Design of In Vitro Hair Follicles for Different Applications in the Treatment of Alopecia-A Review

Tremella polysaccharide microneedles loaded with magnetic dental pulp stem cell intracellular vesicles used for androgenic alopecia

BACKGROUND

Mesenchymal stem cell exosomes are the most extensively researched type of Extracellular vesicles (EVs) that offer novel avenues for hair regeneration. However, their use in the field of hair regeneration was limited by their poor production of exosomes. It has been discovered that intracellular vesicles (IVs), which are produced at a higher rate than exosomes, play a comparable biological purpose. As a result, we developed HTMI-MN, a microneedle that uses tremella, a type of Tremella polysaccharide (TPS), and hyaluronic acid (HA) as matrix materials. It has magnetic intracellular vesicles (Mag-IVs), which work in concert to treat androgenic alopecia (AGA) and encourage hair growth.

METHODS

After characterization of the Mag-IVs, we evaluated the effect on angiogenesis by scratch assay, angiogenesis assay, Western Blot and ELISA assay. In addition, we tested the protective effect of Human hair papillary cells (HHDPCs) by CCK-8 method, Western Blot and flow cytometry. Finally, the effects of tremella polysaccharide on M1/M2 polarization of macrophages were detected by fluorescence staining, Western Blot and flow cytometry. AGA model was established in vivo by DHT, and treatment was given by microneedle injection.

RESULTS

Our study found that Mag-IVs have greater power to promote angiogenesis and protect HHDPCs from apoptosis compared to other vesicles. Besides, tremella polysaccharide can make the transformation of macrophages to anti-inflammatory phenotype. Taken together, in vivo experiments showed that hair regeneration was faster in HTMI-MN-treated mice.

CONCLUSION

These results indicate that Mag-IVs and tremella polysaccharide can synergistically improve the hair microenvironment, which has a promising future for AGA treatment.

Targeting the Complexity of In Vitro Skin Models: A Review of Cutting-Edge Developments

Skin in vitro models offer much promise for research, testing drugs, cosmetics, and medical devices, reducing animal testing and extensive clinical trials. There are several in vitro approaches to mimicking human skin behavior, ranging from simple cell monolayer to complex organotypic and bioengineered 3-dimensional models. Some have been approved for preclinical studies in cosmetics, pharmaceuticals, and chemicals. However, development of physiologically reliable in vitro human skin models remains in its infancy. This review reports on advances in in vitro complex skin models to study skin homeostasis, aging, and skin disease.

Role of epigenetics in the regulation of skin aging and geroprotective intervention: A new sight

Multiple epigenetic factors play a regulatory role in maintaining the homeostasis of cutaneous components and are implicated in the aging process of the skin. They have been associated with the activation of the senescence program, which is the primary contributor to age-related decline in the skin. Senescent species drive a series of interconnected processes that impact the immediate surroundings, leading to structural changes, diminished functionality, and heightened vulnerability to infections. Geroprotective medicines that may restore the epigenetic balance represent valid therapeutic alliances against skin aging. Most of them are well-known Western medications such as metformin, nicotinamide adenine dinucleotide (NAD+), rapamycin, and histone deacetylase inhibitors, while others belong to Traditional Chinese Medicine (TCM) remedies for which the scientific literature provides limited information. With the help of the Geroprotectors.org database and a comprehensive analysis of the referenced literature, we have compiled data on compounds and formulae that have shown potential in preventing skin aging and have been identified as epigenetic modulators.

The promising prospect of human hair follicle regeneration in the shadow of new tissue engineering strategies

Hair loss disorder (alopecia) affects numerous people around the world. The low effectiveness and numerous side effects of common treatments have prompted researchers to investigate alternative and effective solutions. Hair follicle (HF) bioengineering is the knowledge of using hair-inductive (trichogenic) cells. Most bioengineering-based approaches focus on regenerating folliculogenesis through manipulation of regulators of physical/molecular properties in the HF niche. Despite the high potential of cell therapy, no cell product has been produced for effective treatment in the field of hair regeneration. This problem shows the challenges in the functionality of cultured human hair cells. To achieve this goal, research and development of new and practical approaches, technologies and biomaterials are needed. Based on recent advances in the field, this review evaluates emerging HF bioengineering strategies and the future prospects for the field of tissue engineering and successful HF regeneration.

Evaluating the Impact of Hair Care Product Exposure on Hair Follicle and Scalp Health

Human hair follicles traverse the epidermis and dermis, and are comprised of specialised cells including dermal papilla cells (DPCs). DPCs play a critical role in the development and growth of both hair and follicle structure. While exposure of DPCs to undiluted exogenous compounds is unlikely, exposure to diluted compounds is possible should dermal penetration occur. The goal of this study was to evaluate the impact on hair and scalp health following application of a hair care product. Due to the lack of standardised and validated test systems for evaluating hair follicle health, the HairSkin® model, which uses intact human scalp samples, was adapted to evaluate hair follicle and scalp health. Similarly, the Franz diffusion cell assay and matrix-assisted laser desorption ionisation-Fourier transform ion cyclotron resonance (MALDI-FTICR) were adapted to evaluate dermal penetration. The results of this study demonstrate that application of the hair care product does not result in appreciable dermal penetration, suggesting that DPCs are unlikely to be exposed to undiluted product. Additionally, hair follicle health was not impacted following product application. While this study is exploratory, these results suggest that the combination of test systems utilised herein provides valuable insight and warrants further development and validation.

Potential Natural Products Regulation of Molecular Signaling Pathway in Dermal Papilla Stem Cells

Stem cells have demonstrated significant potential for tissue engineering and repair, anti-aging, and rejuvenation. Hair follicle stem cells can be found in the dermal papilla at the base of the follicle and the bulge region, and they have garnered increased attention because of their potential to regenerate hair as well as their application for tissue repair. In recent years, these cells have been shown to affect hair restoration and prevent hair loss. These stem cells are endowed with mesenchymal characteristics and exhibit self-renewal and can differentiate into diverse cell types. As research in this field continues, it is probable that insights regarding stem cell maintenance, as well as their self-renewal and differentiation abilities, will benefit the application of these cells. In addition, an in-depth discussion is required regarding the molecular basis of cellular signaling and the influence of nature-derived compounds in stimulating the stemness properties of dermal papilla stem cells. This review summarizes (i) the potential of the mesenchymal cells component of the hair follicle as a target for drug action; (ii) the molecular mechanism of dermal papilla stem cells for maintenance of their stem cell function; and (iii) the positive effects of the natural product compounds in stimulating stemness in dermal papilla stem cells. Together, these insights may help facilitate the development of novel effective hair loss prevention and treatment.

In vitro hair follicle growth model for drug testing

In vitro models of human hair follicle-like tissue could be fundamental tools to better understand hair follicle morphogenesis and hair drug screening. During prenatal development and postnatal cyclic hair regeneration, hair follicle morphogenesis is triggered by reciprocal interactions and the organization of the epithelial and mesenchymal cell populations. Given this mechanism, we developed an approach to induce hair peg-like sprouting in organoid cultures composed of epithelial and mesenchymal cells. Human fetal/adult epithelial and mesenchymal cells were cultured in a medium supplemented with a low concentration of either Matrigel or collagen I. These extracellular matrices significantly enhanced the self-organization capabilities of the epithelial and mesenchymal cells, resulting in spherical aggregation and subsequent hair peg-like sprouting. The length of the hair peg sprouting and associated gene expression significantly increased in the presence of a well-known hair drug, minoxidil. This approach may be beneficial for testing hair growth-promoting drug candidates.

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

A nanocomposite microneedle (ZCQ/MN) patch containing copper/zinc dual-doped mesoporous silica nanoparticles loaded with quercetin (ZCQ) was developed as a combination therapy for androgenic alopecia (AGA). The degradable microneedle gradually dissolves after penetration into the skin and releases the ZCQ nanoparticles. ZCQ nanoparticles release quercetin (Qu), copper (Cu²⁺) and zinc ions (Zn²⁺) subcutaneously to synergistically promote hair follicle regeneration. The mechanism of promoting hair follicle regeneration mainly includes the regulation of the main pathophysiological phenomena of AGA such as inhibition of dihydrotestosterone, inhibition of inflammation, promotion of angiogenesis and activation of hair follicle stem cells by the combination of Cu²⁺ and Zn²⁺ ions and Qu. This study demonstrates that the systematic intervention targeting different pathophysiological links of AGA by the combination of organic drug and bioactive metal ions is an effective treatment strategy for hair loss, which provides a theoretical basis for development of biomaterial based anti-hair loss therapy.

Tissue Engineering and Regeneration of the Human Hair Follicle in Androgenetic Alopecia: Literature Review

Androgenetic alopecia (AGA) is an androgen-dependent process and represents the most frequent non-scarring alopecia. Treatments for AGA do not always achieve a satisfactory result for the patient, and sometimes cause side effects that lead to discontinuation of treatment. AGA therapeutics currently includes topical and oral drugs, as well as follicular unit micro-transplantation techniques. Tissue engineering (TE) is postulated as one of the possible future solutions to the problem and aims to develop fully functional hair follicles that maintain their cyclic rhythm in a physiological manner. However, despite its great potential, reconstitution of fully functional hair follicles is still a challenge to overcome and the knowledge gained of the key processes in hair follicle morphogenesis and biology has not yet been translated into effective replacement therapies in clinical practice. To achieve this, it is necessary to research and develop new approaches, techniques and biomaterials. In this review, present and emerging hair follicle bioengineering strategies are evaluated. The current problems of these bioengineering techniques are discussed, as well as the advantages and disadvantages, and the future prospects for the field of TE and successful hair follicle regeneration.

In Vitro Hair Growth Promoting Effect of a Noncrosslinked Hyaluronic Acid in Human Dermal Papilla Cells

Dermal papilla cells (DPCs) are a source of nutrients and growth factors, which support the proliferation and growth of keratinocytes as well as promoting the induction of new hair follicles and maintenance of hair growth. The protection from reactive oxygen species (ROS) and the promotion of angiogenesis are considered two of the basal mechanisms to preserve the growth of the hair follicle. In this study, a noncrosslinked hyaluronic acid (HA) filler (HYDRO DELUXE BIO, Matex Lab S.p.A.) containing several amino acids was tested with in vitro assays on human follicle dermal papilla cells (HFDPCs). The experiments were carried out to investigate the possible protection against oxidative stress and the ability to increase the vascular endothelial growth factor (VEGF) release. The results demonstrated the restoration of cell viability against UVB-induced cytotoxicity and an increase in the VEGF secretion. These data demonstrate the capability of the product to modulate human dermal papilla cells, suggesting a future use in mesotherapy, a minimally invasive local intradermal therapy (LIT), after further clinical investigations.