Recent progress in PLGA-based microneedle-mediated transdermal drug and vaccine delivery

Mannose-modified erythrocyte membrane-coated Chuanmingshen violaceum polysaccharide PLGA nanoparticles to improve immune responses in mice

This study developed a poly(lactic-co-glycolic acid) (PLGA) biomimetic nanoparticle (Man-RBC-CVPP) containing Chuanmingshen violaceum polysaccharide (CVP) and coated with a macrophage-targeting mannose receptor (DSPE-PEG-Man) modified RBCM. In vitro experiments demonstrated that Man-RBC-CVPP enhances antigen uptake and immune responses in RAW264.7 cells and can induce an immune response in mouse macrophages by activating the TLR4-mediated NF-κB signaling pathway. In vivo experiments showed that Man-RBC-CVPP promotes the activation of splenic dendritic cells (DCs) by increasing the expression of major histocompatibility complex class II (MHCII), CD80+, and CD86+. Further, it improves the maturation of splenic lymphocytes, increasing the expression of CD4+ and CD8+. It also upregulates the secretion of cytokines, raises serum levels of the specific antibody IgG, and slows the release of OVA at the injection site. In summary, Man-RBC-CVPP can effectively enhance both cellular and humoral immune responses and provide controlled, long-term antigen release.

General fabrication of bioactive dissolving microneedles from whole grain seeds derived starch for transdermal application

Dissolving microneedles (DMNs) have gained increasing attraction for transdermal drug delivery. However, their manufacture is limited due to the lack of suitable fabricating materials. It is highly demanded to explore new materials for DMN preparation. Herein, we were the first to discover that natural grain powders were promising material candidates for DMN manufacture. MD was first used to determine the solvent to prepare microneedles. Then, mold method was used to fabricate five grain seed powders into microneedles. Afterwards, FTIR, XRD, MTT, live/dead assay and antioxidative assays (DPPH and Fenton) were applied to assess the chemical and biological properties of the microneedles. Finally, both in vitro and in vivo experiments were used to assess the transdermal effects of the microneedles. The results demonstrated that the microneedles had excellent biosafety with >90 % of living cells and <5 % of hemolysis rate. Also, the microneedles displayed up to 100 % eradication of free radicals, implying their good antioxidative capabilities. The transdermal study demonstrated that the microneedles could pierce mouse skins and undergo completely and fast dissolving in the skin as quickly as 30 s. This work will motivate more attempts to develop novel transdermal microneedles from natural products for biological applications.

Chlorhexidine-loaded microneedles for treatment of oral diseases

Chlorhexidine (CHX) is a gold standard therapeutic agent against clinical oral pathogens. However, its oral use is limited due to unpleasant taste, alteration in taste buds, staining of teeth and mucous membranes. Therefore, CHX-loaded PLGA microneedles (MNs) were fabricated for local and controlled release in the oral cavity, using a casting mold method. The MNs were well-formed with sharp MN tips and flat baseplates, showing quadrangular pyramidal shapes with average needle height and base width of about 500 and 200 µm, respectively. CHX was successfully incorporated into the PLGA-based MNs, exhibiting high encapsulation efficiency. CHX-PLGA MNs were further characterized in terms of ATR-FTIR and DSC, indicating intermolecular interactions between CHX and PLGA. In vitro CHX release exhibited an initial burst release within the first 24 h, accompanied by a slower release rate, reaching cumulative release of ca. 56 % after 10 days. The antibacterial effect of CHX-PLGA MNs on Streptococcus mutans (S. mutans) was evaluated using different techniques. In agar diffusion assay, the MNs displayed sustained antimicrobial activity over 8 days, while they significantly reduced the bacterial growth of S. mutans on the first 4 days in a planktonic experimental setup. No antibacterial effect was recorded for the blank PLGA MNs that served as a control group. Interestingly, CHX-PLGA MNs eliminated biofilm formation and metabolic activity for 3 days compared with biofilm formed in the presence of blank MNs. Then, a rebound effect was recorded. A weak antibiofilm effect and anti-metabolic activity was observed when MNs tested against pre-formed biofilm. Taken together, CHX-PLGA MNs hold promise as a viable delivery modality for localized and sustainedantimicrobial activity in the oral cavity. Further research is required to optimize the formulation and assess efficacy and safety in clinical settings.

Enhancement of Transdermal Drug Delivery: Integrating Microneedles with Biodegradable Microparticles

This investigation aimed to enhance transdermal methotrexate delivery through human skin by employing Dr. Pen microneedles and poly(d,l-lactide-co-glycolide) acid microparticles formulated from eight polymer grades (Expansorb DLG 95-4A, DLG 75-5A, DLG 50-2A, DLG 50-5A, DLG 50-8A, DLG 50-6P, DLG 50-7P, and DLL 10-15A). A comprehensive characterization of the microparticles was performed, encompassing various parameters such as size, charge, morphology, microencapsulation efficiency, yield, release kinetics, and chemical composition. The efficacy of microneedles in disrupting skin integrity was demonstrated by scanning electron microscopy, dye binding, histological examination, confocal laser microscopy, and pore size analysis. Microneedle-mediated skin microporation led to a substantial reduction in skin electrical resistance and a concomitant increase in transepidermal water loss. In vitro permeation experiments using human skin delivered microparticles into microporated skin and demonstrated a considerable difference in methotrexate delivery among the polymer groups. Microneedle treatment significantly amplified cumulative drug delivery, steady-state flux, diffusion coefficient, permeability coefficient, and drug concentration within skin layers while concurrently diminishing lag time (p < 0.05). Furthermore, a robust correlation was established between microparticle properties (cumulative release, release rate, encapsulation efficiency) and drug deposition in the skin. In conclusion, the synergistic combination of Dr. Pen microneedles and PLGA microparticles facilitated enhanced and regulated transdermal methotrexate delivery.

Liposome-loaded dissolvable microneedle patches for more efficient intradermal antigen delivery of Hepatitis B vaccine

The aim of this study was to improve the efficacy of Hepatitis B surface antigen (HBsAg) vaccination via liposome-loaded dissolvable microneedle (Lipo-dMN) patches. HBsAg liposomes were prepared using the thin-film hydration method and subsequently incorporated into dissolvable microneedle patches via a pre-vacuum approach. Liposomes, dissolvable microneedle patches (dMN), and Lipo-dMN were characterized for encapsulation efficiency, mechanical properties, morphology, skin insertion, in vitro release, cellular uptake, and in vivo vaccination studies. The HBsAg was encapsulated into liposomes with encapsulation efficiencies around 50 %, particle size around 160 nm, and zeta potential around -20 mV. HBsAg can maintain its activity during the preparation of dMN and Lipo-dMN. The intact pyramid microneedle has a sharp end and strong mechanical properties that allow easy insertion into the ex vivo pig skin. The dMN and Lipo-dMN, with a mechanical property of 1.6 N, readily penetrate the epidermis and release the HBsAg and HBsAg liposome to modulate the immune response. A comprehensive comparison of HBsAg subcutaneous injection and intradermal delivery of HBsAg and HBsAg liposome by dMN revealed different levels of anti-HBsAg IgG antibody. Inoculation with dMN and Lipo-dMN resulted in significantly higher levels of anti-HBsAg IgG antibodies (p < 0.01) compared to subcutaneous injection of HBsAg. In addition, we found that IgG levels increased significantly (P < 0.05) with increased dose of subcutaneous injection of HBsAg and intradermal delivery of dMN, but the opposite effect was observed in Lipo-dMN. The possible mechanism for this observation may be the increased cellular uptake of liposomes by BMDCs upon long-term incubation. In summary, this study presents a promising approach to enhance HBsAg vaccination efficacy through the synergistic combination of liposomes and dissolvable microneedles at reduced vaccine doses.

A stimulus responsive microneedle-based drug delivery system for cancer therapy

The intricate nature of the tumor microenvironment (TME) results in the inefficient delivery of anticancer drugs within tumor tissues, significantly compromising the therapeutic effect of cancer treatment. To address this issue, transdermal drug delivery microneedles (MNs) with high mechanical strength have emerged. Such MNs penetrate the skin barrier, enabling efficient drug delivery to tumor tissues. This approach enhances drug bioavailability, while also mitigating concerns such as liver and kidney toxicity associated with intravenous and oral drug administration. Notably, stimulus responsive MNs designed for drug delivery have the capacity to respond to various biological signals and pathological changes. This adaptability enables them to exert therapeutic effects within the TME, exploiting biochemical variations and tailoring treatment strategies to suit tumor characteristics. The present review surveys recent advancements in responsive MN systems. This comprehensive analysis serves as a valuable reference for the prospective application of smart MN drug delivery systems in cancer therapy.

Advancements in Materials for 3D-Printed Microneedle Arrays: Enhancing Performance and Biocompatibility

The rapid advancement of 3D printing technology has revolutionized the fabrication of microneedle arrays (MNAs), which hold great promise in biomedical applications such as drug delivery, diagnostics, and therapeutic interventions. This review uniquely explores advanced materials used in the production of 3D-printed MNAs, including photopolymer resins, biocompatible materials, and composite resins, designed to improve mechanical properties, biocompatibility, and functional performance. Additionally, it introduces emerging trends such as 4D printing for programmable MNAs. By analyzing recent innovations, this review identifies critical challenges and proposes future directions to advance the field of 3D-printed MNAs. Unlike previous reviews, this paper emphasizes the integration of innovative materials with advanced 3D printing techniques to enhance both the performance and sustainability of MNAs.

GelMA microneedle-loaded bio-derived nanovaccine shows therapeutic potential for gliomas

Glioma is the most common primary malignant tumor of the central nervous system in adults. Although immunotherapy, especially tumor vaccines, has made some progress in the treatment of gliomas compared with surgery and radiotherapy. However, the lack of specific or relevant tumor antigens severely limits the further development of tumor vaccines. Here, we report a bio-derived vaccine (TMV@CpG) derived from glioma cell membrane vesicles and carrying TLR9 agonist CpG as adjuvant, which was loaded onto the GelMA microneedle to obtain the microneedle vaccine (MN-TMV@CpG). Microneedle vaccine fully utilize the innate immune cells rich in the skin, inducing stronger cellular immune responses. In subcutaneous tumor models, MN-TMV@CpG reversed the immune-suppressing microenvironment of tumor, and effectively inhibited tumor progression. In an intracranial tumor model, MN-TMV@CpG significantly prolonged the survival duration and induced stronger immune memory responses in tumor bearing mice when combined with anti-PD1 mAb. These results suggest that bio-derived nanovaccines can be used as a potential antitumor immunotherapy strategy.

Novel long-acting treatment for schizophrenia based on paliperidone dissolving and implantable microarray patches

Schizophrenia is a severe mental disorder that affects millions of people worldwide. Several atypical antipsychotic medications, including paliperidone (PPD), has been developed and proven effective in treating it. To date, four PPD extended-release products have been launched commercially, providing up to six months of therapeutic effect with a single administration. However, the need for hospital injections by professional healthcare workers not only lead to poor patients' adherence, but also put additional pressure on the healthcare system. Therefore, three PPD microarray patch (PPD MAP) systems based on dissolving microneedle technology and implantable microneedle technology were developed in this work. The two dissolving microarray patch systems contained either PPD crude drug (PPD DMAP-CD) or PPD nanocrystal (PPD DMAP-NC) and the implantable MAP contained PPD crude drug (PPD IMAP). All three types of PPD MAPs showed excellent mechanical and insertion properties as they achieved over 256 µm insertion depth in skin model. In vitro release study showed that PPD released from IMAP in a much more sustained manner (up to 14 days) than PPD did from DMAPs (7 days), with only 20 % initial burst release from IMAP compared with 43-71 % from DMAPs. The MAP dissolution study showed that both DMAPs can be immediately dissolved within less than 3 min once inserted into the skin, indicating a faster action potential compared with IMAP. Ex vivo delivery study showed that 1.68 ± 0.23 mg, 1.39 ± 0.07 mg, and 1.18 ± 0.12 mg were delivered from DMAP-CD, DMAP-NC and IMAP, respectively, demonstrating that over 50 % and up to 70 % of PPD in the MAPs can be delivered into the skin. The IMAP offers most sustained release of PPD whereas DMAP-NC exhibits fastest PPD release (11.19 % vs 20.01 % into Franz cell receiver compartment over 24 h). This work presents a promising alternative for the sustained delivery of antipsychotic drugs, allowing for patient self-administration and extended release concurrently. Patients may potentially use both DMAP and IMAP to achieve a sustained release of PPD while also avoid having an initial therapeutic lag.

Visualization of the degradation of long-acting microneedles and correlation of drug release in vivo based on FRET mechanism

This study introduces a live imaging technique for real-time, non-invasive monitoring of drug release from long-acting microneedles using FRET (Fluorescence Resonance Energy Transfer). Employing Cy5.5 and Cy7 as FRET pairs and levonorgestrel as the model drug, we fabricated microneedles with varying PLGA molecular weights, demonstrating distinct release profiles. The FRET-PLGA-10-MN demonstrated a rapid drug release profile, reaching nearly complete release within a two-day period, while FRET-PLGA-30-MN showed a sustained release over four days. Sensitized Emission FRET (SE-FRET) optimized the imaging process, providing a robust correlation between FRET signals and drug absorption. This method surpasses traditional pharmacokinetic studies by offering a more efficient and comprehensive analysis of microneedle release dynamics in vivo, paving the way for enhanced long-acting microneedle design and therapeutic outcomes. STATEMENT OF SIGNIFICANCE: 1. FRET technology was applied to microneedle drug delivery system for the first time, which realized real-time, quantitative and non-invasive monitoring of drug release process. 2. The long-term microneedle technique was combined with sensitized emission method, and the FRET remaining ratio was innovatively used to investigate the FRET characteristics of microneedles, and the fluorescence ratio of FRET and donor double-channel was quantitatively calculated. 3. The correlation between visual fluorescence images of FRET effect and semi-quantitative calculation results based on fluorescence intensity and drug release in vivo with drug-loaded microneedles was analyzed.

Biomaterials for non-invasive trans-tympanic drug delivery: requirements, recent advances and perspectives

Various non-invasive delivery systems have recently been developed as an alternative to conventional injections. Local transdermal administration represents the most attractive method due to the low systemic side effects, excellent ease of administration, and persistent drug release. The tympanic membrane (TM), a major barrier between the outer and middle ear, has a similar structure of the stratum corneum compared to the surface of the skin. After several attempts, non-invasive trans-tympanic drug delivery has been regarded as a promising option in the treatment of middle and inner ear diseases. The round window membrane (RWM) was a possible non-invasive delivery approach from the middle to inner ear. The improved permeability of nanocarriers crossing the RWM is a current hotspot in therapeutics for inner ear diseases. In this review, we include the latest studies exploring non-invasive trans-tympanic delivery to treat middle and inner ear diseases. Both passive and active delivery systems are described. A summary of the benefits and disadvantages of various delivery systems in clinical practice and production procedures is introduced. Finally, future possible approaches for its effective application as a non-invasive middle and inner ear drug delivery system are characterised.

Supercritical Fluids: An Innovative Strategy for Drug Development

Nanotechnology plays a pivotal role in the biomedical field, especially in the synthesis and regulation of drug particle size. Reducing drug particles to the micron or nanometer scale can enhance bioavailability. Supercritical fluid technology, as a green drug development strategy, is expected to resolve the challenges of thermal degradation, uneven particle size, and organic solvent residue faced by traditional methods such as milling and crystallization. This paper provides an insight into the application of super-stable homogeneous intermix formulating technology (SHIFT) and super-table pure-nanomedicine formulation technology (SPFT) developed based on supercritical fluids for drug dispersion and micronization. These technologies significantly enhance the solubility and permeability of hydrophobic drugs by controlling the particle size and morphology, and the modified drugs show excellent therapeutic efficacy in the treatment of hepatocellular carcinoma, pathological scarring, and corneal neovascularization, and their performance and efficacy are highlighted when administered through multiple routes of administration. Overall, supercritical fluids have opened a green and efficient pathway for clinical drug development, which is expected to reduce side effects and enhance therapeutic efficacy.

PLGA micro/nanoparticle vaccination elicits non-tumor antigen specific resident memory CD8+ T cell protection from hepatocellular carcinoma

Together, tumor and virus-specific tissue-resident CD8+ memory T cells (TRMs) of hepatocellular carcinoma (HCC) patients with Hepatitis B virus (HBV) infection can provide rapid frontline immune surveillance. The quantity and activity of CD8+ TRMs were correlated with the relapse-free survival of patients with improved health. However, HBV-specific CD8+ TRMs have a more exhausted phenotype and respond more actively under anti-PDL1 or PD1 treatment of HBV+HCC patients. Vaccination strategies that induce a strong and sustained CD8+ TRMs response are quite promising. Herein, a biodegradable poly(D,L-lactide-co-glycolide) microsphere and nanosphere particle (PLGA N.M.P) delivery system co-assembled by anti-PD1 antibodies (aPD1) and loaded with ovalbumin (OVA-aPD1 N.M.P) was fabricated and characterized for size (200 nm and 1 μm diameter), charge (-15 mV), and loading efficiencies of OVA (238 μg mg-1 particles) and aPD1 (40 μg mg-1 particles). OVA-aPD1 N.M.P could stimulate the maturation of BMDCs and enhance the antigen uptake and presentation by 2-fold compared to free OVA. The nanoparticles also induced the activation of macrophages (RAW 264.7) to produce a high level of cytokines, including TNF-α, IL-6 and IL-10. In vivo stimulation of mice using OVA-aPD1 N.M.P robustly enhanced IFN-γ-producing-CD8+ T cell infiltration in tumor tissues and the secretion of IgG and IgG2a/IgG1 antibodies. OVA-aPD1 N.M.P delivered OVA to increase the activation and proliferation of OVA-specific CD8+ TRMs, and its combination with anti-PD1 antibodies promoted complete tumor rejection by the reversal of tumor-infiltrating CD8+ T cell exhaustion. Thus, PLGA N.M.P could induce a strong CD8+ TRMs response, further highlighting its therapeutic potential in enhancing an antitumor immune response.

Polymeric Microneedles Enhance Transdermal Delivery of Therapeutics

This research presents the efficacy of polymeric microneedles in improving the transdermal permeation of methotrexate across human skin. These microneedles were fabricated from PLGA Expansorb® 50-2A and 50-8A and subjected to comprehensive characterization via scanning electron microscopy, Fourier-transform infrared spectroscopy, and mechanical analysis. We developed and assessed a methotrexate hydrogel for physicochemical and rheological properties. Dye binding, histological examinations, and assessments of skin integrity demonstrated the effective microporation of the skin by PLGA microneedles. We measured the dimensions of microchannels in the skin using scanning electron microscopy, pore uniformity analysis, and confocal microscopy. The skin permeation and disposition of methotrexate were researched in vitro. PLGA 50-8A microneedles appeared significantly longer, sharper, and more mechanically uniform than PLGA 50-2A needles. PLGA 50-8A needles generated substantially more microchannels, as well as deeper, larger, and more uniform channels in the skin than PLGA 50-2A needles. Microneedle insertion substantially reduced skin electrical resistance, accompanied by an elevation in transepidermal water loss values. PLGA 50-8A microneedle treatment provided a significantly higher cumulative delivery, flux, diffusion coefficient, permeability coefficient, and predicted steady-state plasma concentration; however, there was a shorter lag time than for PLGA 50-2A needles, base-treated, and untreated groups (p < 0.05). Conclusively, skin microporation using polymeric microneedles significantly improved the transdermal delivery of methotrexate.

A differential-targeting core-shell microneedle patch with coordinated and prolonged release of mangiferin and MSC-derived exosomes for scarless skin regeneration

Microneedles for skin regeneration are conventionally restricted by uncontrollable multi-drug release, limited types of drugs, and poor wound adhesion. Here, a novel core-shell microneedle patch is developed for scarless skin repair, where the shell is composed of hydrophilic gelatin methacryloyl (GelMA) loaded with mangiferin, an anti-inflammatory small molecule, and the core is composed of hydrophobic poly (lactide-co-propylene glycol-co-lactide) dimethacrylates (PGLADMA) loaded with bioactive macromolecule and human mesenchymal stromal cell (hMSC)-derived exosomes. This material choice provides several benefits: the GelMA shell provides a swelling interface for tissue interlocking and rapid release of mangiferin at an early wound healing stage for anti-inflammation, whereas the PGLADMA core offers long-term encapsulation and release of exosomes (30% release in 3 weeks), promoting sustained angiogenesis and anti-inflammation. Our results demonstrate that the core-shell microneedle possesses anti-inflammatory properties and can induce angiogenesis both in vitro in terms of macrophage polarization and tube formation of human umbilical vein endothelial cells (HUVECs), and in vivo in terms of anti-inflammation, re-epithelization, and vessel formation. Importantly, we also observe reduced scar formation in vivo. Altogether, the degradation dynamics of our hydrophilic/hydrophobic materials enable the design of a core-shell microneedle for differential and prolonged release, promoting scarless skin regeneration, with potential for other therapies of long-term exosome release.

Polymeric Microneedles for Health Care Monitoring: An Emerging Trend

Bioanalyte collection by blood draw is a painful process, prone to needle phobia and injuries. Microneedles can be engineered to penetrate the epidermal skin barrier and collect analytes from the interstitial fluid, arising as a safe, painless, and effective alternative to hypodermic needles. Although there are plenty of reviews on the various types of microneedles and their use as drug delivery systems, there is a lack of systematization on the application of polymeric microneedles for diagnosis. In this review, we focus on the current state of the art of this field, while providing information on safety, preclinical and clinical trials, and market distribution, to outline what we believe will be the future of health monitoring.

Microneedles Based on a Biodegradable Polymer-Hyaluronic Acid

Transdermal transport can be challenging due to the difficulty in diffusing active substances through the outermost layer of the epidermis, as the primary function of the skin is to protect against the entry of exogenous compounds into the body. In addition, penetration of the epidermis for substances hydrophilic in nature and particles larger than 500 Da is highly limited due to the physiological properties and non-polar nature of its outermost layer, namely the stratum corneum. A solution to this problem can be the use of microneedles, which "bypass" the problematic epidermal layer by dispensing the active substance directly into the deeper layers of the skin. Microneedles can be obtained with various materials and come in different types. Of special interest are carriers based on biodegradable and biocompatible polymers, such as polysaccharides. Therefore, this paper reviews the latest literature on methods to obtain hyaluronic acid-based microneedles. It focuses on the current advancements in this field and consequently provides an opportunity to guide future research in this area.

Design and Synthesis of Biomedical Polymer Materials

Due to their biocompatibility and non-toxic nature, biomedical polymer materials have found widespread applications and significantly propelled the progress of the biomedical field [...].

Application of hydrogel microneedles in the oral cavity

Microneedles are a transdermal drug delivery system in which the needle punctures the epithelium to deliver the drug directly to deep tissues, thus avoiding the influence of the first-pass effect of the gastrointestinal tract and minimizing the likelihood of pain induction. Hydrogel microneedles are microneedles prepared from hydrogels that have good biocompatibility, controllable mechanical properties, and controllable drug release and can be modified to achieve environmental control of drug release in vivo. The large epithelial tissue in the oral cavity is an ideal site for drug delivery via microneedles. Hydrogel microneedles can overcome mucosal hindrances to delivering drugs to deep tissues; this prevents humidity and a highly dynamic environment in the oral cavity from influencing the efficacy of the drugs and enables them to obtain better therapeutic effects. This article analyzes the materials and advantages of common hydrogel microneedles and reviews the application of hydrogel microneedles in the oral cavity.

Applications and prospects of microneedles in tumor drug delivery

As drug delivery devices, microneedles are used widely in the local administration of various drugs. Such drug-loaded microneedles are minimally invasive, almost painless, and have high drug delivery efficiency. In recent decades, with advancements in microneedle technology, an increasing number of adaptive, engineered, and intelligent microneedles have been designed to meet increasing clinical needs. This article summarizes the types, preparation materials, and preparation methods of microneedles, as well as the latest research progress in the application of microneedles in tumor drug delivery. This article also discusses the current challenges and improvement strategies in the use of microneedles for tumor drug delivery.

Endogenous stimuli-responsive separating microneedles to inhibit hypertrophic scar through remodeling the pathological microenvironment

Hypertrophic scar (HS) considerably affects the appearance and causes tissue dysfunction in patients. The low bioavailability of 5-fluorouracil poses a challenge for HS treatment. Here we show a separating microneedle (MN) consisting of photo-crosslinked GelMA and 5-FuA-Pep-MA prodrug in response to high reactive oxygen species (ROS) levels and overexpression of matrix metalloproteinases (MMPs) in the HS pathological microenvironment. In vivo experiments in female mice demonstrate that the retention of MN tips in the tissue provides a slowly sustained drug release manner. Importantly, drug-loaded MNs could remodel the pathological microenvironment of female rabbit ear HS tissues by ROS scavenging and MMPs consumption. Bulk and single cell RNA sequencing analyses confirm that drug-loaded MNs could reverse skin fibrosis through down-regulation of BCL-2-associated death promoter (BAD), insulin-like growth factor 1 receptor (IGF1R) pathways, simultaneously regulate inflammatory response and keratinocyte differentiation via up-regulation of toll-like receptors (TOLL), interleukin-1 receptor (IL1R) and keratinocyte pathways, and promote the interactions between fibroblasts and keratinocytes via ligand-receptor pair of proteoglycans 2 (HSPG2)-dystroglycan 1(DAG1). This study reveals the potential therapeutic mechanism of drug-loaded MNs in HS treatment and presents a broad prospect for clinical application.

Enhancing cell-scale performance via sustained release of the varicella-zoster virus antigen from a microneedle patch under simulated microgravity

The immune system of astronauts might become weakened in the microgravity environment in space, and the dormant varicella-zoster virus (VZV) in the body might be reactivated, seriously affecting their work and safety. For working in orbit for the long term, there is currently no efficient and durable delivery system of general vaccines in a microgravity environment. Accordingly, based on the previous foundation, we designed, modified, and synthesized a biodegradable and biocompatible copolymer, polyethylene glycol-polysulfamethazine carbonate urethane (PEG-PSCU) that could be mainly adopted to fabricate a novel sustained-release microneedle (S-R MN) patch. Compared with conventional biodegradable microneedles, this S-R MN patch could not only efficiently encapsulate protein vaccines (varicella-zoster virus glycoprotein E, VZV gE) but also further prolong the release time of VZV gE in a simulated microgravity (SMG) environment. Eventually, we verified the activation of dendritic cells by VZV gE released from the S-R MN patch in an SMG environment and the positive bioeffect of activated dendritic cells on lymphocytes using an in vitro lymph node model. This study is of great significance for the exploration of long-term specific immune responses to the VZV in an SMG environment.

Immunogenicity of Recombinant Lipid-Based Nanoparticle Vaccines: Danger Signal vs. Helping Hand

Infectious diseases are a predominant problem in human health. While the incidence of many pathogenic infections is controlled by vaccines, some pathogens still pose a challenging task for vaccine researchers. In order to face these challenges, the field of vaccine development has changed tremendously over the last few years. For non-replicating recombinant antigens, novel vaccine delivery systems that attempt to increase the immunogenicity by mimicking structural properties of pathogens are already approved for clinical applications. Lipid-based nanoparticles (LbNPs) of different natures are vesicles made of lipid layers with aqueous cavities, which may carry antigens and other biomolecules either displayed on the surface or encapsulated in the cavity. However, the efficacy profile of recombinant LbNP vaccines is not as high as that of live-attenuated ones. This review gives a compendious picture of two approaches that affect the immunogenicity of recombinant LbNP vaccines: (i) the incorporation of immunostimulatory agents and (ii) the utilization of pre-existing or promiscuous cellular immunity, which might be beneficial for the development of tailored prophylactic and therapeutic LbNP vaccine candidates.

Botulinum toxin A dissolving microneedles for hyperhidrosis treatment: design, formulation and in vivo evaluation

Multiple periodic injections of botulinum toxin A (BTX-A) are the standard treatment of hyperhidrosis which causes excessive sweating. However, BTX-A injections can create problems, including incorrect and painful injections, the risk of drug entry into the bloodstream, the need for medical expertise, and waste disposal problems. New drug delivery systems can substantially reduce these problems. Transdermal delivery is an effective alternative to conventional BTX-A injections. However, BTX-A's large molecular size and susceptibility to degradation complicate transdermal delivery. Dissolving microneedle patches (DMNPs) encapsulated with BTX-A (BTX-A/DMNPs) are a promising solution that can penetrate the dermis painlessly and provide localized translocation of BTX-A. In this study, using high-precision 3D laser lithography and subsequent molding, DMNPs were prepared based on a combination of biocompatible polyvinylpyrrolidone and hyaluronic acid polymers to deliver BTX-A with ultra-sharp needle tips of 1.5 ± 0.5 µm. Mechanical, morphological and histological assessments of the prepared DMNPs were performed to optimize their physicochemical properties. Furthermore, the BTX-A release and diffusion kinetics across the skin layers were investigated. A COMSOL simulation was conducted to study the diffusion process. The primary stability analysis reported significant stability for three months. Finally, the functionality of the BTX-A/DMNPs for the suppression of sweat glands was confirmed on the hyperhidrosis mouse footpad, which drastically reduced sweat gland activity. The results demonstrate that these engineered DMNPs can be an effective, painless, inexpensive alternative to hypodermic injections when treating hyperhidrosis.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.