Differential expression of stem cell markers in human follicular bulge and interfollicular epidermal compartments.
ABSTRACT Although skin contains a number of stem cell repositories, their characterization has been hindered by a lack of specific markers and an unclear in vivo localization. In this study, we whole mounted single human scalp hair follicles and examined their profiles using in situ immunohistochemistry and multicolor immunofluorescence in search of markers to distinguish between stem cells residing in the interfollicular epidermis (IFE) and bulge. Our study revealed that expression of several biomarkers localized uniquely to the basal IFE (CD34 and CD117), bulge region (CD200), or both (CK15, CD49f, and CD29). In addition, we found that both basal IFE and bulge stem cells did not express CD71 or CD24 suggesting their potential utility as negative selection markers. Dermal papilla but not basal IFE or bulge stem cells expressed CD90, making it a potential positive selection marker for dermal hair follicle stem cells. The markers tested in this study may enable pursuit of cell sorting and purification strategies aimed at determining each stem cell population's unique molecular signature.
SourceAvailable from: Francisco Jimenez[Show abstract] [Hide abstract]
ABSTRACT: Epithelial hair follicle stem cells (eHFSCs) are required to generate, maintain and renew the continuously cycling hair follicle (HF), supply cells that produce the keratinized hair shaft and aid in the reepithelialization of injured skin. Therefore, their study is biologically and clinically important, from alopecia to carcinogenesis and regenerative medicine. However, human eHFSCs remain ill defined compared to their murine counterparts, and it is unclear which murine eHFSC markers really apply to the human HF. We address this by reviewing current concepts on human eHFSC biology, their immediate progeny and their molecular markers, focusing on Keratin 15 and 19, CD200, CD34, PHLDA1, and EpCAM/Ber-EP4. After delineating how human eHFSCs may be selectively targeted experimentally, we close by defining as yet unmet key challenges in human eHFSC research. The ultimate goal is to transfer emerging concepts from murine epithelial stem cell biology to human HF physiology and pathology.BioEssays 05/2014; 36(5). DOI:10.1002/bies.201300166 · 4.84 Impact Factor
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ABSTRACT: The arrector pili muscle (APM) consists of a small band of smooth muscle that connects the hair follicle to the connective tissue of the basement membrane. The APM mediates thermoregulation by contracting to increase air-trapping, but was thought to be vestigial in humans. The APM attaches proximally to the hair follicle at the bulge, a known stem cell niche. Recent studies have been directed toward this muscle's possible role in maintaining the follicular integrity and stability. This review summarizes APM anatomy and physiology and then discusses the relationship between the follicular unit and the APM. The potential role of the APM in hair loss disorders is also described, and a model explaining APM changes in hair loss is proposed.International Journal of Trichology 07/2014; 6(3):88-94. DOI:10.4103/0974-7753.139077
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ABSTRACT: Human embryonic stem cells (hESC) are capable of extensive self-renewal and expansion and can differentiate into any somatic tissue, making them useful for regenerative medicine applications. Allogeneic transplantation of hESC-derived tissues from results in immunological rejection absent adjunctive immunosuppression. The goal of our study was to generate a universal pluripotent stem cell source by nucleofecting a mutated human leukocyte antigen G (mHLA-G) gene into hESC using the PiggyBac transposon. We successfully generated stable mHLA-G(EF1α)-hESC lines using chEF1α promoter system that stably expressed mHLA-G protein during prolonged undifferentiated proliferation andin differentiated embryoid bodies as well as teratomas. Morphology, karyotype, and telomerase activity of mHLA-G expressing hESC were normal. Immunofluorescence staining and flow cytometry analysis revealed persistent expression of pluripotent markers, OCT-3/4 and SSEA-4, in undifferentiated mHLA-G(EF1α)-hESC. Nucleofected hESC formed teratomas and when directed to differentiate into epidermal precursors, expressed high levels of mHLA-G and keratinocyte markers K14 and CD29. Natural killer cell cytotoxicity assays demonstrated a significant decrease in lysis of mHLA-G(EF1a)-hESC targets relative to control cells. Similar results were obtained with mHLA-G(EF1α)-hESC-derived epidermal progenitors (hEEP). One way mixed T lymphocyte reactions unveiled that mHLA-G(EF1a)-hESC and -hEEP restrained the proliferative activity of mixed T lymphocytes. We conclude that heterologous expression of mHLA-G decreases immunogenicity of hESC and their epidermal differentiated derivatives.Stem Cell Research 09/2014; 13(2). DOI:10.1016/j.scr.2014.08.004 · 3.91 Impact Factor