ORCID Profile
0000-0002-4994-2782
Current Organisation
Curtin University
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-04-2005
Abstract: The Drosophila cuticle is essential for maintaining the surface barrier defenses of the fly. Integral to cuticle resilience is the transcription factor grainy head , which regulates production of the enzyme required for covalent cross-linking of the cuticular structural components. We report that formation and maintenance of the epidermal barrier in mice are dependent on a mammalian homolog of grainy head, Grainy head-like 3 . Mice lacking this factor display defective skin barrier function and deficient wound repair, accompanied by reduced expression of transglutaminase 1, the key enzyme involved in cross-linking the structural components of the superficial epidermis. These findings suggest that the functional mechanisms involving protein cross-linking that maintain the epidermal barrier and induce tissue repair are conserved across 700 million years of evolution.
Publisher: Elsevier BV
Date: 08-2000
Publisher: Elsevier BV
Date: 03-2000
DOI: 10.1046/J.1523-1747.2000.00884.X
Abstract: The basal layer of human epidermis is a heterogeneous population of proliferative and differentiating cells that can be ided into at least three functionally discrete compartments: keratinocyte stem cells, transit lifying cells, and postmitotic differentiating cells. Basal cells adhere to the underlying basement membrane via integrins, and although decreased adhesion is a key event in epidermal differentiation, the specific role of particular integrins is poorly understood. We report here on the comparative expression and function of the beta1 versus alpha6beta4 integrins in keratinocyte stem cells, transit lifying cells, and postmitotic differentiating cells of neonatal human foreskin epidermis. Adhesion assays demonstrate that both keratinocyte stem cells and transit lifying cells comprise rapidly adhering cells that exhibit high levels of functional beta1 and alpha6beta4 integrins. Interestingly, a proportion of basal cells that have begun to differentiate in vivo within the basal layer as determined by their expression of the differentiation-specific markers K10 and involucrin also retain high levels of activated beta1 integrin, but downregulate alpha6beta4 expression selectively (termed alpha6dimbeta1bri). These cells also retain their adhesive capacity, indicating that induction of differentiation in vivo does not correlate with decreased beta1 integrin expression or function. We have previously reported on the use of alpha6 integrin in conjunction with a proliferation associated marker (10G7 ag) to separate keratinocyte stem cells (phenotype alpha6bri10G7dim) from other basal cells (Li et al. Proc Natl Acad Sci 95:3902-3907 1998). A comparison of the long-term proliferative potential of beta1bri10G7dim cells with alpha6bri10G7dim showed that selection of alpha6bri10G7dim allows the isolation of a purer fraction of keratinocyte stem cells.
Publisher: Proceedings of the National Academy of Sciences
Date: 15-01-1991
Abstract: We have developed a model system for progression of human epithelial cells to malignancy, using a human papillomavirus type 18 (HPV-18)-immortalized human keratinocyte cell line. Cells of cell line FEP-1811 were nontumorigenic in athymic mice through at least 12 passages in culture, but after 32 passages were weakly tumorigenic, producing tumors that regressed. After 62 passages they produced invasive squamous cell carcinomas that grew progressively. The progression to malignancy was associated with an increase in the efficiency of forming colonies in soft agar and with altered differentiation properties. In an organotypic culture system, FEP-1811 cells at passages 12 and 32 exhibited features typical of premalignant intraepithelial neoplasia in vivo, and cells at passage 68 exhibited features consistent with squamous cell carcinomas. No change in copy number of the transfected HPV-18 genome or in the level of expression of the viral transforming gene products E6 and E7 was detected between tumorigenic and nontumorigenic cells. Cytogenetic analysis of cells at early, middle, and late passage levels and cells cultured from tumors revealed that several chromosomal abnormalities segregated with the tumorigenic cell populations.
Publisher: Springer Science and Business Media LLC
Date: 06-1995
DOI: 10.1007/BF00986660
Publisher: Proceedings of the National Academy of Sciences
Date: 31-03-1998
Abstract: Despite the central role of human epidermal stem cells in tissue homeostasis, wound repair, and neoplasia, remarkably little is known about these cells, largely due to the absence of molecular markers that distinguish them from other proliferative cells within the germinative/basal layer. Epidermal stem cells can be distinguished from other cells in the basal layer by their quiescent nature in vivo and their greater overall proliferative capacity. In this study, we demonstrate enrichment and isolation of a subpopulation of basal epidermal cells from neonatal human foreskin based on cell surface phenotype, which satisfy these criteria. These putative stem cells are distinguished from other basal cells by their characteristic expression of high levels of the adhesion molecule α 6 , a member of the integrin family (α 6 bri ), and low levels of a proliferation-associated cell surface marker recognized by recently described mAb 10G7 (10G7 dim ). We conclude that cells with the phenotype α 6 bri 10G7 dim represent the epidermal stem cell population based on the demonstration that these cells ( i ) exhibit the greatest regenerative capacity of any basal cells, ( ii ) represent a minor subpopulation (≈10%) of immature epidermal cells, which ( iii ) are quiescent at the time of isolation from the epidermis, as determined by cell cycle analysis.
Publisher: Informa UK Limited
Date: 2008
DOI: 10.1080/00365520802102489
Abstract: The molecular and cellular events responsible for regulating development of the oesophageal epithelium are not well understood. At least in part, this is due to the lack of a suitable model system with which to study the process. Here, we report development of a manipulable in vivo transplant model for mouse or human oesophageal epithelium. Epithelial cells were isolated from mouse or human oesophagus and inoculated into de-epithelialized and devitalized rat tracheas. The rat trachea, containing cells, was placed subcutaneously under the dorsal skin of immunodeficient mice. We show that a multilayered stratified squamous epithelium can be generated in 4-6 weeks from as few as 5 x 10(4) isolated oesophageal epithelial cells. The reconstituted epithelium recapitulates many of the structural and histological features of the normal oesophageal epithelium, including a basal layer of cuboidal-like cells, suprabasal layers of differentiating squamous cells and, in the case of murine cells, a superficial layer of cornified material. Our model can be used to generate a multilayered normal murine or human epithelium from a single cell suspension of oesophageal epithelial cells. The ability to genetically manipulate the cells prior to growth in the model is a powerful tool with which to study the molecular mechanisms involved in the development of normal oesophagus or in pathogenic processes such as Barrett's metaplasia or tumorigenesis.
Publisher: Proceedings of the National Academy of Sciences
Date: 29-07-2021
Abstract: Lymphatic vessel networks are important for various biological processes thus, incorporating them into engineered constructs can have both research and clinical implications. Engineered lymphatic vessels can improve biomimicry and functionality of in vitro tissue assays and serve as a treatment for various diseases associated with impaired lymphatic function. In this work, we created functional engineered lymphatic vessels that anastomosed to the host lymphatic system postimplantation. We investigated the effect of supporting cells, cell-secreted extracellular matrix, and mechanical forces on lymphatic vessel formation within engineered constructs. Interestingly, lymphatic vasculature responded differently to cyclic stretch compared to blood vasculature. This phenomenon opens up an avenue for investigating the variability of cellular responses to mechanical stimulation.
Publisher: The Company of Biologists
Date: 15-10-2004
DOI: 10.1242/DEV.01367
Abstract: Despite the well-characterised role of sonic hedgehog (Shh) in promoting interfollicular basal cell proliferation and hair follicle downgrowth, the role of hedgehog signalling during epidermal stem cell fate remains largely uncharacterised. In order to determine whether the three vertebrate hedgehog molecules play a role in regulating epidermal renewal we overexpressed sonic(Shh), desert (Dhh) and Indian (Ihh) hedgehog in the basal cells of mouse skin under the control of the human keratin 14 promoter. We observed no overt epidermal morphogenesis phenotype in response to Ihh overexpression, however Dhh overexpression resulted in a range of embryonic and adult skin manifestations indistinguishable from Shh overexpression. Two distinct novel phenotypes were observed amongst Shh and Dhh transgenics, one exhibiting epidermal progenitor cell hyperplasia with the other displaying a complete loss of epidermal tissue renewal indicating deregulation of stem cell activity. These data suggest that correct temporal regulation of hedgehog activity is a key factor in ensuring epidermal stem cell maintenance. In addition, we observed Shh and Dhh transgenic skin from both phenotypes developed lesions reminiscent of human basal cell carcinoma (BCC), indicating that BCCs can be generated despite the loss of much of the proliferative (basal) compartment. These data suggest the intriguing possibility that BCC can arise outside the stem cell population. Thus the elucidation of Shh (and Dhh)target gene activation in the skin will likely identify those genes responsible for increasing the proliferative potential of epidermal basal cells and the mechanisms involved in regulating epidermal stem cell fate.
Publisher: Wiley
Date: 11-08-2011
DOI: 10.1111/J.1600-0625.2011.01338.X
Abstract: Adult stem cells in rapidly renewing tissues have been classically defined as rare, relatively quiescent cells with the unique capacity to constantly self-renew and regenerate tissues during homeostasis. Although this view remains firmly embedded in the skin field, particularly in the area of hair follicle stem cell biology, it has been challenged by a number of notable publications in 2007. These papers leave an uncomfortable feeling with the reader if one believes that stem cells and transit lifying cells are two polar opposites and 'never the twain shall meet.' Even if you do not subscribe to this extreme view, the implications appear to be far-reaching given that the majority of techniques devised for stem cell identification have used the fundamental tenet that the proliferating compartment is comprised of two distinct, mutually exclusive compartments, i.e. a minor proportion of long-lived quiescent stem cells with unlimited self-renewal and a large pool of rapidly cycling, short-lived transient lifying cells with limited or no self-renewal capacity in normal steady-state conditions. However, these recent findings have resulted in papers that could be described as sensationalistic because they make little or no attempt to reconcile their observations with the large bulk of historical data with direct bearing on the interpretation of stem cell activity in normal steady-state conditions. Here, we offer some explanations that may help to integrate all of the data while presenting a case that both quiescent stem cells and cycling 'transit lifying' cells contribute to epidermal replacement.
Publisher: American Society for Clinical Investigation
Date: 02-2004
DOI: 10.1172/JCI200419140
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.BIOCEL.2018.11.012
Abstract: Ovarian cancer is typically diagnosed at advanced stages (III or IV), with metastasis ensuing at stage III. Complete remission is infrequent and is not achieved in almost half of the women diagnosed with ovarian cancer. Consequently, management and treatment of this disease is challenging as many patients are faced with tumour recurrence disseminating to surrounding organs further complicated with acquired chemo-resistance. The cancer stem cell theory proposes the idea that a drug resistant subset of tumour cells drive tumour progression, metastasis and ultimately, recurrent disease. In the ovarian cancer field, cancer stem cells remain elusive with significant gaps in our knowledge. The characteristics and specific role of ovarian cancer stem cells in recurrence still requires further research since different studies often arrive at contradictory conclusions. Here we present a review and critical analysis of current research conducted in the field of ovarian cancer stem cells and their potential role in drug resistance including several signalling pathways within these cells that affect the viability of targeted therapies.
Publisher: Proceedings of the National Academy of Sciences
Date: 29-08-2006
Abstract: Based on functional studies in the bone marrow, it has been suggested that the ability to efflux Hoechst 33342 may represent a universal stem cell trait. In this phenotypic and functional characterization of the Hoechst side population (SP) in adult murine epidermis, we demonstrate that these cells are a rare subset of the keratinocyte stem cell-enriched α 6 bri CD71 dim fraction comprising SSC low /K14 + /CD34 − /Oil red O − /c- kit − /CD45 − keratinocytes. Epidermal SPs have the smallest cell and nuclear size but exhibit the highest nuclear-to-cytoplasmic ratio of any fraction examined, consistent with a primitive cell type. Although SPs demonstrated poor cumulative in vitro proliferative output, they exhibited sustained epidermal tissue-regenerative activity in vivo compared with unfractionated and non-SP cells. Collectively, these results indicate that the epidermal SP contains the most potent keratinocyte stem cell population in skin epithelium.
Publisher: Oxford University Press (OUP)
Date: 12-10-2007
DOI: 10.1634/STEMCELLS.2006-0421
Abstract: The identification and characterization of esophageal stem cells are critical to our understanding of the biology of the esophageal epithelium in health and disease. However, the proliferative compartment within the mouse esophageal epithelium remains poorly characterized. Here, we report that the basal cells of the mouse esophagus can be separated into three phenotypically and functionally distinct subpopulations based on the expression of α6 integrin and transferrin receptor (CD71). Cells that express high levels of α6 integrin and low levels of CD71, termed α6briCD71dim, are a minor subpopulation of small and undifferentiated cells that are enriched for label-retaining cells and thus represent a putative esophageal stem cell population. Conversely, cells expressing high levels of both α6 integrin and CD71 (α6briCD71bri), the majority of basal esophageal cells, are enriched for actively cycling cells and therefore represent a transit- lifying population. Kinetic analyses revealed that a third cell population, which is α6 integrin-dim and CD71-bright (α6dim), is destined to leave the basal layer and differentiate.
Publisher: IMR Press
Date: 2006
DOI: 10.2741/1861
Abstract: Our understanding of adult epidermal stem cells has increased substantially over the last two decades especially however even more detailed knowledge is imperative for realizing potential medical therapies. We need to know how to identify these cells and what regulates their function. In this review, we describe the literature to date and elucidate the clinical relevance of these findings.
Publisher: Elsevier BV
Date: 09-2004
Publisher: Informa UK Limited
Date: 07-2004
Publisher: EMBO
Date: 10-08-2022
Abstract: Adulte interfollicular epidermis (IFE) renewal is likely orchestrated by physiological demands of its complex tissue architecture comprising spatial and cellular heterogeneity. Mouse tail and back skin display two kinds of basal IFE spatial domains that regenerate at different rates. Here, we elucidate the molecular and cellular states of basal IFE domains by marker expression and single‐cell transcriptomics in mouse and human skin. We uncover two paths of basal cell differentiation that in part reflect the IFE spatial domain organization. We unravel previously unrecognized similarities between mouse tail IFE basal domains defined as scales and interscales versus human rete ridges and inter‐ridges, respectively. Furthermore, our basal IFE transcriptomics and gene targeting in mice provide evidence supporting a physiological role of IFE domains in adaptation to differential UV exposure. We identify Sox6 as a novel UV‐induced and interscale/inter‐ridge preferred basal IFE‐domain transcription factor, important for IFE proliferation and survival. The spatial, cellular, and molecular organization of IFE basal domains underscores skin adaptation to environmental exposure and its unusual robustness in adult homeostasis.
Publisher: Wiley
Date: 10-2002
DOI: 10.1034/J.1600-0625.2002.110501.X
Abstract: We have investigated the expression and function of the isoforms of laminin bearing the alpha5 chain, i.e. laminin-10/11 in neonatal and adult human skin. By immunostaining human skin derived from a variety of anatomic sites, we found that the laminin-alpha5 chain is expressed abundantly in the basement membrane underlying the interfollicular epidermis and the blood vessels in the dermis. Interestingly, while the expression level of the well-studied laminin-5 isoform did not change significantly with age, laminin-10/11 (alpha5 chain) appeared to decrease in the basement membrane underlying the epidermis, in adult skin. In contrast, the levels of laminin-10/11 in the basement membrane underlying blood vessels remained unchanged in neonatal vs. adult skin. Importantly, in vitro cell adhesion assays demonstrated that laminin-10/11 is a potent adhesive substrate for both neonatal and adult keratinocytes and that this adhesion is mediated by the alpha3beta1 and alpha6beta4 integrins. Adhesion assays performed with fractionated basal keratinocytes showed that stem cells, transit lifying cells and early differentiating cells all adhere to purified laminin-10/11 via these receptors. Further, laminin-10/11 provided a proliferative signal for neonatal foreskin keratinocytes, adult breast skin keratinocytes, and even a human papillomavirus type-18 transformed tumorigenic keratinocyte cell line in vitro. Finally, laminin-10/11 was shown to stimulate keratinocyte migration in an in vitro wound healing assay. These results provide strong evidence for a functional role for laminin-10/11 in epidermal proliferation during homeostasis, wound healing and neoplasia.
Publisher: Oxford University Press (OUP)
Date: 02-2005
DOI: 10.1111/J.1365-2133.2004.06350.X
Abstract: The colocalization of insulin-like growth factor binding protein-3 (IGFBP-3) and IGF-I receptor (IGF-IR) in the basal/germinative layer of the epidermis suggests a key role in modulating epidermal homeostasis. We aimed to clarify both the specific cellular localization and the effect of excess epidermal IGFBP-3 on keratinocyte proliferation. (i) Total RNA was isolated from fluorescence-activated cell sorted basal human keratinocyte subtypes [keratinocyte stem cells, transit lifying keratinocytes (TA), postmitotic differentiating keratinocytes (PMD)], and real-time polymerase chain reaction analysis was used to determine the abundance of IGFBP-3 and IGF-IR mRNAs. (ii) An IGFBP-3 transgenic mouse model was then used to assess the effect of excess epidermal IGFBP-3 on keratinocyte proliferation. Excess epidermal IGFBP-3 mRNA and protein was determined by in situ hybridization and immunohistochemistry, respectively. (i) The highest levels of IGFBP-3 mRNA were detected in TA keratinocytes, in contrast to IGF-IR mRNA levels which were highest in PMD keratinocytes. (ii) Elevated human IGFBP-3 mRNA and protein was confirmed in the epidermis of skin derived from transgenic mice. Excess IGFBP-3 reduced the relative percentage of proliferative keratinocytes (Ki67 positive) irrespective of skin location (belly, back and tail). Thus, in the epidermis, IGFBP-3 mRNA is highly expressed by proliferative keratinocytes (TA) and overexpression of IGFBP-3 inhibits keratinocyte proliferation. We conclude that in vivo IGFBP-3 ensures epidermal homeostasis via downregulation of keratinocyte proliferation, and thus modulates the early stages of keratinocyte differentiation.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2008
DOI: 10.1007/S12015-008-9031-3
Abstract: The incidence of adenocarcinoma of the esophagus has increased faster than any other internal malignancy over the last 40 years. Despite this, surprisingly little is known about the basic biology of this tissue, particularly with regards to the organization of cell proliferation within the epithelium. This is a matter of crucial importance for our understanding of the pathogenesis of esophageal cancer. Nevertheless, significant advances have recently been made in the identification and functional characterization of both murine and human esophageal stem cells and their progeny in recent years. This places investigators in an exciting position to gain further insights into the processes of tissue renewal and repair on the one hand and the development of dysplasia and malignancy on the other.
Publisher: Wiley
Date: 2005
DOI: 10.1111/J.0906-6705.2005.00252.X
Abstract: Given that an important functional attribute of stem cells in vivo is their ability to sustain tissue regeneration, we set out to establish a simple and easy technique to assess this property from candidate populations of human keratinocyte stem cells in an in vivo setting. Keratinocytes were inoculated into devitalized rat tracheas and transplanted subcutaneously into SCID mice, and the epithelial lining regenerated characterized to establish the validity of this heterotypic model. Furthermore, the rate and quality of epidermal tissue reconstitution obtained from freshly isolated unfractionated vs. keratinocyte stem cell-enriched populations was tested as a function of (a) cell numbers inoculated and (b) the inclusion of irradiated support keratinocytes and dermal cells. Rapid and sustained epidermal tissue regeneration from small numbers of freshly isolated human keratinocyte stem cells validates the utilization of this simple and reliable model system to assay for enrichment of epidermal tissue-reconstituting cells.
Publisher: Elsevier BV
Date: 10-2004
DOI: 10.1111/J.1432-0436.2004.07208005.X
Abstract: The location and identity of interfollicular epidermal stem cells of adult human skin remain undefined. Based on our previous work in both adult murine and neonatal human foreskin, we demonstrate that cell surface levels of the alpha6 integrin and the transferrin receptor (CD71) are valid markers for resolving a putative stem cell, transit lifying and differentiating compartment in adult human skin by flow cytometry. Specifically, epidermal cells expressing high levels of alpha6 integrin and low levels of the transferrin receptor CD71 (phenotype alpha6 (bri)CD71(dim)) exhibit several stem cell characteristics, comprising a minor population (2%-5%) of the K14(bri) fraction, enriched for quiescent and small blast-like cells with high clonogenic capacity, lacking the differentiation marker K10. Conversely, the majority of K14(bri) K10(neg) epidermal cells express high levels of CD71 (phenotype alpha6 (bri)CD71(bri)), and represent the actively cycling fraction of keratinocytes displaying greater cell size due to an increase in cytoplasmic area, consistent with their being transient lifying cells. The alpha6 (bri)CD71(bri) population exhibited intermediate clonogenic capacity. A third population of K14(dim) but K10 positive epidermal cells could be identified by their low levels of alpha6 integrin expression (i.e. alpha6 (dim) cells), representing the differentiation compartment predictably, this subpopulation exhibited poor clonogenic efficiency. Flow cytometric analysis for the hair follicle bulge region (stem cell) marker K15 revealed preferential expression of this keratin in alpha6 (bri) cells (i.e., both stem and transient lifying fractions), but not the alpha6 (dim) population. Given that K15 positive cells could only be detected in the deep rete ridges of adult skin in situ, we conclude that stem and transient lifying cells reside in this location, while differentiating (K15 negative) cells are found in the shallow rete ridges.
Publisher: American Association for Cancer Research (AACR)
Date: 31-08-2009
Publisher: Elsevier BV
Date: 07-2006
Abstract: Homeostatic epidermal tissue renewal is the result of the combined activity of rare but potent stem cells, and a large pool of short-lived progenitor cells termed transit lifying cells. Although the existence of epidermal stem cells has been known for some decades, their specific role in the processes of wound repair, skin diseases, and carcinogenesis remains unelucidated. Nevertheless, significant advances have been made in the identification and functional characterization of both murine and human epidermal stem cells, which place investigators in an exciting position to gain further insights into the fundamental processes of tissue renewal and repair in the epidermis.
Publisher: Elsevier BV
Date: 11-2009
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1038/JID.2013.42
Publisher: Wiley
Date: 15-12-1989
Abstract: Cytogenetic analysis was performed on human papillomavirus (HPV)-immortalized cell lines. Lines were established by co-transfection of primary human keratinocyte cells with HPV type 16 or 18 DNA and pSV2neo. The resulting clonal lines contained integrated HPV DNA and exhibited extended life spans in culture but were non-tumorigenic in nude mice. Two HPV16-immortalized lines (FEPE1L8 and FEPE1L9) and 4 HPV18-immortalized lines (FEA, FEH18L, FEP18-5 and FEP18-11) were established. Two additional lines were derived by subsequent treatment of the FEA line with TPA and by further transfection with HSVII DNA. Cytogenetic analysis revealed that all lines were abnormal, containing a variety of numerical and structural aberrations. Six of the 8 lines were hyper-triploid and 2 were near-diploid. Examination of lines FEA, FEH18L and FEP18-11 at multiple passages in culture revealed that the lines were clonal and chromosomally stable over extended passage in culture. Structural rearrangements were most common in chromosomes 1 and 3 but also occurred in chromosomes 5, 7, 8, 12, 16 and 22. Marker chromosomes were present in all cell lines. A small metacentric marker, possibly an isochromosome for the short arm of chromosome 5, was consistently present in the FEA line and its derivatives (FEAB10 and FEAT) as well as the FEH18L line. A loss or reduction in copy number of chromosome 13 was seen in 5 of the 8 cell lines.
Publisher: Humana Press
Date: 2012
DOI: 10.1007/978-1-61779-815-3_5
Abstract: Proliferation in mouse oesophageal epithelial cells is confined to the basal layer of the epithelium. Within this population, it is possible to discriminate different sub-populations using a combination of cell kinetic studies and functional assays. In particular, it is possible to distinguish basal epithelial cells, which are post-mitotic and destined to leave the basal layer and differentiate compared with those cells that remain in the cycling pool. Within the cycling basal population, there appears to be a hierarchy with respect to the rate of cell turnover which may reflect a hierarchy of "stemness", although it has not been possible to demonstrate functional differences between these populations using current in vivo tissue reconstitution assays. The aim of this chapter is to describe the development of a quantitative in vivo tissue reconstitution assay to assess the potency of candidate stem cell populations within the mouse oesophageal epithelium.
Publisher: Oxford University Press (OUP)
Date: 26-07-2011
DOI: 10.1002/STEM.675
Abstract: Although homeostatic renewal of human skin epidermis is achieved by the combined activity of quiescent stem cells (SCs) and their actively cycling progeny, whether these two populations are equipotent in their capacity to regenerate tissue has not been determined in biological assays that mimic lifelong renewal. Using fluorescence activated cell separation strategy validated previously by us, human epidermis was fractionated into three distinct subsets: that is, α 6briCD71dim, α 6briCD71bri, and α 6dim with characteristics of keratinocyte stem, transient lifying, and early differentiating cells, respectively. The global gene expression profile of these fractions was determined by microarray, confirming that the α 6briCD71dim subset was quiescent, the α 6briCD71bri was actively cycling, and the α 6dim subset expressed markers of differentiation. More importantly, functional evaluation of these populations in an in vivo model for tissue reconstitution at limiting cell dilutions revealed that the quiescent α 6briCD71dim fraction was the most potent proliferative and tissue regenerative population of the epidermis, capable of long-term (LT) epidermal renewal from as little as 100 cells for up to 10 weeks. In contrast, the cycling α 6briCD71bri fraction was the first to initiate tissue reconstitution, although this was not sustained in the LT, while differentiating α 6dim cells possessed the lowest demonstrable tissue regenerative capacity. Our data suggest that in human skin, the epidermal proliferative compartment is not composed of equipotent cells, but rather is organized in a functionally hierarchical manner with the most potent quiescent SCs at its apex (i.e., α 6briCD71dim) followed by cycling progenitors (i.e., α 6briCD71bri) and finally early differentiating keratinocytes (i.e., α 6dim).
Publisher: American Society for Clinical Investigation
Date: 03-08-2009
DOI: 10.1172/JCI38535
Publisher: Rockefeller University Press
Date: 12-1990
Abstract: Basal cells of stratified epidermis are anchored to the basement membrane zone (BMZ) of skin via hemidesmosomes. We previously identified integrin alpha 3 beta 1, in focal adhesions (FAs), of cultured human keratinocytes (HFKs) as a mediator of HFK adhesion to secreted BMZ-like extracellular matrix (ECM Carter, W.G., E.A. Wayner, T.S. Bouchard, and P. Kaur. 1990. J. Cell Biol. 110: 1387-1404). Here, we have examined the relation of integrins alpha 6 beta 4 and alpha 3 beta 1, to bullous pemphigoid antigen (BPA), a component of hemidesmosomes. We conclude that alpha 6 beta 4 in HFKs localizes in a new stable anchoring contact (SAC) that cooperates with alpha 3 beta 1-FAs to mediate adhesion to ECM, based on the following. (a) Comparison of secreted ECM, with exogenous laminin, fibronectin and collagen identified ECM as the preferred ligand for HFK adhesion and spreading and for formation of both alpha 6 beta 4-SACs and alpha 3 beta 1-FAs. (b) Inhibition of HFK adhesion with combined anti-alpha 3 beta 1 (P1B5) and anti-alpha 6 beta 4 (GoH3) antibodies indicated that both receptors were functional in adhesion to ECM while alpha 3 beta 1 played a dominant role in spreading. (c) alpha 6 beta 4 colocalized with BPA in SACs that were proximal to but excluded from FAs. Both alpha 6 beta 4-SACs and alpha 3 beta 1-FAs were in contact with the adhesion surface as indicated by antibody exclusion and interference reflection microscopy. (d) In contrast to alpha 3 beta 1-FAs, alpha 6 beta 4-SACs were present only in nonmotile cells, not associated with stress fibers, and were relatively stable to detergents and urea, suggesting a nonmotile, or anchoring function for SACs and motility functions for alpha 3 beta 1-FAs. (e) alpha 6 beta 4 formed a detergent-insoluble complex with exogenous ECM in an affinity isolation procedure, confirming the ability of an unidentified ECM ligand to interact with alpha 6 beta 4. (f) We suggest that alpha 6 beta 4/BPA-SACs in culture restrict migration of HFKs on ECM while alpha 3 beta 1-FAs form dynamic adhesions in spreading and migrating cells. alpha 6 beta 4/BPA-SACs in culture bear functional and compositional similarities to hemidesmosomes in skin.
Publisher: Life Science Alliance, LLC
Date: 24-07-2018
Abstract: The cellular and molecular microenvironment of epithelial stem rogenitor cells is critical for their long-term self-renewal. We demonstrate that mesenchymal stem cell–like dermal microvascular pericytes are a critical element of the skin's microenvironment influencing human skin regeneration using organotypic models. Specifically, pericytes were capable of promoting homeostatic skin tissue renewal by conferring more planar cell isions generating two basal cells within the proliferative compartment of the human epidermis, while ensuring complete maturation of the tissue both spatially and temporally. Moreover, we provide evidence supporting the notion that BMP-2, a secreted protein preferentially expressed by pericytes in human skin, confers cell polarity and planar isions on epidermal cells in organotypic cultures. Our data suggest that human skin regeneration is regulated by highly conserved mechanisms at play in other rapidly renewing tissues such as the bone marrow and in lower organisms such as Drosophila . Our work also provides the means to significantly improve ex vivo skin tissue regeneration for autologous transplantation.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
No related grants have been discovered for Pritinder Kaur.