Minoxidil Nanoparticles Targeting Hair Follicles Enhance Hair Growth in C57BL/6 Mice

Minoxidil cyclodextrin inclusion complex-loaded microemulsions and transfersomes for androgen alopecia treatment: a comparative study

Our MXD/SCD@TF designed by the combination of transfersome and inclusion technology was obviously superior to commercial 2% MXD tincture in treating androgenetic alopecia (AGA) in mice, but its complex preparation and poor stability undoubtedly increased both development and usage costs. In this paper, using our previous alcohol-free low surfactant microemulsion technology with VES as auxiliary oil phase, microemulsions loaded with the inclusion complex of MXD and sulfobutylether-β-cyclodextrin (SBE-β-CD) were prepared, optimized and characterized, and the therapeutic effect on AGA C57BL/6 mice was compared with MXD/SCD@TF. According to the ternary phase diagram, steady-state permeation rate of MXD through SD rat skin and drug retention, MXD/SCD@ME was selected as the optimal prescription, composed of 5.25% oil phase, 9.75% surfactants, 10.20% SBE-β-CD, 1.02% MXD and 73.78% water, which conformed to the characteristics of microemulsion. MXD/SCD@ME had good stability, and the application of inclusion technology increased the MXD loading in microemulsion to nearly 5 times. The results of in vivo skin penetration test and laser confocal scanning visualization showed that MXD/SCD@ME was easier to deliver drugs to deeper skin tissues than MXD/SCD@TF. Hair regeneration study demonstrated that MXD/SCD@ME had higher ability than MXD/SCD@TF in promoting hair growth, prolonging hair growth period, reducing ROS level and promoting cell proliferation of hair follicles. In addition, the blank microemulsion of MXD/SCD@ME had certain therapeutic effect on AGA, indicating the synergistic effect between VES and MXD. All these indicated that MXD/SCD@ME is expected to provide a better choice for pharmacological therapy of MXD on AGA than MXD/SCD@TF.

The penetration efficiency of a dissolved model drug into hair follicles depends on the concentration of added nanoparticles

Hair follicles have recently emerged as promising drug delivery targets and gates for skin penetration. The so-called ratchet effect, which is based on an interaction between the hair shaft surface, the intrafollicular stratum corneum and nanoparticles, has proven to be very effective for the transport of active ingredients. Especially the nanoparticle-assisted decolonization of hair follicles constitutes an interesting new area of application. In a recently published work it was shown that small molecules as well as macromolecules solved in an outer phase of a formulation can be transported into the deeper parts of the hair follicles by adding nanoparticles to the formulation. In this case the nanoparticles constitute an entity independent of the drug and the transport is hypothesized to be based on an adhesion effect. In the present work, we focused on the impact of the particle concentration in the formulation on the transport efficiency of the model drug fluorescein sodium into hair follicles utilizing an ex vivo porcine skin model. It was observed that a particle concentration of 4% significantly enhances the transport efficiency of fluorescein as compared to 2% particle concentration. Doubling the concentration to 8% did not significantly increase the penetration depth. The effect evolved more efficiently when using 4 Hz circular motion massage as compared to 100 Hz oscillating massage. These results deliver interesting information on the optimal formulation as well as application parameters for a future application in clinical studies for e.g. skin antisepsis purposes.

Easy to use particle-mediated transport of various dissolved active agents into the hair follicles - A novel platform technology

The use of nanoparticulate systems for the transport of active ingredients into hair follicles has been researched for almost two decades, resulting in countless publications with a wide variety of particle types, release mechanisms and active ingredients. The production of a stable dispersion is often time-consuming and costly. In this publication, we demonstrate for the first time that simply adding diverse submicron particles to a drug solution significantly increases follicular penetration depth by over 160% to 190%, allowing the targeting of subinfundibular structures. Our results indicate that the increase in follicular penetration is independent of the type or sphericity of the particles (nanocrystals (NC) or lipid submicron particles (LN)). Furthermore, this principle can be used with both small molecules and large molecule therapeutics, as demonstrated with the model drugs fluorescein sodium, 6-carboxyfluorescein, green fluorescent protein and FITC-BSA. This highlights the high versatility of this new formulation principle. The system may be used for various hair follicle-associated diseases such as alopecia or for the preoperative disinfection of hair follicles and the transfollicular transport of active pharmaceutical and/or cosmetic ingredients.

Skin Structure, Physiology, and Pathology in Topical and Transdermal Drug Delivery

Several industries are increasingly focused on enhancing the delivery of active ingredients through the skin to optimize therapeutic outcomes. By facilitating the penetration of active ingredients through the skin barrier, these enhancers can significantly improve the efficacy of various formulations, ranging from skincare products to therapeutic agents targeting systemic circulation. As the understanding of skin physiology and the mechanisms of drug absorption deepen, these industries are adopting permeation enhancers more widely, ultimately leading to better patient outcomes and expanded treatment options. However, the structure and physiological function of the skin can vary according to different factors, such as the area of the body and between individuals. These variations, along with external environmental exposures, aging and pathological conditions, introduce complexities that must be carefully considered when designing effective delivery systems. Considering the intricacies of skin structure and physiology, tailoring systems to account for regional differences, individual variability, and changes induced by environmental factors or disease is critical to optimizing therapeutic outcomes. This review discusses the features of skin structure, physiology, and pathologies, as well as the application of permeation enhancers in these contexts. Furthermore, it addresses the use of animal skin models in transdermal delivery and dermatological studies, along with the latest developments in this field.

Delivery of minoxidil encapsulated in cyclodextrins with photoacoustic waves enhances hair growth

The current pharmacological management of androgenetic alopecia is inconvenient and requires a discipline that patients find difficult to follow. This reduces compliance with treatment and satisfaction with results. It is important to propose treatment regimens that increase patient compliance and reduce adverse effects. This work describes transdermal delivery of minoxidil partially encapsulated in β-cyclodextrin and assisted by photoacoustic waves. Photoacoustic waves transiently increase the permeability of the skin and allow for the delivery of encapsulated minoxidil. A minoxidil gel formulation was developed and the transdermal delivery was studied in vitro in the presence and absence of photoacoustic waves. A 5-min stimulus with photoacoustic waves generated by light-to-pressure transducers increases minoxidil transdermal delivery flux by approximately 3-fold. The flux of a 1% minoxidil formulation promoted by photoacoustic waves is similar to the passive flux of a 2% minoxidil commercial formulation. Release of minoxidil from β-cyclodextrin increases dermal exposure without increasing peak systemic exposure. This promotes hair growth with fewer treatments and reduced adverse effects. In vivo studies using encapsulated minoxidil and photoacoustic waves yielded 86% hair coat recovery (vs. 29% in the control group) and no changes in the blood pressure.

Hybrid hair follicle stem cell extracellular vesicles co-delivering finasteride and gold nanoparticles for androgenetic alopecia treatment

Androgenetic alopecia (AGA) is a non-fatal disease prevalent worldwide. However, mixed efficacy has been observed among different therapies for hair regrowth in AGA patients. Thus, a nano-platform with synergistic treatments based on a hybrid extracellular vesicle encapsulating gold nanoparticles (AuNPs) and finasteride (Hybrid/Au@Fi) was constructed through membrane fusion between hair follicle stem cell (HFSC)-derived extracellular vesicles and liposomes. These hybrid vesicles (HVs) not only fuel hair regrowth by providing cellular signals in extracellular vesicles, but also improve storage stability, follicle retention, and drug encapsulation efficiency (EE%) for finasteride inhibiting 5α-reductase, and nano-size AuNPs that simulate low-level laser therapy (LLLT) with similar photothermal effects in vitro. The EE% of finasteride in these HVs reached 45.33%. The dual administration of these extracellular vesicles and finasteride showed a strong synergistic effect on HFSCs in vitro. In an AGA mouse model, once-daily topical Hybrid/Au@Fi (115.07 ± 0.32 nm, -7.50 ± 1.68 mV) gel led to a faster transition of hair follicles (HFs) from the catagen to the anagen, increased hair regrowth coverage, and higher quality of regrowth hair, compared to once-daily 5% minoxidil treatment. Compared to topical minoxidil, the multifaceted synergistic therapy of Hybrid/Au@Fi through topical administration offers a new option for intractable AGA patients with low side effects.

The impact of particle size of nanostructured lipid carriers on follicular drug delivery: A comprehensive analysis of mouse and human hair follicle penetration

Introduction

Follicular delivery is one of the targeted drug delivery methods aiming to target the hair follicles. The accumulation and retention time of targeted drugs is enhanced when nanoparticles are used as drug carriers. Particle size is one of the important factors affecting the penetration and accumulation of particles in the hair follicles, and there is a controversy in different studies for the best particle size for follicular delivery. Mouse models are mostly used in clinical trials for dermal, transdermal, and follicular delivery studies. Also, it is essential to investigate the reliability of the results between human studies and mouse models.

Methods

Curcumin-loaded nanostructured lipid carriers (NLCs), as a fluorescent agent, with three different particle size ranges were prepared using the hot homogenization method and applied topically on the mouse and human study groups. Biopsies were taken from applied areas on different days after using the formulation. The histopathology studies were done on the skin biopsies of both groups using confocal laser scanning microscopy (CLSM). We compared the confocal laser scanning microscope pictures of different groups, in terms of penetration and retention time of nanoparticles in human and mouse hair follicles.

Results

The best particle size in both models was the 400 nm group but the penetration and accumulation of particles in human and mouse hair follicles were totally different even for the 400 nm group. In human studies, 400 nm particles showed good accumulation after seven days; this result can help to increase the formulation using intervals.

Conclusion

The best particle size for human and mouse follicular drug delivery is around 400 nm and although mouse models are not completely suitable for follicular delivery studies, they can be used in some conditions as experimental models.

Gum Arabic Enhances Hair Follicle-Targeting Drug Delivery of Minoxidil Nanocrystal Dispersions

In this study, we attempted to enhance the delivery of minoxidil (MXD) nanocrystals into hair follicles for efficacious hair growth treatment. We applied a bead milling method and designed an MXD nanocrystal dispersion containing methylcellulose (MC) and gum arabic (GA), termed MG-MXD@NP, with a particle size of 110 nm. In vivo studies in C57BL/6 mice showed that MG-MXD@NP improved MXD delivery to the skin tissue, hair bulges, and hair bulbs, resulting in earlier and superior hair growth compared with a commercially available MXD lotion (Riup 5%, CA-MXD). These findings were consistent with the increased MXD contents observed in the hair bulge and hair bulb regions in the MG-MXD@NP-treated mice, and suggested a correlation between the efficiency of MXD delivery and efficacy of promotion of hair growth by products containing MXD. Furthermore, delivery of MXD using MG-MXD@NP was associated with elevated expression levels of CD34 and CD200, markers of hair follicle epithelial stem cells, which are crucial for promoting hair growth. Thus, it is possible that the upregulation of CD34 and CD200 in the MG-MXD@NP-treated mice reflects activation of the papilla cells and hair follicle stem cells known to be closely associated with hair growth enhancement. In conclusion, MG-MXD@NP, containing MXD nanocrystals in combination with MC and GA, exhibited a superior hair growth effect as compared with conventional MXD formulations. These findings suggest that this novel delivery method for MXD could represent a promising treatment approach for hair loss.

Nanodrug Delivery Strategies to Signaling Pathways in Alopecia

Over 50% of the global population suffers from hair loss. The mixed results in the treatment of hair loss reveal the limitations of conventional commercial topical drugs. One the one hand, the definite pathogenesis of hair loss is still an enigma. On the other hand, targeted drug carriers ensure the drug therapeutic effect and low side effects. This review highlights the organization and overview of nine crucial signaling pathways associated with hair loss, as well as the development of nanobased topical delivery systems loading the clinical drugs, which will fuel emerging hair loss treatment strategies.

Biomolecules of Fermented Tropical Fruits and Fermenting Microbes as Regulators of Human Hair Loss, Hair Quality, and Scalp Microbiota

Plant-derived secondary metabolites (polyphenols/terpenes/alkaloids) and microbial exometabolites/membrane components of fermented tropical fruits are known as highly bioavailable biomolecules causing skin and hair improvement effects (wound healing, anti-inflammatory, antioxidant, antidiabetic, antiacne, skin/hair microbiota balancing, hair growth-promoting, and hair loss-inhibiting). Caffein is considered as a hair growth promoter. A randomized placebo- and caffein-controlled clinical trial on the efficacy of fermented papaya (FP) plus fermented mangosteen (FM) towards human hair quality and loss was conducted. Shampoo and lotion hair care products containing FP, FM, and caffein as active agents were developed and applied to 154 subjects of both sexes with clinically confirmed androgenic or diffuse alopecia for 3 months. Their clinical efficacy was assessed subjectively by questionnaires filled in by dermatologists/trichologists, and by the objective trichomicroscopical calculations. Hair and scalp skin quality was determined by microbiota pattern and ATP, SH-groups, protein, and malonyl dialdehyde quantification. Comparative clinical data showed that the experimental hair care cosmetics significantly inhibited hair loss, increased hair density/thickness, and improved hair follicle structure versus placebo and caffein controls. The cosmetics with FP and FM substantially normalized the microbiota pattern and increased ATP content in hair follicle, while inhibiting lipid peroxidation in the scalp skin, and SH-group formation in the hair shaft.

Advanced Skin Antisepsis: Application of UVA-Cleavable Hydroxyethyl Starch Nanocapsules for Improved Eradication of Hair Follicle-Associated Microorganisms

Hair follicles constitute important drug delivery targets for skin antisepsis since they contain ≈25% of the skin microbiome. Nanoparticles are known to penetrate deeply into hair follicles. By massaging the skin, the follicular penetration process is enhanced based on a ratchet effect. Subsequently, an intrafollicular drug release can be initiated by various trigger mechanisms. Here, we present novel ultraviolet A (UVA)-responsive nanocapsules (NCs) with a size between 400 and 600 nm containing hydroxyethyl starch (HES) functionalized by an o-nitrobenzyl linker. A phase transfer into phosphate-buffered saline (PBS) and ethanol was carried out, during which an aggregation of the particles was observed by means of dynamic light scattering (DLS). The highest stabilization for the target medium ethanol as well as UVA-dependent release of ethanol from the HES-NCs was achieved by adding 0.1% betaine monohydrate. Furthermore, sufficient cytocompatibility of the HES-NCs was demonstrated. On ex vivo porcine ear skin, a strong UVA-induced release of the model drug sulforhodamine 101 (SR101) could be demonstrated after application of the NCs in cyclohexane using laser scanning microscopy. In a final experiment, a microbial reduction comparable to that of an ethanol control was demonstrated on ex vivo porcine ear skin using a novel UVA-LED lamp for triggering the release of ethanol from HES-NCs. Our study provides first indications that an advanced skin antisepsis based on the eradication of intrafollicular microorganisms could be achieved by the topical application of UVA-responsive NCs.

[Effects of Skin Environmental Changes by Steam Towel, Ethanol, l-Menthol and Carpronium on the Drug Behavior in the Minoxidil Nanoparticles-applied Mice]

We previously designed the formulation containing minoxidil (MXD) nanoparticles (MXD-NPs), and found that the MXD-NPs can mainly deliver MXD into hair bulbs via hair follicles pathway, and that the therapeutic efficiency for hair growth is higher in comparison with the formulation containing dissolved MXD. In this study, we investigated whether the skin environmental changes by the treatment of steam towel, ethanol, l-menthol and commercially available (CA) carpronium affect the drug behavior in the MXD-NPs-applied mice. The steam towel, ethanol, l-menthol and CA-carpronium were pre-treated 3 min before MXD-NPs application, and the MXD content in the hair bulge, bulb, skin tissue and blood of mice were measured 4 h after MXD-NPs application. No significant difference of MXD levels in the blood was observed by the pre-treatment of steam towel, ethanol, l-menthol and CA-carpronium. On the other hand, the pre-treatment of steam towel and l-menthol enhanced the MXD levels in hair bulge and/or bulb. Although, the MXD levels in hair bulge and bulb were not changed by the pre-treatment of ethanol, the MXD levels in skin tissue was higher than that of saline-pre-treated group (control). The MXD levels in hair bulge, bulb and skin tissue of mice pre-treated with CA-carpronium were remarkably higher in comparison with control. In conclusion, we showed that the changes in skin environment by the steam towel, ethanol, l-menthol and CA-carpronium affected the absorption of MXD-NPs, and these increased MXD levels in the hair bulb and blood by the combination may enhance the therapeutic efficiency without side effects.

Pumpkin Seed Oil-Loaded Niosomes for Topical Application: 5α-Reductase Inhibitory, Anti-Inflammatory, and In Vivo Anti-Hair Loss Effects

Pumpkin seed oil (PSO)-loaded niosomes were prepared from Tween 20 and cholesterol by ethanol injection. Confocal microscopy showed better skin permeation and hair follicle accumulation of the niosomes compared to the PSO solution. The PSO-loaded niosomes inhibited 5α-reductase activity in DU-145 cells and hindered IL-6 activity in RAW 264.7 cells. These effects indicated the great potential of PSO-loaded niosomes to reduce hair loss. The hair scalp serum with PSO-loaded niosomes did not show irritation to reconstructed human skin. This formulation presented a significant decrease in the percentage of fallen hairs by 44.42% in the in vivo 60-second hair count experiment and a significant increase in the anagen to telogen (A/T) ratio (1.4-fold) in the TrichoScan^® evaluation after 8 weeks of treatment compared to the initial conditions, indicating the promising efficacy of PSO-loaded niosomes as a natural alternative for anti-hair loss therapy.