Microneedle applications in improving skin appearance

Advances in microneedle technology for biomedical detection

Microneedles have recently emerged as a groundbreaking technology in the field of biomedical detection. Notable for their small size and ability to penetrate the superficial layers of the skin, microneedles provide an innovative platform for localized and real-time detection. This review explores the integration of various detection methods with microneedle technology, focusing particularly on its applications in biomedical contexts. First, the common detection methods, such as colorimetric, electrochemical, spectrometric, and fluorescence methods, combined with microneedle technology, are summarized. Then we showcase exemplary uses of microneedle technology in biomedical detection, including the monitoring of blood glucose levels, evaluating infection statuses in skin wounds, facilitating point-of-care testing, and identifying biomarkers in the interstitial fluid of the skin. Microneedle-based detection, with its painless, minimally invasive, and biocompatible approach, holds significant promise for enhancing biological assays. Finally, the review concludes by assessing the future potential and challenges of microneedle detection technology, underscoring its transformative capacity to advance personalized medicine and revolutionize healthcare practices.

Augmenting dermal collagen synthesis through hyaluronic acid-based microneedle-mediated delivery of poly(l-lactic acid) microspheres

Poly(L-lactic acid) (PLLA) can stimulate collagen synthesis through a foreign body response. However, inappropriate injection techniques and localized PLLA clustering can lead to complications and adverse events. This study developed a composite microneedle (MN) device comprising an array of PLLA microsphere (PLLA MP)-loaded hyaluronic acid needle tips with a supporting patch (PLLA MP-MN). This device was designed to deliver PLLA MPs precisely and uniformly to the dermis and to provide dual stimulation through MN puncture and MP implantation, thereby enabling the rapid and long-lasting regeneration of dermal collagen. When applied to rat skin, the MN array evenly distributed the PLLA MPs throughout the penetrated regions, which prevented local PLLA overdosing and elicited a milder inflammatory response compared with that induced by intradermal PLLA MP injections. An in vivo efficacy study revealed that MN-mediated delivery of PLLA MPs not only promptly initiated collagen production through microwound-triggered wound-healing cascades in the early treatment stage but also enabled the long-term stimulation of collagen deposition through MP-induced foreign body reactions, thereby significantly enhancing neocollagenesis. This innovative PLLA MP-MN system can augment the benefits and minimize the adverse effects associated with traditional PLLA fillers, providing a safe and reliable anti-aging therapeutic option.

Design of poly(vinyl pyrrolidone) and poly(ethylene glycol) microneedle arrays for delivering glycosaminoglycan, chondroitin sulfate, and hyaluronic acid

Osteoarthritis (OA) is a prevalent joint disorder characterized by cartilage and bone degradation. Medical therapies like glucosaminoglycan (GAG), chondroitin sulfate (CS), and hyaluronic acid (HA) aim to preserve joint function and reduce inflammation but may cause side effects when administered orally or via injection. Microneedle arrays (MNAs) offer a localized drug delivery method that reduces side effects. Thus, this study aims to demonstrate the feasibility of delivering GAG, CS, and HA using microneedles in vitro. An optimal needle geometry is crucial for the successful application of MNA. To address this, here we employ a multi-objective optimization framework using the non-dominated sorting genetic algorithm II (NSGA-II) to determine the ideal MNA design, focusing on preventing needle failure. Then, a three-step fabrication approach is followed to fabricate the MNAs. First, the master (male) molds are fabricated from poly(methyl methacrylate) using mechanical micromachining based on optimized needle geometry. Second, a micro-molding with Polydimethylsiloxane (PDMS) is used for the fabrication of production (female) molds. In the last step, the MNAs were fabricated by microcasting the hydrogels using the production molds. Light microscopy (LIMI) confirms the accuracy of the MNAs manufactured, and in vitro skin insertion tests demonstrate failure-free needle insertion. Subsequently, we confirmed the biocompatibility of MNAs by evaluating their impact on the L929 fibroblast cell line, human chondrocytes, and osteoblasts.

Remote-Controlled Sensing and Drug Delivery via 3D-Printed Hollow Microneedles

Remote health monitoring and treatment serve as critical drivers for advancing health equity, bridging geographical and socioeconomic disparities, ensuring equitable access to quality healthcare for those in underserved or remote regions. By democratizing healthcare, this approach offers timely interventions, continuous monitoring, and personalized care independent of one's location or socioeconomic status, thereby striving for an equitable distribution of health resources and outcomes. Meanwhile, microneedle arrays (MNAs), revolutionize painless and minimally invasive access to interstitial fluid for drug delivery and diagnostics. This paper introduces an integrated theranostic MNA system employing an array of colorimetric sensors to quantitatively measure -pH, glucose, and lactate, alongside a remotely-triggered system enabling on-demand drug delivery. Integration of an ultrasonic atomizer streamlines the drug delivery, facilitating rapid, pumpless, and point-of-care drug delivery, enhancing system portability while reducing complexities. An accompanying smartphone application interfaces the sensing and drug delivery components. Demonstrated capabilities include detecting pH (3 to 8), glucose (up to 16 mm), and lactate (up to 1.6 mm), showcasing on-demand drug delivery, and assessing delivery system performance via a scratch assay. This innovative approach confronts drug delivery challenges, particularly in managing chronic diseases requiring long-term treatment, while also offering avenues for non-invasive health monitoring through microneedle-based sensors.

Microneedle patch casting using a micromachined carbon master for enhanced drug delivery

For successful treatment of diseases, sufficient therapeutics must be provided to the body. Microneedle applications in therapeutic delivery and analytics sampling are restricted because of various issues, including smaller area for drug loading and analytics sampling. To achieve sufficient drug loading and analytics sampling and improve drug penetration while maintaining painless administration, patch-type microneedle arrays were designed and fabricated using polymer casting from a conical cavity mold. Microcavities were formed on a carbon plate via micromechanical machining. A porous polymer layer was coated on a microneedle patch (MNP). The pores of the porous polymer layer provided space and channels for drug delivery. A pH-sensitive polymer layer was employed to cap the porous polymer layer, which prevented drug leakage during storage and provided a stimulus drug release in response to body pH conditions. The drug can be delivered through holes connected to both sides of the patch. The drug release of the MNP was investigated in vitro and in vivo and showed conceptual proof that these MNs have the potential to enhance treatment protocols for various diseases with the flexibility of coating and therapeutic materials and offer significant scope for further variations and advancement.

Low Molecular Weight Hyaluronic Acid Added to Six Specific Amino Acids in the Treatment of Striae Alba (SA): An Observational Study

Striae distensae or stretch marks are a common complaint among women and can be distressing. The present study aimed to assess the efficacy of a mixture of low molecular weight hyaluronic acid and six amino acids when applied with a specific intradermal injection technique known as intra-mural fluid technique. A clinical study was carried out in 32 patients (with a dropout rate by 9.4%) with striae distensae alba (SA) in one or more of the following anatomical areas: breast, abdomen, inner thigh, trochanteric area, gluteal area, posterior supra-iliac area, and lumbar area. Product efficacy was assessed by the investigator using the Global Aesthetic Improvement Scale, while a Likert scale was used to evaluate to score the treatment tolerability and a QoL stretch marks questionnaire was used to investigate the patients' self-body image. The treatment was effective in improving the appearance of SA fifteen days after the second treatment and 6 months after the first treatment (and after a total of 4 treatments). The product efficacy and tolerability were also perceived by the patients during each treatment session. Our results suggest that the test treatment is a valid treatment option to decrease the appearance of SA. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/00266.

Harnessing the role of microneedles as sensors: current status and future perspectives

In recent years, microneedles (MNs) have been transformed to serve a wide range of applications in the biomedical field. Their role as sensors in wearable devices has provided an alternative to blood-based monitoring of health and diagnostic methods. Hence, they have become a topic of research interest for several scientists working in the biomedical field. These MNs as sensors offer the continuous monitoring of biomarkers like glucose, nucleic acids, proteins, polysaccharides and electrolyte ions, which can therefore screen for and diagnose disease conditions in humans. The present review focuses on types of MN sensors and their applications. Various clinical trials and bottlenecks of MN R&D are also discussed.

A flexible and dissolving traditional Chinese medicine microneedle patch for sleep-aid intervention

About a quarter of the world's population suffers from insomnia, and the number of the insomniacs is gradually increasing. However, the current drug therapy and non-drug therapy sleep-aid methods have certain limitations. In general, the sleep-aid effect of drug therapy is better than that of Non-drug therapy, but western medicine may lead to some side effects and drug abuse. Although the side effects of Chinese Herbal Medicine (CHM) are relatively small, making the herbal decoction is complex and time-consuming. Therefore, exploring a novel sleep-aid method is very significant. In this paper, a flexible and dissolving Traditional Chinese Medicine (TCM) microneedle patch is proposed for sleep-aid intervention. The TCM microneedle patch is a micrometer-scale intrusive object, and the herbal extracts are carried by the patch. The materials, design method, and fabrication process of the microneedle patch have been described in detail. Besides, the mechanical characteristics of the microneedle patch, sleep-aid effect evaluation method, and experimental scheme have been presented. Three microneedle tips with radii of 5 μm, 15 μm, and 22 μm are selected for simulation analysis. Abaqus simulation results indicate that the smaller the radius of the microneedle tip, the smaller the piercing force. Considering that the microneedle should easily penetrate the skin without buckling, that is, the piercing force should be larger than the buckling force, thus 15 μm, instead of 5 μm or 22 μm, is more suitable to be adopted as the radius of the microneedle tip. For the microneedle with the radius of 15 μm, the piercing force is 0.033 N, and the difference between the piercing force and buckling force is 0.036 N. Experimental results demonstrate that the fracture force of the microneedle is about 0.29 N, which is far larger than the piercing force and buckling force. The single-lead EEG signals of the frontal lobe are used to evaluate the sleep-aid effect of the TCM microneedle patch. After sleep-aid intervention on the Anmian and Yintang acupoints using the patches, for most subjects, the ratios of the low-frequency brain wave energies to the high-frequency brain wave energies are increased obviously, indicating that the proposed sleep-aid method is effective.

Microneedle-based sampling of dermal interstitial fluid using a vacuum-assisted skin patch

Interstitial fluid (ISF) contains a wealth of biomolecules, yet it is underutilized for diagnostic testing due to a lack of rapid and simple techniques for collecting abundant amounts of fluid. Here, we report a simple and minimally invasive technique for rapidly sampling larger quantities of ISF from human skin. A microneedle array is used to generate micropores in skin from which ISF is extracted using a vacuum-assisted skin patch. Using this technique, an average of 20.8 μL of dermal ISF is collected in 25 min, which is an ∼6-fold improvement over existing sampling methods. Proteomic analysis of collected ISF reveals that it has nearly identical protein composition as blood, and >600 medically relevant biomarkers are identified. Toward this end, we demonstrate the detection of SARS-CoV-2 neutralizing antibodies in ISF collected from COVID-19 vaccinees using two commercial immunoassays, showcasing the utility of this technique for diagnostic testing.

Diagnostic, Therapeutic, and Theranostic Multifunctional Microneedles

Microneedles (MNs) have maintained their popularity in therapeutic and diagnostic medical applications throughout the past decade. MNs are originally designed to gently puncture the stratum corneum layer of the skin and have lately evolved into intelligent devices with functions including bodily fluid extraction, biosensing, and drug administration. MNs offer limited invasiveness, ease of application, and minimal discomfort. Initially manufactured solely from metals, MNs are now available in polymer-based varieties. MNs can be used to create systems that deliver drugs and chemicals uniformly, collect bodily fluids, and are stimulus-sensitive. Although these advancements are favorable in terms of biocompatibility and production costs, they are insufficient for the therapeutic use of MNs. This is the first comprehensive review that discusses individual MN functions toward the evolution and development of smart and multifunctional MNs for a variety of novel and impactful future applications. The study examines fabrication techniques, application purposes, and experimental details of MN constructs that perform multiple functions concurrently, including sensing, drug-molecule release, sampling, and remote communication capabilities. It is highly likely that in the near future, MN-based smart devices will be a useful and important component of standard medical practice for different applications.

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.

Synthetic Polymer Nanoparticles as an Abiotic Artificial Inhibitor of Tyrosinase

An innovative methodology is presented for synthesizing synthetic polymer nanoparticles (TINPs) as potent tyrosinase inhibitors. This inhibition strategy combines the integration of two distinct functionalities, phenol, and phenylboronic acid, within the TINPs structure. The phenyl group mimics the natural monophenol substrate, forming a strong coordination with the catalytic copper ion, significantly inhibiting tyrosinase activity. Additionally, phenylboronic acid interacts with catechol, another tyrosinase substrate, further reducing enzyme efficiency. The shared benzene ring in phenyl and phenylboronic acid enhances binding to tyrosinase's hydrophobic pocket near its copper active site, contributing to potent inhibition. TINPs exhibit exceptional performance, boasting an impressive IC50 value of 3.5×10-8 m and an inhibition constant of 9.8×10-9 m. Validation of the approach is unequivocally demonstrated through the successful inhibition of tyrosinase activity and melanin production, substantiated in both in vitro and in vivo scenarios. The mechanism of TINP inhibition is elucidated through circular dichroism and Fourier transform infrared spectroscopy. This study introduces a versatile design approach for developing abiotic polymer-based enzyme inhibitors, expanding possibilities in enzyme inhibition research.

Comparative Assessment of Gingival Depigmentation Using Scalpel Versus Microneedling With Ascorbic Acid: A Randomized Controlled Trial

Background Gingival pigmentation (GP), characterized by the presence of melanin in the gingival tissues, is a common aesthetic concern in dental practice. While it poses no inherent health risks, the visible discoloration may cause psychological distress for individuals seeking optimal dental aesthetics. Understanding the efficacy of various methods is essential for refining treatment strategies and enhancing patient satisfaction in the realm of gingival depigmentation (GD). Aim The objective of the study was to compare the effectiveness of scalpel and microneedling (MN) with ascorbic acid in the treatment of GD. Materials and methods Sixteen patients who had a complaint of GP were included in the study, of whom eight were allocated for depigmentation with a scalpel, and the other eight patients were treated with the MN technique with ascorbic acid. Postoperative wound healing scores were evaluated on the first and seventh days, respectively. The intensity of depigmentation was assessed at baseline, in the first month, and at the end of the third month, respectively. Results The mean Dummett-Gupta Oral Pigmentation Index (DOPI) score at baseline was 2.65±0.16 and 2.61±0.17 in the surgical and microneedling groups with ascorbic acid, respectively. The mean DOPI score at the end of the third month was 1.67±0.39 and 0.87±0.17 in the scalpel and MN with ascorbic acid groups, respectively. There was a statistically significant difference between the scalpel and MN with ascorbic acid groups at the end of the first and third months, respectively, where MN with ascorbic acid showed aesthetically pleasing outcomes. Patients treated with the scalpel technique showed incomplete healing and ulceration on the first and seventh days after the procedure when compared to the MN technique with ascorbic acid. The healing index scores were statistically significant in the MN with ascorbic acid group. Conclusion The MN technique with ascorbic acid is a successful technique for treating GD. It showed aesthetically gratifying outcomes when compared to the conventional surgical technique.

End-user research into understanding perceptions of and reactions to a microarray patch (MAP) for contraception among women in Ghana, Kenya and Uganda

Introduction

Many organizations are developing new contraceptive products and approaches that promote self-care including a microarray patch (MAP) that has the potential for self-administration with appropriate training. We studied women's perceptions of the MAP technology with the primary goal of providing feedback on product attributes to inform early technical design decisions regarding various MAP contraceptive products in development by MAP developers.

Methods

Our study consisted of a qualitative phase with in-person In-Depth Interviews (IDIs) with a total of 60 women of reproductive age (WRA) and quantitative surveys, via face-to-face computer-assisted interviews of a total of 927 women in Ghana, Kenya and Uganda. Women's perceptions on 12 attributes of the MAP were assessed through written descriptions, a profile, and visual stimuli such as graphics and images.

Results

Overall, the most widely preferred attribute set included: a hand-applied MAP, utilizing one circular patch, with a sticky backing, no larger than 2 cm diameter in size, applied by self, to the arm, offering sensory feedback (clicking sound and/or color change signals) to confirm enough pressure, successful application and removal, lasting 6 months with up to 12 months return to natural state of fertility. There is space to allow for variation in MAP designs (including the use of an applicator or provider administered MAP) if the design promotes and reflects the needs and expectations of users and providers.

Discussion

The contraceptive MAP had a high and broad level of appeal amongst all groups of women who participated in the study and has a strong value proposition around important contraceptive needs such as ease of use, convenience, and discretion.

Microneedle Sensors for Point-of-Care Diagnostics

Point-of-care (POC) has the capacity to support low-cost, accurate and real-time actionable diagnostic data. Microneedle sensors have received considerable attention as an emerging technique to evolve blood-based diagnostics owing to their direct and painless access to a rich source of biomarkers from interstitial fluid. This review systematically summarizes the recent innovations in microneedle sensors with a particular focus on their utility in POC diagnostics and personalized medicine. The integration of various sensing techniques, mostly electrochemical and optical sensing, has been established in diverse architectures of "lab-on-a-microneedle" platforms. Microneedle sensors with tailored geometries, mechanical flexibility, and biocompatibility are constructed with a variety of materials and fabrication methods. Microneedles categorized into four types: metals, inorganics, polymers, and hydrogels, have been elaborated with state-of-the-art bioengineering strategies for minimally invasive, continuous, and multiplexed sensing. Microneedle sensors have been employed to detect a wide range of biomarkers from electrolytes, metabolites, polysaccharides, nucleic acids, proteins to drugs. Insightful perspectives are outlined from biofluid, microneedles, biosensors, POC devices, and theragnostic instruments, which depict a bright future of the upcoming personalized and intelligent health management.

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

The Necessity to Investigate In Vivo Fate of Nanoparticle-Loaded Dissolving Microneedles

Transdermal drug delivery systems are rapidly gaining prominence and have found widespread application in the treatment of numerous diseases. However, they encounter the challenge of a low transdermal absorption rate. Microneedles can overcome the stratum corneum barrier to enhance the transdermal absorption rate. Among various types of microneedles, nanoparticle-loaded dissolving microneedles (DMNs) present a unique combination of advantages, leveraging the strengths of DMNs (high payload, good mechanical properties, and easy fabrication) and nanocarriers (satisfactory solubilization capacity and a controlled release profile). Consequently, they hold considerable clinical application potential in the precision medicine era. Despite this promise, no nanoparticle-loaded DMN products have been approved thus far. The lack of understanding regarding their in vivo fate represents a critical bottleneck impeding the clinical translation of relevant products. This review aims to elucidate the current research status of the in vivo fate of nanoparticle-loaded DMNs and elaborate the necessity to investigate the in vivo fate of nanoparticle-loaded DMNs from diverse aspects. Furthermore, it offers insights into potential entry points for research into the in vivo fate of nanoparticle-loaded DMNs, aiming to foster further advancements in this field.

Comparison the Effect of Fractional RF Laser with Microneedling on Facial Skin Rejuvenation, Open Pores and Skin Lightening: A Non-Randomized Controlled Clinical Trial

Background

Effective skin rejuvenation treatments with RF technologies exist, with potential for personalized combination therapies based on individual factors. We compared microneedling and fractional RF laser effectiveness in rejuvenation, pore healing, and skin lightening.

Method

The research was a non-randomized clinical trial study conducted in 2021 at Ilam Skin Clinic, Ilam, western Iran on people applying for rejuvenation, skin lightening and improvement of open pores. People were voluntarily divided into two groups based on personal preferences (group A: microneedling, 25 people, group B: fractional RF, 25 people). After data collection, SPSS22 software was used for data analysis.

Results

The study revealed significant differences in the rates of low, moderate, and severe pain between the microneedling and fractional groups (10 vs. 16, 14 vs. 4, 1 vs. 5, respectively). Erythema showed no significant difference, with low, moderate, and severe cases reported in both groups. Swelling was lower in the microneedling group, but the difference was not significant. Bruising was similar in both groups, and staining was minimal. No herpes or infections were reported. The microneedling group showed better improvement in skin pores and skin lightening compared to the fractional group, with outcomes rated as good and excellent.

Conclusion

Microneedling surpassed the fractional group in skin rejuvenation, lightening, and improved pores. Considering RF lasers are approximately three times more expensive than microneedling, the research indicates that choosing microneedling is not only more cost-effective but also a superior rejuvenation technique.

Effect of microneedle roller on promoting transdermal absorption of crossbow-medicine liquid via transdermal administration of Traditional Chinese Medicine and the safety of crossbow-medicine needle therapy: An experimental study

ETHNOPHARMACOLOGY RELEVANCE

Crossbow-medicine needle therapy (microneedle roller combined with crossbow-medicine) is one of the external treatment methods of Miao Medicine in China. It is a way of combining acupuncture with Chinese herbal medicine, which is widely used in clinical treatment of pain.

AIM OF THE STUDY

To observe the transdermal absorption promoting effect of microneedle roller via transdermal administration, and to discuss the transdermal absorption characteristics and the safety of crossbow-medicine needle therapy.

METHODS

Based on the determination of the content of the main components of crossbow-medicine prescription in our previous research, the present experiment was conducted in-vitro and in-vivo experiments and the skin of rats was used as the penetration barrier. For in-vitro experiment, the modified Franz diffusion cell method was used to determine the transdermal absorption rate and 24h cumulative transdermal absorption amount of the active ingredients of crossbow-medicine liquid. For in-vivo experiment, tissue homogenization was applied to compare the skin retention amount and plasma concentration of crossbow-medicine liquid absorbed at different time points via the aforementioned two modes of administration. Furthermore, the effect of crossbow-medicine needle on the morphological structure of rat skin stratum corneum was detected by hematoxylin-eosin (HE) staining. The safety of crossbow-medicine needle therapy was evaluated according to the scoring criteria of the skin irritation test.

RESULTS

1. In-vitro experiment: In the microneedle-roller group and crossbow-medicine liquid application group, the effect of transdermal delivery was identified in all the four ingredients of anabasine, chlorogenic acid, mesaconitine and hypaconitine. The 24h cumulative transdermal absorption amount and transdermal absorption rate of each ingredient in microneedle-roller group were significantly higher than those in crossbow-medicine liquid application group (all P < 0.05). 2. In-vivo experiment: Both microneedle-roller and crossbow-medicine liquid application could promote the transdermal absorption of the active ingredients of the drug in the skin and retain in the skin structure. After 8h of administration, the total retention amount of anabasine, chlorogenic acid, mesaconitine and hypaconitine in the skin of rats in the former group was significantly higher than that in the latter group (all P < 0.05). 3. HE staining: In the blank group, the stratum corneum showed an evenly zonal distribution on the active epidermis, and had a close connection with the epidermis, without exfoliation or cell dissociation of the stratum corneum. The crossbow-medicine liquid group had a relatively complete stratum corneum, with a small proportion of exfoliation or cell dissociation, loose arrangement and loose connection with the epidermis. In the microneedle-roller group, the skin had pore channels, and the stratum corneum was loose and exfoliated, which showed zonal distribution in a free state and a high degree of separation. The crossbow-medicine needle group had loose the stratum corneum, broken and exfoliated, which was separated from the active epidermis and showed zonal distribution in a free state. 4.

SAFETY

No obvious erythema, edema and skin protuberance were observed in the skin of rats treated with microneedle roller, crossbow-medicine liquid and crossbow-medicine needle. Additionally, the skin irritative response score was 0.

CONCLUSION

Microneedle roller can promote the transdermal absorption of crossbow-medicine liquid, and crossbow-medicine needle therapy has good safety.

Non-invasive Microneedle Application Increases Ceramide and Natural Moisturizing Factors in a Reconstructed Human Skin Model

Recently, microneedling as a cosmetic product has attracted attention as one way to improve skin barrier function and moisturizing function to reduce wrinkle formation. However, some cases of erythema and edema have been reported as side effects. In order to develop safer microneedle cosmetics, we investigated whether microneedles can improve skin barrier function and moisturizing function even when applied in a non-invasive manner that does not penetrate the stratum corneum. We established the condition of non-penetrating microneedle application on reconstructed human full-thickness skin models and examined the effect on the skin models when microneedles were applied under this condition. Microneedle application increased the gene expression of serine palmitoyltransferase long chain base subunit (SPTLC) 3, filaggrin, and transglutaminase 1. The amount of ceramide produced by SPTLC was also increased by microneedle application. Gene expression of filaggrin-degrading enzymes and the amount of free amino acids, a product of filaggrin degradation, were also increased by microneedling. These results suggest that non-invasive microneedle application can improve skin barrier function and moisturizing function by increasing the amount of ceramide and natural moisturizing factors.

Quantitative Assessment of Hyperpigmentation Changes in Human Skin after Microneedle Mesotherapy Using the Gray-Level Co-Occurrence Matrix (GLCM) Method

AIM

The aim of the study was to quantitatively assess the effectiveness of microneedle mesotherapy in reducing skin discoloration. The results were analyzed using the gray-level co-occurrence matrix (GLCM) method.

MATERIAL AND METHODS

The skin of the forearm (7 × 7 cm) of 12 women aged 29 to 68 was examined. Microneedle mesotherapy was performed using a dermapen with a preparation containing 12% ascorbic acid. Each of the volunteers underwent a series of four microneedle mesotherapy treatments. The effectiveness of the treatment was quantified using the methods of image analysis and processing. A series of clinical images were taken in cross-polarized light before and after a series of cosmetic procedures. Then, the treated areas were analyzed by determining the parameters of the gray-level co-occurrence matrix (GLCM) algorithm: contrast and homogeneity.

RESULTS

During image pre-processing, the volunteers' clinical images were separated into red (R), green (G) and blue (B) channels. The photos taken after the procedure show an increase in skin brightness compared to the photos taken before the procedure. The average increase in skin brightness after the treatment was 10.6%, the average decrease in GLCM contrast was 10.7%, and the average homogeneity increased by 14.5%. Based on the analysis, the greatest differences in the GLCM contrast were observed during tests performed in the B channel of the RGB scale. With a decrease in GLCM contrast, an increase in postoperative homogeneity of 0.1 was noted, which is 14.5%.

Hydrogel-Forming Microneedles with Applications in Oral Diseases Management

Controlled drug delivery in the oral cavity poses challenges such as bacterial contamination, saliva dilution, and inactivation by salivary enzymes upon ingestion. Microneedles offer a location-specific, minimally invasive, and retentive approach. Hydrogel-forming microneedles (HFMs) have emerged for dental diagnostics and therapeutics. HFMs penetrate the stratum corneum, undergo swelling upon contact, secure attachment, and enable sustained transdermal or transmucosal drug delivery. Commonly employed polymers such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone are crosslinked with tartaric acid or its derivatives while incorporating therapeutic agents. Microneedle patches provide suture-free and painless drug delivery to keratinized or non-keratinized mucosa, facilitating site-specific treatment and patient compliance. This review comprehensively discusses HFMs' applications in dentistry such as local anesthesia, oral ulcer management, periodontal treatment, etc., encompassing animal experiments, clinical trials, and their fundamental impact and limitations, for example, restricted drug carrying capacity and, until now, a low number of dental clinical trial reports. The review explores the advantages and future perspectives of HFMs for oral drug delivery.

Microneedling-Associated Procedures to Enhance Facial Rejuvenation

Microneedling, also referred to as percutaneous collagen induction therapy, uses small needles to create mechanical injury to the skin, stimulating the wound-healing cascade and new collagen formation. Compared with other skin resurfacing techniques, microneedling preserves the epidermis and is nonablative, therefore reducing inflammation, downtime, and risk of dyspigmentation. In addition to increasing collagen production in fibroblasts, microneedling also helps normalize cell function of keratinocytes and melanocytes and can be used to increase absorption of topical medications, growth factors, or deliver radiofrequency directly to the dermis. The benefits of microneedling, associated procedures, indications for use, technical considerations, and potential complications are discussed.

Post-Treatment of Micro-Needling with a Dexpanthenol-Containing Ointment Accelerates Epidermal Wound Healing in Human 3D Skin Models

Purpose

In vitro study on the molecular effects of post-treatment after micro-needling applications with a dexpanthenol-containing ointment (DCO) using 3D skin models.

Patients and Methods

In this in vitro study, full-thickness human 3D skin models were treated with a micro-needling device according to its clinical application. For post-treatment, some of the models were additionally treated with a dexpanthenol-containing ointment (DCO). Histological samples were taken at 0, 24 and 48 hours. Gene expression analysis was performed after 24 hours.

Results

Histological examination showed that DCO post-treated 3D skin models revealed a completed wound closure 24 hours after the micro-needling procedure. In contrast, DCO-untreated models still clearly exhibited the micro-needling lesions after the same period of time. After 48 hours, all models revealed a completed wound healing. In skin models that received micro-needling but no post-treatment with DCO, microarray analysis identified an upregulation of proinflammatory cytokines and chemokines and a downregulation of skin barrier and differentiation markers. In contrast, post-treatment with DCO leads to accelerated wound healing without affecting the initial inflammatory response caused by micro-needling, which leads to the subsequent collagen expression. This data was supported by qRT-PCR analyses.

Conclusion

Post-treatment with DCO accelerates epidermal wound healing after micro-needling of 3D skin models without impairing the immunostimulatory properties of micro-needling. These findings can help to optimise the aftercare routine after micro-needling procedures and to shorten the downtime for the patient after treatment.

Flexible Monitoring, Diagnosis, and Therapy by Microneedles with Versatile Materials and Devices toward Multifunction Scope

Microneedles (MNs) have drawn rising attention owing to their merits of convenience, noninvasiveness, flexible applicability, painless microchannels with boosted metabolism, and precisely tailored multifunction control. MNs can be modified to serve as novel transdermal drug delivery, which conventionally confront with the penetration barrier caused by skin stratum corneum. The micrometer-sized needles create channels through stratum corneum, enabling efficient drug delivery to the dermis for gratifying efficacy. Then, incorporating photosensitizer or photothermal agents into MNs can conduct photodynamic or photothermal therapy, respectively. Besides, health monitoring and medical detection by MN sensors can extract information from skin interstitial fluid and other biochemical/electronic signals. Here, this review discloses a novel monitoring, diagnostic, and therapeutic pattern by MNs, with elaborate discussion about the classified formation of MNs together with various applications and inherent mechanism. Hereby, multifunction development and outlook from biomedical/nanotechnology/photoelectric/devices/informatics to multidisciplinary applications are provided. Programmable intelligent MNs enable logic encoding of diverse monitoring and treatment pathways to extract signals, optimize the therapy efficacy, real-time monitoring, remote control, and drug screening, and take instant treatment.

Gingival Depigmentation Using Microneedling Technique With Topical Vitamin C: A Prospective Case Series

Introduction Gingival pigmentation is mainly physiological due to the production of melanin. This study aimed to evaluate the effectiveness of a microneedling technique using topical ascorbic acid in treating gingival hyperpigmentation. Methods A case-series study was established, and 16 out of 42 participants enrolled in this study according to the inclusion and exclusion criteria. A microneedling technique was performed using a Dermapen instrument, followed by the topical application of ascorbic acid on the pigmented gingiva. Variations in the Dummett oral pigmentation index (DOPI) and Hedin melanin index (HMI) scores were considered for each patient. A one-month follow-up was conducted on all patients. Results All the reported cases demonstrated noticeable improvement at the end of the sessions. Moreover, seven patients showed complete depigmentation of the gingiva. Analysis using paired T-tests showed a statistically significant lower post-treatment DOPI score with a mean difference of 1.8 ± 0.7, 95% CI: 0.17-1.49. Similarly, the HMI score was lower post-treatment with a mean difference of 3.1 ± 0.7, 95% CI: 2.74-3.50. Conclusions Microneedling combined with topical ascorbic acid is a novel, non-invasive dental technique that can effectively treat gingival hyperpigmentation.

Viscoelastic Properties of Polymeric Microneedles Determined by Micromanipulation Measurements and Mathematical Modelling

Microneedles, including dissolvable ones made from biocompatible and biodegradable materials, have been widely studied and can potentially be used for transdermal drug delivery, disease diagnosis (sampling), skin care, etc. Characterizing their mechanical properties is essential, as being mechanically strong enough to pierce the skin barrier is one of the most fundamental and crucial requirements for them. The micromanipulation technique was based on compressing single microparticles between two flat surfaces to obtain force and displacement data simultaneously. Two mathematical models had already been developed to calculate the rupture stress and apparent Young's modulus, which can identify variations of these parameters in single microneedles within a microneedle patch. In this study, a new model has been developed to determine the viscoelasticity of single microneedles made of hyaluronic acid (HA) with a molecular weight of 300 kDa loaded with lidocaine by using the micromanipulation technique to gather experimental data. The modelling results from the micromanipulation measurements suggest that the microneedles were viscoelastic and their mechanical behaviour was strain-rate dependent, which implies that the penetration efficiency of viscoelastic microneedles can be improved by increasing their piercing speed into the skin.

Biocompatible Triple-Helical Recombinant Collagen Dressings for Accelerated Wound Healing in Microneedle-Injured and Photodamaged Skin

Skin rejuvenation procedures such as microneedling and laser resurfacing have gained global popularity in medical cosmetology, leading to acute skin wounds with persistent pain, erythema, and edema. A variety of dressings have been explored to repair these postoperative skin injuries; however, their inadequate biocompatibility and bioactivity may raise concerns about undesirable efficacy and complications. Herein, we developed biocompatible and nonirritating triple-helical recombinant collagen (THRC) dressings for accelerated healing of microneedle-injured and photodamaged acute skin wounds. Circular dichroism (CD) measurements of THRC from various batches exhibited triple-helical structure characteristics of collagen. Cell experiments using L929 fibroblasts revealed that THRC dressings possess superior biocompatibility and bioactivity, significantly elevating the proliferation and adhesion of fibroblasts. In vivo, skin irritation tests of New Zealand rabbits demonstrated that the THRC dressings are gentle, safe, and non-irritating. Histological analysis of the animal model studies in photodamaged skin wounds using H&E and Masson’s trichrome staining revealed that 4 days of treatment with the THRC dressings effectively healed the damaged dermis by accelerating re-epithelialization and enhancing collagen deposition. In vivo studies of microneedle-injured rat defects showed that THRC dressings of varying concentrations exhibit the same rapid epithelialization rates at 48 h as commercial bovine collagen dressings. The highly biocompatible and bioactive recombinant collagen dressings may provide an advanced treatment of acute skin wounds, indicating attractive applications in postoperative care of facial rejuvenation.

Mussel adhesive protein treatment delivered by microneedling for sensitive skin: A clinical study

BACKGROUND

Mussel adhesive protein (MAP) is extracted from the mycelial glands of marine mussels. It has anti-inflammatory properties and may relieve skin itching and other symptoms.

AIMS

Based on the anti-inflammatory effect of MAP, this study was designed to treat sensitive skin (SS) using MAP delivered by skin microneedling.

PATIENTS/METHODS

Twenty-three Chinese female patients with SS were enrolled. Treatments were delivered three times at one-month intervals. Symptom improvement and recurrence rates, treatment safety, and patient satisfaction levels were evaluated.

RESULTS

After one course of treatment, 20 patients had a Symptom Score Reducing Index (SSRI) of >20%, with an effectiveness rate of 87%. At the end of treatment, all patients had an SSRI of >20%, and the effectiveness rate was 100%. Dryness, tightness, desquamation, flushing, burning, itching, and tingling improved. After treatment, the Clinical Erythema Assessment and Lesion Severity Index of Facial Telangiectasia scores were significantly decreased. Clinical photographs following treatment revealed improved erythema reaction and decreased capillary density. During treatment, the patients experienced mild pain and erythema and swelling reaction without exudation. Complications, such as pigmentation changes or scarring, were absent. Additionally, there were no cases of recurrence, and patient satisfaction levels were high.

CONCLUSION

MAP combined with microneedling can help treat SS, showing satisfactory safety outcomes and high patient satisfaction.

How to maximize the therapeutic effect of exosomes on skin wounds in diabetes mellitus: Review and discussion

Chronic skin wound healing, especially in diabetes mellitus, is still unsolved. Although many efforts have been made to treat diabetic skin wounds, current strategies have achieved limited effectiveness. Nowadays, a great number of studies have shown that exosomes might be a promising approach for treating diabetic wounds. Many studies and reviews have focused on investigating and discussing the effectiveness and mechanism of exosomes. However, maximizing its value in treating skin wounds in diabetes mellitus requires further consideration. In this review, we reviewed and discussed the aspects that could be further improved in this process, including finding a better source of exosomes, engineering exosomes, adjusting dosage and frequency, and combining more efficient delivery methods. This review provided an overview and idea of what we can do to improve the therapeutic effect of exosomes on skin wounds in diabetes mellitus. Only by combining all the factors that affect the effectiveness of exosomes in diabetic wound healing can we further promote their clinical usefulness.

Pharmaceutical based cosmetic serums

The growth and demand for cosmeceuticals (cosmetic products that have medicinal or drug-like benefits) have been enhanced for the last few decades. Lately, the newly invented dosage form, i.e., the pharmaceutical-based cosmetic serum has been developed and widely employed in various non-invasive cosmetic procedures. Many pharmaceutical-based cosmetic serums contain natural active components that claim to have a medical or drug-like effect on the skin, hair, and nails, including anti-aging, anti-wrinkle, anti-acne, hydrating, moisturizing, repairing, brightening and lightening skin, anti-hair fall, anti-fungal, and nail growth effect, etc. In comparison with other pharmaceutical-related cosmetic products (creams, gels, foams, and lotions, etc.), pharmaceutical-based cosmetic serums produce more rapid and incredible effects on the skin. This chapter provides detailed knowledge about the different marketed pharmaceutical-based cosmetic serums and their several types such as facial serums, hair serums, nail serums, under the eye serum, lip serum, hand, and foot serum, respectively. Moreover, some valuable procedures have also been discussed which provide prolong effects with desired results in the minimum duration of time after the few sessions of the serum treatment.

Metallic Microneedles for Transdermal Drug Delivery: Applications, Fabrication Techniques and the Effect of Geometrical Characteristics

Current procedures for transdermal drug delivery (TDD) have associated limitations including poor administration of nucleic acid, small or large drug molecules, pain and stress for needle phobic people. A painless micro-sized device capable of delivering drugs easily and efficiently, eliminating the disadvantages of traditional systems, has yet to be developed. While polymeric-based microneedle (MN) arrays have been used successfully and clinically as TDD systems, these devices lack mechanical integrity, piercing capacity and the ability to achieve tailored drug release into the systemic circulation. Recent advances in micro/nano fabrication techniques using Additive Manufacturing (AM), also known as 3D printing, have enabled the fabrication of metallic MN arrays, which offer the potential to overcome the limitations of existing systems. This review summarizes the different types of MNs used in TDD and their mode of drug delivery. The application of MNs in the treatment of a range of diseases including diabetes and cancer is discussed. The potential role of solid metallic MNs in TDD, the various techniques used for their fabrication, and the influence of their geometrical characteristics (e.g., shape, size, base diameter, thickness, and tip sharpness) on effective TDD are explored. Finally, the potential and the future directions relating to the optimization of metallic MN arrays for TDD are highlighted.

A Comprehensive Review of Microneedling as a Potential Treatment Option for Androgenetic Alopecia

BACKGROUND

Microneedling refers to a minimally invasive technique that uses multiple fine needles targeted skin epidermis for mechanical stimulation to obtain therapeutic or cosmetic effects. It is suitable for the treatment of a variety of dermatological conditions, including androgenetic alopecia (AGA).

OBJECTIVE

This article aims to make a comprehensive review of the relevant studies on microneedling for the management of AGA.

METHODS

Extensive literature search was performed using PubMed, Web of Science, and EBSCO databases. 4 in vivo studies and 25 clinical trials were included according to the inclusion and exclusion criteria.

RESULTS

The effects of microneedling on AGA was investigated in animal experiments. Several clinical trials, including randomized controlled trials, strengthen the validity of the findings. Microneedling therapy showed some encouraging results with minor complications when used alone or in combination with topical products.

CONCLUSIONS

Microneedling appears to be a safe and effective therapeutic option for AGA. Larger and more randomized controlled trials regarding the role of microneedling in AGA are strongly recommended to provide more definitive evidence.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Observation on the Efficacy of a Combined Treatment for Moderate and Severe Androgenetic Alopecia Incorporating Electric Microneedles

Objective

To evaluate the effectiveness and safety of a combined treatment for moderate and severe androgenetic alopecia (AGA) involving the use of electric microneedles.

Methods

A total of 83 patients with moderate to severe AGA in the Department of Dermatology at Beijing Jishuitan Hospital were included in this study. The male patients were administered finasteride orally and 5% minoxidil for external use, while the female patients were given spironolactone orally or Diane-35 and 2% minoxidil for external use. All the patients were then treated via electric microneedle therapy alongside the YUFA ®medical care package (Foshan, China) once a week for 1-28 weeks. The seven-point method and root hair measurement using a hair mirror were adopted to evaluate the efficacy and any adverse reactions of the combined treatment.

Results

Eleven patients were treated for 1-3 weeks, 60 for 4-12 weeks, and 12 for more than 12 weeks. The efficacy evaluation using the seven-point method for 12 weeks of treatment indicated a 100% response rate, specifically, a 42.1% mild improvement rate, a 38.6% moderate improvement rate, and a 19.3% marked improvement rate. Besides, the efficacy assessment was also completed with root hair count method and the number of hair roots measured at fixed points were 148.67±11.15, 158.13±5.11 and 169.75±2.06 after treatment time at 16, 20 and 24 weeks, respectively. Of note, a statistical difference in the number of hair roots could be observed during the period of week 20-week 24 (P < 0.01).

Conclusion

The combined treatment of moderate to severe AGA using the electric microneedle technique has a clear effect and can effectively increase the hair density. With a simple operation and mild side effects, the technique has wide application prospects.

Efficacy of a triamcinolone acetonide-loaded dissolving microneedle patch for the treatment of hypertrophic scars and keloids: a randomized, double-blinded, placebo-controlled split-scar study

The treatment of hypertrophic scars (HTSs) and keloids remains a challenge. Intralesional triamcinolone acetonide (TAC) is the mainstay treatment for these conditions. Despite its efficacy, TAC has several adverse side effects, including telangiectasias, skin atrophy, pigmentary changes, and skin necrosis. Dissolving microneedles (DMN) use the poke-and-release method to create microchannels that enhance drug delivery to the target tissue in the dermis, without causing pain and with a decreased risk of transmission of blood-borne diseases. To evaluate and compare the efficacy of a TAC-DMN versus a drug-free DMN patch for the treatment of HTSs and keloids, 20 patients (10 with HTSs and 10 with keloids) received a split-scar treatment: one half of the scar length was treated with TAC-DMNs and the other half was treated with drug-free DMN for three sessions at 14-day intervals. Efficacy was assessed by measuring the scar volume through a multispectral imaging system and using the Patient and Observer Scar Assessment Scale (POSAS). The HTSs treated with TAC-DMNs showed a significant reduction in the mean scar volume 2 weeks after the second treatment and 1 month after the third treatment (p = 0.028 and 0.020, respectively), while the HTSs treated with drug-free DMNs showed no significant reduction in the scar volume. Both sides of the keloids showed no significant reduction in mean scar volume. Using the POSAS, significant improvement in the appearance of both halves of the HTSs was observed 1 month after the treatments. A significant improvement (evaluated by POSAS) was also observed in the keloids treated with TAC-DMNs 2 weeks after the second treatment and 1 month after the third treatment. No significant improvement was observed from the patients' perspective as evaluated by POSAS in the keloids treated with drug-free DMNs. However, no significant difference was observed between the treatment and control halves. TAC-DMN is an effective treatment for HTSs. Increasing the dosage and duration of keloid scar treatment is required in future studies to determine whether it would result in a significant therapeutic outcome. This trial is registered in the Thai Clinical Trials Registry (TCTR20220318004; date of registration, March 17, 2022).

Regression of calcinosis cutis after inkless tattoo in a patient with dermatomyositis: therapeutic potential of microneedling

Calcinosis cutis is defined as abnormal deposition of calcium salts in the skin and subcutaneous tissues. Dystrophic calcification, the most common form of calcinosis cutis, is associated with autoimmune connective tissue diseases. This condition is associated with severe pain and can affect the patient's quality of life and lead to long-term disability. Treatment is often challenging, and there is a very limited evidence base for potential treatments of calcinosis cutis associated with systemic sclerosis and dermatomyositis. Inkless tattoo is very similar to microneedling, a minimally invasive procedure stimulating the wound-healing cascade contributing to elastin and collagen formation as well as neovascularization. This technique has not been reported as a potential therapeutic option for calcinosis cutis. Here, we present a patient with calcinosis cutis in the setting of dermatomyositis that responded dramatically to inkless tattoo application. Our results support the need for future studies of microneedling in patients with this disorder.

Utilization of ex vivo tissue model to study skin regeneration following microneedle stimuli

Microneedling is a popular skin resurfacing and rejuvenation procedure. In order to develop better adjunct products for consumers, there is a scientific need to establish greater understanding of the mechanism in which microneedling stimulates regeneration within skin. The purpose of this study is to develop a physiologically relevant ex vivo tissue model which closely mimics the actual microneedling procedure to elucidate its mechanism of action. In this study, human ex vivo skin was subjected to microneedling treatment and cultured for 6 days. Histological analysis demonstrated that the ex vivo skin was able to heal from microneedling injury throughout the culture period. Microneedling treatment stimulated proliferation and barrier renewal of the skin. The procedure also increased the levels of inflammatory cytokines and angiogenic growth factors in a dynamic and time dependent fashion. The tissue demonstrated hallmark signs of epidermal regeneration through morphological and molecular changes after the treatment. This is one of the first works to date that utilizes microneedled ex vivo skin to demonstrate its regenerative behavior. Our model recapitulates the main features of the microneedling treatment and enables the evaluation of future cosmetic active ingredients used in conjunction with microneedling.

Traditional Chinese medicine for hypertrophic scars—A review of the therapeutic methods and potential effects

Hypertrophic scar (HS) is a typical pathological response during skin injury, which can lead to pain, itching, and contracture in patients and even affect their physical and mental health. The complexity of the wound healing process leads to the formation of HS affected by many factors. Several treatments are available for HS, whereas some have more adverse reactions and can even cause new injuries with exacerbated scarring. Traditional Chinese Medicine (TCM) has a rich source, and most botanical drugs have few side effects, providing new ideas and methods for treating HS. This paper reviews the formation process of HS, the therapeutic strategy for HS, the research progress of TCM with its relevant mechanisms in the treatment of HS, and the related new drug delivery system of TCM, aiming to provide ideas for further research of botanical compounds in the treatment of HS, to promote the discovery of more efficient botanical candidates for the clinical treatment of HS, to accelerate the development of the new drug delivery system and the final clinical application, and at the same time, to promote the research on the anti-HS mechanism of multiherbal preparations (Fufang), to continuously improve the quality control and safety and effectiveness of anti-HS botanical drugs in clinical application.

3D-printed microneedle arrays for drug delivery

Microneedle arrays provide an efficient tool for transdermal drug delivery in a minimally invasive and painless manner, showing great potential applications in medicine. However, it remains challenging to fabricate the desired microneedle arrays, because of their micron-scale size and fine structure. Novel manufacturing technologies are very wanted for the development of microneedle arrays, which would solidly advance the clinical translation of microneedle arrays. 3D printing technology is a powerful manufacturing technology with superiority in fabricating personalized and complex structures. Currently, 3D printing technology has been employed to fabricate microneedle arrays, which could push more microneedle arrays into clinic and inspire the development of future microneedle arrays. This work reviews the art of 3D printing microneedle arrays, the benefits of fabricating microneedle arrays with 3D printing, and the considerations for clinical translation of 3D-printed microneedle arrays. This work provides an overview of the current 3D-printed microneedle arrays in drug delivery.

Promising Strategies for Transdermal Delivery of Arthritis Drugs: Microneedle Systems

Arthritis is a general term for various types of inflammatory joint diseases. The most common clinical conditions are mainly represented by rheumatoid arthritis and osteoarthritis, which affect more than 4% of people worldwide and seriously limit their mobility. Arthritis medication generally requires long-term application, while conventional administrations by oral delivery or injections may cause gastrointestinal side effects and are inconvenient for patients during long-term application. Emerging microneedle (MN) technology in recent years has created new avenues of transdermal delivery for arthritis drugs due to its advantages of painless skin perforation and efficient local delivery. This review summarizes various types of arthritis and current therapeutic agents. The current development of MNs in the delivery of arthritis drugs is highlighted, demonstrating their capabilities in achieving different drug release profiles through different self-enhancement methods or the incorporation of nanocarriers. Furthermore, the challenges of translating MNs from laboratory studies to the clinical practice and the marketplace are discussed. This promising technology provides a new approach to the current drug delivery paradigm in treating arthritis in transdermal delivery.

Efficacy of a novel microneedle patch for rejuvenation of the nasolabial fold

BACKGROUND

Skin rejuvenation plays a significant role in the esthetic medicine market. Microneedle patches have been developed for a wide range of applications based on the principles of transdermal drug delivery; however, clinical trials of microneedle patches for skin rejuvenation remain limited.

AIMS

This study was conducted to examine the efficacy of microneedle patches for improving nasolabial folds.

METHODS

A total of 23 Thai women completed this prospective clinical trial. The participants were treated according to a split-face design, with application of microneedle patch plus 1.8% hyaluronic acid solution to the right nasolabial fold and microneedle patch alone to the left nasolabial fold. The treatments were applied to the nasolabial fold for 8 weeks. The test areas were measured before treatment and at 2, 4, 8, 12, and 16 weeks after the use of the test product.

RESULTS

Combination treatment using the microneedle patch plus hyaluronic acid solution and use of the microneedle patch alone both significantly improved the Merz esthetic scales for nasolabial folds. Measurement of the nasolabial fold showed an improvement in the two groups, with no significant differences between the groups. No adverse effects were reported during the study period.

CONCLUSIONS

Application of a microneedle patch with 1.8% hyaluronic acid solution or a microneedle patch alone were both effective treatments for improving facial wrinkles in the nasolabial folds.

Immunotherapy for type 1 diabetes mellitus by adjuvant-free Schistosoma japonicum-egg tip-loaded asymmetric microneedle patch (STAMP)

Background

Type 1 diabetes mellitus (T1DM) is an autoimmune disease mediated by autoreactive T cells and dominated by Th1 response polarization. Insulin replacement therapy faces great challenges to this autoimmune disease, requiring highly frequent daily administration. Intriguingly, the progression of T1DM has proven to be prevented or attenuated by helminth infection or worm antigens for a relatively long term. However, the inevitable problems of low safety and poor compliance arise from infection with live worms or direct injection of antigens. Microneedles would be a promising candidate for local delivery of intact antigens, thus providing an opportunity for the clinical immunotherapy of parasitic products.

Methods

We developed a Schistosoma japonicum-egg tip-loaded asymmetric microneedle patch (STAMP) system, which serves as a new strategy to combat TIDM. In order to improve retention time and reduce contamination risk, a specific imperfection was introduced on the STAMP (asymmetric structure), which allows the tip to quickly separate from the base layer, improving reaction time and patient’s comfort. After loading Schistosoma japonicum-egg as the immune regulator, the effects of STAMP on blood glucose control and pancreatic pathological progression improvement were evaluated in vivo. Meanwhile, the immunoregulatory mechanism and biosafety of STAMP were confirmed by histopathology, qRT-PCR, ELISA and Flow cytometric analysis.

Results

Here, the newly developed STAMP was able to significantly reduce blood glucose and attenuate the pancreatic injury in T1DM mice independent of the adjuvants. The isolated Schistosoma japonicum-eggs micron slowly degraded in the skin and continuously released egg antigen for at least 2 weeks, ensuring localization and safety of antigen stimulation. This phenomenon should be attributed to the shift of Th2 immune response to reduce Th1 polarization.

Conclusion

Our results exhibited that STAMP could significantly regulate the blood glucose level and attenuate pancreatic pathological injury in T1DM mice by balancing the Th1/Th2 immune responses, which is independent of adjuvants. This technology opens a new window for the application of parasite products in clinical immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01581-9.

Magnesium microneedle patches for under‐eye wrinkles

Microneedling is a common cosmetic procedure for improvement of wrinkles, acne, scars, and other conditions. Various microneedle (MN) patches have been developed as home care therapy for wrinkles and skin texture. Most of them are made of soluble and absorbable needles. To evaluate the efficacy and safety of non‐absorbable magnesium (Mg) MN patches on under‐eye wrinkles. A total of 20 subjects aged 27–58 years was enrolled in the study. The subjects applied Mg MN patches on the under‐eye wrinkle area for 1–2 h every other night for 12 weeks. The evaluation comprised grading by clinicians, measuring the wrinkle index with a facial analyzer, and measuring the dermal thickness of the under‐eye area with ultrasonography. Any adverse events and discomfort were addressed during the study. The application of Mg MN patches on under‐eye areas showed improvements in under‐eye grading scale, wrinkle index, and dermal thickness after 12 weeks. The mean grading scale significantly improved after 8 weeks of application (p < 0.01). The wrinkle index showed significant improvement after 12 weeks on the right under‐eye area (p < 0.05). The dermal thickness of the under‐eye area tended to increase, but no statistically significant changes were observed. Non‐absorbable Mg MN patches can be used for under‐eye wrinkles with minimal discomfort.

Efficient dermal delivery of ascorbic acid 2-glucoside with photoacoustic waves

OBJECTIVE

Ascorbic acid (i.e., vitamin C) is an important antioxidant present in skin. The protective role of vitamin C against photoaging motivated numerous attempts to promote its topical delivery, with a success limited by its chemical instability and poor skin permeability. Vitamin C precursors, such as ascorbic acid 2-glucoside (AA2G), that are metabolized to vitamin C by enzymes present in the skin, solve the problem of stability but are limited by low skin permeability. We developed a 2% (w/v) gel formulation of AA2G application (viscosity 4.30 × 10⁴ Pa.s, pH 5.94) and compared its passive dermal delivery with the delivery promoted by photoacoustic waves that transiently perturb the skin barrier.

METHODS

Photoacoustic (PA) waves were generated by laser pulses absorbed by piezophotonic (light-to-pressure) transducers. Pig skin samples were exposed to the 2% AA2G formulation alone or combined with 5 minutes of PA waves. One hour later, AA2G was extracted from the skin and quantified by reverse-phase HPLC. AA2G transdermal fluxes using Franz cells with 760 μm thick pig skin samples were also measured.

RESULTS

PA waves transiently enhanced skin permeability and increased dermal delivery of AA2G. AA2G was released from the formulation nearly quantitatively (92.6 ± 6.2%) in 24 hours, showing a non-Fickian behaviour controlled by diffusion and swelling. AA2G dermal delivery with exposure for 5 minutes to PA waves was compared with passive delivery to pig skin. PA waves increased the delivery of AA2G to the skin by a factor of 15 fold with respect to passive delivery, as measured from skin extracts after 1 hour of contact of the formulation with the skin.

CONCLUSION

5 minutes of exposure to PA waves is a safe and effective method to deliver large quantities of AA2G to the skin.

Dissolving microneedles: Applications and growing therapeutic potential

Microneedles are a rapidly developing method for the transdermal delivery of therapeutic compounds. All types of microneedles, whether solid, hollow, coated, or dissolving function by penetrating the stratum corneum layer of the skin producing a microchannel through which therapeutic agents may be delivered. To date, coated and hollow microneedles have been the most successful, despite suffering from issues such as poor drug loading capabilities and blocked pores. Dissolving microneedles, on the other hand, have superior drug loading as well as other positive attributes that make it an ideal delivery system, including simple methods of fabrication and disposal, and abundantly available materials. Indeed, dissolvable microneedles can even be fabricated entirely from the therapeutic agent itself thus eliminating the requirement for additional excipients. This focused review presents the recent developments and trends of dissolving microneedles as well as potential future directions. The advantages, and disadvantages of dissolving microneedles as well as fabrication materials and methods are discussed. The potential applications of dissolving microneedles as a drug delivery system in different therapeutic areas in both research literature and clinical trials is highlighted. Applications including the delivery of cosmetics, vaccine delivery, diagnosis and monitoring, cancer, pain and inflammation, diabetes, hair and scalp disorders and inflammatory skin diseases are presented. The current trends observed in the microneedle landscape with particular emphasis on contemporary clinical trials and commercial successes as well as barriers impeding microneedle development and commercialisation are also discussed.

A Successful Esthetic Approach of Gingival Depigmentation Using Microneedling Technique and Ascorbic Acid (Vitamin C)

A gingival depigmentation is a periodontal plastic procedure that is performed in order to remove melanocytic pigmentation. A variety of different modalities have been proposed for removing hyperpigmentation involving surgical scraping, gingival autograft, cryotherapy, electrosurgery, and lasers. However, the microneedling technique is a nonsurgical procedure that creates microholes to facilitate the penetration of topical medications across the connective tissues. Case Description. A healthy female patient aged 25 years with a pigmented gingiva seeking gingival depigmentation. On examination, a dark brown ribbon of hyperpigmentation was observed within the mandibular attached gingiva. The case was diagnosed as physiological moderate gingival pigmentation (pigmentation index score = 3). The patient was interested in achieving aesthetic results with minimally invasive, nonexpensive procedures. Based on the patient's concerns, the microneedling technique using vitamin C was suggested and consented. We used a dermapen device to microneedle the gingiva until bleeding pinpoints were observed; then, topical ascorbic acid was applied. After 3 days, our outcomes revealed an excellent aesthetic pink gingival appearance. Conclusions and Practical Implications. Compared to other minimally invasive techniques, our technique is less expensive and more risk-free. Our novel technique of using dermapen and topical ascorbic acid has shown promising results to our case which gives new perspectives for its application in gingival depigmentation.

Minoxidil-loaded hyaluronic acid dissolving microneedles to alleviate hair loss in an alopecia animal model

Alopecia is defined as hair loss in a part of the head due to various causes, such as drugs, stress and autoimmune disorders. Various therapeutic agents have been suggested depending on the cause of the condition and patient sex, and age. Minoxidil (MXD) is commonly used topically to treat alopecia, but its low absorption rate limits widespread use. To overcome the low absorption, we suggest microneedles (MNs) as controlled drug delivery systems that release MXD. We used hyaluronic acid (HA) to construct MN, as it is biocompatible and safe. We examined the effect of HA on the hair dermal papilla (HDP) cells that control the development of hair follicles. HA enhanced proliferation, migration, and aggregation of HDP cell by increasing cell-cell adhesion and decreasing cell substratum. These effects were mediated by the cluster of differentiation (CD)-44 and phosphorylation of serine‑threonine kinase (Akt). In chemotherapy-induced alopecia mice, topical application of HA tended to decrease chemotherapy-induced hair loss. Although the amount of MXD administered by HA-MNs was 10% of topical treatment, the MXD-containing HA-MNs (MXD-HA-MNs) showed better effects on the growth of hair than topical application of MXD. In summary, our results demonstrated that HA reduces hair loss in alopecia mice, and that delivery of MXD and HA using MXD-HA-MNs maximizes therapeutic effects and minimize the side effects of MXD for the treatment of alopecia. STATEMENT OF SIGNIFICANCE: (1) Significance, This work reports a new approach for treatment of alopecia using a dissolving microneedle (MN) prepared with hyaluronic acid (HA). The HA provided a better environment for cellular functions in the hair dermal papilla cells. The HA-MNs containing minoxidil (MXD) exhibited a significant reduction of hair loss, although amount of MXD contained in them was only 10% of topically applied MXD., (2) Scientific impact, This is the first report demonstrating the direct anti-alopecia effects of HA administrated in a transdermal route and the feasibility of novel therapeutics using MXD-containing HA-MNs. We believe that our work will excite interdisciplinary readers of Acta Biomaterialia, those who are interested in the natural polymers, drug delivery, and alopecia.

Long-acting microneedle patch loaded with adipose collagen fragment for preventing the skin photoaging in mice

Skin photoaging is one of the most serious public health problems in the 21st century that may lead to thin, saggy, and structurally weakened skin. Adipokine therapy toward skin photoaging is always associated with poor permeability, biologic stability and the short in vivo release duration. Our laboratory previously extracted an extracellular matrix component of adipose tissue by purely physical methods, namely "adipose collagen fragment (ACF)", which holds promise for preventing skin photoaging. However, the injection treatment of ACF requires repeated preparation processes and injection procedures, which may be time-consuming and painful. Therefore, we describe the fabrication and assessment of a detachable ACF-microneedle (ACF-MN) patch that creates minimally invasive dermal microtrauma upon application. And we evaluated the morphology characterization, mechanical properties and puncture performance in vitro. The delivery efficiency of ACF from the patches was estimated in vitro and vivo. Then, the therapeutic efficacy was identified through applying ACF-MN patches into the dermis of UVA-induced photoaging mice and the related detection of skin photoaging was estimated. Our results demonstrated that ACF-MN exhibited well skin puncture performance and could release ACF component slowly. Meanwhile, this microneedle device loaded with ACF exhibited the treatment efficiency on skin photoaging in a mouse model. Therefore, implantation of the microtrauma-mediated, long-acting ACF-MN system can be utilized as a potential candidate for preventing skin photoaging in the clinic.