Noninvasive Transdermal Administration of mRNA Vaccines Encoding Multivalent Neoantigens Effectively Inhibits Melanoma Growth.

It is difficult to obtain specific tumor antigens, which is one of the main obstacles in the development of tumor vaccines. The vaccines containing multivalent antigens are thought to be more effective in antitumor therapy. In this study, a mRNA encoding three neoantigens of melanoma were prepared and encapsulated into the mannosylated chitosan-modified ethosomes (EthsMC) to obtain a multivalent mRNA vaccine (MmRV) for transcutaneous immunization (TCI). MmRV can effectively induce maturation of dendritic cells, with a better performance than mRNA of a single neoantigen. TCI patches (TCIPs) loading MmRV or siRNA against PDL1 (siPDL1) were prepared and applied to the skin of melanoma-bearing mice. The results showed that TCIPs significantly increase the levels of TNF-α, IFN-γ, and IL-12 in both plasma and tumor tissues, inhibit tumor growth, as well as promote infiltration of CD4+ and CD8+ T cells in the tumor tissues. Furthermore, the combination of MmRV and siPDL1 showed much better antitumor effects than either monotherapy, suggesting a synergistic effect between the vaccine and PDL1 blocker. In addition, the treatment with the TCIPs did not cause damage to the skin, blood, and vital organs of the mice, showing good biosafety. To the best of our knowledge, this work is the first to construct a noninvasive TCI system containing MmRV and siPDL1, providing a convenient and promising approach for tumor treatment.

Tumor-infiltrating CCR2+ inflammatory monocytes counteract specific immunotherapy.

Tumor development and progression is shaped by the tumor microenvironment (TME), a heterogeneous assembly of infiltrating and resident host cells, their secreted mediators and intercellular matrix. In this context, tumors are infiltrated by various immune cells with either pro-tumoral or anti-tumoral functions. Recently, we published our non-invasive immunization platform DIVA suitable as a therapeutic vaccination method, further optimized by repeated application (DIVA2). In our present work, we revealed the therapeutic effect of DIVA2 in an MC38 tumor model and specifically focused on the mechanisms induced in the TME after immunization. DIVA2 resulted in transient tumor control followed by an immune evasion phase within three weeks after the initial tumor inoculation. High-dimensional flow cytometry analysis and single-cell mRNA-sequencing of tumor-infiltrating leukocytes revealed cytotoxic CD8+ T cells as key players in the immune control phase. In the immune evasion phase, inflammatory CCR2+ PDL-1+ monocytes with immunosuppressive properties were recruited into the tumor leading to suppression of DIVA2-induced tumor-reactive T cells. Depletion of CCR2+ cells with specific antibodies resulted in prolonged survival revealing CCR2+ monocytes as important for tumor immune escape in the TME. In summary, the present work provides a platform for generating a strong antigen-specific primary and memory T cell immune response using the optimized transcutaneous immunization method DIVA2. This enables protection against tumors by therapeutic immune control of solid tumors and highlights the immunosuppressive influence of tumor infiltrating CCR2+ monocytes that need to be inactivated in addition for successful cancer immunotherapy.

Construction and application of microneedle-mediated photothermal therapy and immunotherapy combined anti-tumor drug delivery system.

Conventional treatments for tumors were frequently accompanied by drawbacks and side effects. It might be useful to use the revolutionary microneedle technology which combines photothermal therapy with tumor immunotherapy. In this study, we created a microneedle drug delivery system with mercapto-modified gold nanorods and immune checkpoint blocker anti-PD-1 polypeptide. With good mechanical strength, the microneedle system can efficiently penetrate the skin and deliver drugs. When inserted into human skin, anti-PD-1 peptides and gold nanorods can be released, boosting the capacity of cytotoxic T lymphocytes to destroy tumor cells. Additionally, the elimination of the tumor is aided by the production of heat while being exposed to near-infrared light. This microneedle drug delivery system can enhance the immunological reaction and prolong the survival time of mice. Moreover, it has been demonstrated that the system has mild toxic and side effects on normal tissues and can effectively inhibit the growth of tumors, indicating a bright prospect for the treatment of cancers.

Microneedle-Mediated Transcutaneous Immunization: Potential in Nucleic Acid Vaccination.

Efforts aimed at exploring economical and efficient vaccination have taken center stage to combat frequent epidemics worldwide. Various vaccines have been developed for infectious diseases, among which nucleic acid vaccines have attracted much attention from researchers due to their design flexibility and wide application. However, the lack of an efficient delivery system considerably limits the clinical translation of nucleic acid vaccines. As mass vaccinations via syringes are limited by low patient compliance and high costs, microneedles (MNs), which can achieve painless, cost-effective, and efficient drug delivery, can provide an ideal vaccination strategy. The MNs can break through the stratum corneum barrier in the skin and deliver vaccines to the immune cell-rich epidermis and dermis. In addition, the feasibility of MN-mediated vaccination is demonstrated in both preclinical and clinical studies and has tremendous potential for the delivery of nucleic acid vaccines. In this work, the current status of research on MN vaccines is reviewed. Moreover, the improvements of MN-mediated nucleic acid vaccination are summarized and the challenges of its clinical translation in the future are discussed.

Chitosan-coated PLGA nanoparticles for transcutaneous immunization: Skin distribution in lysozyme-sensitized mice.

The effect of transcutaneous immunization was studied using a combined system of poly(DL-lactide-co-glycolide) (PLGA) nanoparticles and iontophoresis (IP). Both hen egg-white lysozyme (HEL)-loaded PLGA nanoparticles coated with chitosan hydroxypropyltrimonium chloride and their fluorescent nanoparticles were prepared using an antisolvent diffusion method. Their mean volume diameters were 87.6 ± 38.9 nm and 84.9 ± 27.6 nm, respectively. It was suggested from the results of the ex vivo skin accumulation study using fluorescent nanoparticles that the HEL released from the nanoparticles to the skin surface was efficiently delivered to antigen-presenting cells. HEL-specific IgG1 and IgG2a titers were determined in an in vivo percutaneous immunoreactivity study using lysozyme-sensitized mice. As results, the group using nanoparticles and IP showed 1.33 times higher HEL-specific IgG1 titer than a sham treatment group. The HEL-specific IgG2a titer was 1.36 times higher in the nanoparticles and IP group than in the HEL solution and IP group. It was suggested from the quantification results of total IgE in serum that the combined use of PLGA nanoparticles and IP reduced the total IgE concentration. The level of cytokines may have decreased due to Th1 cell activation and relative suppression of Th2 cells. The cytokine level is presumed to be reduced by activation of Th1 cells and relative suppression of Th2 cells. The histamine amount in plasma and rectal temperature after the induction of anaphylactic shock using lysozyme-sensitized mice were also studied, which indicates that the combined use of PLGA nanoparticles and IP may provide the same therapeutic effect as an injection.

Transcutaneous immunization via dissolving microneedles protects mice from lethal influenza H7N9 virus challenge.

Avian influenza H7N9 virus has first emerged in 2013 and since then has spread in China in five seasonal waves. In humans, influenza H7N9 virus infection is associated with a high fatality rate; thus, an effective vaccine for this virus is needed. In the present study, we evaluated the usefulness of dissolving microneedles (MNs) loaded with influenza H7N9 vaccine in terms of the dissolution time, insertion capacity, insertion depth, and structural integrity of H7N9 virus in vitro. Our in vitro results showed MNs dissolved within 6 mins. The depth of skin penetration was 270 µm. After coating with a matrix material solution, the H7N9 proteins were agglomerated. We detected the H7N9 delivery time and humoral immune response in vivo. In a mouse model, the antigen retention time was longer for MNs than for intramuscular (IM) injection. The humoral response showed that similar to IM administration, MN administration increased the levels of functional and systematic antibodies and protection against the live influenza A/Anhui/01/2013 virus (Ah01/H7N9). The protection level was determined by the analysis of pathological sections of infected lungs. MN and IM administration yielded results superior to those in the control group. Taken together, these findings demonstrate that the use of dissolving MNs to deliver influenza H7N9 vaccines is a promising immunization approach.

Microneedle-based two-step transdermal delivery of Langerhans cell-targeting immunoliposomes induces a Th1-biased immune response.

Novel Coronavirus is affecting human's life globally and vaccines are one of the most effective ways to combat the epidemic. Transcutaneous immunization based on microneedle (MN) has attracted much attention because of its painlessness, rapidity, high efficiency and good compliance. In this study, CD11c monoclonal antibody-immunoliposomes (OVA@CD11c-ILP) actively targeting to Langerhans cells (LCs) were successfully prepared and were delivered by the microchannels of skin produced by MN to induce an immune response in vivo. OVA@CD11c-ILP could be targeted to LCs by conjugating CD11c monoclonal antibody to the surface of the ILP. OVA@CD11c-ILP promoted the maturation of dendritic cells (DCs) and the uptake and endocytosis of antigen by LCs. Moreover, OVA@CD11c-ILP immunization can significantly inhibit tumor growth and prolong overall survival. Furthermore, a higher antibody's titer ratio of IgG1/IgG2a indicated that the immune response stimulated by this immunization method was Th1-biased and the liposomes showed Th1-type adjuvant effect. In conclusion, the combination delivery system of immunoliposomes and microneedle can significantly improve the efficiency of antigen presentation and effectively activate cellular immune responses in the body, which is expected to be a promising transdermal immune strategy.

Film Forming Nanogels for Needle-Free Transdermal Vaccination.

Transcutaneous immunization (TCI) provides a valuable alternative approach to conventional vaccination because of the high accessibility and the exceptional immunological characteristics of the skin, but its application is limited by the low permeability of the stratum corneum. Although nanogels (NGs) have proven to enhance skin penetration of macromolecules with minimum damage, their use in TCI remains almost unexplored. In this context, this article evaluates the performance of novel film-forming NGs (FF-NGs) as TCI. This TCI platform consists of NGs with multilobular morphology that positively combines the properties of cross-linked poly(N-vinylcaprolactam), like thermoresponsiveness and the ability to load and release a cargo, with the film-forming capacity of low Tg lobes. FF-NGs and formed films are characterized at different levels. Formed films show to be able to uniformly load an antigenic protein and release it with a profile depending on the temperature and on their FF-NGs content. In vivo studies have demonstrated that FF-NGs promote the penetration of not only an antigenic protein, but also an adjuvant until the immunocompetent area of skin, generating an adjuvant-dependent specific immune response. Finally, this study provides a successful proof of concept that FF-NGs can be a powerful tool for the transcutaneous release of complex formulations.

Transcutaneous Administration of Imiquimod Promotes T and B Cell Differentiation into Effector Cells or Plasma Cells.

We are interested in promoting the development of transcutaneous immunization using microneedle technology and attempting to apply an adjuvant with transcutaneous immunization to improve the efficacy and reduce the amount of antigen and number of administrations needed. In this study, we collected basic information to help elucidate the mechanism responsible for the transcutaneous adjuvant activity of imiquimod (IMQ), which is a ligand of toll-like receptor (TLR) 7. In mouse groups administered ovalbumin (OVA), the OVA-specific IgG antibody titer of the IMQ-adjuvanted group was higher than that of the group administered OVA alone. No immune response bias due to transcutaneous IMQ administration was observed in terms of IgG1 (T helper cell [Th]2-type IgG subclass) and IgG2c (Th1-type IgG subclass) antibody titers. After the initial immunization, the IMQ-adjuvanted group showed increased migration of Langerhans cells to draining lymph nodes (dLNs) and active proliferation of OVA-specific CD4+ T cells. Transcutaneously administered IMQ did not affect the direction of CD4+ T cell differentiation, while promoted B cell activation and germinal center (GC) B cell differentiation. Immune staining revealed greater GC formation in the dLNs with the IMQ-adjuvanted group than in the OVA-alone group. In the secondary immune response, effector T cells increased in the dLNs and spleen, and effector memory T cells also increased in the spleen in the IMQ-adjuvanted group. In addition, our results suggested that the administration of IMQ enhanced B cell differentiation into plasma cells and GC B cells in the dLNs and spleen. In this study, we partially clarified the mechanism underlying the adjuvant activity of transcutaneously administered IMQ, which is required for the practical application of transcutaneous immunization with IMQ.

Transcutaneous tumor vaccination combined with anti-programmed death-1 monoclonal antibody treatment produces a synergistic antitumor effect.

Transcutaneous immunization (TCI) has the advantages of safety, high efficiency, non-invasiveness and convenient use. The key for a TCI system is transdermal targeted delivery of antigen to dendritic cells (DCs), the most powerful antigen presenting cells. DCs also play an important role in tumor immunotherapy, which provides a huge imagination for the application of TCI to tumor treatment. In this study, a transcutaneous tumor vaccine (TTV) delivery system was developed using the electrospun silk fibroin (SF) and polyvinyl alcohol (PVA) composite nanofibrous patch loaded with mannosylated polyethyleneimine (PEIman)-modified ethosome (Eth) (termed Eth-PEIman). Eth-PEIman showed a good performance in targeting DCs, and the carriers loaded with antigen (encapsulated in Eths) and adjuvant (absorbed in PEIman) were observed effectively induce DCs maturation in vitro. With the tyrosinase-related protein-2 (TRP2) peptide as antigen and oligodeoxynucleotides containing unmethylated CpG motifs as adjuvant, the TTV-loaded patches (TTVP) significantly inhibited the growth of melanoma in a syngeneic mouse model for melanoma by subcutaneous injection of B16F10 cell lines. Moreover, the combined application of the TTVP and anti-programmed death-1 monoclonal antibody (aPD-1) produced a synergistic antitumor effect, which could be related to the infiltration of more CD4+ and CD8+ T cells in the tumor tissues. The application of TTVP also increased the expression of IL-12, which may be part of the mechanism of synergistic antitumor effect between the TTVP and aPD-1. These results suggest that the combination of the TTVP and immune checkpoint blockers could be an effective strategy for tumor treatment. STATEMENT OF SIGNIFICANCE: Transcutaneous immunization has the advantages of safety, high efficiency, non-invasiveness and convenient use. In this study, a novel transcutaneous tumor vaccine patch (TTVP) was developed using tumor antigens-loaded ethosomes that can target dendritic cells percutaneously. Our data demonstrated that the TTVP can significantly inhibit tumor growth. Furthermore, the combination of TTVP and aPD-1 produced a synergistic anti-melanoma effect. Considering its convenience and non-invasiveness, this TTVP system could find good application prospects in immunotherapy. The combination of TTVP and aPD-1 could be a useful strategy for the prevention and treatment of tumors.

Advances of microneedle vaccines in transcutaneous immunization / 药学学报

Vaccination is an effective way to reduce the morbidity and mortality of infectious diseases. As a needle-free transcutaneous immunization (NF-TCI) vaccination technology, microneedles (MNs), composed of multiple micro-needles orderly attached to a substrate, can overcome the problems of low immune efficiency, poor compliance and waste of resources that exists in the conventional vaccination by injection, thus becoming a research hotspot in biomedicine. The microneedle vaccine can directly break through the stratum corneum barrier of the skin without touching nerves and blood vessels in the dermis, and effectively delivers the vaccine to the immune cells in the skin tissue to initiate the immune response of the body, thus triggering strong humoral and cellular immune processes. Vaccine delivery via the MNs system possesses the advantages of high safety, satisfying immune effect and practical economy, and shows great prospect in the prevention and treatment of infectious diseases and antineoplastic therapy. This article reviews the development background of MNs in transcutaneous immunization, the types of vaccine delivery, the factors affecting the immune effect, the problems to be solved and development direction in the future.

Genetically-engineered "all-in-one" vaccine platform for cancer immunotherapy.

An essential step for cancer vaccination is to break the immunosuppression and elicit a tumor-specific immunity. A major hurdle against cancer therapeutic vaccination is the insufficient immune stimulation of the cancer vaccines and lack of a safe and efficient adjuvant for human use. We discovered a novel cancer immunostimulant, trichosanthin (TCS), that is a clinically used protein drug in China, and developed a well-adaptable protein-engineering method for making recombinant protein vaccines by fusion of an antigenic peptide, TCS, and a cell-penetrating peptide (CPP), termed an "all-in-one" vaccine, for transcutaneous cancer immunization. The TCS adjuvant effect on antigen presentation was investigated and the antitumor immunity of the vaccines was investigated using the different tumor models. The vaccines were prepared via a facile recombinant method. The vaccines induced the maturation of DCs that subsequently primed CD8+ T cells. The TCS-based immunostimulation was associated with the STING pathway. The general applicability of this genetic engineering strategy was demonstrated with various tumor antigens (i.e., legumain and TRP2 antigenic peptides) and tumor models (i.e., colon tumor and melanoma). These findings represent a useful protocol for developing cancer vaccines at low cost and time-saving, and demonstrates the adjuvant application of TCS-an old drug for a new application.

Adjuvant Activity of CpG-Oligonucleotide Administered Transcutaneously in Combination with Vaccination Using a Self-Dissolving Microneedle Patch in Mice.

In this study, we investigated the mechanism of transcutaneous adjuvant activity of the CpG-oligonucleotide (K3) in mice. Transcutaneous immunization (TCI) with an ovalbumin-loaded self-dissolving microneedle patch (OVA-sdMN) and K3-loaded hydrophilic gel patch (HG) increased OVA-specific Th2- and Th1-type IgG subclass antibody titers more rapidly and strongly than those after only OVA-sdMN administration. However, the antigen-specific proliferation of OVA-specific CD4+ T cells was similar between the OVA-only and the OVA+K3 groups. Population analysis of various immune cells in draining lymph nodes (dLNs) in the primary immune response revealed that the OVA+K3 combination doubled the number of dLN cells, with the most significant increase in B cells. Phenotypic analysis by flow cytometry revealed that B-cell activation and maturation were promoted in the OVA+K3 group, suggesting that direct B-cell activation by K3 largely contributed to the rapid increase in antigen-specific antibody titer in TCI. In the secondary immune response, a significant increase in effector T cells and effector memory T cells, and an increase in memory B cells were observed in the OVA+K3 group compared with that in the OVA-only group. Thus, K3, as a transcutaneous adjuvant, can promote the memory differentiation of T and B cells.

Dissolving Microneedles Developed in Association with Nanosystems: A Scoping Review on the Quality Parameters of These Emerging Systems for Drug or Protein Transdermal Delivery.

The largest organ of the body provides the main challenge for the transdermal delivery of lipophilic or high molecular weight drugs. To cross the main barrier of the skin, the stratum corneum, many techniques have been developed and improved. In the last 20 years, the association of microneedles with nanostructured systems has gained prominence for its versatility and for enabling targeted drug delivery. Currently, the combination of these mechanisms is pointed to as an emerging technology; however, some gaps need to be answered to transcend the development of these devices from the laboratory scale to the pharmaceutical market. It is known that the lack of regulatory guidelines for quality control is a hindrance to market conquest. In this context, this study undertakes a scoping review of original papers concerning methods applied to evaluate both the quality and drug/protein delivery of dissolving and hydrogel-forming microneedles developed in association with nanostructured systems.

Dissolvable microneedles based on Panax notoginseng polysaccharide for transdermal drug delivery and skin dendritic cell activation.

This work explored the feasibility of using biological polysaccharide to fabricate dissolvable microneedles (MNs) for the purpose of transdermal drug delivery and skin dendritic cell (DC) activation. Panax notoginseng polysaccharide (PNPS), a naturally derived immunoactive macromolecule, was used to fabricate dissolvable MNs. The prepared PNPS MNs showed a satisfactory mechanical strength and a skin penetration depth. By Franz diffusion cell assay, the PNPS MNs demonstrated a high transdermal delivery amount of model drugs. Furthermore, with the assistance of MNs, PNPS easily penetrated across the stratum corneum and target ear skin DCs, activating the maturation and migration of immunocytes by increasing the expressions of CD40, CD80, CD86, and MHC II of skin DCs. Consequently, the matured DCs migrated to the auricular draining lymph nodes and increased the proportions of CD4+ T and CD8+ T cells. Thus, PNPS might be a promising biomaterial for transdermal drug delivery, with adjuvant potential.

Characteristics of immune induction by transcutaneous vaccination using dissolving microneedle patches in mice.

Transcutaneous immunization (TCI) is an appealing vaccination method. Compared with conventional injectable immunization, TCI is easier and less painful. We previously developed a dissolving microneedle (MN) patch and demonstrated that TCI using MN patches demonstrates high vaccination efficacy without adverse events in humans. In this study, we investigated the immune induction mechanism of TCI using our MN patch, focusing on inflammatory responses in the skin and on the dynamics, activation, and differentiation of various immunocompetent cells in draining lymph nodes (dLNs). We demonstrate that inflammatory cytokines such as IL-6 and TNF-α increased in the skin at an early stage after MN patch application, inducing the infiltration of macrophages and neutrophils and promoting the activation and migration of skin-resident antigen-presenting cells (Langerhans and Langerin- dermal dendritic cells) to dLNs. Moreover, the activated antigen-presenting cells reaching the dLNs enhanced the differentiation of T (Teff, Tem, and Tcm) and B (plasma and memory) cells. This may contribute to the efficient antigen-specific antibody production induced by TCI using MN patches. We believe that our findings reveal a part of the immune induction mechanism by TCI and provide useful information for the development and improvement of TCI formulations based on the immune induction mechanism.

Transdermal delivery of interleukin-12 gene targeting dendritic cells enhances the anti-tumour effect of programmed cell death protein 1 monoclonal antibody.

Recent studies have suggested that the anti-tumour effect of the programmed cell death protein 1 monoclonal antibody (aPD-1) depends on the expression of interleukin-12 (IL-12) by dendritic cells (DCs). Since DCs are abundant in skin tissues, transdermal delivery of IL-12 targeting DCs may significantly improve the anti-tumour effect of aPD-1. In this study, a novel mannosylated chitosan (MC)-modified ethosome (Eth-MC) was obtained through electrostatic adsorption. The Eth-MC loaded with plasmid containing the IL-12 gene (pIL-12@Eth-MC) stimulated DCs to express mature-related molecular markers such as CD86, CD80, and major histocompatibility complex-II in a targeted manner. The pIL-12@Eth-MC was then mixed with polyvinyl pyrrolidone solution to make microspheres using the electrospray technique, and sprayed onto the surface of electrospun silk fibroin-polyvinyl alcohol nanofibres to obtain a PVP-pIL-12@Eth-MC/silk fibroin-polyvinyl alcohol composite nanofibrous patch (termed a transcutaneous immunization (TCI) patch). The TCI patch showed a good performance on transdermal drug release. Animal experiments on melanoma-bearing mice showed that topical application of the TCI patches promoted the expression of IL-12 and inhibited the growth of tumour. Furthermore, combined application of the TCI patch and aPD-1 showed a stronger anti-tumour effect than aPD-1 monotherapy. The combination therapy significantly promoted the expression of IL-12, interferon-γ and tumour necrosis factor-α, the infiltration of CD4+ and CD8+ T cells into tumour tissues, and thus promoted the apoptosis of tumour cells. The present study provides a convenient and non-invasive strategy for improving the efficacy of immune checkpoint inhibitor therapy. This study was approved by the Institutional Animal Care and Use Committee at Donghua University (approval No. DHUEC-NSFC-2020-11) on March 31, 2020.

Genetically-engineered "all-in-one" vaccine platform for cancer immunotherapy

An essential step for cancer vaccination is to break the immunosuppression and elicit a tumor-specific immunity. A major hurdle against cancer therapeutic vaccination is the insufficient immune stimulation of the cancer vaccines and lack of a safe and efficient adjuvant for human use. We discovered a novel cancer immunostimulant, trichosanthin (TCS), that is a clinically used protein drug in China, and developed a well-adaptable protein-engineering method for making recombinant protein vaccines by fusion of an antigenic peptide, TCS, and a cell-penetrating peptide (CPP), termed an "all-in-one" vaccine, for transcutaneous cancer immunization. The TCS adjuvant effect on antigen presentation was investigated and the antitumor immunity of the vaccines was investigated using the different tumor models. The vaccines were prepared

Galactosylated chitosan-modified ethosomes combined with silk fibroin nanofibers is useful in transcutaneous immunization.

Transcutaneous immunization (TCI) has the advantages of avoiding the liver first-pass effect, good compliance and convenient use compared with the traditional oral or injection vaccination. However, the stratum corneum (SC) of the skin is the main obstacle that limits the entry of antigen molecules into the epidermis for activating dendritic cells (DCs). In the present study, the hyaluronic acid (HA) and galactosylated chitosan (GC) modified ethosome (Eth-HA-GC) was prepared through layer-by-layer self-assembly method. Eth-HA-GC has good stability and can be effectively phagocytosed by the bone-marrow-derived DCs (BMDCs) in vitro. The ovalbumin (OVA) loaded Eth-HA-GC (OVA@Eth-HA-GC) can promote BMDCs' expression of CD80, CD86 (DCs maturation-associated marker molecules), TNF-α, IL-2 and IL-6. Subsequently, a novel OVA@Eth-HA-GC-loaded silk fibroin (OVA@Eth-HA-GC/SF) nanofibrous mats were fabricated through green electrospinning. The OVA@Eth-HA-GC/SF mats exhibit good transdermal performance in vitro. Transdermal administration with OVA@Eth-HA-GC/SF mats induced the serum anti-OVA-specific IgG and increased the expression of IFN-γ, IL-2 and IL-6 by spleen cells in vivo. Furthermore, the use of OVA@Eth-HA-GC/SF mats evidently inhibited the growth of EG7 tumor in the murine model. These results demonstrate the OVA@Eth-HA-GC/SF mats can effectively stimulate the immune response to OVA through transdermal administration. In conclusion, the antigens@Eth-HA-GC/SF mats is a promising TCI system.

Dissolving Microneedle Arrays with Optimized Needle Geometry for Transcutaneous Immunization.

In this study, the feasibility of transcutaneous immunization using different needle-geometries dissolving microneedle array (DMNA) were investigated as drug carriers for ovalbumin (OVA) preparations. A two-step molding process was used in which needles were loaded with OVA. The microneedles displayed a geometry and dimensions consistent with the main molds. DMNA with different needle-geometries were compared and characterized. Drug loading of the prepared DMNAs reached ~100 µg measured via BCA assay. The stability of OVA in the DMNAs was investigated by SDS-PAGE electrophoresis and showed that the OVA encapsulated in the DMNAs was stable during preparation. The immune responses induced by the DMNAs and hypodermic needle-based injections were compared through in vivo immunoglobulin G (IgG) production assays. OVA-loaded DMNAs also induced stronger immune responses compared to hypodermic needle-based injections. In conclusion, these results suggest that: (1) the needle-morphology of DMNAs influences their mechanical properties, insertion capacity, and dissolution, thus affecting the immune response; (2) Cone-DMNAs are optimal for transcutaneous immunization. These data provide a theoretical basis for the use of transcutaneous immunization of DMNAs for vaccine development.