Isolation of a novel population of multipotent adult stem cells from human hair follicles

Platelet-Rich Plasma and Micrografts Enriched with Autologous Human Follicle Mesenchymal Stem Cells Improve Hair Re-Growth in Androgenetic Alopecia. Biomolecular Pathway Analysis and Clinical Evaluation

Platelet rich plasma (PRP) and Micrografts containing human follicle mesenchymal stem cells (HF-MSCs) were tried as a potential treatment for androgenetic alopecia (AGA). However, little to no work has yet to be seen wherein the bio-molecular pathway of HF-MSCs or PRP treatments were analyzed. The aims of this work are to report the clinical effectiveness of HF-MSCs and platelet-rich plasma evaluating and reviewing the most updated information related to the bio-molecular pathway. Twenty-one patients were treated with HF-MSCs injections and 57 patients were treated with A-PRP. The Wnt pathway and Platelet derived-growth factors effects were analyzed. 23 weeks after the last treatment with mean hair thickness increments (29 ± 5.0%) over baseline values for the targeted area. 12 weeks after the last injection with A-PRP mean hair count and hair density (31 ± 2%) increases significantly over baseline values. The increment of Wnt signaling in Dermal Papilla Cells evidently is one of the principal factors that enhances hair growth. Signaling from mesenchymal stem cells and platelet derived growth factors positively influences hair growth through cellular proliferation to prolong the anagen phase (FGF-7), inducing cell growth (ERK activation), stimulating hair follicle development (β-catenin), and suppressing apoptotic cues (Bcl-2 release and Akt activation).

Clinicopathological and prognostic significance of octamer-binding transcription factor 4 in patients with gastric cancer: a systematic review and meta-analysis

Aim: The role of octamer-binding transcription factor 4 (Oct4) in gastric cancer (GC) progression is still under debate and reported results are inconsistent. Therefore, we conducted a meta-analysis to evaluate the clinicopathological and prognostic significance of Oct4 expression in patients with GC. Materials & methods: Relevant articles were retrieved from a diverse number of databases, and meta-analysis was completed using STATA software 12.0. Results: Total of 21 studies were included in this analysis (3209 samples). Expression of Oct4 was associated with incidence, tumor size, lymph node metastasis, histological differentiation, pTNM stage, tumor depth of infiltration, vascular invasion and distal metastasis. Additionally, Oct4 expression was correlated with poor overall survival rate. Conclusion: The Oct4 overexpression suggested aggressive biological behaviors and imply that Oct4 may be a useful prognostic biomarker in gastric cancers.

Vitiligo surgery: A journey from tissues via cells to the stems!

Depigmented patches in vitiligo, a common dermatosis, cause a great psychological distress to the patients. Hence, apart from halting the disease process, the strategies to impart normal skin colour to these white patches carry an important role in the management of vitiligo. Surgical procedures are often required for stable vitiligo lesions not responding to medical therapies. It involves "shuffling" of melanocytes from the pigmented skin to the depigmented areas. During the last fifty years, the vitiligo surgery has evolved from tissue transplantation via cellular transplantation to reach a stage where the use of stem cells or immunomodulatory cells is contemplating. We would like to depict this wonderful journey of vitiligo surgery through this viewpoint.

Hair Follicle-Associated Pluripotent(HAP) Stem Cells

The hair follicle has been known, since 1990, to contain stem cells located in the bulge area. In 2003, we reported a new type of stem cell in the hair follicle that expresses the brain stem-cell marker nestin. We have termed these cells as hair-follicle-associated pluripotent (HAP) stem cells. HAP stem cells can differentiate into neuronal and glial cells, beating cardiac-muscle cells, and other cell types in culture. HAP stem cells can be used for nerve and spinal-cord repair such that locomotor activity is recovered. A major function in situ of the HAP stem cells is for growth of the hair follicle sensory nerve. HAP stem cells have critical advantages over embryonic stem cells and induced pluripotent stem (IPS) cells for regenerative medicine in that they are highly accessible, require no genetic manipulation, are nontumorigenic, and do not present ethical issues.

Tyrosinase and nestin immunohistochemical expression in melanocytic nevi as a histopathologic pattern to trace melanocyte differentiation and nevogenesis

While histological analysis represents a powerful tool for the classification of melanocytic lesions as benign or malignant, a clear-cut distinction between a nevus and a melanoma is sometimes a challenging step of the diagnostic process. The immunohistochemical detection of tyrosinase, cardinal melanogenic enzyme during melanocytic maturation, has often been helpful in formulating a differential diagnosis due to the peculiar staining pattern in nevocytes compared with melanoma cells. Tyrosinase distribution in nevi appears to overlap with the cytoarchitectural changes observable within these lesions, that result in epidermal or superficial dermal nevocytes being larger and strongly expressing melanocytic differentiation antigens, such as tyrosinase, compared with deeper dermal nevus cells. Our study aimed to evaluate the immunohistochemical expression pattern of tyrosinase in different histological types of acquired dysplastic melanocytic nevi, including junctional, compound, and intradermal nevi. Moreover, to estimate whether in nevocytes the expression of tyrosinase was associated with their differentiation state, we investigated the expression of two recognized markers of pluripotency, CD34 and nestin. In all examined nevi, our analysis revealed a remarkable immunoreactivity for tyrosinase in junctional and superficial dermal nevocytes and a decreasing gradient of staining in dermal nevocytes, up to become negative in deeper dermis. Meanwhile, junctional and dermal nevocytes were lacking in CD34 protein. Furthermore, nestin immunostaining showed an opposite distribution compared with tyrosinase, leading us to look into the tyrosinase/nestin expression pattern in melanocytic nevus as a tool to better understand the final stages of differentiation of melanocyte precursors toward their ultimate anatomical site into the epidermis.

Beating Heart Cells from Hair-Follicle-Associated Pluripotent (HAP) Stem Cells

The neural stem-cell marker nestin is expressed in hair follicle stem cells located in the bulge area which are termed hair-follicle-associated pluripotent (HAP) stem cells. HAP stem cells can differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Subsequently, we demonstrated that HAP stem cells could affect nerve and spinal cord regeneration in mouse models. We subsequently demonstrated that HAP stem cells differentiated into beating cardiac muscle cells. The differentiation potential to cardiac muscle is greatest in the upper part of the mouse whisker follicle. The beat rate of the cardiac muscle cells differentiated from HAP stem cells was stimulated by isoproterenol and inhibited by propanolol. The addition of activin A, bone morphogenetic protein 4, and basic fibroblast growth factor, along with isoproternal, induced the cardiac muscle cells to form tissue sheets of beating heart muscle cells. Under hypoxic conditions, HAP stem cells differentiated into troponin-positive cardiac-muscle cells at a higher rate that under normoxic conditions. Hypoxia did not influence the differentiation to other cell types. This method is appropriate for future use with human hair follicles to produce hHAP stem cells in sufficient quantities for future heart, nerve, and spinal cord regeneration in the clinic.

Postnatal neural crest stem cells from hair follicle interact with nerve tissue in vitro and in vivo

Neural crest stem cells that located in the postnatal hair follicle (HF-NCSC) are considered a promising tool for treatment of nervous system diseases and injuries. It is well known that HF-NCSC can be used in the spinal cord and sciatic nerve reparation but their ability to restore brain structures is poorly studied. In this article we are investigating the interaction between HF-NCSC and a nerve tissue (embryonic and adult). We have found out that HF-NCSC isolated from adult mice grow and differentiate in accordance with the mouse embryo developmental stage when co-cultured with the embryonic nerve tissue. The HF-NCSC migration is slower in the late embryonic tissue co-culture system compared to the early one. This phenomenon is related to the motor function of the cells but not to their proliferation level. We have demonstrated that the embryonic nerve tissue maintains HF-NCSC an undifferentiated status, while an adult brain tissue inhibits the cell proliferation and activates the differentiation processes. Besides, HF-NCSC pre-differentiated into the neuronal direction shows a higher survival and migration rate after the transplantation into the adult brain tissue compared to the undifferentiated HF-NCSC. Thus, we have investigated the postnatal HF-NCSC response to the nerve tissue microenvironment to analyze their possible application to the brain repair processes.

Stem cell therapy as a novel therapeutic intervention for resistant cases of alopecia areata and androgenetic alopecia

BACKGROUND

Management of alopecia areata (AA) and androgenetic alopecia (AGA) is often challenging as patients may be resistant to currently available modalities of treatment. The use of stem cells may be a novel option for resistant cases.

OBJECTIVE

To evaluate the safety and efficacy of the use of autologous bone marrow derived mononuclear cells (including stem cells) as compared to follicular stems cells for the management of resistant cases of AA and AGA.

METHODS

This study included 40 patients (20 AA patients and 20 AGA patients), all patients were treated with a single session of intradermal injection of autologous stem cells (SCs) therapy. They were divided into four groups according to the applied modality [either autologous bone marrow derived mononuclear cells (bone marrow mononuclear cells [BMMCs] or autologous follicular stem cells [FSC]).

RESULTS

Six months after stem cell therapy (SCT) injection, there was a significant improvement, confirmed by immunostaining and digital dermoscopy. The mean improvement in all groups was "very good". There was no significant difference between both methods in either type of alopecia. No serious adverse events were reported.

CONCLUSION

Autologous BMMCs and FSC seem to be a safe tolerable and effective treatment for the management of both resistant AA and AGA.

Melanoblasts as Multipotent Cells in Murine Skin

Melanoblasts (MBs) are melanocyte precursors that are derived from neural crest cells (NCCs). We recently demonstrated the multipotency of MBs; they differentiate not only into pigmented melanocytes but also other NCC derivatives. We herein describe methods for the isolation of MBs from mouse skin by flow cytometry. Methods to culture isolated MBs that retain their multipotency and isolation methods for MBs using gene-modified mouse are also described.

BRN2, a POUerful driver of melanoma phenotype switching and metastasis

The POU domain family of transcription factors play a central role in embryogenesis and are highly expressed in neural crest cells and the developing brain. BRN2 is a class III POU domain protein that is a key mediator of neuroendocrine and melanocytic development and differentiation. While BRN2 is a central regulator in numerous developmental programs, it has also emerged as a major player in the biology of tumourigenesis. In melanoma, BRN2 has been implicated as one of the master regulators of the acquisition of invasive behaviour within the phenotype switching model of progression. As a mediator of melanoma cell phenotype switching, it coordinates the transition to a dedifferentiated, slow cycling and highly motile cell type. Its inverse expression relationship with MITF is believed to mediate tumour progression and metastasis within this model. Recent evidence has now outlined a potential epigenetic switching mechanism in melanoma cells driven by BRN2 expression that induces melanoma cell invasion. We summarize the role of BRN2 in tumour cell dissemination and metastasis in melanoma, while also examining it as a potential metastatic regulator in other tumour models.

Review of human hair optical properties in possible relation to melanoma development

Immigration and epidemiological studies provide evidence indicating the correlation of high ultraviolet exposure during childhood and increased risks of melanoma in later life. While the explanation of this phenomenon has not been found in the skin, a class of hair has been hypothesized to be involved in this process by transmitting sufficient ultraviolet rays along the hair shaft to possibly cause damage to the stem cells in the hair follicle, ultimately resulting in melanoma in later life. First, the anatomy of hair and its possible contribution to melanoma development, and the tissue optical properties are briefly introduced to provide the necessary background. This paper emphasizes on the review of the experimental studies of the optical properties of human hair, which include the sample preparation, measurement techniques, results, and statistical analysis. The Monte Carlo photon simulation of human hair is next outlined. Finally, current knowledge of the optical studies of hair is discussed in the light of their possible contribution to melanoma development; the necessary future work needed to support this hypothesis is suggested.

Hair Follicle-Associated Pluripotent (HAP) Stem Cells in Gelfoam® Histoculture for Use in Spinal Cord Repair

The stem cell marker, nestin, is expressed in the hair follicle, both in cells in the bulge area (BA) and the dermal papilla (DP). Nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells of both the BA and DP have been previously shown to be able to form neurons, heart muscle cells, and other non-follicle cell types. The ability of the nestin-expressing HAP stem cells from the BA and DP to repair spinal cord injury was compared. Nestin-expressing HAP stem cells from both the BA and DP grew very well on Gelfoam^®. The HAP stem cells attached to the Gelfoam^® within 1 h. They grew along the grids of the Gelfoam^® during the first 2 or 3 days. Later they spread into the Gelfoam^®. After transplantation of Gelfoam^® cultures of nestin-expressing BA or DP HAP stem cells into the injured spinal cord (including the Gelfoam^®) nestin-expressing BA and DP cells were observed to be viable over 100 days post-surgery. Hematoxylin and eosin (H&E) staining showed connections between the transplanted cells and the host spine tissue. Immunohistochemistry showed many Tuj1-, Isl 1/2, and EN1-positive cells and nerve fibers in the transplanted area of the spinal cord after BA Gelfoam^® or DP Gelfoam^® cultures were transplanted to the spine. The spinal cord of mice was injured to effect hind-limb paralysis. Twenty-eight days after transplantation with BA or DP HAP stem cells on Gelfoam^® to the injured area of the spine, the mice recovered normal locomotion.

Bioprinting of skin constructs for wound healing

Extensive burns and full-thickness skin wounds are difficult to repair. Autologous split-thickness skin graft (ASSG) is still used as the gold standard in the clinic. However, the shortage of donor skin tissues is a serious problem. A potential solution to this problem is to fabricate skin constructs using biomaterial scaffolds with or without cells. Bioprinting is being applied to address the need for skin tissues suitable for transplantation, and can lead to the development of skin equivalents for wound healing therapy. Here, we summarize strategies of bioprinting and review current advances of bioprinting of skin constructs. There will be challenges on the way of 3D bioprinting for skin regeneration, but we still believe bioprinting will be potential skills for wounds healing in the foreseeable future.

Isolation and Culture of Neural Crest Stem Cells from Human Hair Follicles

The hair follicle undergoes lifelong cycling and growth. Previous studies have been focused on epithelial stem cells in the hair follicles. Neural crest stem cells (NCSCs) are pluripotent cells that can persist in adult tissues. We have previously demonstrated that human NCSCs can be isolated from hair follicles. Here, we present a protocol to isolate NCSCs from human hair follicles based on their specific surface-marker expression of CD271/HNK1 or CD271/CD49D (alpha4 integrin). NCSCs can be expanded in the culture as neural spheres or attached cells.

Nerve Growth and Interaction in Gelfoam® Histoculture: A Nervous System Organoid

Nestin-expressing hair follicle-associated pluripotent (HAP) stem cells reside mainly in the bulge area (BA) of the hair follicle but also in the dermal papilla (DP). The BA appears to be origin of HAP stem cells. Long-term Gelfoam^® histoculture was established of whiskers isolated from transgenic mice, in which there is nestin-driven green fluorescent protein (ND-GFP). HAP stem cells trafficked from the BA toward the DP area and extensively grew out onto Gelfoam^® forming nerve-like structures. These fibers express the neuron marker β-III tubulin-positive fibers and consisted of ND-GFP-expressing cells and extended up to 500 mm from the whisker nerve stump in Gelfoam^® histoculture. The growing fibers had growth cones on their tips expressing F-actin indicating that the fibers were growing axons. HAP stem cell proliferation resulted in elongation of the follicle nerve and interaction with other nerves in 3D Gelfoam^® histoculture, including the sciatic nerve, trigeminal nerve, and trigeminal nerve ganglion.

Direct Conversion of Mouse Embryonic Fibroblasts into Neural Crest Cells

Neural crest cells (NCCs) are multipotent cells that emerge from the edges of the neural folds and extensively migrate throughout developing embryos. Dorsolaterally migrating NCCs colonize skin, differentiate into skin melanocytes, and lose their multipotency. Multipotent NCCs or NCCs derived multipotent stem cells (MSCs) were recently detected in their migrated locations, including skin, despite restrictions in cell fate acquisition following migration. Since many features of NCCs have yet to be revealed, the novel properties of NCCs represent an important and interesting field in stem cell biology. We previously reported the direct conversion of mouse embryonic fibroblasts (MEFs) into NCCs by the forced expression of the transcription factors C-MYC, KLF4, and SOX10. We herein describe the methods employed for direct conversion: retrovirus infection for the forced expression of transcription factors, a flow cytometry-sorting method for the isolation of converted NCCs, and culture methods for the maintenance and differentiation of the converted NCCs.

Distinguishing States of Arrest: Genome-Wide Descriptions of Cellular Quiescence Using ChIP-Seq and RNA-Seq Analysis

Regenerative potential in adult stem cells is closely associated with the establishment of-and exit from-a temporary state of quiescence. Emerging evidence not only provides a rationale for the link between lineage determination programs and cell cycle regulation but also highlights the understanding of quiescence as an actively maintained cellular program, encompassing networks and mechanisms beyond mitotic inactivity or metabolic restriction. Interrogating the quiescent genome and transcriptome using deep-sequencing technologies offers an unprecedented view of the global mechanisms governing this reversibly arrested cellular state and its importance for cell identity. While many efforts have identified and isolated pure target stem cell populations from a variety of adult tissues, there is a growing appreciation that their isolation from the stem cell niche in vivo leads to activation and loss of hallmarks of quiescence. Thus, in vitro models that recapitulate the dynamic reversibly arrested stem cell state in culture and lend themselves to comparison with the activated or differentiated state are useful templates for genome-wide analysis of the quiescence network.In this chapter, we describe the methods that can be adopted for whole genome epigenomic and transcriptomic analysis of cells derived from one such established culture model where mouse myoblasts are triggered to enter or exit quiescence as homogeneous populations. The ability to synchronize myoblasts in G₀ permits insights into the genome in "deep quiescence." The culture methods for generating large populations of quiescent myoblasts in either 2D or 3D culture formats are described in detail in a previous chapter in this series (Arora et al. Methods Mol Biol 1556:283-302, 2017). Among the attractive features of this model are that genes isolated from quiescent myoblasts in culture mark satellite cells in vivo (Sachidanandan et al., J Cell Sci 115:2701-2712, 2002) providing a validation of its approximation of the molecular state of true stem cells. Here, we provide our working protocols for ChIP-seq and RNA-seq analysis, focusing on those experimental elements that require standardization for optimal analysis of chromatin and RNA from quiescent myoblasts, and permitting useful and revealing comparisons with proliferating myoblasts or differentiated myotubes.

In vitro identification of a stem cell population from canine hair follicle bulge region

Skin is an extensive and easily accessible organ possessing various cell types that are constantly renewed. Previous studies have suggested the presence of a stem cell niche at the bulge region of the hair follicle, which contains cells positive for CD200 and CD34. Thus, this study sought to identify these cell populations in canine skin cells using the following methods 1- collecting samples of adult and fetal skin and isolating and culturing these cells using a method of simple enzymatic digestion and 2- testing the cell cultures for CD200 and CD34 in vitro and comparing them with skin tissue samples (in situ). Immunofluorescence results were negative for both CD200 and CD34 in frozen and paraffin embedded tissue, whereas the analysis showed that cultured cells positive for CD34, CD200 and double positive cells could be visualized in different percentages. Additionally, the pluripotency marker OCT4 was positive in the isolated cells. Analysis of CD34, CD200 and OCT4 by RT-qPCR showed that there is expression in fetal and adult cells, although no difference was observed between groups. Our results suggest that bulge stem cells from both fetuses and adult dogs were reported with the use of CD34 and CD200 markers in this study, and further techniques for cell isolation and in vitro cultivation are needed in order to obtain enriched populations of skin stem cells in dogs.

The patterns of birthmarks suggest a novel population of melanocyte precursors arising around the time of gastrulation

Systematic work in the mouse and chicken has mapped out two neural crest-derived pathways of melanocyte precursor migration. With these in mind, this study reappraises the patterns of congenital pigmentary disorders in humans and identifies three recurrent patterns consistent across genetically different diseases. Only two of these are seen in diseases known to be melanocyte cell-autonomous. The segmental pattern correlates well with the classical dorsolateral population from animal studies, demonstrating respect of the midline, cranio-caudal axial mixing, unilateral migration and involvement of key epidermally derived structures. Importantly however, the melanocyte precursors responsible for the non-segmental pattern, which demonstrates circular, bilateral migration centred on the midline, and not involving key epidermally derived structures, have not been identified previously. We propose that this population originates around the time of gastrulation, most likely within the mesoderm, and ultimately resides within the dermis. Whether it contributes to mature melanocytes in non-disease states is not known; however, parallels with the patterns of acquired vitiligo would suggest that it does. The third pattern, hypo- or hyperpigmented fine and whorled Blaschko's lines, is proposed to be non-cell-autonomous.

Hair follicle-associated-pluripotent (HAP) stem cells

Various types of stem cells reside in the skin, including keratinocyte progenitor cells, melanocyte progenitor cells, skin-derived precursors (SKPs), and nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells. HAP stem cells, located in the bulge area of the hair follicle, have been shown to differentiate to nerve cells, glial cells, keratinocytes, smooth muscle cells, cardiac muscle cells, and melanocytes. HAP stem cells are positive for the stem-cell marker CD34, as well as K15-negative, suggesting their relatively undifferentiated state. Therefore, HAP stem cells may be the most primitive stem cells in the skin. Moreover, HAP stem cells can regenerate the epidermis and at least parts of the hair follicle. These results suggest that HAP stem cells may be the origin of other stem cells in the skin. Transplanted HAP stem cells promote the recovery of peripheral-nerve and spinal-cord injuries and have the potential for heart regeneration as well. HAP stem cells are readily accessible from everyone, do not form tumors, and can be cryopreserved without loss of differentiation potential. These results suggest that HAP stem cells may have greater potential than iPS or ES cells for regenerative medicine.

Bulge Region as a Putative Hair Follicle Stem Cells Niche: A Brief Review

BACKGROUND

Hair follicle stem cells exist in different sites. Most of the hair follicle stem cells are reside in niche called bulge. Bulge region is located between the opening of sebaceous gland and the attachment site of the arrector pili muscle.

METHODS

Data were collected using databases and resources of PubMed, Web of Science, Science Direct, Scopus, MEDLINE and their references from the earliest available published to identify English observational studies on hair follicle bulge region.

RESULTS

Bulge stem cells are pluripotent with high proliferative capacity. Specific markers allow the bulge cells to be isolated from mouse or human hair follicle. Stem cells isolated from bulge region are label retaining and slow cycling hence these cells are defined as label-retaining cells. Bulge cell populations, due to their plasticity nature are able to differentiate into distinct linage and could contribute in tissue regeneration.

CONCLUSION

The current review discuss about bulge stem cells characteristics and biology including their cycle, location, plasticity, specific markers and regenerative nature. Also the differences between mouse and human hair follicles are investigated.

Stem cells from human hair follicles: first mechanical isolation for immediate autologous clinical use in androgenetic alopecia and hair loss

BACKGROUND

Hair follicles are known to contain a well-characterized niche for adult stem cells: the bulge, which contains epithelial and melanocytic stem cells. Stem cells in the hair bulge, a clearly demarcated structure within the lower permanent portion of hair follicles, can generate the interfollicular epidermis, hair follicle structures, and sebaceous glands. The bulge epithelial stem cells can also reconstitute in an artificial in vivo system to a new hair follicle.

METHODS

In this study, we have developed a new method to isolate human adult stem cells by mechanical centrifugation of punch biopsy from human hair follicles without culture condition. Here, we used human follicle stem cells (HFSCs), to improve the hair density in 11 patients (38 to 61 years old) affected by AGA in stage 3-5 as determined by the Norwood-Hamilton classification scale.

RESULTS

The primary outcomes were microscopic identification and counting of HFSCs. The secondary outcomes were clinical preliminary results and safety and feasibility in HFSCs-treated scalp. Each scalp tissue suspension contained about 3,728.5±664.5 cells. The percentage of hair follicle-derived mesenchymal stem cells CD44+ [from dermal papilla (DP)] was about 5%+0.7% whereas the percentage of hair follicle epithelial stem cells CD200+ (from the bulge) was about 2.6%+0.3%. In total, 23 weeks after the last treatment with HFSCs mean hair count and hair density increases over baseline values. In particular, a 29%±5% increase in hair density for the treated area and less than a 1% increase in hair density for the placebo area.

CONCLUSIONS

We have shown that the isolated cells are capable to improve the hair density in patients affected by androgenetic alopecia (AGA). These cells appear to be located in the bulge area of human.

Hair & skin derived progenitor cells: In search of a candidate cell for regenerative medicine

BACKGROUND & OBJECTIVES

Skin is an established tissue source for cell based therapy. The hair follicle has been introduced later as a tissue source for cell based therapy. The ease of tissue harvest and multipotent nature of the resident stem cells in skin and hair follicle has promoted basic and clinical research in this area. This study was conducted to evaluate skin stem cells (SSCs) and hair follicle stem cells (HFSCs) as candidate cells appropriate for neuronal and melanocyte lineage differentiation.

METHODS

In this study, SSCs and hair follicle stem cells (HFSCs) were expanded in vitro by explant culture method and were compared in terms of proliferative potential and stemness; differentiation potential into melanocytes and neuronal lineage.

RESULTS

SSCs were found to be more proliferative in comparison to HFSCs, however, telomerase activity was more in HFSCs in comparison to SSCs. Capacity to differentiate into two lineages of ectoderm origin (neuronal and melanocyte) was found to be different. HFSCs cells showed more propensities towards melanocyte lineage, whereas SSCs were more inclined towards neuronal lineage.

INTERPRETATION & CONCLUSIONS

The study showed that SSCs had differential advantage over the HFSCs for neuronal cell differentiation, whereas, the HFSCs were better source for melanocytic differentiation.

Differentiation of nestin‑negative human hair follicle outer root sheath cells into neurons in vitro

A specialized quiescent population of hair follicle stem cells, residing in the hair follicle outer root sheath cells (ORSCs), has previously demonstrated pluripotency for differentiation into neural stem cells (NSCs). A previous study indicated that nestin-positive hair follicle ORSCs are able to differentiate into neurons. However, little has been reported on the isolation of nestin-negative human ORSCs and whether they can successfully differentiate into neurons in vitro. In the present study, nestin-positive ORSCs were significantly reduced with a prolonged incubation time in vitro. Following 9 days of primary culture, nestin-expressing ORSCs disappeared entirely, and ORSCs remained nestin-negative following 5 days of subculture. Notably, nestin was identified in ORSCs following a three-step process of neuro-induction. In addition, neruodevelopmental markers were detected in the ORSC-derived nestin-positive spherical cell mass, including the induction of the neuronal specific markers growth associated protein-43, neurotensin receptor-3 and p75 neurotrophin receptor, and also the gliocyte markers, glial fibrillary acidic protein and S100. These sphere-forming cells did not express the mature neuron-associated markers neurofilament medium, neuronal nuclei and neuron-specific enolase, which suggested that sphere-forming cells may preferentially differentiate into neural stem cell-like cells as opposed to mature neurons or neurogliocyte. In conclusion, ORSC-driven neural differentiation may be a suitable treatment strategy for neurodegenerative diseases and may possess an important value in regenerative medicine.

Induction of osteoblastic differentiation of neural crest-derived stem cells from hair follicles

The neural crest (NC) arises near the neural tube during embryo development. NC cells migrate throughout the embryo and have potential to differentiate into multiple cell types, such as peripheral nerves, glial, cardiac smooth muscle, endocrine, and pigment cells, and craniofacial bone. In the present study, we induced osteoblast-like cells using whisker follicles obtained from the NC of mice. Hair follicle cells derived from the NC labeled with enhanced green fluorescent protein (EGFP) were collected from protein zero-Cre/floxed-EGFP double transgenic mice and cultured, then treated and cultured in stem cell growth medium. After growth for 14 days, results of flow cytometry analysis showed that 95% of the EGFP-positive (EGFP+) hair follicle cells derived from the NC had proliferated and 76.2% of those expressed mesenchymal stem cells markers, such as platelet-derived growth factor α and stem cell antigen-1, and also showed constitutive expression of Runx2 mRNA. Cells stimulated with bone morphogenetic protein-2 expressed osteocalcin, osterix, and alkaline phosphatase mRNA, resulting in production of mineralized matrices, which were detected by von Kossa and alizarin red staining. Moreover, EGFP+ hair follicle cells consistently expressed macrophage colony-stimulating factor and osteoprotegerin (OPG). Addition of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] (10-8 M) to the cultures suppressed OPG expression and induced RANKL production in the cells. Furthermore, multinucleated osteoclasts appeared within 6 days after starting co-cultures of bone marrow cells with EGFP+ cells in the presence of 1,25(OH)2D3 and PGE2. These results suggest that NC-derived hair follicle cells possess a capacity for osteoblastic differentiation and may be useful for developing new bone regenerative medicine therapies.

Neuronal Differentiation Capability of Nasal Polyps of Chronic Rhinosinusitis

Chronic rhinosinusitis with nasal polyps is considered a subgroup of chronic rhinosinusitis and a significant health problem, but the pathogenesis remains unclear to date. Therefore, we investigated the stemness to determine the role of stem cells in nasal polyps, with additional analysis of the neuronal differentiation potential of nasal polyp cells. We determined gene and protein expression profiles of stem cells in nasal polyp tissues, using whole genome microarray, quantitative real-time PCR (qPCR), immunohistochemistry, and flow cytometry. To evaluate the neuronal differentiation potential of nasal polyp cells, we used an efficient xenogeneic co-culture model with unsliced adult rat brain biopsies, followed by qPCR, immunohistochemistry, and growth factor antibody arrays. During gene expression analysis and immunohistochemistry, we were able to detect different stem cell markers, like Oct-4, Sox2, Klf4, c-Myc, ABCG2, Nanog, CD133, and Nestin, which confirmed the existence of stem cell like cells within nasal polyps. In addition, co-culture experiments give evidence for a guided differentiation into the neuronal lineage by overexpression of Nestin, Neurofilament, and GM-CSF. Our study demonstrated the expression of stem cell-related markers in nasal polyps. Furthermore, we characterized, for the first time, the stemness and neuronal differentiation potential of nasal polyp cells. These results gave new insights into the pathogenesis of nasal polyps and its therapeutic effectiveness could represent a promising strategy in the future.

Intermediate Reprogramming of Mouse Skin Fibroblasts into Stem-Like Cells by Bone Morphogenetic Protein 4

Specific transcription factors are sufficient to reprogram fully induced pluripotent stem cells or other types of cells. These findings raise the question of whether chemical molecules or proteins can replace transcription factors to alter the defined cell fate. In this study, we treated mouse skin fibroblasts (MSFs) with bone morphogenetic protein 4 (BMP4) and examined intermediate reprogramming of MSFs into stem-like cells. Putative epidermal stem cells isolated from the ventral skin epidermis of an adult mouse were used to confirm the reprogramming activity of BMP4, which increased the proliferation of these cells. After these cells formed spheroids, they were treated with BMP4 and cultured for 5 days. Following BMP4 treatment, the characteristics of these cells changed, and they expressed Oct-4 and its target transcripts Nanog, Sox2, and alkaline phosphatase. To confirm the stem cell potency of these cells, we induced their differentiation into cardiomyocytes. Stem-like cell-derived cardiomyocytes exhibited mRNA expression of cardiac mesoderm markers such as Nk2 transcription factor-related locus 5 and connexin 40, and the cardiomyocyte marker troponin T. These differentiated cells exhibited contracting masses. These results suggest that BMP4-mediated somatic stem cell reprogramming may become an alternative approach for cell therapy.

A Novel View of the Adult Stem Cell Compartment From the Perspective of a Quiescent Population of Very Small Embryonic-Like Stem Cells

Evidence has accumulated that adult hematopoietic tissues and other organs contain a population of dormant stem cells (SCs) that are more primitive than other, already restricted, monopotent tissue-committed SCs (TCSCs). These observations raise several questions, such as the developmental origin of these cells, their true pluripotent or multipotent nature, which surface markers they express, how they can be efficiently isolated from adult tissues, and what role they play in the adult organism. The phenotype of these cells and expression of some genes characteristic of embryonic SCs, epiblast SCs, and primordial germ cells suggests their early-embryonic deposition in developing tissues as precursors of adult SCs. In this review, we will critically discuss all these questions and the concept that small dormant SCs related to migratory primordial germ cells, described as very small embryonic-like SCs, are deposited during embryogenesis in bone marrow and other organs as a backup population for adult tissue-committed SCs and are involved in several processes related to tissue or organ rejuvenation, aging, and cancerogenesis. The most recent results on successful ex vivo expansion of human very small embryonic-like SC in chemically defined media free from feeder-layer cells open up new and exciting possibilities for their application in regenerative medicine.

Lentiviral transduction and subsequent loading with nanoparticles do not affect cell viability and proliferation in hair-follicle-bulge-derived stem cells in vitro

The application of stem cells in the treatment of various degenerative diseases is highly promising. However, cell-based therapy could be limited by the problem of low viability of grafted cells and uncertainty about their fate. The combination of molecular imaging and contrast-enhanced MRI may give more insight into the survival and behavior of grafted stem cells. We explore hair-follicle-bulge-derived stem cells (HFBSCs) as a potential candidate for autologous cell-based therapy. HFBSCs are transduced with a lentiviral construct with genes coding for bioluminescent (Luc2) and fluorescent (copGFP) reporter proteins, and subsequently loaded with magnetic nanoparticles to enable MRI visualization. Thus, we investigate for the first time if lentiviral transduction and cellular loading with nanoparticles have a cytotoxic effect upon these stem cells. Transduction efficiency, proliferation rate, cell viability and reporter protein co-expression during long-term culture of transduced HFBSCs were studied using fluorescence and bioluminescence microscopy. In addition, the effect of TMSR50 nanoparticles on proliferation and viability was investigated using the MTS assay and bioluminescence microscopy. The amount of TMSR50-loaded HFBSCs needed to reach signal threshold for MRI was assessed using an agarose phantom. Transduction with the Luc2-copGFP construct did not influence senescence, proliferation, doubling time, and differentiation of the HFBSCs. CopGFP expression was visible immediately after transduction and persisted for at least 15 passages, concomitantly with Luc2 expression. Cellular loading with TMSR50 nanoparticles did not affect cell viability and proliferation. The results imply that combined MRI and bioluminescence imaging may enable in vivo localization and long-term monitoring of grafted viable HFBSCs. Copyright © 2016 John Wiley & Sons, Ltd.

Engineering of the human vessel wall with hair follicle stem cells in vitro

Hair follicle stem cells (HFSCs) are increasingly used as a stem cell paradigm in vascular tissue engineering due to the fact that they are a rich source of easily accessible multipotent adult stem cells. Promising results have been demonstrated with small diameter (less than 6 mm) tissue engineered blood vessels under low blood pressure, however engineering large vessels (>6 mm in diameter) remains a challenge due to the fact it demands a higher number of seed cells and higher quality biomechanical properties. The aim of the current study was to engineer a large vessel (6 mm in diameter) with differentiated smooth muscle cells (SMCs) induced from human (h)HFSCs using transforming growth factor‑β1 and platelet‑derived growth factor BB in combination with low‑serum culture medium. The cells were seeded onto polyglycolic acid and then wrapped around a silicone tube and further cultured in vitro. A round vessel wall was formed subsequent to 8 weeks of culture. Histological examination indicated that layers of smooth muscle‑like cells and collagenous fibres were oriented in the induced group. In contrast, disorganised cells and collagenous fibres were apparent in the undifferentiated group. The approach developed in the current study demonstrated potential for constructing large muscular vessels with differentiated SMCs induced from hHFSCs.

Human hair-follicle associated pluripotent (hHAP) stem cells differentiate to cardiac-muscle cells

We have previously demonstrated that nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells are located in the bulge area. HAP stem cells have been previously shown to differentiate to neurons, glial cells, keratinocytes, smooth-muscle cells, melanocytes and cardiac-muscle cells in vitro. Subsequently, we demonstrated that HAP stem cells could effect nerve and spinal cord regeneration in mouse models, differentiating to Schwann cells and neurons. In previous studies, we established an efficient protocol for the differentiation of cardiac-muscle cells from mouse HAP stem cells. In the present study, we isolated the upper part of human hair follicles containing human HAP (hHAP) stem cells. The upper parts of human hair follicles were suspended in DMEM containing 10% FBS where they differentiated to cardiac-muscle cells as well as neurons, glial cells, keratinocytes and smooth-muscle cells. This method is appropriate for future use with human hair follicles to produce hHAP stem cells in sufficient quantities for future heart, nerve and spinal cord regeneration in the clinic.

PRDM1/BLIMP1 is widely distributed to the nascent fetal-placental interface in the mouse gastrula

BACKGROUND

PRDM1 is a transcriptional repressor that contributes to primordial germ cell (PGC) development. During early gastrulation, epiblast-derived PRDM1 is thought to be restricted to a lineage-segregated germ line in the allantois. However, given recent findings that PGCs overlap an allantoic progenitor pool that contributes widely to the fetal-umbilical interface, posterior PRDM1 may also contribute to soma.

RESULTS

Within the posterior mouse gastrula (early streak, 12-s stages, embryonic days ∼6.75-9.0), PRDM1 localized to all tissues containing putative PGCs; however, PRDM1 was also found in all three primary germ layers, their derivatives, and two presumptive growth centers, the allantoic core domain and ventral ectodermal ridge. While PRDM1 and STELLA colocalized predominantly within the hindgut, where putative PGCs reside, other colocalizing cells were found in non-PGC sites. Additional PRDM1 and STELLA cells were found independent of each other throughout the posterior region, including the hindgut. The Prdm1-Cre-driven reporter supported PRDM1 localization in the majority of sites; however, some Prdm1 descendants were found in sites independent of PRDM1 protein, including allantoic mesothelium and hindgut endoderm.

CONCLUSIONS

Posterior PRDM1 contributes more broadly to the developing fetal-maternal connection than previously recognized, and PRDM1 and STELLA, while overlapping in putative PGCs, also co-localize in several other tissues. Developmental Dynamics 246:50-71, 2017. © 2016 Wiley Periodicals, Inc.

Induced pluripotent stem cells from human hair follicle keratinocytes as a potential source for in vitro hair follicle cloning

Background

Human hair follicles are important for the renewal of new hairs and their development. The generation of induced pluripotent stem cells (iPSCs) from hair follicles is easy due to its accessibility and availability. The pluripotent cells derived from hair follicles not only have a higher tendency to re-differentiate into hair follicles, but are also more suited for growth in hair scalp tissue microenvironment.

Methods

In this study, human hair follicular keratinocytes were used to generate iPSCs, which were then further differentiated in vitro into keratinocytes. The derived iPSCs were characterised by using immunofluorescence staining, flow cytometry, and reverse-transcription PCR to check for its pluripotency markers expression.

Results

The iPSC clones expressed pluripotency markers such as TRA-1-60, TRA-1-81, SSEA4, OCT4, SOX2, NANOG, LEFTY, and GABRB. The well-formed three germ layers were observed during differentiation using iPSCs derived from hair follicles. The successful formation of keratioctyes from iPSCs was confirmed by the expression of cytokeratin 14 marker.

Discussion

Hair follicles represent a valuable keratinocytes source for in vitro hair cloning for use in treating hair balding or grafting in burn patients. Our significant findings in this report proved that hair follicles could be used to produce pluripotent stem cells and suggested that the genetic and micro-environmental elements of hair follicles might trigger higher and more efficient hair follicles re-differentiation.

Comparative Transcriptome Analysis Reveals that a Ubiquitin-Mediated Proteolysis Pathway Is Important for Primary and Secondary Hair Follicle Development in Cashmere Goats

Background

The fleece of cashmere goats contains two distinct populations of fibers, a short and fine non-medullated insulating cashmere fiber and a long and coarse medullated guard hair. The former is produced by secondary follicles (SFs) and the later by primary follicles (PFs). Evidence suggests that the induction of PFs and SFs may require different signaling pathways. The regulation of BMP2/4 signaling by noggin and Edar signaling via Downless genes are essential for the induction of SFs and PFs, respectively. However, these differently expressed genes of the signaling pathway cannot directly distinguish between the PFs and SFs.

Results

In this study, we selected RNA samples from 11 PFs and 7 SFs that included 145,525 exons. The pathway analysis of 4512 differentially expressed exons revealed that the most statistically significant metabolic pathway was related to the ubiquitin–mediated proteolysis pathway (UMPP) (P<3.32x 10⁻⁷). In addition, the 51 exons of the UMPP that were differentially expressed between the different types of hair follicle (HFs) were compared by cluster analysis. This resulted in the PFs and SFs being divided into two classes. The expression level of two selected exons was analyzed by qRT-PCR, and the results indicated that the expression patterns were consistent with the deep sequencing results obtained by RNA-Seq.

Conclusions

Based on the comparative transcriptome analysis of 18 HFs from cashmere goats, a large number of differentially expressed exons were identified using a high-throughput sequencing approach. This study suggests that UMPP activation is a prominent signaling pathway for distinguishing the PFs and SFs of cashmere goats. It is also a meaningful contribution to the theoretical basis of the biological study of the HFs of cashmere goats and other mammals.

Identification and isolation of kidney-derived stem cells from transgenic rats with diphtheria toxin-induced kidney damage

Adult stem cells have been well characterized in numerous organs, with the exception of the kidneys. Therefore, the present study aimed to identify and isolate kidney-derived stem cells. A total of 12 Fischer 344 transgenic rats expressing the human diphtheria toxin receptor in podocyte cells of the kidney, were used in the present study. The rats were administered 5-bromo-2′-deoxyuridine (BrdU) in order to detect cellular proliferation. After 60 days, the rats were treated with the diphtheria toxin (DT), in order to induce kidney injury. Immunohistochemical analysis indicated that the number of BrdU-positive cells were increased following DT treatment. In addition, the expression of octamer-binding transcription factor 4 (Oct-4), a stem cell marker, was detected and suggested that kidney-specific stem cells were present in the DT-treated tissue samples. Furthermore, tissue samples exhibited repair of the DT-induced injury. Further cellular culturing was conducted in order to isolate the kidney-specific stem cells. After 5 weeks of culture, the majority of the cells were non-viable, with the exception of certain specialized, unique cell types, which were monomorphic and spindle-shaped in appearance. The unique cells were isolated and subjected to immunostaining and reverse transcription-polymerase chain reaction analyses in order to reconfirm the expression of Oct-4 and to detect the expression of Paired box 2 (Pax-2), which is necessary for the formation of kidney structures. The unique cells were positive for Oct-4 and Pax-2; thus suggesting that the identified cells were kidney-derived stem cells. The results of the present study suggested that the unique cell type identified in the kidneys of the DT-treated rats were kidney-specific stem cells that may have been involved in the repair of DT-induced tissue injury. In addition, these cells may provide a useful cell line for studying the fundamental characteristics of kidney stem cells, as well as identifying kidney-specific stem cell markers.

Expression of pluripotency markers in Arbas Cashmere goat hair follicle stem cells

In our previous work, we found that the Inner Mongolia Arbas Cashmere goat hair follicle stem cells (gHFSCs) can be successfully differentiated into adipocyte, chondrocyte, and osteocyte lineages. In this study, we further examined the expression of the pluripotency and stemness markers Oct4, Nanog, Sox2, AKP, and TERT in gHFSCs by immunocytochemistry, flow cytometry, real-time PCR, and Western blot. Immunofluorescent staining showed that the gHFSCs were positive for all five markers. Fluorescence-activated cell sorting (FACS) further analyzed the positive expression of Oct4, Nanog, and Sox2 in the gHFSCs. Compared with Arbas Cashmere goat adipose-derived stem cells (gADSCs) at the mRNA expression level, Oct4 was relatively highly expressed in gHFSCs, 41.36 times of the gADSCs, and Nanog was 5.61, AKP was 2.74, and TERT was 2.10 times, respectively (p < 0.01). Western blot indicated that all markers are expressed at the protein level in the gHFSCs. When compared with gADSCs, using α-tubulin as a reference protein, gray intensity analysis showed that the expression of Oct4, Nanog, AKP, and TERT were, respectively, 5.94, 10.78, 1.33, and 1.39 times of gADSCs. Additionally, mRNA and protein expression of Sox2 were detected in the gHFSCs but not in the gADSCs. The protein expression pattern of these markers was consistent with the mRNA results.

Studying the expression patterns of OCT4 and SOX2 proteins in regenerating rabbit ear tissue

Epimorphic regeneration in New Zealand rabbit ear is an interesting example of mammalian wound healing in which blastema formation is involved in replacement of injured tissues. It has been suggested that isolated cells from regenerating rabbit ear possess stem-like properties. In this study, we aimed to determine the expression of stemness markers, OCT4 and SOX2 proteins, in regenerating rabbit tissues by immunohistochemistry. Results indicated that both proteins could be detected in epithelial cells, hair follicle cells and perichondrium cells. Expression pattern analysis of OCT4 and SOX2 proteins showed no clear differences between regenerative and non-regenerative control tissues. According to several reports of OCT4 and SOX2 proteins expression in adult stem cells, it could be proposed that OCT4 and SOX2 expressing cells in regenerating rabbit ear tissues are progenitor/adult stem cells which are resident in these tissues, and other markers should be used for detection of blastema cells.

Lgr5 Marks Neural Crest Derived Multipotent Oral Stromal Stem Cells

It has been suggested that multipotent stem cells with neural crest (NC) origin persist into adulthood in oral mucosa. However their exact localization and role in normal homeostasis is unknown. In this study, we discovered that Lgr5 is expressed in NC cells during embryonic development, which give rise to the dormant stem cells in the adult tongue and oral mucosa. Those Lgr5 positive oral stromal stem cells display properties of NC stem cells including clonal growth and multipotent differentiation. RNA sequencing revealed that adult Lgr5+ oral stromal stem cells express high number of neural crest related markers like Sox9, Twist1, Snai1, Myc, Ets1, Crabp1, Epha2, and Itgb1. Using lineage-tracing experiments, we show that these cells persist more than a year in the ventral tongue and some areas of the oral mucosa and give rise to stromal progeny. In vivo transplantation demonstrated that these cells reconstitute the stroma. Our studies show for the first time that Lgr5 is expressed in the NC cells at embryonic day 9.5 (E9.5) and is maintained during embryonic development and postnataly in the stroma of the ventral tongue, and some areas of the oral mucosa and that Lgr5+ cells participate in the maintenance of the stroma.

Introduction to Hair-Follicle-Associated Pluripotent Stem Cells

Nestin-expressing stem cells of the hair follicle, discovered by our laboratory, have been shown to be able to form outer-root sheaths of the follicle as well as neurons and many other non-follicle cell types. We have termed the nestin-expressing stem cells of the hair follicle as hair-follicle-associated pluripotent (HAP) stem cells. We have shown that the HAP stem cells from the hair follicle can effect the repair of peripheral nerve and spinal cord injury. The hair follicle stem cells differentiate into neuronal and glial cells after transplantation to the injured peripheral nerve and spinal cord, and enhance injury repair and locomotor recovery. When the excised hair follicle with its nerve stump was placed in Gelfoam(®) 3D histoculture, HAP stem cells grew and extended the hair follicle nerve which consisted of βIII-tubulin-positive fibers with F-actin expression at the tip. These findings indicate that βIII-tubulin-positive fibers elongating from the whisker follicle sensory nerve stump were growing axons. The growing whisker sensory nerve was highly enriched in HAP stem cells, which appeared to play a major role in its elongation and interaction with other nerves in 3D Gelfoam(®) histoculture, including the sciatic nerve, the trigeminal nerve, and the trigeminal nerve ganglion. These results suggest that a major function of the HAP stem cells in the hair follicle is for growth of the follicle sensory nerve. Recently, we have shown that HAP stem cells can differentiate into beating cardiac muscle cells. HAP stem cells have critical advantages for regenerative medicine over embryonic stem (ES) cells and induced pluripotent stem (iPS) cells in that they are highly accessible from each patient, thereby eliminating immunological issues since they are autologous, require no genetic manipulation, are non-tumorigenic, and do not present ethical issues.

Comparison of autologous versus allogeneic epithelial-like stem cell treatment in an in vivo equine skin wound model

BACKGROUND AIMS

Several studies report beneficial effects of autologous and allogeneic stem cells on wound healing. However, no comparison between autologous versus allogeneic epithelial-like stem cells (EpSCs) has been made so far. For this reason, we first hypothesize that both EpSC types enhance wound healing in comparison to vehicle treatment and untreated controls. Second, on the basis of other studies, we hypothesized that there would be no difference between autologous and allogeneic EpSCs.

METHODS

Twelve full-thickness skin wounds were created in six horses. Each horse was subjected to (i) autologous EpSCs, (ii) allogeneic EpSCs, (iii) vehicle treatment or (iv) untreated control. Wound evaluation was performed at day 3, 7 and 14 through wound exudates and at week 1, 2 and 5 through biopsies.

RESULTS

Wound circumference and surface were significantly smaller in autologous EpSC-treated wounds. A significantly lower amount of total granulation tissue (overall) and higher vascularization (week 1) was observed after both EpSC treatments. Significantly more major histocompatibility complex II-positive and CD20-positive cells were noticed in EpSC-treated wounds at week 2. In autologous and allogeneic groups, the number of EpSCs in center biopsies was low after 1 week (11.7% and 6.1%), decreased to 7.6% and 1.7%, respectively (week 2), and became undetectable at week 5.

CONCLUSIONS

These results confirm the first hypothesis and partially support the second hypothesis. Besides macroscopic improvements, both autologous and allogeneic EpSCs had similar effects on granulation tissue formation, vascularization and early cellular immune response.

Hair follicle stem cells: In vitro and in vivo neural differentiation

Hair follicle stem cells (HFSCs) normally give rise to keratinocytes, sebocytes, and transient amplifying progenitor cells. Along with the capacity to proliferate rapidly, HFSCs provide the basis for establishing a putative source of stem cells for cell therapy. HFSCs are multipotent stem cells originating from the bulge area. The importance of these cells arises from two important characteristics, distinguishing them from all other adult stem cells. First, they are accessible and proliferate for long periods. Second, they are multipotent, possessing the ability to differentiate into mesodermal and ectodermal cell types. In addition to a developmental capacity in vitro, HFSCs display an ability to form differentiated cells in vivo. During the last two decades, numerous studies have led to the development of an appropriate culture condition for producing various cell lineages from HFSCs. Therefore, these stem cells are considered as a novel source for cell therapy of a broad spectrum of neurodegenerative disorders. This review presents the current status of human, rat, and mouse HFSCs from both the cellular and molecular biology and cell therapy perspectives. The first section of this review highlights the importance of HFSCs and in vitro differentiation, while the final section emphasizes the significance of cell differentiation in vivo.

From hair to heart: nestin-expressing hair-follicle-associated pluripotent (HAP) stem cells differentiate to beating cardiac muscle cells

We have previously demonstrated that the neural stem-cell marker nestin is expressed in hair follicle stem cells located in the bulge area which are termed hair-follicle-associated pluripotent (HAP) stem cells. HAP stem cells from mouse and human could form spheres in culture, termed hair spheres, which are keratin 15-negative and CD34-positive and could differentiate to neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Subsequently, we demonstrated that nestin-expressing stem cells could effect nerve and spinal cord regeneration in mouse models. In the present study, we demonstrated that HAP stem cells differentiated to beating cardiac muscle cells. We separated the mouse vibrissa hair follicle into 3 parts (upper, middle, and lower), and suspended each part separately in DMEM containing 10% FBS. All three parts of hair follicle differentiated to beating cardiac muscle cells as well as neurons, glial cells, keratinocytes and smooth muscle cells. The differentiation potential to cardiac muscle is greatest in the upper part of the follicle. The beat rate of the cardiac muscle cells was stimulated by isoproterenol and inhibited by propanolol. HAP stem cells have potential for regenerative medicine for heart disease as well as nerve and spinal cord repair.

In vitro neural differentiation of CD34 (+) stem cell populations in hair follicles by three different neural induction protocols

Differentiation of hair follicle stem cells (HFSCs) into neurons and glial cells represents a promising cell-based therapy for neurodegenerative diseases. The hair follicle bulge area is reported as a putative source of new stem cell population for many years. In vitro studies have implicated neural differentiation of HFSCs. Here, we report the identification and purification of CD34 (+) cells from hair follicle by magnetic activated cell sorting (MACS). We next determined the cytotoxic effects of all-trans retinoic acid (RA) by using cell viability assays. Moreover, the neural differentiation potential of CD34 (+) cells was evaluated in the presence of RA, serum-free condition, and neural differentiation medium (NDM) treatments by using immunocytochemistry and reverse transcription polymerase chain reaction (RT-PCR). Our results showed that the isolated CD34 (+) stem cells were 12% of the total cells in the bulge area, and the neural cells derived from the stem cells expressed nestin, microtubule-associated protein 2 (MAP2), and glial fibrillary acidic protein (GFAP). Interestingly, all the neural induction media supported neuronal differentiation most effectively, but treatment with serum-free medium significantly increased the number of GFAP-positive glial cells. Moreover, increasing RA concentration (≥10 μM) leads to increased cell death in the cells, but a lower concentration of RA (1 μM) treatment results in a decrease in CD34-expressing stem cells. These findings show an instructive neuronal effect of three neural induction media in HFSCs, indicating the important role of this induction media in the specification of the stem cells toward a neural phenotype.

Augmenting peripheral nerve regeneration using stem cells: A review of current opinion

Outcomes following peripheral nerve injury remain frustratingly poor. The reasons for this are multifactorial, although maintaining a growth permissive environment in the distal nerve stump following repair is arguably the most important. The optimal environment for axonal regeneration relies on the synthesis and release of many biochemical mediators that are temporally and spatially regulated with a high level of incompletely understood complexity. The Schwann cell (SC) has emerged as a key player in this process. Prolonged periods of distal nerve stump denervation, characteristic of large gaps and proximal injuries, have been associated with a reduction in SC number and ability to support regenerating axons. Cell based therapy offers a potential therapy for the improvement of outcomes following peripheral nerve reconstruction. Stem cells have the potential to increase the number of SCs and prolong their ability to support regeneration. They may also have the ability to rescue and replenish populations of chromatolytic and apoptotic neurons following axotomy. Finally, they can be used in non-physiologic ways to preserve injured tissues such as denervated muscle while neuronal ingrowth has not yet occurred. Aside from stem cell type, careful consideration must be given to differentiation status, how stem cells are supported following transplantation and how they will be delivered to the site of injury. It is the aim of this article to review current opinions on the strategies of stem cell based therapy for the augmentation of peripheral nerve regeneration.

Stem cells and aberrant signaling of molecular systems in skin aging

The skin is the body's largest organ and it is able to self-repair throughout an individual's life. With advanced age, skin is prone to degenerate in response to damage. Although cosmetic surgery has been widely adopted to rejuvinate skin, we are far from a clear understanding of the mechanisms responsible for skin aging. Recently, adult skin-resident stem/progenitor cells, growth arrest, senescence or apoptotic death and dysfunction caused by alterations in key signaling genes, such as Ras/Raf/MEK/ERK, PI3K/Akt-kinases, Wnt, p21 and p53, have been shown to play a vital role in skin regeneration. Simultaneously, enhanced telomere attrition, hormone exhaustion, oxidative stress, genetic events and ultraviolet radiation exposure that result in severe DNA damage, genomic instability and epigenetic mutations also contribute to skin aging. Therefore, cell replacement and targeting of the molecular systems found in skin hold great promise for controlling or even curing skin aging.