Two-phase delivery using a horse oil and adenosine-loaded dissolving microneedle patch for skin barrier restoration, moisturization, and wrinkle improvement

Adenosine metabolism and receptors in aging of the skin, musculoskeletal, immune and cardiovascular systems

Aging populations worldwide face an increasing burden of age-related chronic conditions, necessitating a deeper understanding of the underlying mechanisms. Purine metabolism has emerged as a crucial player in the pathophysiology of aging, affecting various tissues and organs. Dysregulation of purine metabolism, particularly alterations in extracellular adenosine levels and adenosine receptor signaling, contributes to age-related musculoskeletal problems, cardiovascular diseases, inflammation, and impaired immune responses. Changes in purine metabolism are associated with diminished tissue repair and regeneration, altered bone density, and impaired muscle regeneration. Mechanistically, age-related alterations in purine metabolism involve reductions in extracellular adenosine production, impaired autocrine signaling, and dysregulated expression of CD73 and CD39. Targeting adenosine receptors, such as A2A and A2B receptors, emerges as a promising therapeutic approach to mitigate age-related conditions, including sarcopenia, obesity, osteoarthritis, and impaired wound healing. Since we cannot reverse time, understanding the intricate molecular interplay between purine metabolism and aging-related pathologies holds significant potential for developing novel therapeutic strategies to improve the health and quality of life of aging populations. In this review, we compile the findings related to purine metabolism during aging in several tissues and organs and provide insights into how these signals can be manipulated to circumvent the deleterious effects of the passage of time on our body.

Advances in the Application of Black Phosphorus-Based Composite Biomedical Materials in the Field of Tissue Engineering

Black Phosphorus (BP) is a new semiconductor material with excellent biocompatibility, degradability, and optical and electrophysical properties. A growing number of studies show that BP has high potential applications in the biomedical field. This article aims to systematically review the research progress of BP composite medical materials in the field of tissue engineering, mining BP in bone regeneration, skin repair, nerve repair, inflammation, treatment methods, and the application mechanism. Furthermore, the paper discusses the shortcomings and future recommendations related to the development of BP. These shortcomings include stability, photothermal conversion capacity, preparation process, and other related issues. However, despite these challenges, the utilization of BP-based medical materials holds immense promise in revolutionizing the field of tissue repair.

Drug Delivery Systems based on Microneedles for Dermatological Diseases and Aesthetic Enhancement

Microneedle (MN) devices comprise of micron-sized structures that circumvent biological barriers in a minimally invasive manner. MN research continues to grow and evolve; the technology was recently identified as one of the top ten overall emerging technologies of 2020. There is a growing interest in using such devices in cosmetology and dermatological conditions where the MNs mechanically disrupt the outer skin barrier layer, creating transient pathways that allow the passage of materials to underlying skin layers. This review aims to appraise the application of microneedle technologies in skin science, provide information on potential clinical benefits, as well as indicate possible dermatological conditions that can benefit from this technology, including autoimmunemediated inflammatory skin diseases, skin aging, hyperpigmentation, and skin tumors. A literature review was carried out to select studies that evaluated the use of microneedles to enhance drug delivery for dermatologic purposes. MN patches create temporary pathways that allow the passage of therapeutic material to deeper layers of the skin. Given their demonstrable promise in therapeutic applications it will be essential for healthcare professionals to engage with these new delivery systems as they transition to the clinic.

Micro-pillar tunnel stamp for enhanced transdermal delivery of topical drug formulations

Dissolving microneedles (DMNs), despite their minimally invasive drug administration, face challenges in skin insertion and drug-loading capacity, which lead to less effective drug delivery. The micro-pillar tunnel stamp (MPTS) was designed to enhance the transdermal delivery efficacy of externally provided topical formulations via the creation of microchannels. The tunnel and canal of the MPTS enable the simultaneous application of DMNs and topical drugs. The application of micro-pillar-polycaprolactone (MP-PCL), which is a DMN made of a slowly dissolving polymer, exhibited a drug permeation rate 1.3-fold and 2.6-fold higher than that of micro-pillar-hyaluronic acid (MP-HA), a DMN made of a rapidly dissolving polymer, and the topical group, respectively. The base diameter of MP-PCL was set to 700 μm for maximized delivery efficacy, achieving 2.8-fold higher L-ascorbic acid accumulation than that of the topical group. In vivo analysis showed that, compared to topical administration, MPTS-delivered lidocaine had 5-fold greater permeation and the MPTS-delivered group showed 1.25-fold higher skin residual amount, confirming enhanced delivery. Thus, the optimized MPTS system can be presented as an attractive alternative to overcome the limitations of the existing MN systems such as incomplete insertion and limited drug-loading capacity, enhancing the delivery of topical formulations in the transdermal market. STATEMENT OF SIGNIFICANCE: We developed a micro-pillar tunnel stamp (MPTS) to enhance the delivery of externally provided topical formulations. The functional tunnel and canal of the MPTS enabled the simultaneous application of a dissolving microneedle (DMN) array insertion and administration of external topical drugs. Upon insertion, the DMNs created skin microchannels that allowed the externally administered drug to diffuse. DMNs were fabricated using polycaprolactone (PCL), a slowly dissolving polymer, to maintain their structure inside the skin and prolong the opening duration of the microchannels. This system achieved significantly improved delivery of topically administered external drugs via integration with slowly dissolving DMNs, while offering the possibility of its development as a universal delivery system for various topical pharmaceuticals.

Sustained Release Microneedles: Materials and Applications in Facial Rejuvenation

Wrinkled and loose skin resulting from collagen degradation along with fibers decreasing reflects the youth diminishing. Microneedles (MNs) have opened up new avenues for the development of painless and noninvasive transdermal drug delivery systems for facial rejuvenation. Encapsulated drugs or molecules are transmitted to targeted tissues via percutaneous microchannels, which eliminate potential gastric stimulation or first-pass metabolic effects, as well as boost patient compliance. Although MNs are considered effective and feasible therapeutic alternatives to metals, silicon, and polymers, traditional procedures with reduction processes continue to encounter methodological limitations. In recent years, promising additive manufacturing processes such as three-dimensional printing and two-photon polymerization manufacturing have been developed with the aim of overcoming the limitations by traditional processes to facilitate an efficient and economic production mode. This review summarizes the design, material selection, and manufacturing method for recently advanced MN systems. Furthermore, we also highlight specific polymeric or natural microneedle products, like hyaluronan, plant derivates, and vitamins, for esthetic applications in this review. Impact Statement In this review, the materials and manufactural routes of microneedles (MNs) are detailed. Moreover, similar to the diagnostic or therapeutic MNs, the feature of dispensation with training and ready-to-use is perfect for beautification and anti-aging, which necessitate repeated and long-term usage. Furthermore, the specific polymeric or natural products for esthetic applications of MNs are highlighted in this review.

3D Printed Hollow Microneedles for Treating Skin Wrinkles Using Different Anti-Wrinkle Agents: A Possible Futuristic Approach

Skin wrinkles are an inevitable phenomenon that is brought about by aging due to the degradation of scleroprotein fibers and significant collagen reduction, which is the fundamental basis of anti-wrinkle technology in use today. Conventional treatments such as lasering and Botulinum toxin have some drawbacks including allergic skin reactions, cumbersome treatment procedures, and inefficient penetration of the anti-wrinkle products into the skin due to the high resistance of stratum corneum. Bearing this in mind, the cosmetic industry has exploited the patient-compliant technology of microneedles (MNs) to treat skin wrinkles, developing several products based on solid and dissolvable MNs incorporated with antiwrinkle formulations. However, drug administration via these MNs is limited by the high molecular weight of the drugs. Hollow MNs (HMNs) can deliver a wider array of active agents, but that is a relatively unexplored area in the context of antiwrinkle technology. To address this gap, we discuss the possibility of bioinspired 3D printed HMNs in treating skin wrinkles in this paper. We compare the previous and current anti-wrinkling treatment options, as well as the techniques and challenges involved with its manufacture and commercialization.

Dissolving microneedles for effective and painless intradermal drug delivery in various skin conditions: A systematic review

Intra- and transdermal administration of substances via percutaneous injection is effective but considered painful, and inconvenient in addition to bringing forth biohazardous waste material. In contrast to injection, topical drug application, which includes ointments, creams and lotions, increases the local drug load. Moreover, it has reduced side effects compared to systemic administration. However, the epidermis poses a barrier to high molecular weight substances, limiting the delivery efficiency. Dissolving microneedles (DMN) are hydrophilic, mostly polymer-based constructs that are capable of skin penetration and were developed to provide painless and direct dermal drug delivery. This systematic review provides a comprehensive overview of the available clinical evidence for the use of DMN to treat various skin conditions. According to the PRISMA statement, a systematic search for articles on the use of DMN for dermatological indications was conducted on three different databases (Pubmed, Embase, and the Cochrane library). Only human clinical trials were considered. Qualitative assessment was done by two separate reviewers using the Cochrane risk of bias (RoB 2) and Chambers' criteria assessment tools. The search yielded 1090 articles. After deduplication and removal of ineligible records, 889 records were screened on title and abstract. Full text screening was done for 18 articles and ultimately 17 articles were included of which 15 were randomized controlled trials and two were case series. The quality assessment showed that the majority of included studies had low to no risk of bias. Clinical data supports that DMN are an excellent, effective, and pain free drug delivery method for multiple dermatological disorders including skin aging, hyperpigmentation, psoriasis, warts, and keloids by supplying a painless and effective vehicle for intradermal/intralesional drug administration. Microneedle technology provides a promising non- to minimally-invasive alternative to percutaneous injection.

Advances in microneedles research based on promoting hair regrowth

Alopecia is the most common and difficult-to-treat hair disorder. It usually brings a significant psychological burden to the patients. With the growing popularity of alopecia, the study of alopecia has gained more attention. Currently, only minoxidil and finasteride have been approved by the FDA for the treatment of alopecia, but the efficacy has always been unsatisfactory. As a new form of transdermal drug delivery, microneedles have been widely used in the treatment of alopecia and have proven to be effective. Microneedles delivery can improve the efficiency of local drug delivery and patients' compliance, which can achieve better therapeutic effects on hair-related diseases. Therefore, microneedles have gained much attention in the field of alopecia and hair regrowth promotion in recent years. This review summarizes the last decade of research on the microneedles delivery design for the treatment of alopecia or promotion of hair regrowth and provides a comprehensive evaluation of this field.

The possible role of the nucleoside adenosine in countering skin aging: A review

Skin aging is a complex biological process. Skin aspect is considered as a sign of well-being and of beauty. In view of this, noninvasive and/or minimally invasive anti-aging strategies were developed. Adenosine, a well-known nucleoside, may play a role in skin rejuvenation. Adenosine receptors belong to the G protein-coupled receptors superfamily and are divided into four subtypes: A₁ , A_2A , A_2B , and A₃ . The adenosine receptors expressed by skin are mainly the A₁ and A_2A subtypes. In the hypodermis, adenosine through the A₁ receptor stimulates lipogenesis and adipogenesis. In the dermis, adenosine through the A_2A receptor subtype stimulates collagen production. Moreover, the nucleoside increases new DNA synthesis and subsequently protein synthesis in dermal cells. Activation of adenosine receptors by interacting with various skin layers may induce a decrease in the amount of wrinkles, roughness, dryness, and laxity. This article has reviewed the mechanisms through which adenosine modulates biological mechanisms in the skin tissues and the effect of preparations containing adenosine or its derivatives on the skin.

Characterization of skin aging through high-frequency ultrasound imaging as a technique for evaluating the effectiveness of anti-aging products and procedures: A review

INTRODUCTION

High-frequency ultrasound skin imaging analysis (HFUS) is a non-invasive technique that allows a unique approach to the analysis of skin aging, as well as in evaluating the effectiveness of dermatological and cosmetic products, especially for skin rejuvenation.

OBJECTIVE

To describe the impact of skin aging and different anti-aging strategies from the perspective of high-frequency ultrasound.

METHODS

A bibliographic survey was carried out, selecting relevant articles that evaluated the characterization of the skin features from different points of view such as gender (male and female), age (young skin and mature skin), and ethnicity, in addition to individual variations between body regions and daily variations.

RESULTS

Some studies also evaluated the impact of cosmetic treatments and esthetic procedures in the skin. Parameters such as dermal thickness, echogenicity, skin texture, and subepidermal low-echogenic band (SLEB) were analyzed. It can be concluded that there is a trend, although not unanimous in the consequences of aging on the skin, being different between men and women, plus the individual nuances resulted from each one's lifestyle and exposure to the sun.

CONCLUSION

As for the technique, it is concluded that high-frequency ultrasound is an important evaluative alternative for dermatological studies and the effectiveness of anti-aging products and treatments.

Microneedle for transdermal drug delivery: current trends and fabrication

Background

Transdermal delivery has the advantage of bypassing the first-pass effect and allowing sustained release of the drug. However, the drug delivery is limited owing to the barrier created by the stratum corneum. Microneedles are a transdermal drug delivery system that is painless, less invasive, and easy to self-administer, with a high drug bioavailability.

Area covered

The dose, delivery rate, and efficacy of the drugs can be controlled by the microneedle design and drug formulations. This review introduces the types of microneedles and their design, materials used for fabrication, and manufacturing methods. Additionally, recent biological applications and clinical trials are introduced.

Expert opinion

With advancements made in formulation technologies, the drug-loading capability of microneedles can be improved. 3D printing and digital technology contribute to the improvement of microneedle fabrication technology. However, regulations regarding the manufacture of microneedle products should be established as soon as possible to promote commercialization.

Microneedle Arrays Combined with Nanomedicine Approaches for Transdermal Delivery of Therapeutics

Organic and inorganic nanoparticles (NPs) have shown promising outcomes in transdermal drug delivery. NPs can not only enhance the skin penetration of small/biomacromolecule therapeutic agents but can also impart control over drug release or target impaired tissue. Thanks to their unique optical, photothermal, and superparamagnetic features, NPs have been also utilized for the treatment of skin disorders, imaging, and biosensing applications. Despite the widespread transdermal applications of NPs, their delivery across the stratum corneum, which is the main skin barrier, has remained challenging. Microneedle array (MN) technology has recently revealed promising outcomes in the delivery of various formulations, especially NPs to deliver both hydrophilic and hydrophobic therapeutic agents. The present work reviews the advancements in the application of MNs and NPs for an effective transdermal delivery of a wide range of therapeutics in cancer chemotherapy and immunotherapy, photothermal and photodynamic therapy, peptide/protein vaccination, and the gene therapy of various diseases. In addition, this paper provides an overall insight on MNs' challenges and summarizes the recent achievements in clinical trials with future outlooks on the transdermal delivery of a wide range of nanomedicines.

A Semi-Dissolving Microneedle Patch Incorporating TEMPO-Oxidized Bacterial Cellulose Nanofibers for Enhanced Transdermal Delivery

Although dissolving microneedles have garnered considerable attention as transdermal delivery tools, insufficient drug loading remains a challenge owing to their small dimension. Herein, we report a one-step process of synthesizing semi-dissolving microneedle (SDMN) patches that enable effective transdermal drug delivery without loading drugs themselves by introducing TEMPO-oxidized bacterial cellulose nanofibers (TOBCNs), which are well dispersed, while retaining their unique properties in the aqueous phase. The SDMN patch fabricated by the micro-molding of a TOBCN/hydrophilic biopolymer mixture had a two-layer structure comprising a water-soluble needle layer and a TOBCN-containing insoluble backing layer. Moreover, the SDMN patch, which had a hole in the backing layer where TOBCNs are distributed uniformly, could offer novel advantages for the delivery of large quantities of active ingredients. In vitro permeation analysis confirmed that TOBCNs with high water absorption capacity could serve as drug reservoirs. Upon SDMN insertion and the application of drug aqueous solution through the drug inlet hole, the TOBCNs rapidly absorbed the solution and supplied it to the needle layer. Simultaneously, the needle layer dissolved in body fluids and the drug solution to form micro-channels, which enabled the delivery of larger quantities of drugs to the skin compared to that enabled by solution application alone.

Physical drug delivery enhancement for aged skin, UV damaged skin and skin cancer: Translation and commercialization

This review analyses physical drug delivery enhancement technologies with a focus on improving UV damaged skin, actinic keratoses and non-melanoma skin cancer treatment. In recent years, physical drug delivery enhancement has been shown to enhance cosmeceutical and skin cancer treatment efficacy, but there are pros and cons to each approach which we discuss in detail. Mechanisms of action, clinical efficacy, experimental design, outcomes in academic publications, clinical trial reports and patents are explored to evaluate each technology with a critical, translation focused lens. We conclude that the commercial success of cosmeceutical applications, e.g. microneedles, will drive further innovation in this arena that will impact how actinic keratoses and non-melanoma skin cancers are clinically managed.