Towards the development of a pragmatic technique for isolating and differentiating nestin-positive cells from human scalp skin into neuronal and glial cell populations: generating neurons from human skin?

Keratin Microspheres as Promising Tool for Targeting Follicular Growth

Skin is the body barrier that constrains the infiltration of particles and exogenous aggression, in which the hair follicle plays an important role. Recent studies have shown that small particles can penetrate the skin barrier and reach the hair follicle, making them a potential avenue for delivering hair growth-related substances. Interestingly, keratin-based microspheres are widely used as drug delivery carriers in various fields. In this current study, we pursue the effect of newly synthesized 3D spherical keratin particles on inducing hair growth in C57BL/6 male mice and in human hair follicle dermal papilla cells. The microspheres were created from partially sulfonated, water-soluble keratin. The keratin microspheres swelled in water to form spherical gels, which were used for further experiments. Following topical application for a period of 20 days, we observed a regrowth of hair in the previously depleted area on the dorsal part of the mice in the keratin microsphere group. This observation was accompanied by the regulation of hair-growth-related pathways as well as changes in markers associated with epidermal cells, keratin, and collagen. Interestingly, microsphere keratin treatment enhanced the cell proliferation and the expression of hair growth markers in dermal papilla cells. Based on our data, we propose that 3D spherical keratin has the potential to specifically target hair follicle growth and can be employed as a carrier for promoting hair growth-related agents.

Exploring the human hair follicle microbiome

Human hair follicles (HFs) carry complex microbial communities that differ from the skin surface microbiota. This likely reflects that the HF epithelium differs from the epidermal barrier in that it provides a moist, less acidic, and relatively ultraviolet light-protected environment, part of which is immune-privileged, thus facilitating microbial survival. Here we review the current understanding of the human HF microbiome and its potential physiological and pathological functions, including in folliculitis, acne vulgaris, hidradenitis suppurativa, alopecia areata and cicatricial alopecias. While reviewing the main human HF bacteria (such as Propionibacteria, Corynebacteria, Staphylococci and Streptococci), viruses, fungi and parasites as human HF microbiome constituents, we advocate a broad view of the HF as an integral part of the human holobiont. Specifically, we explore how the human HF may manage its microbiome via the regulated production of antimicrobial peptides (such as cathelicidin, psoriasin, RNAse7 and dermcidin) by HF keratinocytes, how the microbiome may impact on cytokine and chemokine release from the HF, and examine hair growth-modulatory effects of antibiotics, and ask whether the microbiome affects hair growth in turn. We highlight major open questions and potential novel approaches to the management of hair diseases by targeting the HF microbiome.

Human skin-derived precursor cells xenografted in aganglionic bowel

PURPOSE

One in 5000 newborns is diagnosed with Hirschsprung disease each year in the United States. The potential of employing neural crest stem cells to restore the enteric nervous system has been investigated. Skin-derived precursor cells (SKPs) are multipotent progenitor cells that can differentiate into neurons and gliocytes in vitro and generate enteric ganglion-like structures in rodents. Here we examined the behavior of human SKPs (hSKPs) after their transplantation into a large animal model of colonic aganglionosis.

METHODS

Juvenile minipigs underwent a chemical denervation of the colon to establish an aganglionosis model. The hSKPs were generated from human foreskin and were cultured in neuroglial-selective medium. Cells were labeled with a fluorescent dye and were injected into the porcine aganglionic colon. After one week, transplanted hSKPs were assessed by immunofluorescence for markers of multipotency and neuroglial differentiation.

RESULTS

In culture, hSKPs expressed nestin and S100b indicative of neuroglial precursors. After xenografting in pigs, hSKPs were identified in the myenteric and submucosal plexuses of the colons. The hSKPs expressed nestin and early neuroglial differentiation markers.

CONCLUSIONS

Human SKPs transplanted into aganglionic colon demonstrated immunophenotypes of neuroglial progenitors, suggesting their potential use for Hirschsprung disease.

Therapeutic implications of immunohistochemical expression pattern of the cancer stem cell marker (nestin) in basal and squamous cell carcinomas

Cancer stem cells (CSC) are populations of cells responsible for tumor initiation, progression and therapeutic resistance in many cancers. In the present study, we aimed to investigate the expression pattern and clinical significance of the stem cell marker nestin, in Squaous cell carcinoma (SCC) and basal cell carcinoma (BCC). The samples (23 cases of BCC and 22 cases of SCC) were immunohistochemically examined for the expression of nestin and its correlation with the corresponding clinical and pathological parameters. Nestin was expressed in four out of the 23 cases of BCC (17.4%) and was expressed in 10 out of the 22 cases of SCC (45.5%). Nestin expression between the two tumors was statistically significant (P = .042). Although a direct relationship was found between the tumor grade and nestin expression, the results were statistically insignificant (P = .495). The results of this study suggest that BCC and SCC may share some cellular origin but with different biologic behavior. The relation of nestin expression to the grade of SCC, although statistically insignificant, may suggest its role in predicting the biologic behavior of this tumor.

The Fate of Transplanted Olfactory Progenitors Is Conditioned by the Cell Phenotypes of the Receiver Brain Tissue in Cocultures

Among the numerous candidates for cell therapy of the central nervous system (CNS), olfactory progenitors (OPs) represent an interesting alternative because they are free of ethical concerns, are easy to collect, and allow autologous transplantation. In the present study, we focused on the optimization of neuron production and maturation. It is known that plated OPs respond to various trophic factors, and we also showed that the use of Nerve Growth Factor (NGF) allowed switching from a 60/40 neuron/glia ratio to an 80/20 one. Nevertheless, in order to focus on the integration of OPs in mature neural circuits, we cocultured OPs in primary cultures obtained from the cortex and hippocampus of newborn mice. When dissociated OPs were plated, they differentiated into both glial and neuronal phenotypes, but we obtained a 1.5-fold higher viability in cortex/OP cocultures than in hippocampus/OP ones. The fate of OPs in cocultures was characterized with different markers such as BrdU, Map-2, and Synapsin, indicating a healthy integration. These results suggest that the integration of transplanted OPs might by affected by trophic factors and the environmental conditions/cell phenotypes of the host tissue. Thus, a model of coculture could provide useful information on key cell events for the use of progenitors in cell therapy.

Nestin+ progenitor cells isolated from adult human sweat gland stroma promote reepithelialisation and may stimulate angiogenesis in wounded human skin ex vivo

The combination of an aging population and an increasing prevalence of diseases associated with impaired-wound healing, including obesity, peripheral vascular disease and diabetes, is likely to result in a dramatic increase in the incidence and prevalence of chronic skin wounds. Indeed, systemic reviews are now not only trying to establish both the prevalence and the often under-estimated socio-economic costs of chronic skin wounds, but most importantly are addressing the impact that chronic wounds have on quality of life. Given the clear need for novel approaches to the management of chronic skin ulceration, ideally developed and tested in the human system in a manner that can be rapidly translated into clinical practice, we examined the effects of multipotent primary human nestin⁺ progenitor cells on human wound healing in an ex vivo model. Human sweat gland-derived nestin⁺ cells demonstrated the capacity to significantly promote two key wound healing parameters, i.e., both reepithelialisation and angiogenesis in experimentally wounded, organ-cultured human skin. The current data further support the use of full-thickness human skin wound-healing models ex vivo to pre-clinically test wound healing-promoting candidate agents. Whilst larger studies are required to substantiate a firm “proof-of-concept,” our preliminary studies encourage further efforts to systemically determine the potential of cell-based regenerative medicine strategies in general, and the use of skin appendage-associated human nestin⁺ cells in particular, as novel treatment strategies for chronic skin ulceration.

Early IV-injected human dermis-derived mesenchymal stem cells after transient global cerebral ischemia do not pass through damaged blood-brain barrier

There is lack of researches on effects of intravenously injected mesenchymal stem cells (MSCs) against transient cerebral ischemia (TCI). We investigated the disruption of the neurovascular unit (NVU), which comprises the blood-brain barrier and examined entry of human dermis-derived MSCs (hDMSCs) into the damaged hippocampal CA1 area in a gerbil model of TCI and their subsequent effects on neuroprotection and cognitive function. Impairments of neurons and blood-brain barrier were examined by immunohistochemistry, electron microscopy, and Evans blue and immunoglobulin G leakage. Neuronal death was observed in pyramidal neurons 5-day postischemia. NVU were structurally damaged; in particular, astrocyte end-feet were severely damaged from 2-day post-TCI and immunoglobulin G leaked out of the CA1 area 2 days after 5 min of TCI; however, Evans blue extravasation was not observed. On the basis of the results of NVU damages, ischemic gerbils received PKH2-transfected hDMSCs 3 times at early times (3 hr, 2, and 5 days) after TCI, and fluorescence imaging was used to detect hDMSCs in the tissue. PKH2-transfected hDMSCs were not found in the CA1 from immediate time to 8 days after injection, although they were detected in the liver. Furthermore, hDMSCs transplantation did not protect CA1 pyramidal neurons and did not improve cognitive impairment. Intravenously transplanted hDMSCs did not migrate to the damaged CA1 area induced by TCI. These findings suggest no neuroprotection and cognitive improvement by intravenous hDMSCs transplantation after 5 min of TCI.

Cell-based therapies of liver diseases: age-related challenges

The scope of this review is to revise recent advances of the cell-based therapies of liver diseases with an emphasis on cell donor's and patient's age. Regenerative medicine with cell-based technologies as its integral part is focused on the structural and functional restoration of tissues impaired by sickness or aging. Unlike drug-based medicine directed primarily at alleviation of symptoms, regenerative medicine offers a more holistic approach to disease and senescence management aimed to achieve restoration of homeostasis. Hepatocyte transplantation and organ engineering are very probable forthcoming options of liver disease treatment in people of different ages and vigorous research and technological innovations in this area are in progress. Accordingly, availability of sufficient amounts of functional human hepatocytes is crucial. Direct isolation of autologous hepatocytes from liver biopsy is problematic due to related discomfort and difficulties with further expansion of cells, particularly those derived from aging people. Allogeneic primary human hepatocytes meeting quality standards are also in short supply. Alternatively, autologous hepatocytes can be produced by reprogramming of differentiated cells through the stage of induced pluripotent stem cells. In addition, fibroblasts and mesenchymal stromal cells can be directly induced to undergo advanced stage hepatogenic differentiation. Reprogramming of cells derived from elderly people is accompanied by the reversal of age-associated changes at the cellular level manifesting itself by telomere elongation and the U-turn of DNA methylation. Cell reprogramming can provide high quality rejuvenated hepatocytes for cell therapy and liver tissue engineering. Further technological advancements and establishment of national and global registries of induced pluripotent stem cell lines homozygous for HLA haplotypes can allow industry-style production of livers for immunosuppression-free transplantation.

LPS-Stimulated Human Skin-Derived Stem Cells Enhance Neo-Vascularization during Dermal Regeneration

High numbers of adult stem cells are still required to improve the formation of new vessels in scaffolds to accelerate dermal regeneration. Recent data indicate a benefit for vascularization capacity by stimulating stem cells with lipopolysaccharide (LPS). In this study, stem cells derived from human skin (SDSC) were activated with LPS and seeded in a commercially available dermal substitute to examine vascularization in vivo. Besides, in vitro assays were performed to evaluate angiogenic factor release and tube formation ability. Results showed that LPS-activated SDSC significantly enhanced vascularization of the scaffolds, compared to unstimulated stem cells in vivo. Further, in vitro assays confirmed higher secretion rates of proangiogenic as well as proinflammatoric factors in the presence of LPS-activated SDSC. Our results suggest that combining activated stem cells and a dermal substitute is a promising option to enhance vascularization in scaffold-mediated dermal regeneration.

TAT conjugated cationic noble metal nanoparticles for gene delivery to epidermal stem cells

Most nonviral gene delivery systems are not efficient enough to manipulate the difficult-to-transfect cell types, including non-dividing, primary, neuronal or stem cells, due to a lack of an intrinsic capacity to enter the membrane and nucleus, release its DNA payload, and activate transcription. Noble metal nanoclusters have emerged as a fascinating area of widespread interest in nanomaterials. Herein, we report the synthesis of the TAT peptide conjugated cationic noble metal nanoparticles (metal NPs@PEI-TAT) as highly efficient carriers for gene delivery to stem cells. The metal NPs@PEI-TAT integrate the advantages of metal NPs and peptides: the presence of metal NPs can effectively decrease the cytotoxicity of cationic molecules, making it possible to apply them in biological systems, while the cell penetrating peptides are essential for enhanced cellular and nucleus entry to achieve high transfection efficiency. Our studies provide strong evidence that the metal NPs@PEI-TAT can be engineered as gene delivery agents for stem cells and subsequently enhance their directed differentiation for biomedical application.

Immunohistological localization of endogenous unlabeled stem cells in wounded skin

Various types of endogenous stem cells (SCs) participate in wound healing in the skin at different anatomical locations. SCs need to be identified through multiple markers, and this is usually performed using flow cytometry. However, immunohistological identification of endogenous stem cells in the skin at different anatomical locations by co-staining multiple SC markers has been seldom explored. We examined the immunohistological localization of four major types of SCs in wounded skin by co-staining for their multiple markers. Hematopoietic SCs were co-stained for Sca1 and CD45; mesenchymal SCs for Sca1, CD29, and CD106; adipose SCs for CD34, CD90, and CD105; and endothelial progenitor cells and their differentiated counterparts were co-stained for CD34, Tie2, and von Willebrand factor. We found Sca1(+)CD45(+) SCs in the epidermis, dermis and hypodermis of wounded skin. Sca1(+)CD29(+) and Sca1(+)CD106(+) mesenchymal SCs, CD34(+)CD105(+), CD34(+)CD90(+), and CD90(+)CD105(+) adipose SCs, as well as CD34(+)Tie2(+) endothelial progenitor cells were also located in the epidermis, dermis, and hypodermis. This study demonstrates the feasibility of using immunohistological staining to determine the location of SCs in wounded skin and the intracellular distribution of their molecular markers.

Differentiating the stem cell pool of human hair follicle outer root sheath into functional melanocytes

Bench-to-Bedside concepts for regenerative therapy place significant weight on noninvasive approaches, with harvesting of the starting material as a header. This is particularly important in autologous treatments, which use one's bodily constituents for therapy. Precisely the stretch between obtaining therapeutic elements invasively and noninvasively places non-intrusive "sampling" rather than "biopsy" in the center of the road map of developing an autologous regenerative therapy. We focus on such a noninvasively available source of adult stem cells that we carry with us throughout our life, available at our fingertips-or shall we say hair roots, by a simple plucking of hair: the human hair follicle. This chapter describes an explant procedure for cultivating melanocytes differentiated from the stem cell pool of the hair follicle Outer Root Sheath (ORS). In vivo, the most abundant derivatives of the heterogeneous ORS stem cell pool are epidermal cells-melanocytes and keratinocytes which complete their differentiation-either spontaneously or upon picking up regenerative cues from damaged skin-and migrate from the ORS towards the adjacent regenerating area of the epidermis. We have taken advantage of the ORS developmental potential by optimizing explant primary culture, expansion and melanogenic differentiation of resident ORS stem cells towards end-stage melanocytes in order to obtain functional melanocytes noninvasively for the purposes of transplantation and use them for the treatment of depigmentation disorders. Our protocol specifies sampling of hair with their ORS, follicle medium-air interface primary culture, stimulation of cell outgrowth, adherent culture and differentiation of ORS stem cells and precursors towards fully functional melanocytes. Along with cultivation, we describe selection techniques for establishing and maintaining a pure melanocyte population and methods suitable for determining melanocyte identity.

Multipotent nestin-positive stem cells reside in the stroma of human eccrine and apocrine sweat glands and can be propagated robustly in vitro

Human skin harbours multiple different stem cell populations. In contrast to the relatively well-characterized niches of epidermal and hair follicle stem cells, the localization and niches of stem cells in other human skin compartments are as yet insufficiently investigated. Previously, we had shown in a pilot study that human sweat gland stroma contains Nestin-positive stem cells. Isolated sweat gland stroma-derived stem cells (SGSCs) proliferated in vitro and expressed Nestin in 80% of the cells. In this study, we were able to determine the precise localization of Nestin-positive cells in both eccrine and apocrine sweat glands of human axillary skin. We established a reproducible isolation procedure and characterized the spontaneous, long-lasting multipotent differentiation capacity of SGSCs. Thereby, a pronounced ectodermal differentiation was observed. Moreover, the secretion of prominent cytokines demonstrated the immunological potential of SGSCs. The comparison to human adult epidermal stem cells (EpiSCs) and bone marrow stem cells (BMSCs) revealed differences in protein expression and differentiation capacity. Furthermore, we found a coexpression of the stem cell markers Nestin and Iα6 within SGSCs and human sweat gland stroma. In conclusion the initial results of the pilot study were confirmed, indicating that human sweat glands are a new source of unique stem cells with multilineage differentiation potential, high proliferation capacity and remarkable self renewal. With regard to the easy accessibility of skin tissue biopsies, an autologous application of SGSCs in clinical therapies appears promising.

Human foreskin fibroblast-like stromal cells can differentiate into functional hepatocytic cells

Foreskin fibroblast-like stromal cells (FDSCs) are progenitors isolated from human tissue that can differentiate into diverse cell types. Many types of stem cells can differentiate into hepatocyte-like cells, which could be used for drug testing or in liver regeneration therapy, but whether FDSCs can be converted into functional hepatocytes is unknown. FDSCs show divergent properties when cultured in distinct media, forming spheres in Dulbecco's modified Eagle's medium (DMEM) containing F12, epidermal growth factor (EGF), and basic fibroblast growth factor (b-FGF), but have fibroblast-like morphology when cultured in DMEM-based growth medium. Both cell populations express the typical mesenchymal stem cell markers CD90, CD105, and CD73, but the p75 neurotrophin receptor (p75NTR) was detected only in FDSC spheres. Both types of FDSCs can differentiate into hepatocyte-like cells, which express typical liver markers, including albumin and hepatocyte paraffin 1 (Hep Par1), along with liver-specific biological activities. When plasmids containing the human hepatitis B virus (HBV) genome were transfected transiently into FDSCs, differentiated hepatocyte-like cells secrete large amounts of HBe and HBs antigens. FDSCs could be used for clinical hepatic therapy and/or serve as a model of HBV.

Mammary gland-derived nestin-positive cell populations can be isolated from human male and female donors

Introduction

Nestin-expressing cells isolated from different human tissues reveal self-renewal capacity and a multilineage differentiation potential. In particular, adult stem/progenitor cell populations from exocrine glands such as the pancreas, salivary gland and sweat gland are characterized by prominent nestin expression. Interestingly, human mammary gland histological examinations also demonstrated the existence of nestin-positive cells in the ductal compartments. Within the scope of our previous work we wonder whether an isolation of nestin-positive cell populations from human mammary gland biopsies is possible and what characteristics they have in vitro. Cell populations from both sexes were propagated and subjected to a comparison with other gland-derived cell populations.

Methods

Human mammary tissue biopsies were mechanically and enzymatically treated, and the isolated acini structures were observed with time-lapse microscopy to track adherently outgrowing cells. The proliferation potential of the cell population was assessed by performing growth curves. On the gene and protein levels we investigated the expression of stem cell markers as well as markers indicating multilineage differentiation.

Results

We succeeded in establishing proliferating cell populations from breast tissue biopsies of both sexes. Our results display several similarities to the glandular stem cell populations from other exocrine glands. Beside their proliferation capacity during in vitro culture, the obtained cell populations are characterized by their prominent nestin expression. The cells share surface proteins commonly expressed on adult stem cells. We demonstrated the expression of stem cell-related genes like Oct4, Sox2, KLF4 and Nanog, and confirmed multipotent differentiation capacity by detecting transcripts expressed in endodermal, mesodermal and ectodermal cell types.

Conclusion

With this study we present an efficient procedure for isolation and propagation of nestin-positive stem cells obtained from male and female breast tissue, which is frequently available. The established multipotent cell populations could be easily expanded in vitro and thus hold promise for cell-based therapies and personalized medicine.

Improved method of differentiation, selection and amplification of human melanocytes from the hair follicle cell pool

Hair root harbours a complex cell pool with an immense developmental potential. Several lineages, including skin, can be differentiated from the multipotent to pluripotent cells of outer root sheath (ORS) of hair follicle. Outer root sheath presents the most opulent non-invasively gained adult stem cell source known. For the purposes of cultivating melanocytes designated for graft-based treatments of depigmentation disorders, we have established an ex vivo/in vitro cultivation method by introducing several methodological improvements to the ORS explant method of Dieckmann. As a result, we gained a higher, purer yield of differentiated melanocytes in half the time (at least 10(6) of 95% pure cells in 4 weeks). This reliable cultivation procedure begins with the epilation of 60 hairs and yields high numbers of ORS melanocytes that could be used for grafting applications. The procedure not only utilises the developmental potential of hair root cell pool and favors differentiation into melanocytes, but also contributes to the general trend of minimal-to-non-invasive strategies for regenerative medicine.

Follicle and melanocyte stem cells, and their application in neuroscience: A Web of Science-based literature analysis

OBJECTIVE:

To identify global research trends of follicle and melanocyte stem cells, and their application in neuroscience.

DATA RETRIEVAL:

We performed a bibliometric analysis of studies from 2002 to 2011 on follicle and melanocyte stem cells, and their application in neuroscience, which were retrieved from the Web of Science, using the key words follicle stem cell or melanocyte stem cell, and neural, neuro or nerve.

SELECTION CRITERIA:

Inclusion criteria: (a) peer-reviewed published articles on follicle and melanocyte stem cells, and their application in neuroscience, which were indexed in the Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items. Exclusion criteria: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) a number of corrected papers from the total number of articles.

MAIN OUTCOME MEASURES:

(1) Distribution of publications on follicle and melanocyte stem cells by years, journals, countries, institutions, institutions in China, and most cited papers. (2) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by years, journals, countries, institutions, and most cited papers.

RESULTS:

Of the 348 publications from 2002 to 2011 on follicle and melanocyte stem cells, which were retrieved from the Web of Science, more than half were from American authors and institutes. The most prolific institutions in China for publication of papers on follicle and melanocyte stem cells were the Fourth Military Medical University and Third Military Medical University. The most prolific journals for publication of papers on follicle and melanocyte stem cells were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research. Of the 63 publications from 2002 to 2011 on the application of follicle and melanocyte stem cells in neuroscience, which were retrieved from the Web of Science, more than half were from American authors and institutes, and no papers were from Chinese authors and institutes. The most prolific journals for publication of papers on the application of follicle and melanocyte stem cells in neuroscience were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research.

CONCLUSION:

Based on our analysis of the literature and research trends, we found that follicle stem cells might offer further benefits in neural regenerative medicine.

Telocytes in human skin--are they involved in skin regeneration?

Telocytes (TCs), a particular interstitial cell type, have been recently described in a wide variety of mammalian organs (www.telocytes.com). The TCs are identified morphologically by a small cell body and extremely long (tens to hundreds of μm), thin prolongations (less than 100 nm in diameter, below the resolving power of light microscopy) called telopodes. Here, we demonstrated with electron microscopy and immunofluorescence that TCs were present in human dermis. In particular, TCs were found in the reticular dermis, around blood vessels, in the perifollicular sheath, outside the glassy membrane and surrounding sebaceous glands, arrector pili muscles and both the secretory and excretory portions of eccrine sweat glands. Immunofluorescence screening and laser scanning confocal microscopy showed two subpopulations of dermal TCs; one expressed c-kit/CD117 and the other was positive for CD34. Both subpopulations were also positive for vimentin. The TCs were connected to each other by homocellular junctions, and they formed an interstitial 3D network. We also found TCs adjoined to stem cells in the bulge region of hair follicles. Moreover, TCs established atypical heterocellular junctions with stem cells (clusters of undifferentiated cells). Given the frequency of allergic skin pathologies, we would like to emphasize the finding that close, planar junctions were frequently observed between TCs and mast cells. In conclusion, based on TC distribution and intercellular connections, our results suggested that TCs might be involved in skin homeostasis, skin remodelling, skin regeneration and skin repair.

The ventral proximal nail fold: stem cell niche of the nail and equivalent to the follicular bulge--a study on developing human skin

BACKGROUND

Although the bulge is well characterized as a stem cell niche of the hair follicle, comparatively little is known about the location of stem cells in the nail. Herein, we describe the spatiotemporal expression pattern of six stem cell markers in the developing human nail and compared it with the embryonic and fetal human hair follicle. The areas of proliferative activity were additionally examined using labeling with Ki-67.

METHODS

We examined immunohistochemically samples from embryonic and fetal human nail, hair and skin for the expression of cytokeratin 15 (CK15, two clones), cytokeratin 19 (CK19), PHLDA1, CD200, nestin and Ki-67 using standard techniques.

RESULTS

CK15 (clone LHK15), CK19 and PHLDA1 are negative in the nail and hair matrix but positive in the ventral proximal nail fold and in the follicular bulge. Over the course of embryogenesis they display a highly specific spatiotemporal expression pattern both in the nail and in the hair follicle.

CONCLUSIONS

We propose that at least during embryogenesis the proximal ventral nail fold represents the niche for the nail stem cells. In contrast to animal experiments, autoradiographic pulse-chasing studies cannot be performed in human, and immunohistochemical studies are a valid alternative although they have their limitations. Further studies on adult human nail units are suggested.

Impact of eugenol and isoeugenol on AhR translocation, target gene expression, and proliferation in human HaCaT keratinocytes

The phenolic derivatives eugenol and isoeugenol, which are naturally found in essential oils of different spices, are commonly used as fragrances. Recently data demonstrated that growth suppression produced by these substances occurs in keratinocytes and that the effects may be mediated via aryl hydrocarbon receptor (AhR) interactions. In this study the effects of eugenol and isoeugenol were determined on intracellular localization of AhR, AhR target gene expression, AhR-dependent cell cycle regulation, and proliferation in HaCaT cells. Both compounds produced a rapid and marked translocation of AhR into the nucleus, induced the expression of the AhR target genes cytochrome P-450 1A1 (CYP1A1) and AhR repressor (AhRR), and inhibited proliferation of HaCaT cells. Among the G(1) phase cell cycle-related proteins, levels of the retinoblastoma protein (RB), which is known to interact with AhR, and levels of the cyclin dependent kinase (CDK) 6 were reduced by eugenol and isoeugenol, whereas steady-state levels of CDK2 and CDK4 remained unaffected. Protein levels of CDK inhibitor (CKI) p27(KIP1), known to be modulated in an AhR-dependent manner, were increased after treatment with both substances. In conclusion, data show that the antiproliferative properties of eugenol and isoeugenol in HaCaT cells are mediated through AhR, and thereby the molecular mechanisms of action in these cells were identified for the first time in this study.

Human dermis harbors distinct mesenchymal stromal cell subsets

Multipotent mesenchymal stromal cells (MSCs) are found in a variety of adult tissues including human dermis. These MSCs are morphologically similar to bone marrow-derived MSCs, but are of unclear phenotype. To shed light on the characteristics of human dermal MSCs, this study was designed to identify and isolate dermal MSCs by a specific marker expression profile, and subsequently rate their mesenchymal differentiation potential. Immunohistochemical staining showed that MSC markers CD73/CD90/CD105, as well as CD271 and SSEA-4, are expressed on dermal cells in situ. Flow cytometric analysis revealed a phenotype similar to bone marrow-derived MSCs. Human dermal cells isolated by plastic adherence had a lower differentiation capacity as compared with bone marrow-derived MSCs. To distinguish dermal MSCs from differentiated fibroblasts, we immunoselected CD271(+) and SSEA-4(+) cells from adherent dermal cells and investigated their mesenchymal differentiation capacity. This revealed that cells with increased adipogenic, osteogenic, and chondrogenic potential were enriched in the dermal CD271(+) population. The differentiation potential of dermal SSEA-4(+) cells, in contrast, appeared to be limited to adipogenesis. These results indicate that specific cell populations with variable mesenchymal differentiation potential can be isolated from human dermis. Moreover, we identified three different subsets of dermal mesenchymal progenitor cells.

Expression of stem cell markers nestin and cytokeratin 15 and 19 in cutaneous malignancies

BACKGROUND

Emerging evidence is implicating stem cells in the pathogenesis of different cutaneous neoplasms. The immunohistochemical use of stem cell markers has facilitated stem cell identification. While few studies have examined the expression of cytokertatin (CK)15 and cytokeratin (CK)19 in basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), only rarely have nestin expression been examined in these two malignancies. Furthermore, stem cell marker expression, to the best of our knowledge, has not been examined in Merkel cell carcinoma (MCC).

METHODS

In this study, we examined the expression of stem cell markers CK15, CK19 and nestin in 51 overall cases (11 cases of MCC and 20 cases each of BCC and SCC) retrieved from the pathology files of Skin Pathology Laboratory, Boston University School of Medicine.

RESULTS

Cytokeratin 15 immunoreactivity was observed in 30% of BCC cases and only a single (5%) SCC case, while all MCC cases were negative. While 60% of BCC cases and 30% of SCC cases stained positively with CK19, all MCC cases showed positive immunostaining in a dot-like pattern. While negative in BCC and MCC, nestin expression was interestingly seen in 45% of SCC cases.

CONCLUSIONS

Our study described the expression profiles of stem cell markers CK15, CK19 and nestin in BCC, SCC and MCC. In addition to confirming results of the previous reports, our study also showed positive nestin expression in around half of SCC cases, which adds this malignancy to the cutaneous tumours that have been so far reported to exhibit nestin expression.

Basal cell carcinoma: cell of origin, cancer stem cell hypothesis and stem cell markers

Cancer stem cells have recently been described in several high-grade neoplasms. It is still unclear if they also occur in cutaneous malignancies. Cancer stem cells are not identical with somatic stem cells. The presence of tumour stem cells in a neoplasm does not in itself equal that the tumour derives from a somatic stem cell. A cell originally lacking stem cell characteristics could also acquire those features during the course of carcinogenesis and then becomes the clonal founder cell of a tumour. Basal cell carcinoma (BCC) is the most common cutaneous malignancy. A plethora of various stem cell markers has been applied to study its cellular origin. Intriguingly, the anatomical origin of BCC is still uncertain. This review will discuss the various stem cell markers used in BCC and the cellular origin of this tumour, and touches briefly on the possibility of cancer stem cells in BCC. If BCC or other skin cancers harbour tumour stem cells, these cells could be specifically targeted, making use of specific cell surface molecules such as receptor proteins. Novel drugs directed against those receptor proteins could replace currently available shotgun approaches including imiquimod.

Adult epidermal Notch activity induces dermal accumulation of T cells and neural crest derivatives through upregulation of jagged 1

Notch signalling regulates epidermal differentiation and tumour formation via non-cell autonomous mechanisms that are incompletely understood. This study shows that epidermal Notch activation via a 4-hydroxy-tamoxifen-inducible transgene caused epidermal thickening, focal detachment from the underlying dermis and hair clumping. In addition, there was dermal accumulation of T lymphocytes and stromal cells, some of which localised to the blisters at the epidermal-dermal boundary. The T cell infiltrate was responsible for hair clumping but not for other Notch phenotypes. Notch-induced stromal cells were heterogeneous, expressing markers of neural crest, melanocytes, smooth muscle and peripheral nerve. Although Slug1 expression was expanded in the epidermis, the stromal cells did not arise through epithelial-mesenchymal transition. Epidermal Notch activation resulted in upregulation of jagged 1 in both epidermis and dermis. When Notch was activated in the absence of epidermal jagged 1, jagged 1 was not upregulated in the dermis, and epidermal thickening, blister formation, accumulation of T cells and stromal cells were inhibited. Gene expression profiling revealed that epidermal Notch activation resulted in upregulation of several growth factors and cytokines, including TNFα, the expression of which was dependent on epidermal jagged 1. We conclude that jagged 1 is a key mediator of non-cell autonomous Notch signalling in skin.

[Cutaneous mesenchymal stem cells. Current status of research and potential clinical applications]

Within the next decade stem cell-based therapies can be expected to be part of clinical medicine. In regard to the skin, the focus of stem cell research is on the epidermis and the hair follicle. In 2001, mesenchymal stem cells residing within the dermis were first isolated which have the capacity to differentiate into adipocytes, smooth muscle cells, osteocytes, chondrocytes and even neurons and glia as well as hematopoietic cells of myeloid and erythroid lineage. The perifollicular connective tissue sheath and the papilla represent the likely anatomical niche for these multipotent dermal cells. They have the potential to function as an easily accessible, autologous source for future stem cell transplantation. Potential therapeutic applications include the treatment of acute and steroid-refractory graft-versus-host disease, systemic lupus erythematosus, idiopathic pulmonary fibrosis and arthritis. The neuronal differentiation potential of cutaneous mesenchymal stem cells may also be exploited in the treatment of neurodegenerative disorders and traumatic spinal injury. The most immediate impact can be expected in the field of wound healing.

Multilineage differentiation potential of fibroblast-like stromal cells derived from human skin

Adult stem cells that reside in adult tissues have been deemed to possess great potential for clinical application because of their capabilities of self-renewal and differentiation. However, the limitations such as infection risks and low isolation rate make the search for appropriate source to be continued. Here, we demonstrate isolation of progenitors from human foreskin tissue samples, which have fibroblast-like morphology and could be easily propagated for more than 50 passages. These foreskin-derived fibroblast-like stromal cells (FDSCs) expressed CD90, CD105, CD166, CD73, SH3, and SH4, which is similar to the immunophenotypes of human bone marrow-derived mesenchymal stem cells. In comparison with Hs68, the human fibroblast cell line, FDSCs are positive for CD105 and absent for CD54 expression. Further, FDSCs could be induced to differentiate into osteocytes, adipocytes, neural cells, smooth muscle cells, Schwann-like cells, and hepatocyte-like cells. Interestingly, when cultured in Dulbecco's modified Eagle's medium/F12 medium, FDSCs can form spheres with increased expression levels of fibronectin and vimentin. In conclusion, foreskin can serve as a valuable source of multipotent cells with the capabilities for endodermal, mesodermal, and ectodermal cells. Coupled with the advantages of their easy access, isolation, and propagation, these foreskin-derived stromal cells might be of potential use in future studies in stem cell differentiation and therapeutic application.

Primary neuroblastoma in the skin of an adult shih tzu dog

A subcutaneous mass arising in the right gluteal area of an 11-year-old female shih tzu dog was surgically excised. Histologically, the mass was composed of small round or ovoid neoplastic cells that were arranged in nests of various sizes. The neoplastic cells generally had hyperchromatic nuclei and scanty eosinophilic cytoplasm, and were surrounded by a pale pink fibrillar area. Immunohistochemically, the neoplastic cells were positive for vimentin, S-100 protein, neurone-specific enolase and synaptophysin, but negative for cytokeratin, neurofilament protein, glial fibrillary acidic protein and chromogranin A. On ultrastructural observation, aggregates of thin cytoplasmic processes were frequently seen among the neoplastic cells. Based on these features, the tumour was diagnosed as a neuroblastoma. To the authors' knowledge, this is the first description of a neuroblastoma originating from the skin in an adult dog.

Neuro-muscular differentiation of adult porcine skin derived stem cell-like cells

Background

Due to the genetic relationship to humans, porcine stem cells are a very important model system to investigate cell differentiation, associated cell signaling pathways, and cell fate. Porcine skin derived stem cells have been isolated from mid-gestation porcine fetus recently. To our knowledge, stem cells from the skin of the adult porcine organism have not been isolated until now. Hence, to our knowledge, we here describe the isolation, expansion, characterization and differentiation of multipotent porcine skin derived stem cell-like cells (pSSCs) from the adult porcine organism for the first time.

Methodology/Principal Findings

pSSCs had a spindle shaped morphology similar to mesenchymal stem cells (MSCs). They could be maintained proliferatively active in vitro for more than 120 days and were able to form colonies from single cells. pSSCs expressed Sox2 and Oct3/4, both transcription factors essential to the pluripotent and self-renewing phenotypes of embryonic stem cells, which recently gained attention due to their function in inducing pluripotent stem cells. Furthermore, the expression of the progenitor marker nestin, the somatic stem cell markers Bcrp1/ABCG2, Bmi1, and Stat3 was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in undifferentiated pSSCs. Flow cytometry revealed the expression of the MSC related proteins CD9, CD29, CD44 and CD105, but not CD90. After neuronal differentiation cells with a characteristic morphology of neuronal and smooth muscle-like cells were present in the cultures. Subsequent immunochemistry and flow cytometry revealed the down-regulation of nestin and the up-regulation of the neuron specific protein beta-III-tubulin and the astrocyte marker GFAP. Also, alpha-SMA expressing cells increased during differentiation suggesting the neuro-muscular differentiation of these skin derived cells. pSSCs could also be induced to differentiate into adipocyte-like cells when cultured under specific conditions.

Conclusions/Significance

Adult porcine skin harbors a population of stem cell-like cells (pSSCs) that can be isolated via enzymatic digestion. These pSSCs show characteristic features of MSCs originated in other tissues and express the embryonic stem cell marker Oct3/4, Sox2, and Stat3. Furthermore, pSSCs have the potential to differentiate into cells from two different germ lines, the ectoderm (neurons, astrocytes) and the mesoderm (smooth muscle cells, adipocytes).

Cutaneous mesenchymal stem cells: status of current knowledge, implications for dermatopathology

Stem cell biology is currently making its impact on medicine, which will probably increase over the next decades. It not only influences our therapeutic thinking caused by the enormous plasticity of stem cells but also affects diagnostic and conceptual aspects of dermatopathology. Although our knowledge of the keratinocytic stem cells located within the follicular bulge has exploded exponentially since their discovery in 1990, the concept of cutaneous mesenchymal stem cells (MSCs) is new. Described initially in 2001 in mice, MSCs later were also found in the human dermis. The connective tissue sheath and the papilla of the hair follicle probably represent the anatomical niche for cutaneous MSCs. In line with the cancer stem cell hypothesis, mutations of these cells may be the underlying basis of mesenchymal skin neoplasms, such as dermatofibrosarcoma protuberans. Furthermore, research on cutaneous MSCs may impact our thinking on the interaction of the epithelial component of skin neoplasms with their surrounding stroma. We are only in the early stages to recognize the importance of the potential contributions of cutaneous MSC research to dermatopathology, but it is not inconceivable to assume that they could be tremendous, paralleling the early discovery of the follicular bulge as a stem cell niche.

Exploring the role of stem cells in cutaneous wound healing

The skin offers a perfect model system for studying the wound healing cascade, which involves a finely tuned interplay between several cell types, pathways and processes. The dysregulation of these factors may lead to wound healing disorders resulting in chronic wounds, as well as abnormal scars such as hypertrophic and keloid scars. As the contribution of stem cells towards tissue regeneration and wound healing is increasingly appreciated, a rising number of stem cell therapies for cutaneous wounds are currently under development, encouraged by emerging preliminary findings in both animal models and human studies. However, we still lack an in-depth understanding of the underlying mechanisms through which stem cells contribute to cutaneous wound healing. The aim of this review is, therefore, to present a critical synthesis of our current understanding of the role of stem cells in normal cutaneous wound healing. In addition to summarizing wound healing principles and related key molecular and cellular players, we discuss the potential participation of different cutaneous stem cell populations in wound healing, and list corresponding stem cells markers. In summary, this review delineates current strategies, future applications, and limitations of stem cell-based or stem cell-targeted therapy in the management of acute and chronic skin wounds.

Stem cell-based therapies for spinal cord injury

Spinal cord injury (SCI) results in loss of nervous tissue and consequently loss of motor and sensory function. There is no treatment available that restores the injury-induced loss of function to a degree that an independent life can be guaranteed. Transplantation of stem cells or progenitors may support spinal cord repair. Stem cells are characterized by self-renewal and their ability to become any cell in an organism. Promising results have been obtained in experimental models of SCI. Stem cells can be directed to differentiate into neurons or glia in vitro, which can be used for replacement of neural cells lost after SCI. Neuroprotective and axon regeneration-promoting effects have also been credited to transplanted stem cells. There are still issues related to stem cell transplantation that need to be resolved, including ethical concerns. This paper reviews the current status of stem cell application for spinal cord repair.

The mesenchymal component of hair follicle neogenesis: background, methods and molecular characterization

Hair follicle morphogenesis and regeneration occur by an extensive and collaborative crosstalk between epithelial and mesenchymal skin components. A series of pioneering studies, which revealed an indispensable role of follicular dermal papilla and dermal sheath cells in this crosstalk, has led workers in the field to study in detail the anatomical distribution, functional properties, and molecular signature of the trichogenic dermal cells. The purpose of this paper was to provide a practical summary of the development and recent advances in the study of trichogenic dermal cells. Following a short review of the relevant literature, the methods for isolating and culturing these cells are summarized. Next, the bioassays, both in vivo and in vitro, that enable the evaluation of trichogenic properties of tested dermal cells are described in detail. A list of trichogenic molecular markers identified by those assays is also provided. Finally, this methods review is completed by defining some of the major questions needing resolution.