Induction of cytotoxic T-lymphocytes by electroporation-enhanced needle-free skin immunization

Polydioxanone Bioactive Sutures-Acetyl Hexapeptide-8 (Argireline): An Intelligent System for Controlled Release in Facial Harmonization

Introduction

We propose a new facial lifting protocol using polydioxanone (PDO) threads embedded in acetyl hexapeptide-8 (Argireline [Arg]). We assume that Arg reinforces the effects of PDO threads, as it is a mimetic of botulinum toxin. Because the PDO suture is hydrolyzable, this assumption is analyzed by instrumental analysis.

Objective

To demonstrate the capacity of the PDO suture as a system for the controlled release of acetyl hexapeptide-8 to apply in deep wrinkles of the upper third.

Materials and Methods

Three segments of 1-cm long 21G PDO threads immersed in 1 mL of Arg. PDO threads were observed under an optical, electron microscope at 24, 48, and 72 h later. They were also weighed before and after being soaked in Arg, and employing ultraviolet (UV)-visible spectroscopy, the release rate of Arg from the PDO suture was measured. Finally, was insert the thread PDO-Arg following a protocol designed especially for deep static wrinkles in the upper third.

Results

The electronic weighing revealed that the PDO thread enjoys capillarity by the peptide, doubling its weight every 24 h. UV spectra revealed that PDO thread is a well-controlled release system for Arg, allowing its sustained release for 1 h. Optical and electronic photomicrographs confirm the swelling of the PDO thread by absorbing Arg by its capillarity, but this hydrophilicity does not lead to its premature physical degradation.

Conclusions

The PDO thread system with Arg is an intelligent bioactive system useful in facial harmonization. It recommend conduct clinical trial to verify his superior lifting effect.

Electro-responsive silk fibroin microneedles for controlled release of insulin

To date, very limited work has been done on convenient and active control of insulin release. Herein, we report an electro-responsive insulin delivery system based on thiolated silk fibroin. The disulfide cross-linking points in TSF were reduced and broken to form sulfhydryl groups under electrification, which led to the increase of microneedle swelling degree and promoted insulin release. After power failure, the sulfhydryl group is oxidised to form disulfide bond crosslinking point again, resulting in the reduction of microneedle swelling degree and thus the reduction of release rate. The insulin loaded in the electro-responsive insulin delivery system showed good reversible electroresponsive release performance. The addition of graphene reduced the microneedle resistance and increased the drug release rate under current conditions. In vivo studies on type 1 diabetic mice show that electro-responsive insulin delivery system effectively controls the blood glucose before and after feeding by switching on and off the power supply, and this blood glucose control can be maintained within the safe range (100-200 mg/dL) for a long time (11h). Such electrically responsive delivery microneedles show potential for integration with glucose signal monitoring and are expected to build closed-loop insulin delivery systems.

Enhancement of skin permeation of fluorescein isothiocyanate-dextran 4 kDa (FD4) and insulin by thermalporation

Thermalporation has gained attention as a physical means to enhance skin permeation by creating micropores in the primary skin barrier, stratum corneum, which allows much higher permeation of middle and high molecular weight biopharmaceuticals. In the present study, a PassPort® system (PS) was used as a thermalporation device, and the obtained change in permeation resistance of drugs was evaluated using a parallel skin permeation-resistance model. In addition, the blood concentration-time profile after topical application of insulin was also investigated with the PS treatment. Fluorescein isothiocyanate-dextran (FD-4) and insulin were used as model middle molecular weight drugs. Micropores created by the PS treatment were measured using an optical microscope. An in vitro skin permeation and an in vivo pharmacokinetics experiments were done with FD-4 and insulin, respectively. Barrier function recovery after the PS treatment was evaluated with changes in the electrical skin resistance. About 960-fold higher skin permeation of FD-4 was observed by PSs treatment (4 milliseconds (ms), 200 micropores/cm²). A gradually increased blood concentration of insulin was observed by the PSs treatment, and the relative bioavailability of insulin was 21.1% compared with subcutaneous injection. Skin resistance value was dramatically decreased immediately after the PS treatment, but its value was turned into the initial one by 12 h. The thermalporation is effective for improving skin permeation of FD-4 and transdermal absorption of insulin. These results suggested that the PS treatment may be utilized to increase the skin permeation of topically applied FD-4 and insulin.

Transdermal Drug Delivery in the Pig Skin

Transdermal delivery can be accomplished through various mechanisms including formulation optimization, epidermal stratum corneum barrier disruption, or directly by removing the stratum corneum layer. Microneedling, electroporation, a combination of both and also the intradermal injection known as mesotherapy have proved efficacy in epidermal-barrier disruption. Here we analyzed the effects of these methods of epidermal-barrier disruption in the structure of the skin and the absorption of four compounds with different characteristics and properties (ketoprofen, biotin, caffein, and procaine). Swine skin (Pietrain x Durox) was used as a human analogue, both having similar structure and pharmacological release. They were biopsied at different intervals, up to 2 weeks after application. High-pressure liquid chromatography and brightfield microscopy were performed, conducting a biometric analysis and measuring histological structure and vascular status. The performed experiments led to different results in the function of the studied molecules: ketoprofen and biotin had the best concentrations with intradermal injections, while delivery methods for obtaining procaine and caffein maximum concentrations changed on the basis of the lapsed time. The studied techniques did not produce significant histological alterations after their application, except for an observed increase in Langerhans cells and melanocytes after applying electroporation, and an epidermal thinning after using microneedles, with variable results regarding dermal thickness. Although all the studied barrier disruptors can accomplish transdermal delivery, the best disruptor is dependent on the particular molecule.

Vaccine and vaccination as a part of human life: In view of COVID-19

Background

Vaccination created a great breakthrough toward the improvement to the global health. The development of vaccines and their use made a substantial decrease and control in infectious diseases. The abundance and emergence of new vaccines has facilitated targeting populations to alleviate and eliminate contagious pathogens from their innate reservoir. However, along with the infections like malaria and HIV, effective immunization remains obscure and imparts a great challenge to science.

Purpose and scope

The novel Corona virus SARS‐CoV‐2 is the reason for the 2019 COVID‐19 pandemic in the human global population, in the first half of 2019. The need for establishing a protected and compelling COVID‐19 immunization is a global prerequisite to end this pandemic.

Summary and conclusion

The different vaccine technologies like inactivation, attenuation, nucleic acid, viral vector, subunit, and viral particle based techniques are employed to develop a safe and highly efficient vaccine. The progress in vaccine development for SARS‐CoV2 is much faster in the history of science. Even though there exist of lot of limitations, continuous efforts has put forward so as to develop highly competent and effective vaccine for many human and animal linked diseases due to its unlimited prospective. This review article focuses on the historical outlook and the development of the vaccine as it is a crucial area of research where the life of the human is saved from various potential diseases.

Transdermal drug delivery systems for fighting common viral infectious diseases

Transdermal drug delivery systems (TDDS) have many advantages and represent an excellent alternative to oral delivery and hypodermic injections. TDDS are more convenient and less invasive tools for disease and viral infection treatment, prevention, detection, and surveillance. The emerging development of microneedles for TDDS has facilitated improved skin barrier penetration for the delivery of macromolecules or hydrophilic drugs. Microneedle TDDS patches can be fabricated to deliver virus vaccines and potentially provide a viable alternative vaccine modality that offers improved immunogenicity, thermostability, simplicity, safety, and compliance as well as sharp-waste reduction, increased cost-effectiveness, and the capacity for self-administration, which could improve vaccine distribution. These advantages make TDDS-based vaccine delivery an especially well-suited option for treatment of widespread viral infectious diseases including pandemics. Because microneedle-based bioassays employ transdermal extraction of interstitial fluid or blood, they can be used as a minimally invasive approach for surveying disease markers and providing point-of-care (POC) diagnostics. For cutaneous viral infections, TDDS can provide localized treatment with high specificity and less systemic toxicity. In summary, TDDS, especially those that employ microneedles, possess special attributes that can be leveraged to reduce morbidity and mortality from viral infectious diseases. In this regard, they may have considerable positive impact as a modality for improving global health. In this article, we introduce the possible role and summarize the current literature regarding TDDS applications for fighting common cutaneous or systemic viral infectious diseases, including herpes simplex, varicella or herpes zoster, warts, influenza, measles, and COVID-19.

Transdermal immunomodulation: Principles, advances and perspectives

Immunomodulation, manipulation of the immune responses towards an antigen, is a promising strategy to treat cancer, infectious diseases, allergies, and autoimmune diseases, among others. Unique features of the skin including the presence of tissue-resident immune cells, ease of access and connectivity to other organs makes it a unique target organ for immunomodulation. In this review, we summarize advances in transdermal delivery of agents for modulating the immune responses for vaccination as well as tolerization. The biological foundation of skin-based immunomodulation and challenges in its implementation are described. Technological approaches aimed at enhancing the delivery of immunomodulatory therapeutics into skin are also discussed in this review. Progress made in the treatment of several specific diseases including cancer, infections and allergy are discussed. Finally, this review discusses some practical considerations and offers some recommendations for future studies in the field of transdermal immunomodulation.

Enhanced Skin Permeation of Anti-wrinkle Peptides via Molecular Modification

Wrinkles can have a negative effect on quality of life and Botox is one of the most effective and common treatments. Argireline (Arg0), a mimetic of Botox, has been found to be safer than Botox and effective in reducing wrinkles, with efficacies up to 48% upon 4 weeks of twice daily treatment. However, the skin permeation of Arg0 is poor, due to its large molecular weight and hydrophilicity. Arg0 exists in zwitterionic form and this charged state hindered its skin permeation. Chemical modification of the peptide structure to reduce the formation of zwitterions may result in increased skin permeability. We investigated a total of 4 peptide analogues (Arg0, Arg1, Arg2, Arg3), in terms of skin permeation and wrinkle reduction. The 4 peptides were dissolved in various propylene glycol and water co-solvents. Enhanced human skin permeation was demonstrated by both Arg2 and Arg3 in vitro. On the other hand, the abilities of the 4 analogues to reduce wrinkle formation were also compared using primary human dental pulp stem cells derived neurons. By measuring the inhibition of glutamate release from the neurons in vitro, it was shown that Arg3 was the most effective, followed by Arg1, Arg0 and Arg2.

Electroporation as a vaccine delivery system and a natural adjuvant to intradermal administration of plasmid DNA in macaques

In vivo electroporation (EP) is used to enhance the uptake of nucleic acids and its association with DNA vaccination greatly stimulates immune responses to vaccine antigens delivered through the skin. However, the effect of EP on cutaneous cell behavior, the dynamics of immune cell recruitment and local inflammatory factors, have not been fully described. Here, we show that intradermal DNA vaccination combined with EP extends antigen expression to the epidermis and the subcutaneous skin muscle in non-human primates. In vivo fibered confocal microscopy and dynamic ex vivo imaging revealed that EP promotes the mobility of Langerhans cells (LC) and their interactions with transfected cells prior to their migration from the epidermis. At the peak of vaccine expression, we detected antigen in damaged keratinocyte areas in the epidermis and we characterized recruited immune cells in the skin, the hypodermis and the subcutaneous muscle. EP alone was sufficient to induce the production of pro-inflammatory cytokines in the skin and significantly increased local concentrations of Transforming Growth Factor (TGF)-alpha and IL-12. Our results show the kinetics of inflammatory processes in response to EP of the skin, and reveal its potential as a vaccine adjuvant.

Skin vaccination via fractional infrared laser ablation - Optimization of laser-parameters and adjuvantation

BACKGROUND

Methods to deliver an antigen into the skin in a painless, defined, and reproducible manner are essential for transcutaneous immunization (TCI). Here, we employed an ablative fractional infrared laser (P.L.E.A.S.E. Professional) to introduce clinically relevant vaccines into the skin. To elicit the highest possible antibody titers with this system, we optimized different laser parameters, such as fluence and pore number per area, and tested various adjuvants.

METHODS

BALB/c mice were immunized with Hepatitis B surface antigen (HBsAg) by laser-microporation. Adjuvants used were alum, CRM₁₉₇, monophosphoryl lipid A, heat-labile enterotoxin subunit B of E. coli (LT-B), and CpG ODN1826. The influence of different fluences (2.1 to 16.8J/cm²) and pore densities (5-15%) was investigated. Furthermore, immunogenicity of HBsAg and the commercially available conjugate vaccines ActHIB® and Menveo® applied via TCI was compared to standard i.m. injection. Antigen-specific antibody titers were assessed by luminometric ELISA.

RESULTS

Antibody titers against HBsAg were dependent on pore depth and peaked at a fluence of 8.4J/cm². Immunogenicity was independent of pore density. Adjuvantation with alum significantly reduced antibody titers after TCI, whereas other adjuvants only induced marginal changes in total IgG titers. LT-B and CpG shifted the polarization of the immune response as indicated by decreased IgG1/IgG2a ratios. HBsAg/LT-B applied via TCI induced similar antibody titers compared to i.m. injection of HBsAg/alum. In contrast to i.m. injection, we observed a dose response from 5 to 20μg after TCI. Both, ActHIB® and Menveo® induced high antibody titers after TCI, which were comparable to i.m. injection.

CONCLUSIONS

Alum, the most commonly used adjuvant, is contraindicated for transcutaneous vaccination via laser-generated micropores. TCI with optimized laser parameters induces high antibody titers, which cannot be significantly increased by the tested adjuvants. Commercially available vaccines formulated without alum have the potential for successful TCI via laser-generated micropores, without the need for reformulation.

Effective transcutaneous immunization using a combination of iontophoresis and nanoparticles

Needle-free immunization strategies have been sought for years. Transcutaneous immunization using electroporation has been studied, but the high electrical voltage that must be applied may be painful and cause irreversible cell damage. The application of a weak electric field, such as in iontophoresis, has never been attempted. The aim of this work was to verify the potential of employing iontophoresis for transcutaneous immunization using ovalbumin (OVA) as a model antigen. To target the antigen presenting cells that are located in the viable epidermis, a vaccine formulation composed of OVA-loaded liposomes and silver nanoparticles (NPAg) was developed. In vitro cathodal iontophoresis of the OVA-liposomes associated with NPAg increased OVA penetration into the viable epidermis by 92-fold in comparison to passive delivery. In vivo, transcutaneous immunization with a suitable combination of liposome and iontophoresis induced the production of antibodies, differentiation of immune-competent cells and appeared to present an alternative strategy for needle-free vaccination.

Recent insights into cutaneous immunization: How to vaccinate via the skin

Technologies and strategies for cutaneous vaccination have been evolving significantly during the past decades. Today, there is evidence for increased efficacy of cutaneously delivered vaccines allowing for dose reduction and providing a minimally invasive alternative to traditional vaccination. Considerable progress has been made within the field of well-established cutaneous vaccination strategies: Jet and powder injection technologies, microneedles, microporation technologies, electroporation, sonoporation, and also transdermal and transfollicular vaccine delivery. Due to recent advances, the use of cutaneous vaccination can be expanded from prophylactic vaccination for infectious diseases into therapeutic vaccination for both infectious and non-infectious chronic conditions. This review will provide an insight into immunological processes occurring in the skin and introduce the key innovations of cutaneous vaccination technologies.

Enabling skin vaccination using new delivery technologies

The skin is known to be a highly immunogenic site for vaccination, but few vaccines in clinical use target skin largely because conventional intradermal injection is difficult and unreliable to perform. Now, a number of new or newly adapted delivery technologies have been shown to administer vaccine to the skin either by non-invasive or minimally invasive methods. Non-invasive methods include high-velocity powder and liquid jet injection, as well as diffusion-based patches in combination with skin abrasion, thermal ablation, ultrasound, electroporation, and chemical enhancers. Minimally invasive methods are generally based on small needles, including solid microneedle patches, hollow microneedle injections, and tattoo guns. The introduction of these advanced delivery technologies can make the skin a site for simple, reliable vaccination that increases vaccine immunogenicity and offers logistical advantages to improve the speed and coverage of vaccination.

Ionic liquid-mediated transcutaneous protein delivery with solid-in-oil nanodispersions

We report a novel ionic liquid (IL)-mediated transcutaneous vaccine formulation consisting of a solid-in-oil nanodispersion of antigen coated with pharmaceutically accepted surfactants dispersed in IL-containing oil. The introduction of IL in the formulation significantly enhanced the skin permeability of ovalbumin, a model antigen.

[From basic principles to clinical applications on transcutaneous vaccine]

The recent vigorous transnational migration of people and materials reflecting the development of transportation facilities, changes in social structure, and war disasters has increased the global spread of emerging and re-emerging infectious diseases. Vaccine, which is the major fundamental prophylaxis against infectious diseases, has greatly contributed to the maintenance and improvement of human health worldwide. However, the disadvantages of conventional injection systems hamper the speedy mass-vaccination and the global distribution of vaccines. Transcutaneous immunization systems, which are easy-to-use and low-invasive methods of vaccination, have the potential to overcome certain issues associated with injectable vaccinations. In this review, we provide an outline of recent trends in the development of techniques for the transcutaneous delivery of vaccine antigens. We also introduce basic and clinical research involving our transcutaneous immunization systems that incorporate self-dissolving microneedle patch.

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

Transcutaneous immunization (TCI) systems that use the skin's 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.

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.

[Development of transcutaneous vaccination system for infectious disease countermeasure]

The recent vigorous transnational migration of people and materials reflecting the development of transportation facilities, changes in social structure, and war disasters has increased the global spread of emerging and re-emerging infections. Once, as the 2009 pandemic influenza A (H1N1) virus, person-to-person transmission was achieved, the spread of pandemic cannot be contained in reality. Thus enhancement of the crisis-management structure against pandemic is critically important to maintain national function. On the basis of this social background, the development of vaccination, which is the only fundamental prophylaxis, is in attention, and earliest possible establishment of system that supply mass-vaccines in a short time is required. Even if, however, rapid manufacture of vaccine antigen is actualized, there are several problems that vaccine is not easily spread across the developing country and mass vaccination is not performed immediately at the time of the crisis, because conventional vaccination is performed mainly by injection. Our research group developed transcutaneous vaccine devices; a hydrogel patch and a dissolving microneedle array which delivered antigens to antigen-presenting cells in the epidermal layer. Our transcutaneous vaccination system receives a high evaluation as novel, easy-to-use, and less-invasive vaccination method against infections from home and abroad. In this review, we introduce the research progress resulted from our basic, preclinical, and clinical study for practical use.

Hollow copper sulfide nanoparticle-mediated transdermal drug delivery

A photothermal ablation-enhanced transdermal drug delivery methodology is developed based on hollow copper sulfide nanoparticles (HCuSNPs) with intense photothermal coupling effects. Application of nanosecond-pulsed near-infrared laser allows rapid heating of the nanoparticles and instantaneous heat conduction. This provides very short periods of time but extremely high temperatures in local regions, with focused thermal ablation of the stratum corneum. The depth of skin perforations can be controlled by adjusting the laser power. Skin disruption by HCuSNP-mediated photothermal ablation significantly increases the permeability of human growth hormone. This technique offers compelling opportunities for macromolecular drug and vaccine delivery.

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

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 48 h. Next, the hydrogel patch, containing 2 mg tetanus toxoid (TT) and 2 mg diphtheria toxoid (DT) as the TCI formulation, was applied to 27 healthy volunteers for 24 h 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.

Delivery systems for intradermal vaccination

Intradermal (ID) vaccination can offer improved immunity and simpler logistics of delivery, but its use in medicine is limited by the need for simple, reliable methods of ID delivery. ID injection by the Mantoux technique requires special training and may not reliably target skin, but is nonetheless used currently for BCG and rabies vaccination. Scarification using a bifurcated needle was extensively used for smallpox eradication, but provides variable and inefficient delivery into the skin. Recently, ID vaccination has been simplified by introduction of a simple-to-use hollow microneedle that has been approved for ID injection of influenza vaccine in Europe. Various designs of hollow microneedles have been studied preclinically and in humans. Vaccines can also be injected into skin using needle-free devices, such as jet injection, which is receiving renewed clinical attention for ID vaccination. Projectile delivery using powder and gold particles (i.e., gene gun) have also been used clinically for ID vaccination. Building off the scarification approach, a number of preclinical studies have examined solid microneedle patches for use with vaccine coated onto metal microneedles, encapsulated within dissolving microneedles or added topically to skin after microneedle pretreatment, as well as adapting tattoo guns for ID vaccination. Finally, technologies designed to increase skin permeability in combination with a vaccine patch have been studied through the use of skin abrasion, ultrasound, electroporation, chemical enhancers, and thermal ablation. The prospects for bringing ID vaccination into more widespread clinical practice are encouraging, given the large number of technologies for ID delivery under development.

Transdermal delivery of proteins

Transdermal delivery of peptides and proteins avoids the disadvantages associated with the invasive parenteral route of administration and other alternative routes such as the pulmonary and nasal routes. Since proteins have a large size and are hydrophilic in nature, they cannot permeate passively across the skin due to the stratum corneum which allows the transport of only small lipophilic drug molecules. Enhancement techniques such as chemical enhancers, iontophoresis, microneedles, electroporation, sonophoresis, thermal ablation, laser ablation, radiofrequency ablation and noninvasive jet injectors aid in the delivery of proteins by overcoming the skin barrier in different ways. In this review, these enhancement techniques that can enable the transdermal delivery of proteins are discussed, including a discussion of mechanisms, sterility requirements, and commercial development of products. Combination of enhancement techniques may result in a synergistic effect allowing increased protein delivery and these are also discussed.

Microfluidic devices for bioapplications

Harnessing the ability to precisely and reproducibly actuate fluids and manipulate bioparticles such as DNA, cells, and molecules at the microscale, microfluidics is a powerful tool that is currently revolutionizing chemical and biological analysis by replicating laboratory bench-top technology on a miniature chip-scale device, thus allowing assays to be carried out at a fraction of the time and cost while affording portability and field-use capability. Emerging from a decade of research and development in microfluidic technology are a wide range of promising laboratory and consumer biotechnological applications from microscale genetic and proteomic analysis kits, cell culture and manipulation platforms, biosensors, and pathogen detection systems to point-of-care diagnostic devices, high-throughput combinatorial drug screening platforms, schemes for targeted drug delivery and advanced therapeutics, and novel biomaterials synthesis for tissue engineering. The developments associated with these technological advances along with their respective applications to date are reviewed from a broad perspective and possible future directions that could arise from the current state of the art are discussed.

Enhancement of protein vaccine potency by in vivo electroporation mediated intramuscular injection

Protein-based vaccines have emerged as a potentially promising approach for the generation of antigen-specific immune responses. However, due to their low immunogenicity, there is a need for innovative approaches to enhance protein-based vaccine potency. One approach to enhance protein-based vaccine potency is the employment of toll-like receptor ligands, such as CpG oligonucleotides, to activate the antigen-specific T cell immune responses. Another approach involves employing a method capable of improving the delivery of protein-based vaccine intramuscularly to lead to the slow release of the protein, resulting in improved vaccine potency. In the current study, we aimed to determine whether intramuscular injection of protein-based vaccines in conjunction with CpG followed by electroporation can lead to increased delivery of the protein-based vaccine into muscle cells, resulting in enhanced protein-based vaccine potency. We found that intramuscular injection followed by electroporation can effectively transduce the protein-based vaccine into the muscle cells. Furthermore, we found that intramuscular vaccination with OVA protein in combination with CpG followed by electroporation generates the best OVA-specific CD8+ T cell immune responses as well as the best protective and therapeutic antitumor effects in vaccinated mice. CD8+ T cells were found to play an important role in the observed protective antitumor effects generated by the vaccination. Similar results were observed using the HPV-16 E7 protein-based vaccination system. Thus, our data indicate that intramuscular administration of protein-based vaccines in conjunction with CpG followed by electroporation can significantly enhance the antigen-specific CD8+ T cell immune responses. The clinical implications of the study are discussed.

Transcutaneous immunization by a solid-in-oil nanodispersion

We have successfully achieved transcutaneous immunization without the use of any skin pre-treatment or immune-stimulant adjuvant by applying a solid-in-oil (S/O) nanodispersion: an oil-based nanodispersion of antigens coated with hydrophobic surfactant molecules. This finding indicates that the S/O nanodispersion has great promise for effective transcutaneous vaccination.

Langerhans cells as targets for immunotherapy against skin cancer

Cancer is the second most common cause of death in the world. Treatment of cancer is very challenging and immunotherapy has been developed as a potential way to fight cancer. The main obstacle with immunotherapy is that cancer cells evolve from healthy body cells in response to an accumulation of genetic mutations. As a consequence, the immune system struggles to detect the abnormal cells as they are mainly recognized as self. This implies that equipping the immune system to eliminate cancer cells is tricky, yet represents a very efficient way to constrain the growth of tumors. We became interested in developing immunotherapeutical strategies against skin cancer in the context of our observations that Langerhans cells (LC) are very potent antigen presenting cells and are able to incorporate protein antigens and present them to CD4(+) and CD8(+) T cells in the skin-draining lymph nodes. As a consequence, we developed an immunization strategy through the skin, termed epicutaneous immunization. Protein antigen applied onto barrier-disrupted skin induces long-lasting cytotoxic T-cell responses, potent enough to control and inhibit tumor growth. In this review, we suggest that immunization strategies through the skin could be a promising new approach for the treatment of skin cancer.

Epicutaneous allergen administration as a novel method of allergen-specific immunotherapy

BACKGROUND

Subcutaneous allergen-specific immunotherapy is an effective treatment of IgE-mediated allergies, but it requires repeated allergen injections with a risk of systemic allergic reactions. Transcutaneous immunotherapy may improve patient compliance and safety.

OBJECTIVE

To assess the safety and efficacy of epicutaneous allergen immunotherapy.

METHODS

This monocentric, placebo-controlled, double-blind trial was conducted from March 2006 to December 2007 at the University Hospital Zurich. Thirty-seven adult patients with positive skin prick and nasal provocation tests to grass pollen were randomized to receive patches containing either allergen (n = 21) or placebo (n = 16). Treatment took place before and during the pollen season 2006, and follow-up visits took place before (n = 26) and after the pollen season 2007 (n = 30). The primary outcome measures were nasal provocation tests.

RESULTS

Allergen-treated patients showed significantly decreased scores in nasal provocation tests in the first (P < .001) and second year (P = .003) after treatment. In contrast, placebo-treated patients had decreased scores in the first treatment year, 2006 (P = .03), but the effect diminished in the second year (P = .53). Although improvement of nasal provocation test scores was not significantly better in the verum versus placebo group, the overall treatment success was rated significantly higher by the allergen-treated group than by the placebo group (2006, P = .02; 2007, P = .005). No severe adverse events were observed. Occurrence of eczema after allergen patch applications proved stimulation of specific T-cell responses, but was noted as an adverse effect of the treatment.

CONCLUSION

Epicutaneous allergen immunotherapy is a promising strategy to treat allergies and merits further investigation.

Electroporation as an efficient physical enhancer for skin drug delivery

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injection. However, the stratum corneum acts as a barrier that limits the penetration of substances through the skin. Application of high-voltage pulses to the skin increases its permeability (electroporation) and enables the delivery of various substances into and through the skin. The application of electroporation to the skin has been shown to increase transdermal drug delivery. Moreover, electroporation, used alone or in combination with other enhancement methods, expands the range of drugs (small to macromolecules, lipophilic or hydrophilic, charged or neutral molecules) that can be delivered transdermally. The efficacy of transport depends on the electrical parameters and the physicochemical properties of drugs. The in vivo application of high-voltage pulses is well tolerated, but muscle contractions are usually induced. The electrode and patch design is an important issue to reduce the discomfort of the electrical treatment in humans. This review presents the main findings in the field of electroporation-namely, transdermal drug delivery. Particular attention is paid to proposed enhancement mechanisms and trends in the field of topical and transdermal delivery.

Transcutaneous immunization using common chemicals

Transcutaneous immunization, topical application of vaccines on skin, provides several advantages over needle based immunization. However, simple topical application of vaccines does not generate sufficient immune response due to limited transport of vaccines across the stratum corneum of skin. Here we report that chemicals used in common skin products can enhance the immunogenicity of topically applied antigens. Six hundred formulations of commonly used chemicals were screened systematically for their potency (delivery of antigen) in vitro. A selected subset of these formulations was subsequently tested for their adjuvanticity (activation of immune response) in vitro. Lead formulations were tested in vivo for their ability to generate antibody titers against topically applied ovalbumin, a model antigen. Lead formulations were significantly more effective in generating anti-ovalbumin IgG titers. Our results demonstrate that chemical formulations can be successfully used to deliver antigens and that such formulations can be rationally designed by combinatorial screening of individual chemical components.

Efficacy of a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in pigs naturally exposed to a heterologous European (Italian cluster) field strain: Clinical protection and cell-mediated immunity

The purpose of this study was to assess clinical protection in pigs vaccinated with a commercially available attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine (Porcilis) PRRS) and then naturally exposed under field conditions to a heterologous (Italian cluster) strain of virulent PRRSV. A total of 30, 4-week-old pigs seronegative for PRRSV were allocated to 1 of 3 groups (IM, ID, and C groups). At 5 weeks of age, pigs of groups IM (n=10 pigs) and ID (n=10 pigs) were vaccinated intramuscularly and intradermally, respectively, with modified live PRRSV-1 vaccine (Porcilis) PRRS). Pigs of group C (n=10 pigs) were kept as non-vaccinated controls. At post-vaccination (PV) days 0, 7, 14, 28, and 45, blood samples were collected for detection of vaccine virus (PCR) and antibody response (ELISA), identification of changes in lymphocyte subpopulations by cytometry, and IFN-gamma PRRSV-specific secreting cells (SC) by ELISpot. At PV day 45, pigs of A, B, and C groups were moved to a site 3 conventional finishing herd with a history of respiratory disease caused by PRRSV and the most common bacteria to be exposed to a natural challenge. The PRRSV field strain, belonging to the Italian cluster of the PRRSV-1, demonstrated a 84% identity with the vaccine virus (DV strain) at ORF5 sequencing. At 0 (exposure day=45 days PV), 4, 7, 11, 14, 19, 21, 28, and 34 days post-exposure (PE) blood samples were collected for detection and titration of PRRSV and antibody, as well as for lymphocyte and IFN-gamma measurement as described above. Throughout the post-exposure period, all pigs were observed daily for clinical signs. The overall clinical signs were reduced by 68 and 72%, respectively in the intramuscularly and intradermally vaccinated pigs compared to controls. Respiratory signs were reduced by 72 and 80%, respectively in the IM and ID groups. Clinical protection was associated with marked activation of cell-mediated immune response. The highest levels of specific IFN-gamma production at 21-34 days PE were concomitant and associated to changes in natural killer (NK) cells, gamma/delta T, and cytotoxic T lymphocytes in the blood. In our field study, evidences of EU attenuated vaccine-induced clinical protection against natural exposure to a genetically diverse (84% homology) PRRSV-1 isolate (Italian cluster) was demonstrated by the statistically significant reduction in clinical signs in terms of incidence, duration and severity and by a more efficient cell-mediated immune response in the vaccinated pigs as compared to the unvaccinated controls.

Immune modulation by adjuvants combined with diphtheria toxoid administered topically in BALB/c mice after microneedle array pretreatment

Purpose

In this study, modulation of the immune response against diphtheria toxoid (DT) by various adjuvants in transcutaneous immunization (TCI) with microneedle array pretreatment was investigated.

Methods

TCI was performed on BALB/c mice with or without microneedle array pretreatment using DT as a model antigen co-administrated with lipopolysaccharide (LPS), Quil A, CpG oligo deoxynucleotide (CpG) or cholera toxin (CT) as adjuvant. The immunogenicity was evaluated by measuring serum IgG subtype titers and neutralizing antibody titers.

Results

TCI with microneedle array pretreatment resulted in a 1,000-fold increase of DT-specific serum IgG levels as compared to TCI. The immune response was further improved by co-administration of adjuvants, showing a progressive increase in serum IgG titers when adjuvanted with LPS, Quil A, CpG and CT. IgG titers of the CT-adjuvanted group reached levels comparable to those obtained after DT-alum subcutaneous injection. The IgG1/IgG2a ratio of DT-specific antibodies decreased in the following sequence: plain DT, Quil A, CT and CpG, suggesting that the immune response was skewed towards the Th1 direction.

Conclusions

The potency and the quality of the immune response against DT administered by microneedle array mediated TCI can be modulated by co-administration of adjuvants.

Transdermal drug delivery

Transdermal drug delivery has made an important contribution to medical practice, but has yet to fully achieve its potential as an alternative to oral delivery and hypodermic injections. First-generation transdermal delivery systems have continued their steady increase in clinical use for delivery of small, lipophilic, low-dose drugs. Second-generation delivery systems using chemical enhancers, noncavitational ultrasound and iontophoresis have also resulted in clinical products; the ability of iontophoresis to control delivery rates in real time provides added functionality. Third-generation delivery systems target their effects to skin's barrier layer of stratum corneum using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound. Microneedles and thermal ablation are currently progressing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. Using these novel second- and third-generation enhancement strategies, transdermal delivery is poised to significantly increase its impact on medicine.

Transdermal drug delivery

Transdermal drug delivery has made an important contribution to medical practice, but has yet to fully achieve its potential as an alternative to oral delivery and hypodermic injections. First-generation transdermal delivery systems have continued their steady increase in clinical use for delivery of small, lipophilic, low-dose drugs. Second-generation delivery systems using chemical enhancers, noncavitational ultrasound and iontophoresis have also resulted in clinical products; the ability of iontophoresis to control delivery rates in real time provides added functionality. Third-generation delivery systems target their effects to skin's barrier layer of stratum corneum using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound. Microneedles and thermal ablation are currently progressing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. Using these novel second- and third-generation enhancement strategies, transdermal delivery is poised to significantly increase its impact on medicine.

Overview of drug delivery and alternative methods to electroporation

This chapter provides an overview of the application of electroporation to areas other than gene delivery. These areas include the delivery of drugs and vaccines to tissues and tumors as well as into and through the skin. Achievements and limitations of electroporation in these areas are presented. Alternative physical methods for gene and drug delivery besides electroporation are described. The advantages and drawbacks of electroporation, compared with these methods, are also discussed.

Transcutaneous immunization by merely prolonging the duration of antigen presence on the skin of mice induces a potent antigen-specific antibody response even in the absence of an adjuvant

Transcutaneous immunization (TCI) is a promising needle-free technique for vaccination. In this method, strong adjuvants, such as the cholera toxin, are generally crucial to elicit a robust immune response. Here, we showed that prolonged antigen presence on the skin of mice during TCI could effectively enhance the immune response. Substantial antigen-specific antibodies were produced in the sera of mice even after non-adjuvanted TCI when the antigen presence was for longer than 16 h. This non-adjuvanted TCI method was applied using the tetanus toxoid, and potent tetanus toxoid-specific antibodies were successfully induced in the sera of mice; they survived a lethal tetanus toxin challenge with no clinical signs. Thus, non-adjuvanted approach might be a possible option for TCI, and this method might improve the safety and practicality of transcutaneous vaccination.