profile. Different spatial distributions of Cy5 labeled mRNA and eGFP expression were observed, depending on the delivery modality; localization of eGFP expression pointed to the cells responsible. Delivery efficiencies and knowledge of delivery sites can facilitate development of efficient, targeted mRNA-based therapeutics.

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

Under the pandemic situation, there is an urgent need to produce and acquire sufficient quantities of prophylactic vaccines. It becomes important to devise a way to achieve reliable immunity with lower doses to distribute limited supplies of vaccines to maximum number of people very quickly. Intradermal (ID) vaccination is one such method to increase the effectiveness of vaccines. However, this method has not been widely used in general clinical practice because it is technically difficult to inject vaccines precisely into the ID tissue. Therefore, new ID delivery systems that allow reliable ID administration are under development. In this paper, we summarize its design and present the results of performance and usability testing for the Immucise™ Intradermal Injection System (Immucise™). This study showed that Immucise™ can reduce dead volume and inject drugs precisely into the ID tissues of subjects from infants to the elderly and can be used correctly and safely by healthcare professionals. This randomized controlled trial compared ID administration with Immucise™ and standard subcutaneous (SC) administration of seasonal influenza vaccine by analyzing the efficacy of the vaccine in the elderly group at 90 days and 180 days after administration. It was found that the vaccine for the ID group was as effective or more effective than that for the SC group up to 180 days later. It was also found that the geometric mean titer values, especially for B strains, were higher in the two-dose ID group than in the two-dose SC group. These findings suggest that Immucise™ is one of the best devices to distribute a small amount of vaccine quickly and widely to a larger number of people with little loss of vaccine during a pandemic.

Hyaluronic acid soft tissue filler delayed inflammatory reaction following COVID-19 vaccination - A case report.

BACKGROUND: The use of hyaluronic acid soft tissue fillers in aesthetic medicine exploded in recent years for many reasons, including being relatively safe. Incidence of delayed inflammatory reactions (DIRs) to hyaluronic acid soft tissue fillers range between 0.3% and 4.25%. These reactions are mediated by T-lymphocytes and can be triggered by flu-like illnesses, including SARS-CoV-2 infection. Vaccination may also induce hypersensitivity. AIM: In this case report, we present two cases of delayed reaction after hyaluronic acid soft tissue filler treatment of the tear trough area and following mRNA vaccination against SARS-Cov-2, also known as COVID-19, months later. PATIENTS: A 39-year old female who previously had her tear trough area treated with hyaluronic acid soft tissue filler developed swelling days after getting the mRNA Pfizer-BioNTech COVID-19 vaccine. Another patient, a 61-year-olf female, developed intermittent facial swelling in areas previously treated with hyaluronic acid soft tissue fillers days after receiving her first dose of the mRNA Pfizer-BioNTech COVID-19 vaccine. RESULTS: As demonstrated in our case report, vaccination against COVID-19 may induce DIRs in patients who previously had hyaluronic soft tissue fillers. CONCLUSION: Delayed inflammatory reactions to hyaluronic acid soft tissue fillers are uncommon and usually self-limited, with frequent spontaneous resolution. However, considering the ongoing pandemic and the worldwide demand for vaccines against COVID-19, the aesthetic providers should be conscious of the risks posed by the interaction of such vaccines in patients who previously had or seeking hyaluronic acid soft tissue filler injections.