Bulge cells of human hair follicles: segregation, cultivation and properties

FGF20 Secreted From Dermal Papilla Cells Regulate the Proliferation and Differentiation of Hair Follicle Stem Cells in Fine-Wool Sheep

Wool traits determine the market value of fine-wool sheep, and wool fibre-breaking elongation (fibres can be stretched or elongated before they break) is one of the important wool traits. The interaction between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) determines hair follicle development in fine wool sheep, thereby directly influencing wool traits. A genome-wide association study based on pre-sequencing data identified FGF20, which was significantly associated with wool fibre-breaking elongation. The study reveals that the regulatory mechanism of FGF20 secreted from DPCs affects the proliferation and differentiation of HFSCs through a co-culture system, to provide a new perspective for fine-wool sheep breeding. After knocking down FGF20 expression in DPCs, the results showed that the expression of fibroblast growth factor receptor 2 (FGFR2) and fibroblast growth factor receptor 3 (FGFR3) in DPCs and HFSCs was significantly decreased (p < 0.05), the number of EdU-positive cells and cell viability was significantly decreased (p < 0.01), and the apoptosis rate was significantly increased (p < 0.05). Meanwhile, the differentiation markers of SOX9, NOTCH1 and β-Catenin in HFSCs were also significantly reduced (p < 0.05). These findings indicate that FGF20-knockdown in DPCs of fine-wool sheep inhibits the proliferation and differentiation of HFSCs in the co-culture system, providing a theoretical basis for elucidating the regulatory mechanism of hair follicle self-renewal and differentiation of fine-wool sheep and providing a co-culture system for regenerative medicine.

Isolation, Expansion, and Characterization of Rat Hair Follicle Stem Cells and Their Secretome: Insights into Wound Healing Potential

Background: Stem cells are capable of self-renewal and differentiation into various specialized cells, making them a potential therapeutic option in regenerative medicine. This study establishes a comprehensive methodology for isolating, culturing, and characterizing rat hair follicle stem cells. Methods and Results: Hair follicles were harvested from Sprague-Dawley rats and subjected to two different isolation techniques. Immunohistochemical analysis and real-time PCR confirm the expression of specific surface markers and genes, validating the cells' identity. Growth kinetics, colony formation units (CFU), and tri-differentiation capacity were also assessed. Additionally, the cells' secretome was analyzed, regarding its content in biofactors with wound healing properties. Conclusions: These findings highlight the potential of these cells as a valuable cell source for skin regeneration applications. They contribute to advancing our understanding of stem cell applications in regenerative medicine and hold promise for therapeutic interventions in various clinical contexts, aligning with broader research on the diverse capabilities of hair follicle stem cells.

A systematic summary of survival and death signalling during the life of hair follicle stem cells

Hair follicle stem cells (HFSCs) are among the most widely available resources and most frequently approved model systems used for studying adult stem cells. HFSCs are particularly useful because of their self-renewal and differentiation properties. Additionally, the cyclic growth of hair follicles is driven by HFSCs. There are high expectations for the use of HFSCs as favourable systems for studying the molecular mechanisms that contribute to HFSC identification and can be applied to hair loss therapy, such as the activation or regeneration of hair follicles, and to the generation of hair using a tissue-engineering strategy. A variety of molecules are involved in the networks that critically regulate the fate of HFSCs, such as factors in hair follicle growth and development (in the Wnt pathway, Sonic hedgehog pathway, Notch pathway, and BMP pathway), and that suppress apoptotic cues (the apoptosis pathway). Here, we review the life cycle, biomarkers and functions of HFSCs, concluding with a summary of the signalling pathways involved in HFSC fate for promoting better understanding of the pathophysiological changes in the HFSC niche. Importantly, we highlight the potential mechanisms underlying the therapeutic targets involved in pathways associated with the treatment of hair loss and other disorders of skin and hair, including alopecia, skin cancer, skin inflammation, and skin wound healing.

Hair Follicle Generation by Injections of Adult Human Follicular Epithelial and Dermal Papilla Cells into Nude Mice

Objective

Dermal papilla and hair epithelial stem cells regulate hair formation and the growth cycle. Damage to or loss of these cells can cause hair loss. Although several studies claim to reconstitute hairs using rodent cells in an animal model, additional research is needed to develop a stable human hair follicle reconstitution protocol. In this study, we have evaluated hair induction by injecting adult cultured human dermal papilla cells and a mixture of hair epithelial and dermal papilla cells in a mouse model.

Materials and Methods

In this experimental study, discarded human scalp skins were used to obtain dermal papilla and hair epithelial cells. After separation, cells were cultured and assessed for their characteristics. We randomly allocated 15 C57BL/6 nude mice into three groups that received injections in their dorsal skin. The first group received cultured dermal papilla cells, the second group received a mixture of cultured epithelial and dermal papilla cells, and the third group (control) received a placebo [phosphate-buffered saline (PBS-)].

Results

Histopathologic examination of the injection sites showed evidence of hair growth in samples that received cells compared with the control group. However, the group that received epithelial and dermal papilla cells had visible evidence of hair growth. PKH tracing confirmed the presence of transplanted cells in the new hair.

Conclusion

Our data showed that injection of a combination of adult human cultured dermal papilla and epithelial cells could induce hair growth in nude mice. This study emphasized that the combination of human adult cultured dermal papilla and epithelial cells could induce new hair in nude mice.

Investigation of Transcriptional Gene Profiling in Normal Murine Hair Follicular Substructures Using Next-Generation Sequencing to Provide Potential Insights Into Skin Disease

Skin diseases, including hair-related diseases and neoplasia, are a major public health problem. While their prevalence is increasing, their treatment options are limited. Researchers have tried to investigate the genes and signal pathways underlying hair follicles (HFs) to develop genetically targeted therapies through microarrays, which represent an appropriate modality for the analysis of small genomes. To enable the comprehensive transcriptome analysis of large and/or complex transcriptomes, we performed RNA-seq using next-generation sequencing (NGS). We isolated interfollicular keratinocytes (IFKs), HFs, and dermal fibroblasts including dermal papilla cells (DFs-DPCs) from normal C57BL/6 murine skin, transplanted combinations of these samples into nude mice, and followed the mice over time. Sustained hair growth was supported by HFs and DFs-DPCs. We then investigated the pathways and the relevant gene ontology associated with any identified differentially expressed genes (DEGs). In addition, in the culture and flow cytometry (FCM), the HFs had a more quiescent cell cycle pattern than did the IFKs and DFs-DPCs. Therefore, the representative cell cycle-related gene expression of IFKs, HFs, and DFs-DPCs was analyzed by NGS. Our study will allow researchers to further investigate the potential interactions and signaling pathways that are active in HF-related diseases and cancer and may aid in future bioengineering applications.

Rat hair follicle stem cells differentiate and promote recovery following spinal cord injury

Emerging studies of treating spinal cord injury (SCI) with adult stem cells led us to evaluate the effects of transplantation of hair follicle stem cells in rats with a compression-induced spinal cord lesion. Here, we proposed a hypothesis that rat hair follicle stem cell transplantation can promote the recovery of injured spinal cord. Compression-induced spinal cord injury was induced in Wistar rats in this study. The bulge area of the rat vibrissa follicles was isolated, cultivated and characterized with nestin as a stem cell marker. 5-Bromo-2'-deoxyuridine (BrdU) labeled bulge stem cells were transplanted into rats with spinal cord injury. Immunohistochemical staining results showed that some of the grafted cells could survive and differentiate into oligodendrocytes (receptor-interacting protein positive cells) and neuronal-like cells (βIII-tubulin positive cells) at 3 weeks after transplantation. In addition, recovery of hind limb locomotor function in spinal cord injury rats at 8 weeks following cell transplantation was assessed using the Basso, Beattie and Bresnahan (BBB) locomotor rating scale. The results demonstrate that the grafted hair follicle stem cells can survive for a long time period in vivo and differentiate into neuronal- and glial-like cells. These results suggest that hair follicle stem cells can promote the recovery of spinal cord injury.

Extracted hair follicle outer root sheath cell suspension for pigment cell restoration in vitiligo

Vitiligo surgery has come up a long way from punch skin grafts to epidermal cell suspension and latest to the extracted hair follicle outer root sheath cell suspension (EHF-ORS-CS) transplantation. The progressive development from one technique to the other is always in a quest for the best. In the latest development- EHF-ORS-CS, which is an enriched source of follicular inactive melanocyte (melanocyte stem cells), seems to be a good addition to the prevailing cell-based therapies for vitiligo; however, need to be explored further in larger, and preferably randomized blinded studies. This review discusses the principle, technical details, and stem cell composition of hair follicular outer root sheath cell suspension.

Lef1 contributes to the differentiation of bulge stem cells by nuclear translocation and cross-talk with the Notch signaling pathway

Lymphoid enhancer binding factor-1 (Lef1) is an essential regulatory protein in the Wnt signal pathway, which controls cell growth and differentiation. Investigators in the field of skin biology have confirmed that multipotent bulge stem cells (BSCs) are responsible for hair follicle development and regeneration. However, the role of Lef1 remains poorly understood. In this study, we investigated the pattern of Lef1 expression at different stages of the hair growth cycle. Lef1 was strongly expressed during anagen but attenuated in both catagen- and telogen-phase hair follicles in vivo. When stem cells were induced to differentiate toward a hair fate in a co-culture system, Lef1 was notably up-regulated and accumulated in the nucleus, appearing to activate the target protein c-myc and jagged1. Simultaneously, the Wnt and Notch signaling pathways were co-activated, as confirmed by the increased expression of β-catenin and notch1. Plasmids expressing Lef1 and ΔNLef1, a construct in which the β-catenin-binding domain of Lef1 was deleted, were used to evaluate the effects of Lef1 on stem cell differentiation. Lef1 overexpression promoted bulge stem cell differentiation toward a hair fate, which was accompanied by the subsequent migration of β-catenin into the nucleus, whereas no changes were observed in the control group. Taken together, our results demonstrate that Lef1 plays an important role in bulge stem cell differentiation, promoting β-catenin translocation into the nucleus, activating downstream signaling molecules, eventually causing hair follicle bulge stem cells to adopt the hair fate.

Towards expansion of human hair follicle stem cells in vitro

OBJECTIVES

Multipotential human hair follicle stem cells can differentiate into various cell lineages and thus are investigated here as potential autologous sources for regenerative medicine. Towards this end, we have attempted to expand these cells, directly isolated from minimal amounts of hair follicle explants, to numbers more suitable for stem-cell therapy.

MATERIALS AND METHODS

Two types of human follicle stem cells, commercially available and directly isolated, were cultured using an in-house developed medium. The latter was obtained from bulge areas of hair follicles by mechanical and enzymatic dissociation, and was magnetically enriched for its CD200(+) fraction. Isolated cells were cultured for up to 4 weeks, on different supports: blank polystyrene, laminin- and Matrigel(TM) -coated surfaces.

RESULTS

Two-fold expansion was found, highlighting the slow-cycling nature of these cells. Flow cytometry characterization revealed: magnetic enrichment increased the proportion of CD200(+) cells from initially 43.3% (CD200+, CD34: 25.8%; CD200+, CD34+: 17.5%) to 78.2% (CD200+, CD34: 41.5%; CD200+, CD34+: 36.7%). Enriched cells seemed to have retained and passed on their morphological and molecular phenotypes to their progeny, as isolated CD200(+) presenting cells expanded in our medium to a population with 80% of cells being CD200(+): 51.5% (CD200(+), CD34(-)) and 29.6% (CD200(+), CD34(+)).

CONCLUSIONS

This study demonstrates the possibility of culturing human hair follicle stem cells without causing any significant changes to phenotypes of the cells.

Primary cultures from rat vibrissae as a potential cell source for in vitro construction of urinary bladder wall grafts

BACKGROUND

In vitro-constructed grafts can be used for human bladder augmentation. There are many diseases in which autologous cells cannot be used for this purpose. The aim of the present study was to examine the potential of rat vibrissae hair follicle cells to form cultures, which could serve as a source for in vitro creation of urinary bladder wall grafts.

METHODS

Two hundred vibrissae were excised from young Wistar male rats. Two different digestions were performed, in dispase and in collagenase. All follicles were additionally incubated in trypsin and ethylenediamine tetraacetic acid. Two different culture media based on DMEM (Dulbecco's Modified Eagle's Medium) were used: the first was supplemented with keratinocyte growth factor (KGF) and the second with epidermal growth factor. Immunocytochemical detection of cytokeratin, CD34, p63, Ki-67 (proliferation index), and HMB45 (Human Melanoma Black 45) was performed.

RESULTS

Forty-eight primary cultures of rat follicle vibrissae cells were established from 200 hair follicles (24% successful rate). Twenty-four primary cultures were obtained after dispase digestion and 24 after collagenase treatment. Each group was cultured in 2 different media. A heterogeneity of primary cultures was observed. Cells formed a monolayer within a period of 2 to 4 weeks. The 24 primary cultures established after dispase treatment exhibited monolayers of small cuboid cells expressing cytokeratin and CD34. In the 40th passage 20%-40% of cells expressed p63; 85% of these cells from late passages were positive for Ki-67, indicating preserved mitotic potential. Epithelial-like phenotype was observed after dispase digestion and cultivation in KGF-supplemented medium. After 3 weeks, the morphology of these cells changed into fibroblast-like. These cultures were negative for CD34. Fibroblast-like cell growth was observed after collagenase treatment in both KGF- and EGF-supplemented media. These cells were positive for the melanocyte cell marker (HMB45).

CONCLUSIONS

Culture media and isolation conditions influence hair follicle stem cell differentiation. The stem cell niche within the hair follicles is a reservoir of cells, which can be potentially used for in vitro creation of urinary bladder wall grafts.

Expression of mesenchymal stem cell marker CD90 on dermal sheath cells of the anagen hair follicle in canine species

The dermal sheath (DS) of the hair follicle is comprised by fibroblast-like cells and extends along the follicular epithelium, from the bulb up to the infundibulum. From this structure, cells with stem characteristics were isolated: they have a mesenchymal origin and express CD90 protein, a typical marker of mesenchymal stem cells. It is not yet really clear in which region of hair follicle these cells are located but some experimental evidence suggests that dermal stem cells are localized prevalently in the lower part of the anagen hair follicle. As there are no data available regarding DS stem cells in dog species, we carried out a morphological analysis of the hair follicle DS and performed both an immunohistochemical and an immunocytochemical investigation to identify CD90+ cells. We immunohistochemically evidenced a clear and abundant positivity to CD90 protein in the DS cells located in the lower part of anagen hair follicle. The positive cells showed a typical fibroblast-like morphology. They were flat and elongated and inserted among bundles of collagen fibres. The whole structure formed a close and continuous sleeve around the anagen hair follicle. Our immunocytochemical study allowed us to localize CD90 protein at the cytoplasmic membrane level.

Hair regeneration from transected follicles in duplicative surgery: rate of success and cell populations involved

BACKGROUND

The use of bisected hair follicles in hair transplantation has been previously reported, but the capacity of each half to regenerate the entire hair has not been clarified.

OBJECTIVE

To evaluate duplicative surgery rate of success and to analyze the cell populations involved in hair regeneration.

METHODS

We screened 28 patients undergoing duplicative surgery. Approximately 100 hair follicles from each patient were horizontally bisected and implanted. Upper and lower portions were stained for the known epithelial stem cell markers CD200, p63, beta1-integrin, CD34, and K19.

RESULTS

Similar percentages of hair regrowth after 12 months were observed when implanting the upper (72.7 +/- 0.4%) and lower (69.2 +/- 1.1%) portions. Expression of CD200, p63, and beta1-integrin was detected in both portions, whereas K19 and CD34 stained different cell populations in the upper and lower fragment, respectively.

CONCLUSION

Duplicative surgery might represent a successful alternative for hair transplantation, because both portions are capable of regenerating a healthy hair. Moreover, our results suggest the possible presence of stem cells in both halves of the follicle.

Immunophenotyping of the human bulge region: the quest to define useful in situ markers for human epithelial hair follicle stem cells and their niche

Since the discovery of epithelial hair follicle stem cells (eHFSCs) in the bulge of human hair follicles (HFs) an important quest has started: to define useful markers. In the current study, we contribute to this by critically evaluating corresponding published immunoreactivity (IR) patterns, and by attempting to identify markers for the in situ identification of human eHFSCs and their niche. For this, human scalp skin cryosections of at least five different individuals were examined, employing standard immunohistology as well as increased sensitivity methods. Defined reference areas were compared by quantitative immunohistochemistry for the relative intensity of their specific IR. According to our experience, the most useful positive markers for human bulge cells turned out to be cytokeratin 15, cytokeratin 19 and CD200, but were not exclusive, while beta1 integrin and Lhx2 IR were not upregulated by human bulge keratinocytes. Absent IR for CD34, connexin43 and nestin on human bulge cells may be exploited as negative markers. alpha6 integrin, fibronectin, nidogen, fibrillin-1 and latent transforming growth factor (TGF)-beta-binding protein-1 were expressed throughout the connective tissue sheath of human HFs. On the other hand, tenascin-C was upregulated in the bulge and may thus constitute a component of the bulge stem cell niche of human HFs. These immunophenotyping results shed further light on the in situ expression patterns of claimed follicular 'stem cell markers' and suggest that not a single marker alone but only the use of a limited corresponding panel of positive and negative markers may offer a reasonable and pragmatic compromise for identifying human bulge stem cells in situ.