Selective activation of the versican promoter by epithelial- mesenchymal interactions during hair follicle development

Large-Scale Preparation of Hair Follicle Germs Using a Microfluidic Device

Hair follicle morphogenesis during embryonic development is driven by the formation of hair follicle germs (HFGs) via interactions between epithelial and mesenchymal cells. Bioengineered HFGs are potential tissue grafts for hair regenerative medicine because they can replicate interactions and hair follicle morphogenesis after transplantation. However, a mass preparation approach for HFGs is necessary for clinical applications, given that thousands of de novo hair follicles are required to improve the appearance of a single patient with alopecia. In this study, we developed a microfluidics-based approach for the large-scale preparation of HFGs. A simple flow-focusing microfluidic device allowed collagen solutions containing epithelial and mesenchymal cells to flow and generate collagen microbeads with distinct Janus structures. During the 3 days of culture, the collagen beads contracted owing to cellular traction forces, resulting in collagen- and cell-dense HFGs. The transplantation of HFGs into nude mice resulted in highly efficient de novo hair follicle regeneration. This method provides a scalable and robust tissue graft preparation approach for hair regeneration.

Exosomes for hair growth and regeneration

Exosomes are lipid bilayer vesicles, 30-200 nm in diameter, that are produced by cells and play essential roles in cell-cell communication. Exosomes have been studied in several medical fields including dermatology. Hair loss, a major disorder that affects people and sometimes causes mental stress, urgently requires more effective treatment. Because the growth and cycling of hair follicles are governed by interactions between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs), a better understanding of the mechanisms responsible for hair growth and cycling through exosomes may provide new insights into novel treatments for hair loss. In this review, we focused on the comprehensive knowledge and recent studies on exosomes in the field of hair development and regeneration. We classified exosomes of several cellular origins for the treatment of hair loss. Exosomes and their components, such as microRNAs, are promising drugs for effective hair loss treatment.

Establishment and functional characterization of immortalized rabbit dermal papilla cell lines

Hair follicle (HF) undergo periodic growth and development in mammals, which regulated by dermal papilla cells (DPCs) are reported to play an important role in HF morphogenesis and development. However, primary DPCs have low proliferative activity, age quickly, and fresh cell isolation is both time-consuming and laborious. In this study, we introduced the SV40 large T antigen (SV40T) into dissociated early passage rabbit vibrissae DPCs with lentiviral vectors and established seven immortalized DPC lines (R-1, R-2, R-3, R-4, R-5, R-6 and R-7). These cell lines displayed early passage morphology and high alkaline phosphatase activity. RT-PCR and immunofluorescence staining showed that all the immortalized cell lines expressed the DPC markers (α-SMA, IGF1, ALPL, FGF2, BMP2 and TGFβ2), but α-SMA was only expressed well in R-3, R-4, and R-7. Furthermore, it was found that R-7 was the only line to survive beyond 50 passages. Compared to melanoma cells, R-7 did not undergo malignant transformation. Karyotyping and cell growth viability analysis illustrated that the R-7 cell line preserved the basic characteristics of primary DPCs. The R-7 DPCs established have potential application for future hair research. The study provides the theoretical basis in the cell research of HF growth and development.

Effects of oxytocin on the hair growth ability of dermal papilla cells

Oxytocin (OXT) is a neuropeptide hormone termed "love hormone" produced and released during childbirth and lactation. It is also produced in response to skin stimulation (e.g., during hugging and massaging) and music therapy. The effects of OXT on various organs have been revealed in recent years; however, the relationship between hair follicles and OXT remains unclear. In this study, we examined the effects of OXT on dermal papilla (DP) cells that control hair growth by secreting growth/regression signals. Gene expression analysis revealed that DP signature markers were significantly upregulated in DP cells treated with OXT. In addition, we tested the hair growth-promoting effects of OXT using in vitro hair follicle organoids. OXT promoted the growth of hair peg-like sprouting by upregulating the expression of growth-promoting factors, including genes encoding vascular endothelial growth factor A (VEGFA). This study highlights the positive effects of OXT in hair follicles and may assist in the development of new treatments for alopecia.

V3: an enigmatic isoform of the proteoglycan versican

V3 is an isoform of the extracellular matrix (ECM) proteoglycan (PG) versican generated through alternative splicing of the versican gene such that the two major exons coding for sequences in the protein core that support chondroitin sulfate (CS) glycosaminoglycan (GAG) chain attachment are excluded. Thus, versican V3 isoform carries no GAGs. A survey of PubMed reveals only 50 publications specifically on V3 versican, so it is a very understudied member of the versican family, partly because to date there are no antibodies that can distinguish V3 from the CS-carrying isoforms of versican, that is, to facilitate functional and mechanistic studies. However, a number of in vitro and in vivo studies have identified the expression of the V3 transcript during different phases of development and in disease, and selective overexpression of V3 has shown dramatic phenotypic effects in "gain and loss of function" studies in experimental models. Thus, we thought it would be useful and instructive to discuss the discovery, characterization, and the putative biological importance of the enigmatic V3 isoform of versican.

In vitro strategies for mimicking dynamic cell-ECM reciprocity in 3D culture models

The extracellular microenvironment regulates cell decisions through the accurate presentation at the cell surface of a complex array of biochemical and biophysical signals that are mediated by the structure and composition of the extracellular matrix (ECM). On the one hand, the cells actively remodel the ECM, which on the other hand affects cell functions. This cell-ECM dynamic reciprocity is central in regulating and controlling morphogenetic and histogenetic processes. Misregulation within the extracellular space can cause aberrant bidirectional interactions between cells and ECM, resulting in dysfunctional tissues and pathological states. Therefore, tissue engineering approaches, aiming at reproducing organs and tissues in vitro, should realistically recapitulate the native cell-microenvironment crosstalk that is central for the correct functionality of tissue-engineered constructs. In this review, we will describe the most updated bioengineering approaches to recapitulate the native cell microenvironment and reproduce functional tissues and organs in vitro. We have highlighted the limitations of the use of exogenous scaffolds in recapitulating the regulatory/instructive and signal repository role of the native cell microenvironment. By contrast, strategies to reproduce human tissues and organs by inducing cells to synthetize their own ECM acting as a provisional scaffold to control and guide further tissue development and maturation hold the potential to allow the engineering of fully functional histologically competent three-dimensional (3D) tissues.

Hypoxia inducible factor-1α promotes trichogenic gene expression in human dermal papilla cells

Dermal papilla cells (DPCs) play critical roles in hair follicle development, but the underlying mechanisms that contribute to hair regeneration have yet to be fully elucidated, particularly in terms of alterations in androgenetic alopecia patients. In this study, we demonstrated that hypoxia-inducible factor-1α (HIF-1α) is suppressed in scalp tissues of androgenetic alopecia patients and potentially associated with hair follicle development. Using RT-qPCR and western blot, we found that mRNA and protein levels of trichogenic genes, LEF1 and versican (VCAN), were attenuated in HIF-1α knockdown DPCs. Under an in vivo mimicked environment in a three-dimensional spheroid culture, HIF-1α-suppressed DPCs downregulated the expression of hair induction-related genes. Finally, treatment with a HIF-1α activator resulted in the elevated expression of trichogenic genes in DPCs. This study highlights the importance of dermal HIF-1α expression in regulating trichogenic genes and provides a promising therapeutic target and a fundamental tissue engineering approach for hair loss treatment.

Regulation of stem cell fate by HSPGs: implication in hair follicle cycling

Heparan sulfate proteoglycans (HSPGs) are part of proteoglycan family. They are composed of heparan sulfate (HS)-type glycosaminoglycan (GAG) chains covalently linked to a core protein. By interacting with growth factors and/or receptors, they regulate numerous pathways including Wnt, hedgehog (Hh), bone morphogenic protein (BMP) and fibroblast growth factor (FGF) pathways. They act as inhibitor or activator of these pathways to modulate embryonic and adult stem cell fate during organ morphogenesis, regeneration and homeostasis. This review summarizes the knowledge on HSPG structure and classification and explores several signaling pathways regulated by HSPGs in stem cell fate. A specific focus on hair follicle stem cell fate and the possibility to target HSPGs in order to tackle hair loss are discussed in more dermatological and cosmeceutical perspectives.

Differentiation of pluripotent stem cells for modeling human skin development and potential applications

The skin of mammals is a multilayered and multicellular tissue that forms an environmental barrier with key functions in protection, regulation, and sensation. While animal models have long served to study the basic functions of the skin in vivo, new insights are expected from in vitro models of human skin development. Human pluripotent stem cells (PSCs) have proven to be invaluable tools for studying human development in vitro. To understand the mechanisms regulating human skin homeostasis and injury repair at the molecular level, recent efforts aim to differentiate PSCs towards skin epidermal keratinocytes, dermal fibroblasts, and skin appendages such as hair follicles and sebaceous glands. Here, we present an overview of the literature describing strategies for human PSC differentiation towards the components of skin, with a particular focus on keratinocytes. We highlight fundamental advances in the field employing patient-derived human induced PSCs (iPSCs) and skin organoid generation. Importantly, PSCs allow researchers to model inherited skin diseases in the search for potential treatments. Skin differentiation from human PSCs holds the potential to clarify human skin biology.

Reprogramming of three-dimensional microenvironments for in vitro hair follicle induction

During embryonic development, reciprocal interactions between epidermal and mesenchymal layers trigger hair follicle morphogenesis. This study revealed that microenvironmental reprogramming via control over these interactions enabled hair follicle induction in vitro. A key approach is to modulate spatial distributions of epithelial and mesenchymal cells in their spontaneous organization. The de novo hair follicles with typical morphological features emerged in aggregates of the two cell types, termed hair follicloids, and hair shafts sprouted with near 100% efficiency in vitro. The hair shaft length reached ~3 mm in culture. Typical trichogenic signaling pathways were up-regulated in hair follicloids. Owing to replication of hair follicle morphogenesis in vitro, melanosome production and transportation were also monitored in the hair bulb region. This in vitro hair follicle model might be valuable for better understanding hair follicle induction, evaluating hair growth and inhibition of hair growth by drugs, and modeling gray hairs in a well-defined environment.

Single-cell transcriptomics reveals the natural product Shi-Bi-Man promotes hair regeneration by activating the FGF pathway in dermal papilla cells

BACKGROUND

Finasteride and minoxidil are two commonly used drugs for the treatment of hair loss. However, these two drugs have certain side effects. Thus, the further elucidation of treatments for hair loss, including those using Chinese herbal medicine, remains important clinically. Shi-Bi-Man (SBM) is a hair health supplement that darkens hair and contains ginseng radix, tea polyphenols, polygonum multiflorum, radix angelicae sinensis, aloe, linseed, and green tea extract.

PURPOSE

This study aimed to find potential effective monomer components to promote hair regeneration from SBM and to explore the mechanism of SBM to promote hair regeneration.

METHODS

Supplementation with the intragastric administration or smear administration of SBM in artificially shaved C57BL/6 mice, observe its hair growth. UPLC/MS and UPLC/LTQ-Orbitrap-MS detect the main components in SBM and the main monomers contained in the skin after smearing, respectively. A network pharmacology study on the main components of SBM and single-cell RNA sequencing was performed to explore the role of SBM for hair regeneration.

RESULTS

SBM significantly induced hair growth compared with a control treatment. TSG and EGCG were the main monomers in the skin after SBM smearing. The results of single-cell sequencing revealed that after SBM treatment, the number of hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) increased significantly. Cell interactions and volcano dots show that the interaction of the FGF signaling pathway was significantly enhanced, in which Fgf7 expression was especially upregulated in DPCs. In addition, the Wnt signaling pathway also had a partially enhanced effect on the interactions between various cells in the skin. The network pharmacology study showed that the promotion of the FGF and Wnt pathways by SBM was also enriched in alopecia diseases.

CONCLUSION

We report that SBM has a potential effect on the promotion of hair growth by mainly activating the FGF signaling pathway. The use of SBM may be a novel therapeutic option for hair loss.

Autologously transplanted dermis-derived cells alleviated monobenzone-induced vitiligo in mouse

Vitiligo is a depigmentation disease which affects skin and hair follicles with a prevalence of 0.5-1% worldwide. In this study, we aimed to investigate treatmental potential of dermis-derived cells in monobenzone (MBEH)-induced mouse vitiligo model with light and electron microscopy. MBEH (40%) cream was topically applied to C57BL/6 mice until depigmentation occured in vitiligo and experimental groups. In experimental groups, dermis-derived cells obtained from back skin biopsy samples before induction of vitiligo, were injected intradermally to vitiligo mice. On day 3 and 15 after cell transplantation to experimental groups, skin biopsies were compared with biopsies of control and vitiligo groups. Dermis-derived cells obtained from back skin biopsy samples of experimental groups showed nestin and versican immunoreactivity. Melanin in hair follicles of control group was detected by histochemical stainings (Hematoxylin&Eosin and Fontana-Masson) whereas sparse melanin granules were observed in hair follicles of vitiligo group. In experimental groups, there was an increase in the number of hair follicles with melanin compared to vitiligo group. We observed MART-1 immunoreactive cells mostly around the hair follicles in control group and within dermis in vitiligo group. Electron microscopic investigation showed presence of melanosomes in hair follicles of control group and lacking in vitiligo group. In experimental groups, both type of hair follicles were observed with electron microscope. Our data suggest that autologously transplanted dermis-derived cells may be effective in vitiligo treatment by contrubuting to melanin production.

Large-scale isolation of functional dermal papilla cells using novel surface marker LEPR

Dermal papilla (DP) cells regulate hair follicle epithelial cells and melanocytes by secreting functional factors, playing a key role in hair follicle morphogenesis and hair growth. DP cells can reconstitute new hair follicles and induce hair regeneration, providing a potential therapeutic strategy for treating hair loss. However, current methods for isolating DP cells are either inefficient (physical microdissection) or only applied to genetically labeled mice. We systematically screened for the surface proteins specifically expressed in skin DP using mRNA expression databases. We identified two antibodies against receptors LEPR and SCARA5 which could specifically label and isolate DP cells by flow cytometry from mice back skin at the growth phase. The sorted LEPR⁺ cells maintained the DP characteristics after culturing in vitro, expressing DP marker alkaline phosphatase and functional factors including RSPO1/2 and EDN3, the three major DP secretory factors that regulate hair follicle epithelial cells and melanocytes. Furthermore, the low-passage LEPR⁺ DP cells could reconstitute hair follicles on nude mice using chamber graft assay when combined with epithelial stem cells. The method of isolating functional DP cells we established here lays a solid foundation for developing DP cell-based therapy. This article is protected by copyright. All rights reserved.

Extremely Low-Frequency Electromagnetic Fields Increase Cytokines in Human Hair Follicles through Wnt/β-Catenin Signaling

Hair loss is a chronic disorder that affects many people; however, a complete treatment has not yet been developed. Therefore, new therapeutic agents for preventing hair loss must be developed, and electromagnetic field (EMF) therapy has been proven to be a promising medical treatment in various fields, including hair loss treatment. This study evaluated the effect of extremely low-frequency electromagnetic field (ELF-EMF) intensity and exposure time by analyzing the expression of cytokines and anagen-related molecules, which influence hair activation and growth, in hair bulb spheroid (HBS) and hair follicle (HF) organ cultures. ELF-EMFs did not induce toxicity in the HBSs, as verified via the lactate dehydrogenase (LDH) assay. Moreover, an ELF-EMF intensity of 5–20 G promoted the expression of ALP, versican, β-catenin, and several cytokines (VEGF, PDGF, FGF-10, and ET-1) in HBSs. Immunohistochemical staining showed that ELF-EMF at an intensity of 5–20 G upregulated ALP and β-catenin and decreased TUNEL staining in HBS. Moreover, HFs exposed to ELF-EMF for 60 min exhibited an increase in hair length and a 1.5-fold increase in IL-4, ICAM-1, ALP, and versican mRNA expression compared to the control. Immunohistochemical staining indicated that 60 min of ELF-EMF can increase the expression of ALP and β-catenin and decreases TUNEL staining in organ cultures. Collectively, our results demonstrated that ELF-EMF exposure at a 10 G intensity for 60 min promoted hair shaft growth in HFs due to the effect of cytokines and adhesion molecules via the Wnt/β-catenin pathway. Therefore, ELF-EMF is a promising treatment for hair loss.

Aggrecan and versican: two brothers close or apart

Aggrecan (Acan) and versican (Vcan) are large chondroitin sulfate proteoglycans of the extracellular matrix. They share the same structural domains at both N and C-termini. The N-terminal G1 domain binds hyaluronan (HA), forms an HA-rich matrix, and regulates HA-mediated signaling. The C-terminal G3 domain binds other extracellular matrix molecules and forms a supramolecular structure that stores TGFb and BMPs and regulates their signaling. EGF-like motifs in the G3 domain may directly act like an EGF ligand. Both Acan and Vcan are present in cartilage, intervertebral disc, brain, heart, and aorta. Their localizations are essentially reciprocal. This review describes their structural domains, expression patterns and functions, and regulation of their expression.

Engineered extracellular vesicle mimetics from macrophage promotes hair growth in mice and promotes human hair follicle growth

Recent studies clearly show that cell-derived extracellular vesicles (EVs, including exosomes) can promote hair growth. However, large-scale production of EVs remains a big hurdle. Recently, extracellular vesicle mimetics (EMs) engineered by extrusion through various membranes are emerging as a complementary approach for large-scale production. In this study, to investigate their ability to induce hair growth, we generated macrophage-engineered EMs (MAC-EMs) that activated the human dermal papilla (DP) cells in vitro. MAC-EMs intradermally injected into the skin of C57BL/6 mice were retained for up to 72 h. Microscopy imaging revealed that MAC-EMs were predominately internalized into hair follicles. The MAC-EMs treatment induced hair regrowth in mice and hair shaft elongation in a human hair follicle, suggesting the potential of MAC-EMs as an alternative to EVs to overcome clinical limitation.

Human iPS Cell-Derived Cell Aggregates Exhibited Dermal Papilla Cell Properties in in vitro Three-Dimensional Assemblage Mimicking Hair Follicle Structures

Current approaches for human hair follicle (HF) regeneration mostly adopt cell-autonomous tissue reassembly in a permissive murine intracorporeal environment. This, together with the limitation in human-derived trichogenic starting materials, potentially hinders the bioengineering of human HF structures, especially for the drug discovery and treatment of hair loss disorders. In this study, we attempted to reproduce the anatomical relationship between an epithelial main body and the dermal papilla (DP) within HF in vitro by three-dimensionally assembling columnarly molded human keratinocytes (KCs) and the aggregates of DP cells and evaluated how HF characteristics were reproduced in the constructs. The replaceability of human-induced pluripotent stem cell (hiPSC)-derived DP substitutes was assessed using the aforementioned reconstruction assay. Human DP cell aggregates were embedded into Matrigel as a cluster. Subsequently, highly condensed human KCs were cylindrically injected onto DP spheroids. After 2-week culture, the structures visually mimicking HFs were obtained. KC-DP constructs partially reproduced HF microanatomy and demonstrated differential keratin (KRT) expression pattern in HFs: KRT14 in the outermost part and KRT13, KRT17, and KRT40, respectively, in the inner portion of the main body. KC-DP constructs tended to upregulate HF-related genes, KRT25, KRT33A, KRT82, WNT5A, and LEF1. Next, DP substitutes were prepared by exposing hiPSC-derived mesenchymal cells to retinoic acid and subsequently to WNT, BMP, and FGF signal activators, followed by cell aggregation. The resultant hiPSC-derived DP substitutes (iDPs) were combined with KCs in the invented assay. KC-iDP constructs morphologically resemble KC-DP constructs and analogously mimicked KRT expression pattern in HF. iDP in the constructs expressed DP-related markers, such as vimentin and versican. Intriguingly, KC-iDP constructs more intensely expressed KRT33A, KRT82, and LEF1, which were stepwisely upregulated by the addition of WNT ligand and the mixture of WNT, SHH, and EDA signaling activators, supporting the idea that iDP exhibited biological properties analogous to DP cell aggregates in the constructs in vitro. These preliminary findings suggested the possibility of regenerating DP equivalents with in vitro hair-inductive capacity using hiPSC-derived cell composites, which potentially reduce the necessity of human tissue-derived trichogenic cell subset and eventually allow xeno-free bioengineering of human HFs.

Detecting the Mechanism behind the Transition from Fixed Two-Dimensional Patterned Sika Deer (Cervus nippon) Dermal Papilla Cells to Three-Dimensional Pattern

The hair follicle dermal papilla is critical for hair generation and de novo regeneration. When cultured in vitro, dermal papilla cells from different species demonstrate two distinguishable growth patterns under the conventional culture condition: a self-aggregative three dimensional spheroidal (3D) cell pattern and a two dimensional (2D) monolayer cell pattern, correlating with different hair inducing properties. Whether the loss of self-aggregative behavior relates to species-specific differences or the improper culture condition remains unclear. Can the fixed 2D patterned dermal papilla cells recover the self-aggregative behavior and 3D pattern also remains undetected. Here, we successfully constructed the two growth patterns using sika deer (Cervus nippon) dermal papilla cells and proved it was the culture condition that determined the dermal papilla growth pattern. The two growth patterns could transit mutually as the culture condition was exchanged. The fixed 2D patterned sika deer dermal papilla cells could recover the self-aggregative behavior and transit back to 3D pattern, accompanied by the restoration of hair inducing capability when the culture condition was changed. In addition, the global gene expressions during the transition from 2D pattern to 3D pattern were compared to detect the potential regulating genes and pathways involved in the recovery of 3D pattern and hair inducing capability.

Versican contributes to ligament formation of knee joints

Versican is a large proteoglycan in the extracellular matrix. During embryonic stages, it plays a crucial role in the development of cartilage, heart, and dermis. Previously, we reported that Prx1-Vcan conditional knockout mice, lacking Vcan expression in mesenchymal condensation areas of the limb bud, show the impaired joint formation and delayed cartilage development. Here, we investigated their phenotype in adults and found that they develop swelling of the knee joint. Histologically, their newborn joint exhibited impaired formation of both anterior and posterior cruciate ligaments. Immunostaining revealed a decrease in scleraxis-positive cells in both articular cartilage and ligament of Prx1-Vcan knee joint, spotty patterns of type I collagen, and the presence of type II collagen concomitant with the absence of versican expression. These results suggest that versican expression during the perinatal period is required for cruciate ligaments’ formation and that its depletion affects joint function in later ages.

HaCaT‑conditioned medium supplemented with the small molecule inhibitors SB431542 and CHIR99021 and the growth factor PDGF‑AA prevents the dedifferentiation of dermal papilla cells in vitro

Hair loss, including alopecia, is a common and distressing problem for men and women, and as a result, there is considerable interest in developing treatments that can prevent or reverse hair loss. Dermal papillae closely interact with epidermal cells and play a key role during hair follicle induction and hair morphogenesis. As dermal papilla cells (DPCs) lose their hair‑inducing ability in monolayer cultures in vitro, it is difficult to obtain de novo hair follicle structures following DPC transplantation in vivo. The present study aimed to explore culture conditions to maintain DPC characteristics using conditioned media (CM) from the supernatant of cultured HaCaT keratinocyte cells supplemented with other components. Initially, it was observed that during passaging of in vitro monolayer DPC cultures, the Wnt/β‑catenin pathway was repressed, while the TGF‑β/Smad pathway was activated, and that HaCaT cells cultivated in 1% fetal bovine serum had higher levels of expression of Wnt3a and Wnt10b compared with normal keratinocytes. Culturing of high‑passage (P7) DPCs in CM from HaCaT cells (HaCaT‑CM) actively stimulated cell proliferation and maintained Sox2 and Versican expression levels. Supplementation of HaCaT‑CM with SB431542 (SB, a TGF‑β receptor inhibitor), CHIR99021, (CHIR, a GSK3α/β inhibitor and activator of Wnt signaling) and platelet‑derived growth factor (PDGF)‑AA further increased the expression levels of Sox2, Versican and alkaline phosphatase (ALP) in P7 DPCs. Three‑dimensional culture of P7 DPCs using hanging drop cultures in HaCaT‑CM supplemented with SB, CHIR and PDGF‑AA resulted in larger cell aggregates and a further significant upregulation of Sox2, ALP and Versican expression levels. Taken together, these findings demonstrated that HaCaT‑CM supplemented with SB, CHIR and PDGF‑AA may preserve the hair‑inducing ability of high‑passage DPCs and may therefore be useful in reconstructing new hair follicles in vivo.

Impact of adipose-derived stem cells on engineering hair follicle germ-like tissue grafts for hair regenerative medicine

Hair regenerative medicine has emerged as a promising treatment strategy for severe hair loss, such as end-stage androgenetic alopecia. Various approaches to engineering three-dimensional tissue grafts have been explored since they drive the ability to regenerate hair follicles when transplanted. In the present study, we demonstrated the assembly of human adipose-derived stem cells (hASCs) into hair follicle germ (HFG)-like aggregates for de novo hair regeneration. We mixed human dermal papilla cells (hDPCs), murine embryonic epithelial cells, and hASCs in suspension, and allowed them to form aggregates. During three days of culture, cells initially formed a single aggregate with a random distribution of the three cell types, but the epithelial and dermal papilla cells subsequently separated from each other and formed a dumbbell-shaped HFG, with hASCs localized on the hDPC aggregate side. The involvement of hASCs significantly increased gene expression associated with hair morphogenesis compared to HFGs without hASCs. The self-organization of the three cell types was observed in our scalable lab-made chip device. HFGs containing hASCs efficiently generated hair shafts upon transplantation to nude mice, while only a few shafts were generated with HFGs without hASCs. This approach may be a promising strategy for fabricating tissue grafts for hair regenerative medicine.

Investigating PEGDA and GelMA Microgel Models for Sustained 3D Heterotypic Dermal Papilla and Keratinocyte Co-Cultures

Hair follicle morphogenesis is heavily dependent on reciprocal, sequential, and epithelial-mesenchymal interaction (EMI) between epidermal stem cells and the specialized cells of the underlying mesenchyme, which aggregate to form the dermal condensate (DC) and will later become the dermal papilla (DP). Similar models were developed with a co-culture of keratinocytes and DP cells. Previous studies have demonstrated that co-culture with keratinocytes maintains the in vivo characteristics of the DP. However, it is often challenging to develop three-dimensional (3D) DP and keratinocyte co-culture models for long term in vitro studies, due to the poor intercellular adherence between keratinocytes. Keratinocytes exhibit exfoliative behavior, and the integrity of the DP and keratinocyte co-cultured spheroids cannot be maintained over prolonged culture. Short durations of culture are unable to sufficiently allow the differentiation and re-programming of the keratinocytes into hair follicular fate by the DP. In this study, we explored a microgel array approach fabricated with two different hydrogel systems. Using poly (ethylene glycol) diacrylate (PEGDA) and gelatin methacrylate (GelMA), we compare their effects on maintaining the integrity of the cultures and their expression of important genes responsible for hair follicle morphogenesis, namely Wnt10A, Wnt10B, and Shh, over prolonged duration. We discovered that low attachment surfaces such as PEGDA result in the exfoliation of keratinocytes and were not suitable for long-term culture. GelMA, on the hand, was able to sustain the integrity of co-cultures and showed higher expression of the morphogens overtime.

Hair follicle germs containing vascular endothelial cells for hair regenerative medicine

Hair regenerative medicine has emerged as a promising approach for the treatment of severe hair loss. Recent advances in three-dimensional tissue engineering, such as formation of hair follicle germs (HFGs), have considerably improved hair regeneration after transplantation in animal models. Here, we proposed an approach for fabricating HFGs containing vascular endothelial cells. Epithelial, dermal papilla, and vascular endothelial cells initially formed a single aggregate, which subsequently became a dumbbell-shaped HFG, wherein the vascular endothelial cells localized in the region of dermal papilla cells. The HFGs containing vascular endothelial cells exhibited higher expression of hair morphogenesis-related genes in vitro, along with higher levels of hair shaft regeneration upon transplantation to the dorsal side of nude mice, than those without vascular endothelial cells. The generated hair follicles represented functional characteristics, such as piloerection, as well as morphological characteristics comparable to those of natural hair shafts. This approach may provide a promising strategy for fabricating tissue grafts with higher hair inductivity for hair regenerative medicine.

Effects of platelet-rich plasma on in vitro hair follicle germ preparation for hair regenerative medicine

Hair regenerative medicine is a promising approach for the treatment of hair loss and involves the transplantation of follicular stem cells into bald spots to regenerate hair. Various approaches have been investigated to engineer tissue grafts for use in hair regenerative medicine. Tissue-like three-dimensional aggregates, such as bioengineered hair follicle germs (HFGs), have shown great promise for hair regeneration, with normal tissue morphology and hair cycles. However, these approaches have not yet been applied in clinical settings, and further studies are needed to improve hair generation efficiency. The biological molecules in in vivo microenvironments around HFGs may provide cues for the in vitro preparation of HFGs with higher trichogenic functionalities. Activated platelet-rich plasma releasate (PRPr) is an autologous source of signaling molecules including growth factors and cytokines. In this study, we investigated the effects of PRPr on the preparation of HFGs in vitro. The presence of PRPr did not hinder the spontaneous formation of dumbbell-like HFGs from a suspension of embryonic skin-derived epithelial and mesenchymal cells in a custom-designed HFG culture plate. HFGs prepared with PRPr displayed greater levels of follicular gene expression compared to those prepared in the absence of PRPr. Moreover, the hair regeneration ability upon intracutaneous transplantation was significantly improved in the presence of PRPr. These results suggest that PRPr is beneficial for engineering HFGs for autologous hair regenerative medicine.

LncRNA-599547 contributes the inductive property of dermal papilla cells in cashmere goat through miR-15b-5p/Wnt10b axis

The lncRNA-599547 (619-nt in length) is identified in secondary hair follicle (SHF) of cashmere goat, but its functional roles in regulating the inductive property of dermal papilla cells (DPCs) remains unknown. We found that lncRNA-599547 had significantly higher expression in dermal papilla of cashmere goat SHF at anagen than its counterpart at telogen. The overexpression of lncRNA-599547 led to a significant increase of ALP and LEF1 expression in DPCs (p < 0.05), whereas, the siLncRNA-1 mediated silencing of lncRNA-599547 significantly down-regulated the expression of ALP and LEF1 in DPCs (p < 0.05). Based on biotin-labeled RNA pull-down assay, we found that lncRNA-599547 directly interacted with chi-miR-15b-5p in DPCs. Based on both overexpression and silencing analysis of lncRNA-599547, our results indicate that lncRNA-599547 promotes the expression of Wnt10b in DPCs but without modulating its promoter methylation level. Using the mRNA-3'UTR fragments of goat Wnt10b containing the predicted binding sites of chi-miR-15b-5p in Dual-luciferase Reporter Assays, we show that lncRNA-599547 modulates the expression of Wnt10b at the chi-miR-15b-5p mediated post-transcriptional level. Taken together, our results indicate that lncRNA-599547 sponges miR-15b-5p to positively regulate the expression of Wnt10 gene, and thereby contributes the inductive property of DPCs in cashmere goat.

Low-frequency electromagnetic fields promote hair follicles regeneration by injection a mixture of epidermal stem cells and dermal papilla cells

The bioeffects of low-frequency electromagnetic fields (EMF) on a bio-engineered hair follicle generation had not been fully elucidated. This present study was designed to evaluat the therapeutically effective of low frequency EMF on hair follicles regeneration. In this experiment, epidermal stem cells (ESCs) and dermal papilla (DP) cells were isolated and culture-expanded. Then the mixture containing of ESCs and DP cells was implanted into the epidermal layer or corium layer of nude mice. Those mice were  divided at random into the control group and EMF group, 7 days or 14 days later, the skin specimens were harvested to assess for hair regeneration or a bio-engineered skin formation using H&E staining. After injection of the mixture into the epidermal layer of nude mice for 14 days, H&E staining showed that the new hair formed the correct structure comprising hair matrix, hair shaft, and inner root sheath, outer root sheath, and DP. Comparing to the control, the hair follicles erupted at a higher density in the EMF group. When the mixture was implanted into the corium layer for 7 days, comparing with the characteristics of new hair follicles in the control group, H&E staining also showed the mixture induced to form 4 ~ 6 epidermal layers with a higher density of hair follicle like-structures in the bioengineered epithelial layers after EMF exposure. Our results suggested that the injection of a mixture of ESCs and DP cells in combination with EMF exposure facilitated the induction of hair follicle regeneration and a bioengineered skin formation with hair follicle-like structures.

Preliminary studies of hair follicle regeneration by injections of epidermal stem cells and dermal papilla cells into nude mice

The ultimate goal of organ regenerative therapy is to reproduce fully functional organs to replace which have been damaged as a result of diseases or injury. Although several studies claimed that using different types of cells in some animal models promote hair follicles regeneration, more researches can be done to develop a sufficient and efficient protocol to induce hair generation from different animal models. In this study, we investigated the therapeutic potentials for hair follicle formation by injecting a mixture of epidermal stem cells and dermal papilla cells. Those cells were isolated and culture-expanded. Then we randomly allocated 8 nude mice into two groups. The experiment group received an injection of a mixture that containing of epidermal stem cells and dermal papilla cells. The control group received injection of keratinocyte serum-free medium. The hair follicles regeneration was observed and the injection area was harvested for HE staining. 14 day later, the regenerated hair shafts were observed and HE staining indicated that the newly hair follicle formed the correct structures in experiment group. Furthermore, the mixture injection induced a regular and multilayered stratified epidermis and the epidermis contained of hair follicle-likes structures. Our data showed that injection of a mixture of epidermal stem cells and dermal papilla cells could induce hair follicles regeneration and well-ordered epidermis formation. This study emphasized that the rearrangement of the interactions during seed cells and the niches of the seed cells is essential and necessary for tissue-engineered construct success.

Integral Roles of Specific Proteoglycans in Hair Growth and Hair Loss: Mechanisms behind the Bioactivity of Proteoglycan Replacement Therapy with Nourkrin® with Marilex® in Pattern Hair Loss and Telogen Effluvium

Follicular proteoglycans are key players with structural, functional, and regulatory roles in the growth and cycling behaviour of the hair follicles. The expression pattern of specific proteoglycans is strongly correlated with follicular phase transitions, which further affirms their functional involvement. Research shows that bioactive proteoglycans, e.g., versican and decorin, can actively trigger follicular phase shift by their anagen-inducing, anagen-maintaining, and immunoregulatory properties. This emerging insight has led to the recognition of “dysregulated proteoglycan metabolism” as a plausible causal or mediating pathology in hair growth disorders in both men and women. In support of this, declined expression of proteoglycans has been reported in cases of anagen shortening and follicular miniaturisation. To facilitate scientific communication, we propose designating this pathology “follicular hypoglycania (FHG),” which results from an impaired ability of follicular cells to replenish and maintain a minimum relative concentration of key proteoglycans during anagen. Lasting FHG may advance to structural decay, called proteoglycan follicular atrophy (PFA). This process is suggested to be an integral pathogenetic factor in pattern hair loss (PHL) and telogen effluvium (TE). To address FHG and PFA, a proteoglycan replacement therapy (PRT) program using oral administration of a marine-derived extract (Nourkrin® with Marilex®, produced by Pharma Medico Aps, Aarhus, Denmark) containing specific proteoglycans has been developed. In clinical studies, this treatment significantly reduced hair fall, promoted hair growth, and improved quality of life in patients with male- and female-pattern hair loss. Accordingly, PRT (using Nourkrin® with Marilex®) can be recommended as an add-on treatment or monotherapy in patients with PHL and TE.

Culture and Differentiation of Human Hair Follicle Dermal Papilla Cells in a Soft 3D Self-Assembling Peptide Scaffold

Hair follicle dermal papilla cells (HFDPC) are a specialized cell population located in the bulge of the hair follicle with unique characteristics such as aggregative behavior and the ability to induce new hair follicle formation. However, when expanded in conventional 2D monolayer culture, their hair inductive potency is rapidly lost. Different 3D culture techniques, including cell spheroid formation, have been described to restore, at least partially, their original phenotype, and therefore, their hair inductive ability once transplanted into a recipient skin. Moreover, hair follicle dermal papilla cells have been shown to differentiate into all mesenchymal lineages, but their differentiation potential has only been tested in 2D cultures. In the present work, we have cultured HFDPC in the 3D self-assembling peptide scaffold RAD16-I to test two different tissue engineering scenarios: restoration of HFDPC original phenotype after cell expansion and osteogenic and adipogenic differentiation. Experimental results showed that the 3D environment provided by RAD16-I allowed the restoration of HFDPC signature markers such as alkaline phosphatase, versican and corin. Moreover, RAD16-I supported, in the presence of chemical inductors, three-dimensional osteogenic and adipogenic differentiation. Altogether, this study suggests a potential 3D culture platform based on RAD16-I suitable for the culture, original phenotype recovery and differentiation of HFDPC.

Macrophage-Derived Extracellular Vesicle Promotes Hair Growth

Hair loss is a common medical problem affecting both males and females. Dermal papilla (DP) cells are the ultimate reservoir of cells with the potential of hair regeneration in hair loss patients. Here, we analyzed the role of macrophage-derived Wnts (3a and 7b) and macrophage extracellular vesicles (MAC-EVs) in promoting hair growth. We studied the proliferation, migration, and expression of growth factors of human-DP cells in the presence or absence of MAC-EVs. Additionally, we tested the effect of MAC-EV treatment on hair growth in a mouse model and human hair follicles. Data from western blot and flow cytometry showed that MAC-EVs were enriched with Wnt3a and Wnt7b, and more than 95% were associated with their membrane. The results suggest that Wnt proteins in MAC-EVs activate the Wnt/β-catenin signaling pathways, which leads to activation of transcription factors (Axin2 and Lef1). The MAC-EVs significantly enhanced the proliferation, migration, and levels of hair-inductive markers of DP cells. Additionally, MAC-EVs phosphorylated AKT and increased the levels of the survival protein Bcl-2. The DP cells treated with MAC-EVs showed increased expression of vascular endothelial growth factor (VEGF) and keratinocyte growth factor (KGF). Treatment of Balb/c mice with MAC-EVs promoted hair follicle (HF) growth in vivo and also increased hair shaft size in a short period in human HFs. Our findings suggest that MAC-EV treatment could be clinically used as a promising novel anagen inducer in the treatment of hair loss.

Isolation, culture and growth characteristics of dermal papilla cells from Rex rabbits

Dermal papilla cells (DPCs) is the key dermal component of the hair follicle that directly regulates hair follicle development, growth and regeneration. Successfully isolated and cultured DPCs of Rex rabbit could provide a good model for the study of hair follicle development mechanism in vitro. Skin samples were collected from 30-day old Rex rabbits and separated by combination of Dispase II and Collagenase D, separation, culture, and purification of DPCs. The morphology of DPCs in vitro was observed and the growth curve was drawn, the number of DPCs presented progressive increase in a logarithmic model between the 4^th day and the 7^th day. The results of immune chemical and immune fluorescence shown that α smooth muscle actin (α-SMA) and versican were positive in cells. Growth character of the passages 3 (P3), P6, P9 and P12 DPCs were observed using MTT at 24 h, 48 h, 72 h, 96 h, 120 h and 144 h. The cell density of P12 was lower than P3 (P < 0.05); the flow cytometric analysis showed that DPCs at resting state/first gap (G0/G1) stage of P3 was higher than P12 (P < 0.05), and second gap/mitosis (G2/M) stage of P3 was lower than P12 (P < 0.05). However, the DPCs of P12 present triangular or short fusiform, retaining their unique aggregative growth characteristics. This results shown that the DPCs properties of P12 from Rex rabbits, still fit functional research in vitro. In conclusion, we successfully established the culturing condition of DPCs from Rex rabbits, and provide a material for studying the molecular mechanism of hair follicle development.

CRH receptor antagonists from Pulsatilla chinensis prevent CRH-induced premature catagen transition in human hair follicles

BACKGROUND

There is a growing interest in the relationship among stress hormones, neuroendocrine signaling, and skin diseases, including hair loss. Previous reports showed that stress hormones inhibit human hair growth and induce early catagen transition. Moreover, a CRH receptor antagonist reversed CRH-induced alopecia in a mouse model, suggesting that antagonization of the CRH receptor is a key clinical strategy to treat stress-induced hair loss.

OBJECTIVES

The aim of this study was to investigate the protective effect of CRH receptor antagonists from Pulsatilla chinensis on human hair follicles (hHFs) and human dermal papilla cells (hDPCs).

METHODS

hHFs were observed and scored by hair cycle. The levels of cAMP, a second messenger, were measured in each group. In addition, the mRNA and protein levels of factors related to the hair cycle were measured. Furthermore, the expression levels of various members of the mitogen-activated protein kinase (MAPK) signaling pathway related to stress were measured.

RESULTS

CRH induced early catagen transition in an ex vivo hair organ culture model. In addition, CRH downregulated the levels of alkaline phosphatase (ALP) and hair anagen-related cytokines in cultured hDPCs. Moreover, CRH induced the phosphorylation of JNK, c-Jun, p38, ERK, and Akt in cultured hDPCs. CRH receptor antagonists isolated from P chinensis reversed these CRH-induced modulations in both ex vivo hair follicles (HFs) and cultured hDPCs.

CONCLUSIONS

These results indicate that P chinensis effectively blocks CRH receptor function and that saponin derivatives from P chinensis could be a pharmaceutical and cosmetic approach to treat stress-induced hair loss.

Extremely Low-Frequency Electromagnetic Fields Increase the Expression of Anagen-Related Molecules in Human Dermal Papilla Cells via GSK-3β/ERK/Akt Signaling Pathway

Despite advances in medical treatments, the proportion of the population suffering from alopecia is increasing, thereby creating a need for new treatments to control hair loss and prevent balding. Human hair follicle dermal papilla cells (hDPCs), a type of specialized fibroblast in the hair bulb, play an essential role in controlling hair growth and in conditions like androgenic alopecia. This study aimed to evaluate the intensity-dependent effect of extremely low-frequency electromagnetic fields (ELF-EMFs) on the expression of anagen-related molecules in hDPCs in vitro. We examined the effect of ELF-EMF on hDPCs to determine whether activation of the GSK-3β/ERK/Akt signaling pathway improved hDPC activation and proliferation; hDPCs were exposed to ELF-EMFs at a frequency of 70 Hz and at intensities ranging from 5 to 100 G, over four days. Various PEMF intensities significantly increased the expression of anagen-related molecules, including collagen IV, laminin, ALP, and versican. In particular, an intensity of 10 G is most potent for promoting the proliferation of hDPC and expression of anagen-related molecules. Moreover, 10 G ELF-EMF significantly increased β-catenin and Wnt3α expression and GSK-3β/ERK/Akt phosphorylation. Our results confirmed that ELF-EMFs enhance hDPC activation and proliferation via the GSK-3β/ERK/Akt signaling pathway, suggesting a potential treatment strategy for alopecia.

Optimal stimulation toward the dermal papilla lineage can be promoted by combined use of osteogenic and adipogenic inducers

Dermal papilla cells (DPCs) play crucial roles in hair regeneration, but they readily lose their hair‐forming ability during in vitro culture. Although the formation of spheroids partially restores the ability, shrinkage of the spheroids makes it difficult to maintain cellular viability. To address this problem, we stimulated DPCs with factors known to induce adipogenic and/or osteogenic differentiation, because DPCs share unique gene expression profiles with adipocytes and osteocytes. We isolated DPCs from versican (vcan)–GFP mice, in which GFP is expressed under the control of a vcan promoter, which is strongly active in DPCs of anagen hair follicles. GFP fluorescence was most intense when the spheroids were made from DPCs cultured in a half‐diluted combination of adipogenic and osteogenic media (CAO1/2), a Dulbecco’s modified Eagle’s medium‐based medium that contains 10% FBS, 275 nm dexamethasone, 2.5 mm β‐glycerol phosphate, 12.5 µg·mL⁻¹ ascorbic acid, 0.125 µm isobutylmethylxanthine and 2.5 ng·mL⁻¹ insulin. The dose of each additive used was less than the optimal dose for adipogenic or osteogenic differentiation, and shrinkage of the spheroids was avoided through the addition of fibroblast growth factor 2 and platelet‐derived growth factor‐AA to  CAO1/2. In addition, the gene and protein expression of vcan, osteopontin, alkaline phosphatase and α‐smooth muscle actin in the spheroids were augmented to levels similar to those of the intact dermal papillae, which exhibited restored hair‐forming activity. In conclusion, a combination of certain adipogenic and osteogenic inducers, together with fibroblast growth factor 2 and platelet‐derived growth factor‐AA, can promote differentiation toward the DPC lineage.

Keratinocytes maintain compartmentalization between dermal papilla and fibroblasts in 3D heterotypic tri-cultures

OBJECTIVES

Reproducing human hair follicles in vitro is often limited by various reasons such as the lack of a systematic approach to culture distinct hair follicle cell types to reproduce their spatial relationship. Here, we reproduce hair follicle-like constructs resembling the spatial orientation of different cells in vivo, to study the role of keratinocytes in maintaining cellular compartmentalization among hair follicle-related cells.

MATERIALS AND METHODS

Dermal papilla (DP) cells, HaCaT keratinocytes and human dermal fibroblast (HDF) cells were seeded sequentially into three-dimensional (3D) microwells fabricated from polyethylene glycol diacrylate hydrogels. Quantitative polymerase chain reaction was used to compare inductive gene expression of 3D and two-dimensional (2D) DP. DP and HaCaT cells were transfected with green fluorescent protein and red fluorescent protein lentivirus, respectively, to enable cell visualization using confocal microscopy.

RESULTS

The 3D DP cultures showed significantly enhanced expression of essential DP genes as compared 2D cultures. Core-shell configurations containing keratinocytes forming the outer shell and DP forming the core were observed. Migratory polarization was mediated by cell-cell interaction between the keratinocytes and HDF cells, while preserving the aggregated state of the DP cells.

CONCLUSIONS

Keratinocytes may play a role in maintaining compartmentalization between the DP and the surrounding HDF residing in the dermis, and therefore maintains the aggregative state of the DP cells, necessary for hair follicle development and function.

Culture of the human pilosebaceous unit, hair follicle and sebaceous gland

Terence Kealey first pioneered the isolation and organ maintenance of human eccrine and sebaceous glands in the early to mid-1980. This led to subsequent methods describing the isolation and culture of human hair follicles, the human pilosebaceous unit as well as the sebaceous duct. The importance of these models in the study of the biology of human skin glands and appendages has been demonstrated in numerous publications and their importance as models for animal replacement, refinement and reduction (3Rs) is increasingly important. In particular, in vitro (ex vivo) hair follicle culture has played a significant part in helping elucidate the role of signalling molecules in regulating hair growth and hair fibre formation and has been especially useful in understanding metabolic aspects of hair growth. However, obtaining sufficient numbers of hair follicles is becoming increasingly difficult as plastic surgery becomes less invasive and smaller skin samples provided. There is therefore an urgent requirement for the next generation of in vitro models using cell lines and tissue engineering, and this has led to the development of immortalised cell lines as well as attempts to model hair follicle embryogenesis in vitro and development of skin on a chip.

Use of human intra-tissue stem/progenitor cells and induced pluripotent stem cells for hair follicle regeneration

Background

The hair follicle (HF) is a unique miniorgan, which self-renews for a lifetime. Stem cell populations of multiple lineages reside within human HF and enable its regeneration. In addition to resident HF stem/progenitor cells (HFSPCs), the cells with similar biological properties can be induced from human-induced pluripotent stem cells (hiPSCs). As approaches to regenerate HF by combining HF-derived cells have been established in rodents and a huge demand exists to treat hair loss diseases, attempts have been made to bioengineer human HF using HFSPCs or hiPSCs.

Main body of the abstract

The aim of this review is to comprehensively summarize the strategies to regenerate human HF using HFSPCs or hiPSCs. HF morphogenesis and regeneration are enabled by well-orchestrated epithelial-mesenchymal interactions (EMIs). In rodents, various combinations of keratinocytes with mesenchymal (dermal) cells with trichogenic capacity, which were transplanted into in vivo environment, have successfully generated HF structures. The regeneration efficiency was higher, when epithelial or dermal HFSPCs were adopted. The success in HF formation most likely depended on high receptivity to trichogenic dermal signals and/or potent hair inductive capacity of HFSPCs. In theory, the use of epithelial HFSPCs in the bulge area and dermal papilla cells, their precursor cells in the dermal sheath, or trichogenic neonatal dermal cells should elicit intense EMI sufficient for HF formation. However, technical hurdles, represented by the limitation in starting materials and the loss of intrinsic properties during in vitro expansion, hamper the stable reconstitution of human HFs with this approach. Several strategies, including the amelioration of culture condition or compartmentalization of cells to strengthen EMI, can be conceived to overcome this obstacle. Obviously, use of hiPSCs can resolve the shortage of the materials once reliable protocols to induce wanted HFSPC subsets have been developed, which is in progress. Taking advantage of their pluripotency, hiPSCs may facilitate previously unthinkable approaches to regenerate human HFs, for instance, via bioengineering of 3D integumentary organ system, which can also be applied for the treatment of other diseases.

Short conclusion

Further development of methodologies to reproduce bona fide EMI in HF formation is indispensable. However, human HFSPCs and hiPSCs hold promise as materials for human HF regeneration.

LncRNA-000133 from secondary hair follicle of Cashmere goat: identification, regulatory network and its effects on inductive property of dermal papilla cells

Long noncoding RNAs (lncRNAs), a class of non-protein conding RNAs > 200 nt in length, were thought to play critical roles in regulating the expression of protein-coding genes. Here, we identified and characterized a novel lncRNA-000133 from the secondary hair follicle (SHF) of cashmere goat with its ceRNA network analysis, as well as, its potential effects on inductive property of dermal papilla cells were evaluated through overexpression analysis. Expression analysis indicated that lncRNA-000133 had a significantly higher expression at anagen than that at telogen in SHF of Cashmere goat, suggesting that lncRNA-000133 might be involved in the reconstruction of SHF with the formation and growth of cashmere fiber. Taken together with methylation analysis, we showed that 5' regulatory region methylation of the lncRNA-000133 gene might be involved in its expression suppression in SHF of Cashmere goat. The ceRNA regulatory network showed that a rich and complex regulatory relationship between lncRNA-000133 and related miRNAs with their target genes. The overexpression of lncRNA-000133 led to a significant increasing in the relative expression of ET-1, SCF, ALP and LEF1 in dermal papilla cells suggesting that lncRNA-000133 appears to contribute the inductive property of dermal papilla cells.

Heat stress decreased hair follicle population in rex rabbits

The aim of this study was conducted to investigate the effect of heat stress on the hair follicle population and related signalling pathways in rex rabbits. Forty-eight rabbits were randomly divided into two groups: one group in a high ambient environment (32 ± 2°C, heat stress) and the other group with normal temperature (20 ± 2°C, control). The results show that heat stress decreased the body weight gain and feed conversion rate, rabbit hair length and hair follicle density (p < 0.05). Besides, heat stress suppressed the gene expression of noggin, insulin-like growth factor 1 (IGF-1) and IGF-1 receptor and protein expression of phosphorylated mechanistic target of rapamycin (mTOR) in rabbit skin (p < 0.05), while stimulated significantly the gene expression of bone morphogenetic protein 2 (BMP2) and BMP4 (p < 0.05). Heat exposure did not alter significantly the gene expression of alkaline phosphatase, versican and hepatocyte growth factor compared with the control (p > 0.05). In conclusion, noggin-BMP, IGF-1 and mTOR signalling pathways may be associated with the process of heat stress-repressing hair follicle development.

Impact of substrate stiffness on dermal papilla aggregates in microgels

Interaction between cells and the extracellular environment plays a vital role in cellular development. The mechanical property of a 3-dimensional (3D) culture can be modified to mimic in vivo conditions. Dermal papilla (DP) cells are shown to gradually lose their inductivity in hair cycle development in a 2-dimensional culture. They are shown to partially restore their inductivity when transferred into a 3D microenvironment. In this study, a microarray fabricated from three different concentrations of poly-ethylene-glycol-diacrylate 3500, namely 5%, 10% and 15% w/v, yielded increasing substrate stiffness. The impact of varying substrate stiffness was tested for DP cell viability, attachment, and selected hair inductive markers. DP aggregates were shown to be viable and exhibited greater spreading with increasing substrate stiffness. Moreover, DP aggregates cultured on a softer substrate showed a greater fold change of gene and protein expressions than those cultured on a harder substrate.

Effect of laser diode light irradiation on growth capability of human hair follicle dermal papilla cells

Low level laser therapy is widely used to relieve pain and inflammation, and to restore cellular functions. The photons of light are absorbed by mitochondria in cells, leading to an increase in the production of adenosine triphosphate (ATP), nitric oxide release, blood flow, and reactive oxygen species (ROS). This study proposed the use of a laser diode array at 808 nm to stimulate the proliferation and to activate the functions of dermal papilla cells, which were an important part of the hair growth cycle. These cells were isolated from human hair follicles and were exposed to 808 nm light at various doses from 0.5, 1, 2.5, 4, and 6 J/cm². The rate of cell proliferation and the gene expression profile of dermal papilla cells were investigated and compared with the control in which the cells did not received any light treatment. The growth curves of the dermal papilla cells were used to determine the specific growth rates. Higher specific growth rates were observed in the cells exposed to laser at doses higher than 0.5 J/cm². The effect of the laser light treatment on several gene markers, specifically for dermal papilla cells, was evaluated using real-time polymerase chain reaction (qPCR). Our result shows that collagen type 1 (Col1), alkaline phosphatase (Alp), and versican (Vcan) did not increase when the cells were irradiated by the laser light. Interestingly, sex determining region y-box 2 (Sox2) gene was up-regulated when 0.5 J/cm², and 1 J/cm² light was used, while an increase in the level of fibroblast growth factor 7 (Fgf7) gene was observed with light irradiation at 0.5 J/cm², 1 J/cm², 2.5 J/cm², and 4 J/cm². Too high irradiation dose was shown to yield no effect on the gene expression of dermal papilla cells.

Spontaneous hair follicle germ (HFG) formation in vitro, enabling the large-scale production of HFGs for regenerative medicine

Hair follicle morphogenesis is triggered by reciprocal interactions between hair follicle germ (HFG) epithelial and mesenchymal layers. Here, we developed a method for large-scale preparation of HFGs in vitro via self-organization of cells. We mixed mouse epidermal and mouse/human mesenchymal cells in suspension and seeded them in microwells of a custom-designed array plate. Over a 3-day culture period, cells initially formed a randomly distributed single cell aggregate and then spatially separated from each other, exhibiting typical HFG morphological features. These self-sorted hair follicle germs (ssHFGs) were shown to be capable of efficient hair-follicle and shaft generation upon intracutaneous transplantation into the backs of nude mice. This finding facilitated the large-scale preparation of approximately 5000 ssHFGs in a microwell-array chip made of oxygen-permeable silicone. We demonstrated that the integrity of the oxygen supply through the bottom of the silicone chip was crucial to enabling both ssHFG formation and subsequent hair shaft generation. Finally, spatially aligned ssHFGs on the chip were encapsulated into a hydrogel and simultaneously transplanted into the back skin of nude mice to preserve their intervening spaces, resulting in spatially aligned hair follicle generation. This simple ssHFG preparation approach is a promising strategy for improving current hair-regenerative medicine techniques.

As a carrier-transporter for hair follicle reconstitution, platelet-rich plasma promotes proliferation and induction of mouse dermal papilla cells

Morphogenesis of hair follicles during development and in hair reconstitution assays involves complex interactions between epithelial cells and dermal papilla cells (DPCs). DPCs may be a source of cells for hair regeneration in alopecia patients. Reconstitution of engineered hair follicles requires in vitro culture of trichogenic cells, a three-dimensional scaffolds, and biomolecular signals. However, DPCs tend to lose their biological activity when cultured as trichogenic cells, and scaffolds currently used for hair follicle regeneration lack biological efficiency and biocompatibility. Platelet-rich plasma (PRP) gel forms a three-dimensional scaffold that can release endogenous growth factors, is mitogenic for a variety of cell types and is used in model tissue repair and regeneration systems. We found that 5% activated PRP significantly enhanced cell proliferation and hair-inductive capability of mouse and human DPCs in vitro and promoted mouse hair follicle formation in vivo. PRP also formed a three-dimensional gel after activation. We used PRP gel as a scaffold to form many de novo hair follicles on a plane surface, showing it to be candidate bioactive scaffold capable of releasing endogenous growth factors for cell-based hair follicle regeneration.

A Wnt/Notch/Pax7 signaling network supports tissue integrity in tongue development

The tongue is one of the major structures involved in human food intake and speech. Tongue malformations such as aglossia, microglossia, and ankyloglossia are congenital birth defects, greatly affecting individuals' quality of life. However, the molecular basis of the tissue-tissue interactions that ensure tissue morphogenesis to form a functional tongue remains largely unknown. Here we show that Shh^Cre -mediated epithelial deletion of Wntless (Wls), the key regulator for intracellular Wnt trafficking, leads to lingual hypoplasia in mice. Disruption of epithelial Wnt production by Wls deletion in epithelial cells led to a failure in lingual epidermal stratification and loss of the lamina propria and the underlying superior longitudinal muscle in developing mouse tongues. These defective phenotypes resulted from a reduction in epithelial basal cells positive for the basal epidermal marker protein p63 and from impaired proliferation and differentiation in connective tissue and paired box 3 (Pax3)- and Pax7-positive muscle progenitor cells. We also found that epithelial Wnt production is required for activation of the Notch signaling pathway, which promotes proliferation of myogenic progenitor cells. Notch signaling in turn negatively regulated Wnt signaling during tongue morphogenesis. We further show that Pax7 is a direct Notch target gene in the embryonic tongue. In summary, our findings demonstrate a key role for the lingual epithelial signals in supporting the integrity of the lamina propria and muscular tissue during tongue development and that a Wnt/Notch/Pax7 genetic hierarchy is involved in this development.

Provisional matrix: A role for versican and hyaluronan

Hyaluronan and versican are extracellular matrix (ECM) components that are enriched in the provisional matrices that form during the early stages of development and disease. These two molecules interact to create pericellular "coats" and "open space" that facilitate cell sorting, proliferation, migration, and survival. Such complexes also impact the recruitment of leukocytes during development and in the early stages of disease. Once thought to be inert components of the ECM that help hold cells together, it is now quite clear that they play important roles in controlling cell phenotype, shaping tissue response to injury and maintaining tissue homeostasis. Conversion of hyaluronan-/versican-enriched provisional matrix to collagen-rich matrix is a "hallmark" of tissue fibrosis. Targeting the hyaluronan and versican content of provisional matrices in a variety of diseases including, cardiovascular disease and cancer, is becoming an attractive strategy for intervention.