A combination therapy for androgenic alopecia based on quercetin and zinc/copper dual-doped mesoporous silica nanocomposite microneedle patch

Tumor Microenvironment-Responsive Biodegradable Nanomedicine for Self-Enhanced Synergistic Chemo-, Photothermal, and Chemodynamic Therapy

The nanoscale multidrug codelivery system for synergistic therapy is an effective strategy for tumor treatment. However, the low drug delivery efficiency and poor therapeutic effects limit its application. Here, based on the coordination effect of Artemisinin (Art), quercetin (Qc), and Fe3+, we had constructed a safe and efficient carrier-free hyaluronic acid (HA)-modified Art-Fe-Qc nanoparticles (AFQ@HA NPs) for enhanced chemotherapy/photothermal therapy (PTT)-chemodynamic therapy (CDT) synergistic therapy, which achieved an ultrahigh drug loading efficiency and a multifunction anticancer strategy. The results showed that high drug loading was achieved based on drug coordination self-assembly, with Art and Qc contents of 38.6 and 42.7%, respectively. At the same time, based on the Qc-Fe coordination molecular network, the system had excellent photothermal conversion performance with an efficiency of 57.3% and could effectively inhibit the expression of HSP70, achieving enhanced PTT. Further, under the stimulation of excessive H2O2 and glutathione (GSH) in the tumor microenvironment, the AFQ@HA NPs were continuously degraded, while releasing Art and Fe3+/Fe2+ to achieve iron ion-enhanced CDT. The results of in vitro and in vivo experiments showed that AFQ@HA NPs could achieve chemotherapy-PTT-CDT synergistic therapy in response to tumor microenvironment by passively targeting and actively targeting tumor cells with CD44, demonstrating its excellent targeted antitumor effects.

Biological Fate Tracking of Nitric Oxide-Propelled Microneedle Delivery System Using an Aggregation-Caused Quenching Probe

Nanoparticle-loaded dissolving microneedles (DMNs) have attracted increasing attention due to their ability to provide high drug loading, adjustable drug release behavior, and enhanced therapeutic efficiency. However, such delivery systems still face unsatisfied drug delivery efficiency due to insufficient driving force to promote nanoparticle penetration and the lack of in vivo fate studies to guide formulation design. Herein, an aggregation-caused quenching (ACQ) probe (P4) was encapsulated in l-arginine (l-Arg)-based nanomicelles, which was further formulated into nitric oxide (NO)-propelled nanomicelle-integrated DMNs (P4/l-Arg NMs@DMNs) to investigate their biological fate. The P4 probe could emit intense fluorescence signals in intact nanomicelles, while quenching with the dissociation of nanomicelles, providing a "distinguishable" method for tracking the fate of nanomicelles at a different status. l-Arg was demonstrated to self-generate NO under the tumor microenvironment with excessive reactive oxygen species (ROS), providing a pneumatic force to promote the penetration of nanomicelles in both three-dimensional (3D)-cultured tumor cells and melanoma-bearing mice. Compared with passive microneedles (P4 NMs@DMNs) without a NO propellant, the P4/l-Arg NMs@DMNs possessed a good NO production performance and higher nanoparticle penetration capacity. In conclusion, this study offered an ACQ probe-based biological fate tracking approach to demonstrate the potential of NO-propelled nanoparticle-loaded DMNs in penetration enhancement for topical tumor therapy.

Microneedle system for tissue engineering and regenerative medicines: a smart and efficient therapeutic approach

The global demand for an enhanced quality of life and extended lifespan has driven significant advancements in tissue engineering and regenerative medicine. These fields utilize a range of interdisciplinary theories and techniques to repair structurally impaired or damaged tissues and organs, as well as restore their normal functions. Nevertheless, the clinical efficacy of medications, materials, and potent cells used at the laboratory level is always constrained by technological limitations. A novel platform known as adaptable microneedles has been developed to address the abovementioned issues. These microneedles offer a solution for the localized distribution of various cargos while minimizing invasiveness. Microneedles provide favorable patient compliance in clinical settings due to their effective administration and ability to provide a painless and convenient process. In this review article, we summarized the most recent development of microneedles, and we started by classifying various microneedle systems, advantages, and fundamental properties. Subsequently, it provides a comprehensive overview of different types of microneedles, the material used to fabricate microneedles, the fundamental properties of ideal microneedles, and their applications in tissue engineering and regenerative medicine, primarily focusing on preserving and restoring impaired tissues and organs. The limitations and perspectives have been discussed by concluding their future therapeutic applications in tissue engineering and regenerative medicines.

Explore the genetic exposure to alopecia areata

BACKGROUND

Alopecia areata is an autoimmune hair loss disorder with an incompletely understood etiology. Although trace elements, serum metabolites, and inflammatory factors are implicated in the disease, the potential causal relationships between these factors and alopecia areata require further investigation.

METHODS

This study employed Mendelian randomization (MR), utilizing data from genome-wide association studies, to explore the causal relationships between 15 trace elements, 1400 serum metabolites, and 91 inflammatory factors and alopecia areata. The analysis was conducted using the inverse variance weighted (IVW) method complemented by various sensitivity analyses, including Cochran's Q test, MR-Egger regression intercept test, MR-PRESSO global test, and leave-one-out analysis, to assess the robustness of the results.

RESULTS

MR analysis indicated a negative correlation between copper levels and the risk of developing alopecia areata (odds ratio = 0.86, 95% confidence interval: 0.75-0.99, p = 0.041). Additionally, causal relationships were identified between 15 serum metabolites and 6 inflammatory factors and the risk of alopecia areata (IVW, all p values < 0.05).

CONCLUSION

This study provides genetic evidence of the relationships between trace elements, serum metabolites, and alopecia areata, underscoring the potential value of targeted therapeutic strategies and preventive measures. Future research should expand to diverse populations and further explore the specific roles of these biomarkers in the disease mechanism.

Enhancing hair regeneration: Recent progress in tailoring nanostructured lipid carriers through surface modification strategies

Background and purpose

Hair loss is a prevalent problem affecting millions of people worldwide, necessitating innovative and efficient regrowth approaches. Nanostructured lipid carriers (NLCs) have become a hopeful option for transporting bioactive substances to hair follicles because of their compatibility with the body and capability to improve drug absorption.

Review approach

Recently, surface modification techniques have been used to enhance hair regeneration by improving the customization of NLCs. These techniques involve applying polymers, incorporating targeting molecules, and modifying the surface charge.

Key results

The conversation focuses on how these techniques enhance stability, compatibility with the body, and precise delivery to hair follicles within NLCs. Moreover, it explains how surface-modified NLCs can improve the bioavailability of hair growth-promoting agents like minoxidil and finasteride. Furthermore, information on how surface-modified NLCs interact with hair follicles is given, uncovering their possible uses in treating hair loss conditions.

Conclusion

This review discusses the potential of altering the surface of NLCs to customize them for enhanced hair growth. It offers important information for upcoming studies on hair growth.

Bioinspired engineering ADSC nanovesicles thermosensitive hydrogel enhance autophagy of dermal papilla cells for androgenetic alopecia treatment

Androgenic alopecia (AGA) is a highly prevalent form of non-scarring alopecia but lacks effective treatments. Stem cell exosomes have similar repair effects to stem cells, suffer from the drawbacks of high cost and low yield yet. Cell-derived nanovesicles acquired through mechanical extrusion exhibit favorable biomimetic properties similar to exosomes, enabling them to efficiently encapsulate substantial quantities of therapeutic proteins. In this study, we observed that JAM-A, an adhesion protein, resulted in a significantly increased the adhesion and resilience of dermal papilla cells to form snap structures against damage caused by dihydrotestosterone and macrophages, thereby facilitating the process of hair regrowth in cases of AGA. Consequently, adipose-derived stem cells were modified to overexpress JAM-A to produce engineered JAM-A overexpressing nanovesicles (JAM-AOE@NV). The incorporation of JAM-AOE@NV into a thermosensitive hydrogel matrix (JAM-AOE@NV Gel) to effectively addresses the limitations associated with the short half-life of JAM-AOE@NV, and resulted in the achievement of a sustained-release profile for JAM-AOE@NV. The physicochemical characteristics of the JAM-AOE@NV Gel were analyzed and assessed for its efficacy in promoting hair regrowth in vivo and vitro. The JAM-AOE@NV Gel, thus, presents a novel therapeutic approach and theoretical framework for promoting the treatment of low cell adhesion diseases similar to AGA.

CuCS/Cur composite wound dressings promote neuralized skin regeneration by rebuilding the nerve cell "factory" in deep skin burns

Regenerating skin nerves in deep burn wounds poses a significant clinical challenge. In this study, we designed an electrospun wound dressing called CuCS/Cur, which incorporates copper-doped calcium silicate (CuCS) and curcumin (Cur). The unique wound dressing releases a bioactive Cu2+-Cur chelate that plays a crucial role in addressing this challenge. By rebuilding the "factory" (hair follicle) responsible for producing nerve cells, CuCS/Cur induces a high expression of nerve-related factors within the hair follicle cells and promotes an abundant source of nerves for burn wounds. Moreover, the Cu2+-Cur chelate activates the differentiation of nerve cells into a mature nerve cell network, thereby efficiently promoting the reconstruction of the neural network in burn wounds. Additionally, the Cu2+-Cur chelate significantly stimulates angiogenesis in the burn area, ensuring ample nutrients for burn wound repair, hair follicle regeneration, and nerve regeneration. This study confirms the crucial role of chelation synergy between bioactive ions and flavonoids in promoting the regeneration of neuralized skin through wound dressings, providing valuable insights for the development of new biomaterials aimed at enhancing neural repair.

A target-triggered strand displacement-assisted target recycling based on carbon dots-based fluorescent probe and MSNs@PDA nanoparticles for miRNA amplified detection and fluorescence imaging

A target-triggered strand displacement-assisted target recycling based on carbon dots-based fluorescent probe and mesoporous silica nanoparticles@polydopamine (MSNs@PDA) was established to detect miRNA. The surface of MSNs rich in mesopores was coated with a layer of PDA, which can adsorb and quench the fluorescence of single-stranded Fuel DNA with fluorescent carbon dots (CDs) modified at the end through fluorescence resonance energy transfer (FRET). After adding double-stranded DNA-gold nanoparticles (dsDNA-AuNPs) and target let-7a, it will trigger two toehold-mediated strand displacement reactions (TSDR), leading to the recovery of fluorescence and the recycling of target let-7a (excitation wavelength: 380 nm; emission wavelength: 458 nm). The recovery value of fluorescence is proportional to the logarithm of the target microRNA let-7a concentration, thus realizing the sensitivity amplification detection of disease markers. The MSNs@PDA@Fuel DNA-CDs/dsDNA-AuNPs nanoplatform based on the strategy of "on-off-on" and TSDR cyclic amplification may hold great potential as an effective and safe nanoprobe for accurate fluorescence imaging of diseases related to miRNA with low abundances.

Polydopamine Synergizes with Quercetin Nanosystem to Reshape the Perifollicular Microenvironment for Accelerating Hair Regrowth in Androgenetic Alopecia

Accumulated reactive oxygen species (ROS) and their resultant vascular dysfunction in androgenic alopecia (AGA) hinder hair follicle survival and cause permanent hair loss. However, safe and effective strategies to rescue hair follicle viability to enhance AGA therapeutic efficiency remain challenging. Herein, we fabricated a quercetin-encapsulated (Que) and polydopamine-integrated (PDA@QLipo) nanosystem that can reshape the perifollicular microenvironment to initial hair follicle regeneration for AGA treatment. Both the ROS scavenging and angiogenesis promotion abilities of PDA@QLipo were demonstrated. In vivo assays revealed that PDA@QLipo administrated with roller-microneedles successfully rejuvenated the "poor" perifollicular microenvironment, thereby promoting cell proliferation, accelerating hair follicle renewal, and facilitating hair follicle recovery. Moreover, PDA@QLipo achieved a higher hair regeneration coverage of 92.5% in the AGA mouse model than minoxidil (87.8%), even when dosed less frequently. The nanosystem creates a regenerative microenvironment by scavenging ROS and augmenting neovascularity for hair regrowth, presenting a promising approach for AGA clinical treatment.

Biomaterial-based mechanical regulation facilitates scarless wound healing with functional skin appendage regeneration

Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages, ultimately impairing its normal physiological function. Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration, promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions. The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties. However, a comprehensive understanding of the underlying mechanisms remains somewhat elusive, limiting the broader application of these innovations. In this review, we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin. The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration. The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity, facilitating efficient cellular reprogramming and, consequently, promoting the regeneration of skin appendages. In summary, the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing, coupled with the restoration of multiple skin appendage functions.

Thermodynamically stable ionic liquid microemulsions pioneer pathways for topical delivery and peptide application

Copper peptides (GHK-Cu) are a powerful hair growth promoter with minimal side effects when compared with minoxidil and finasteride; however, challenges in delivering GHK-Cu topically limits their non-invasive applications. Using theoretical calculations and pseudo-ternary phase diagrams, we designed and constructed a thermodynamically stable ionic liquid (IL)-based microemulsion (IL-M), which integrates the high drug solubility of ILs and high skin permeability of microemulsions, thus improving the local delivery of copper peptides by approximately three-fold while retaining their biological function. Experiments in mice validated the effectiveness of our proposed IL-M system. Furthermore, the exact effects of the IL-M system on the expression of growth factors, such as vascular endothelial growth factor, were revealed, and it was found that microemulsion increased the activation of the Wnt/β-catenin signaling pathway, which includes factors involved in hair growth regulation. Overall, the safe and non-invasive IL microemulsion system developed in this study has great potential for the clinical treatment of hair loss.

Design and fabrication of customizable microneedles enabled by 3D printing for biomedical applications

Microneedles (MNs) is an emerging technology that employs needles ranging from 10 to 1000 μm in height, as a minimally invasive technique for various procedures such as therapeutics, disease monitoring and diagnostics. The commonly used method of fabrication, micromolding, has the advantage of scalability, however, micromolding is unable to achieve rapid customizability in dimensions, geometries and architectures, which are the pivotal factors determining the functionality and efficacy of the MNs. 3D printing offers a promising alternative by enabling MN fabrication with high dimensional accuracy required for precise applications, leading to improved performance. Furthermore, enabled by its customizability and one-step process, there is propitious potential for growth for 3D-printed MNs especially in the field of personalized and on-demand medical devices. This review provides an overview of considerations for the key parameters in designing MNs, an introduction on the various 3D-printing techniques for fabricating this new generation of MNs, as well as highlighting the advancements in biomedical applications facilitated by 3D-printed MNs. Lastly, we offer some insights into the future prospects of 3D-printed MNs, specifically its progress towards translation and entry into market.

Observing the clinical efficacy of combined serum microneedle therapy for moderate to severe androgenetic alopecia in scalp repair

OBJECTIVE

In this study, the safety and efficacy of scalp repair serum microneedles combined with oral drug administration and topical medication were investigated for the treatment of moderate to severe androgenetic alopecia.

METHODS

Twenty patients, consisting of 4 males and 16 females, who sought treatment for moderate to severe androgenetic alopecia at our hair medicine research center alopecia specialty clinic between August and December 2022 were randomly selected for the study. Male patients underwent oral administration of finasteride topical application of 5% minoxidil, and biweekly scalp repair serum microneedle therapy. Female patients were administered spironolactone or Diane-35 orally and applied 2% minoxidil topically, paired with biweekly scalp repair serum microneedle therapy sessions. After seven treatments, the scalp repair serum microneedle was discontinued, but oral administration and topical applications were continued, followed by a 1-month follow-up. Using a hair dermoscopy, hair follicles in a fixed region on the top of the head were manually counted per unit area to evaluate the hair restoration status of the patients quantitatively.

RESULTS

All 20 patients completed 3 months of combined therapy and a 1-month follow-up. On average, the patients experienced an increase of 42.6 hairs, with an efficiency rate of 100%. Significant differences were observed in hair count between any two of the first seven treatments (p < 0.001). A significant negative correlation was discovered between the initial pre-treatment hair count and the total improvement of hair (p < 0.001), indicating that the greater the degree of hair loss before treatment, the more pronounced the improvement.

CONCLUSION

Scalp repair serum microneedle combined therapy in moderate to severe androgenetic alopecia significantly reduces the number of microneedle treatments required, enhances treatment efficacy, and improves therapeutic outcomes.

A novel target-triggered signal chemiluminescence kit for thrombin detection based on fusiform Au/MIL-53(Fe)

In this work, a fusiform Au/MIL-53(Fe) catalyst was used to construct a chemiluminescence (CL) kit for the sensitive and rapid detection of thrombin (THR). The porous silica microspheres encapsulated with luminol in holes by thrombin aptamer (THR-APT/Luminol/SPSiO2) and the fusiform Au/MIL-53(Fe) modified with thrombin aptamer complementary chains (Au/MIL-53(Fe)-SSDNA) were prepared. Then, a CL kit for THR detection was constructed by using the prepared composites. When thrombin is added to the reaction system, it binds to its aptamer (THR-APT) to open the holes of SPSiO2, which cause luminol and Au/MIL-53(Fe) release. Released luminol enters the detection system and triggers the reaction of luminol-H2O2-NaOH with the catalyst of Au/MIL-53(Fe), and produces a CL signal. The detection limit and the linear range of the kit were 4.7 × 10-15 M and 1.5 × 10-14 - 3.5 × 10-10 M, respectively. The CL kit also showed high stability, selectivity and reproducibility, and was successfully applied to the determination of THR in serum samples. Therefore, the proposed method for detecting THR has great application potential in the diagnosis of blood-related disease markers.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Recent Trends in Macromolecule-Based Approaches for Hair Loss Treatment

Macromolecules are large, complex molecules composed of smaller subunits known as monomers. The four primary categories of macromolecules found in living organisms are carbohydrates, lipids, proteins, and nucleic acids; they also encompass a broad range of natural and synthetic polymers. Recent studies have shown that biologically active macromolecules can help regenerate hair, providing a potential solution for current hair regeneration therapies. This review examines the latest developments in the use of macromolecules for the treatment of hair loss. The fundamental principles of hair follicle (HF) morphogenesis, hair shaft (HS) development, hair cycle regulation, and alopecia have been introduced. Microneedle (MN) and nanoparticle (NP) delivery systems are innovative treatments for hair loss. Additionally, the application of macromolecule-based tissue-engineered scaffolds for the in vitro and in vivo neogenesis of HFs is discussed. Furthermore, a new research direction is explored wherein artificial skin platforms are adopted as a promising screening method for hair loss treatment drugs. Through these multifaceted approaches, promising aspects of macromolecules for future hair loss treatments are identified.

Fetal milieu-simulating hyaluronic acid-dopamine-chondroitin sulfate hydrogel promoting angiogenesis and hair regeneration for wound healing

Wound regeneration with complete functions and skin appendages is still challenging in wound dressing application. Inspired by the efficient wound healing in the fetal environment, we developed a fetal milieu-mimicking hydrogel for accelerating wound healing simultaneously with hair follicle regeneration. To mimic the fetal extracellular matrix (ECM), which contains high content of glycosaminoglycans, hyaluronic acid (HA) and chondroitin sulfate (CS) were selected to fabricate hydrogels. Meanwhile, dopamine (DA) modification endowed hydrogels with satisfactory mechanical properties and multi-functions. The hydrogel encapsulated atorvastatin (ATV) and zinc citrate (ZnCit), namely HA-DA-CS/Zn-ATV, exhibited tissue adhesion, self-healing capacity, good biocompatibility, excellent anti-oxidant ability, high exudate absorption, and hemostasis property. In vitro results revealed that hydrogels exerted significant angiogenesis and hair follicle regeneration efficacy. In vivo results confirmed that hydrogels significantly promoted wound healing, and the closure ratio reached over 94 % after 14 days of hydrogels-treatment. The regenerated skin exhibited a complete epidermis, dense and ordered collagen. Furthermore, the number of neovessels and hair follicles in the HA-DA-CS/Zn-ATV group were 1.57- and 3.05-fold higher than those of the HA-DA-CS group. Thus, HA-DA-CS/Zn-ATV serves as multifunctional hydrogels for simulating the fetal milieu and achieving efficient skin reconstruction with hair follicle regrowth, exhibiting potential in clinical wound healing.

Dissolving microneedles for alopecia treatment

Alopecia is a treatable benign disease, however, approximately 15-30% of women and 50% of men suffer from alopecia, which greatly affects patient's self-esteem and quality of life. Currently, commercial products for alopecia treatment include topical minoxidil solution, oral finasteride tablets and oral baricitinib tablets. However, the barrier of stratum corneum, systemic adverse effects and poor cure rate limit the application of commercial products. Therefore, researchers investigated the mechanism of alopecia, and developed new drugs that could target lactate dehydrogenase-related pathways, remove excessive reactive oxygen in hair follicles, and reduce the escape of hair follicle stem cells, thus injecting new strength into the treatment of alopecia. Moreover, starting from improving drug stratum corneum penetration and reducing side effects, researchers have developed hair loss treatment strategies based on dissolved microneedles (MNs), such as drug powders/microparticles, nanoparticles, biomimetic cell membranes, phototherapy and magnetically responsive soluble microneedles, which show exciting alopecia treatment effects. However, there are still some challenges in the practical application of the current alopecia treatment strategy with soluble microneedles, and further studies are needed to accelerate its clinical translation.

3D multicellular micropatterning biomaterials for hair regeneration and vascularization

Hair loss caused by the abnormal functions of hair follicles in skin can seriously impact the quality of an individual's life. The development of sophisticated skin tissue-engineered constructs is required to enable the function recovery of hair follicles. However, effective hair regrowth in skin substitutes still remains a great challenge. In this study, a 3D multicellular micropattern was successfully fabricated by arranging the hair follicle-related cells orderly distributed in the interval of vascular-cell networks via bioprinting technology. By combining the stable biomimetic micropattern structure and the bio-inducing substrate incorporated with magnesium silicate (MS) nanomaterials, the 3D multicellular micropattern possessed significant follicular potential and angiogenic capacity in vitro. Furthermore, the 3D multicellular micropattern with MS incorporation contributed to efficient hair regrowth during skin tissue regeneration in both immunodeficient mice and androgenetic alopecia (AGA) mice models. Thus, this study proposes a novel 3D micropatterned multicellular system assembling a biomimetic micro-structure and modulating the cell-cell interaction for hair regeneration during skin reconstruction.

Application of stem cells in regeneration medicine

Regeneration is a complex process affected by many elements independent or combined, including inflammation, proliferation, and tissue remodeling. Stem cells is a class of primitive cells with the potentiality of differentiation, regenerate with self-replication, multidirectional differentiation, and immunomodulatory functions. Stem cells and their cytokines not only inextricably linked to the regeneration of ectodermal and skin tissues, but also can be used for the treatment of a variety of chronic wounds. Stem cells can produce exosomes in a paracrine manner. Stem cell exosomes play an important role in tissue regeneration, repair, and accelerated wound healing, the biological properties of which are similar with stem cells, while stem cell exosomes are safer and more effective. Skin and bone tissues are critical organs in the body, which are essential for sustaining life activities. The weak repairing ability leads a pronounced impact on the quality of life of patients, which could be alleviated by stem cell exosomes treatment. However, there are obstacles that stem cells and stem cells exosomes trough skin for improved bioavailability. This paper summarizes the applications and mechanisms of stem cells and stem cells exosomes for skin and bone healing. We also propose new ways of utilizing stem cells and their exosomes through different nanoformulations, liposomes and nanoliposomes, polymer micelles, microspheres, hydrogels, and scaffold microneedles, to improve their use in tissue healing and regeneration.

From Plants to Wound Dressing and Transdermal Delivery of Bioactive Compounds

Transdermal delivery devices and wound dressing materials are constantly improved and upgraded with the aim of enhancing their beneficial effects, biocompatibility, biodegradability, and cost effectiveness. Therefore, researchers in the field have shown an increasing interest in using natural compounds as constituents for such systems. Plants, as an important source of so-called "natural products" with an enormous variety and structural diversity that still exceeds the capacity of present-day sciences to define or even discover them, have been part of medicine since ancient times. However, their benefits are just at the beginning of being fully exploited in modern dermal and transdermal delivery systems. Thus, plant-based primary compounds, with or without biological activity, contained in gums and mucilages, traditionally used as gelling and texturing agents in the food industry, are now being explored as valuable and cost-effective natural components in the biomedical field. Their biodegradability, biocompatibility, and non-toxicity compensate for local availability and compositional variations. Also, secondary metabolites, classified based on their chemical structure, are being intensively investigated for their wide pharmacological and toxicological effects. Their impact on medicine is highlighted in detail through the most recent reported studies. Innovative isolation and purification techniques, new drug delivery devices and systems, and advanced evaluation procedures are presented.

Stöber method and its nuances over the years

Some characteristics of silica-based materials, such as the control/adjustment of their physical and chemical properties, compatibility, and friendly-use synthesis methods, have held the attention of several scientific groups over the years. This condition of prominence becomes even more evident when we seek these characteristics at the micro- and/or nanoscale. Among existing methods to obtain these micro/nanomaterials, the Stöber method is the focus of this review. This method is known to enable the production of silica micro- or nanoparticles from reagents of medium-easy manipulation under mild conditions using equipment that is common in most laboratories. However, this method has many nuances that must be considered to guarantee accurate results, either in size or distribution, and to ensure result reproducibility. Thus, in this review, we discuss the effects of the primary components used in the synthesis of these materials (i.e., TEOS, ammonia, and water), as well as those of other reaction conditions, such as solvent, temperature, and ionic strength. Therefore, we discuss studies involving the synthesis and characterization of micro- and nanoparticles over the years to establish discussions between their experimental observations and proposed models. This review provides experimental observations about the synthesis of these materials, as well as discussions according to complementary and/or contradictory evidence found over the years. This review seeks to help those who intend to work with this method and provide certain key points that, in our experience, can be important to obtain desired results.