scholarly journals Differentiation-related expression of a major 64K corneal keratin in vivo and in culture suggests limbal location of corneal epithelial stem cells.

1986 ◽  
Vol 103 (1) ◽  
pp. 49-62 ◽  
Author(s):  
A Schermer ◽  
S Galvin ◽  
T T Sun
Keyword(s):  
Stem Cells ◽  
Strong Support ◽  
Transitional Zone ◽  
Basal Cells ◽  
Epithelial Stem Cells ◽  
Corneal Epithelial ◽  
Differentiated Cells ◽  
Limbal Epithelium ◽  
Cell Layers

In this paper we present keratin expression data that lend strong support to a model of corneal epithelial maturation in which the stem cells are located in the limbus, the transitional zone between cornea and conjunctiva. Using a new monoclonal antibody, AE5, which is highly specific for a 64,000-mol-wt corneal keratin, designated RK3, we demonstrate that this keratin is localized in all cell layers of rabbit corneal epithelium, but only in the suprabasal layers of the limbal epithelium. Analysis of cultured corneal keratinocytes showed that they express sequentially three major keratin pairs. Early cultures consisting of a monolayer of "basal" cells express mainly the 50/58K keratins, exponentially growing cells synthesize additional 48/56K keratins, and postconfluent, heavily stratified cultures begin to express the 55/64K corneal keratins. Cell separation experiments showed that basal cells isolated from postconfluent cultures contain predominantly the 50/58K pair, whereas suprabasal cells contain additional 55/64K and 48/56K pairs. Basal cells of the older, postconfluent cultures, however, can become AE5 positive, indicating that suprabasal location is not a prerequisite for the expression of the 64K keratin. Taken together, these results suggest that the acidic 55K and basic 64K keratins represent markers for an advanced stage of corneal epithelial differentiation. The fact that epithelial basal cells of central cornea but not those of the limbus possess the 64K keratin therefore indicates that corneal basal cells are in a more differentiated state than limbal basal cells. These findings, coupled with the known centripetal migration of corneal epithelial cells, strongly suggest that corneal epithelial stem cells are located in the limbus, and that corneal basal cells correspond to "transient amplifying cells" in the scheme of "stem cells----transient amplifying cells----terminally differentiated cells."

Corneal Epithelial Stem Cell and Disease – Past, Present and Future

2009 ◽  
Vol 03 (02) ◽  
pp. 82
Author(s):  
Sophie X Deng ◽  
Keyword(s):  
Stem Cells ◽  
Basal Layer ◽  
Superficial Layer ◽  
Regenerative Process ◽  
Epithelial Stem Cells ◽  
Limbal Stem Cells ◽  
Corneal Surface ◽  
Current Management ◽  
Corneal Epithelial ◽  
Limbal Epithelium

The ocular surface is covered by non-keratinised stratified epithelial cells that provide the first line of defence against external insults. Under normal conditions, the superficial layer of the corneal epithelium undergoes constant desquamation and is maintained by the basal layer through the regenerative process of self-renewal. This regeneration capacity depends on the corneal epithelial stem cells that are believed to reside at the basal layer of the limbal epithelium and hence are called limbal stem cells (LSCs). Deficiency of LSCs seen in many ocular diseases leads to the loss of vision as a result of invasion of the conjunctival epithelium and neovascularisation of the corneal surface. In this article, the aetiology, clinical presentation, diagnosis and current management of LSC deficiency are discussed, with an emphasis on new tissueengineering techniques to expand and regenerate LSCs for transplantation.

scholarly journals Regulation of ERK basal and pulsatile activity control proliferation and exit from the stem cell compartment in mammalian epidermis

2020 ◽  
Vol 117 (30) ◽  
pp. 17796-17807 ◽  
Author(s):  
Toru Hiratsuka ◽  
Ignacio Bordeu ◽  
Gunnar Pruessner ◽  
Fiona M. Watt
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Basal Cells ◽  
Mammalian Development ◽  
Down Regulation ◽  
Cell Dynamics ◽  
Erk Mapk ◽  
Differentiated Cells ◽  
Erk Activity

Fluctuation in signal transduction pathways is frequently observed during mammalian development. However, its role in regulating stem cells has not been explored. Here we tracked spatiotemporal ERK MAPK dynamics in human epidermal stem cells. While stem cells and differentiated cells were distinguished by high and low stable basal ERK activity, respectively, we also found cells with pulsatile ERK activity. Transitions from Basalhi-Pulselo(stem) to Basalhi-Pulsehi, Basalmid-Pulsehi, and Basallo-Pulselo(differentiated) cells occurred in expanding keratinocyte colonies and in response to differentiation stimuli. Pharmacological inhibition of ERK induced differentiation only when cells were in the Basalmid-Pulsehistate. Basal ERK activity and pulses were differentially regulated by DUSP10 and DUSP6, leading us to speculate that DUSP6-mediated ERK pulse down-regulation promotes initiation of differentiation, whereas DUSP10-mediated down-regulation of mean ERK activity promotes and stabilizes postcommitment differentiation. Levels of MAPK1/MAPK3 transcripts correlated with DUSP6 and DUSP10 transcripts in individual cells, suggesting that ERK activity is negatively regulated by transcriptional and posttranslational mechanisms. When cells were cultured on a topography that mimics the epidermal−dermal interface, spatial segregation of mean ERK activity and pulses was observed. In vivo imaging of mouse epidermis revealed a patterned distribution of basal cells with pulsatile ERK activity, and down-regulation was linked to the onset of differentiation. Our findings demonstrate that ERK MAPK signal fluctuations link kinase activity to stem cell dynamics.

scholarly journals Identification and isolation of human prostate epithelial stem cells based on α2β1-integrin expression

2001 ◽  
Vol 114 (21) ◽  
pp. 3865-3872 ◽  
Author(s):  
Anne T. Collins ◽  
Fouad K. Habib ◽  
Norman J. Maitland ◽  
David E. Neal
Keyword(s):  
Stem Cells ◽  
Type I Collagen ◽  
Specific Antigen ◽  
Basal Layer ◽  
Basement Membranes ◽  
Type I ◽  
Integrin Subunit ◽  
Basal Cells ◽  
Epithelial Stem Cells

A major impediment to our understanding of the biology of stem cells is the inability to distinguish them from their differentiating progeny. We made use of the known association of stem cells with basement membranes to isolate prostate epithelial stem cells. We show that, in vivo, putative stem cells express higher levels of the α2-integrin subunit than other cells within the basal layer. Approximately 1% of basal cells examined by confocal microscopy were integrin ‘bright’, and these cells can be selected directly from the tissue on the basis of rapid adhesion to type I collagen. This selected population has a basal phenotype, as determined by expression of CK5 and CK14 and lack of expression of the differentiation-specific markers prostate specific antigen (PSA) and prostatic acid phosphatase (PAP), and has a fourfold greater ability to form colonies in vitro than the total basal population. These putative stem cells are distinguished from other basal cells by their ability to generate prostate-like glands in vivo with morphologic and immuno-histochemical evidence of prostate-specific differentiation. These properties are consistent with a stem cell origin. Furthermore, the presence of surface integrins on prostate stem cells suggests that these cells share common pathways with stem cells in other tissues.

scholarly journals Stem Cells in the Path of Light, from Corneal to Retinal Reconstruction

Biomedicines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 873
Author(s):  
Ovidiu Samoila ◽  
Lacramioara Samoila
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Clinical Success ◽  
Corneal Stroma ◽  
Cell Transplant ◽  
Inclusion Criteria ◽  
Epithelial Stem Cells ◽  
Corneal Epithelial ◽  
Stem Cells Transplantation ◽  
Limbal Epithelial Stem Cells

The future of eye reconstruction invariably includes stem cells transplantation. Corneal limbus, corneal stroma, trabeculum, retinal cells, optic nerve, and all structures that are irreversibly damaged and have no means to be repaired or replaced, through conventional treatment or surgery, represent targets for stem cell reconstruction. This review tries to answer the question if there is any clinical validation for stem therapies, so far, starting from the cornea and, on the path of light, arriving to the retina. The investigation covers the last 10 years of publications. From 2385 published sources, we found 56 clinical studies matching inclusion criteria, 39 involving cornea, and 17 involving retina. So far, corneal epithelial reconstruction seems well validated clinically. Enough clinical data are collected to allow some form of standardization for the stem cell transplant procedures. Cultivated limbal epithelial stem cells (CLET), simple limbal epithelial transplant (SLET), and oral mucosa transplantation are implemented worldwide. In comparison, far less patients are investigated in retinal stem reconstructions, with lower anatomical and clinical success, so far. Intravitreal, subretinal, and suprachoroidal approach for retinal stem therapies face specific challenges.

scholarly journals In vivo Polycomb kinetics and mitotic chromatin binding distinguish stem cells from differentiated cells

2012 ◽  
Vol 26 (8) ◽  
pp. 857-871 ◽  
Author(s):  
J. P. Fonseca ◽  
P. A. Steffen ◽  
S. Muller ◽  
J. Lu ◽  
A. Sawicka ◽  
...  
Keyword(s):  
Stem Cells ◽  
Chromatin Binding ◽  
Differentiated Cells ◽  
Mitotic Chromatin

A 300 bp 5′-upstream sequence of a differentiation-dependent rabbit K3 keratin gene can serve as a keratinocyte-specific promoter

1993 ◽  
Vol 105 (2) ◽  
pp. 303-316 ◽  
Author(s):  
R.L. Wu ◽  
S. Galvin ◽  
S.K. Wu ◽  
C. Xu ◽  
M. Blumenberg ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Transcription Initiation ◽  
Gene Transfection ◽  
Consensus Sequence ◽  
Upstream Sequence ◽  
Basal Cells ◽  
Epithelial Stem Cells ◽  
Keratin Gene ◽  
Corneal Epithelial

Keratinocytes of the suprabasal compartment of many stratified epithelia synthesize as a major differentiation product a keratin pair, consisting of an acidic and a basic keratin, which accounts for 10–20% of the newly synthesized proteins. While genes of several differentiation-related keratins have been cloned and studied, relatively little is known about the molecular basis underlying their tissue-specific and differentiation-dependent expression. We have chosen to study, as a prototype of these genes, the gene of K3 keratin, which has the unique property of being expressed in the majority of corneal epithelial basal cells but suprabasally in peripheral cornea, the site of corneal epithelial stem cells. Using a monoclonal antibody, AE5, specific for K3 keratin, and a fragment of human K3 gene as probes, we have isolated several cDNA and genomic clones of rabbit K3 keratin. One genomic clone has been sequenced and characterized, and the identity of its coding sequence with that of cDNAs indicates that it corresponds to the single, functional rabbit K3 gene. Transfection assays showed that its 3.6 kb 5′-upstream sequence can drive a chloramphenicol acetyl transferase (CAT) reporter gene to express in cultured corneal and esophageal epithelial cells, but not in mesothelial and kidney epithelial cells or fibroblasts, all of rabbit origin. Serial deletion experiments narrowed this keratinocyte-specific promoter to within -300 bp upstream of the transcription initiation site. Its activity is not regulated by the coding or 3′-noncoding sequences that have been tested so far. This 300 bp 5′-upstream sequence of K3 keratin gene, which can function in vitro as a keratinocyte-specific promoter, contains two clusters of partially overlapping motifs, one with an NFkB consensus sequence and another with a GC box. The combinatorial effects of these multiple motifs and their cognate binding proteins may play an important role in regulating the expression of this tissue-restricted and differentiation-dependent keratin gene.

scholarly journals MicroRNA Profiling of Highly Enriched Human Corneal Epithelial Stem Cells by Small RNA Sequencing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lavanya Kalaimani ◽  
Bharanidharan Devarajan ◽  
Umadevi Subramanian ◽  
Vanniarajan Ayyasamy ◽  
Venkatesh Prajna Namperumalsamy ◽  
...  
Keyword(s):  
Stem Cells ◽  
Rna Sequencing ◽  
Small Rna ◽  
Small Rna Sequencing ◽  
Epithelial Stem Cells ◽  
Corneal Epithelial ◽  
Microrna Profiling

scholarly journals PDGF-AB and 5-Azacytidine induce conversion of somatic cells into tissue-regenerative multipotent stem cells

2016 ◽  
Vol 113 (16) ◽  
pp. E2306-E2315 ◽  
Author(s):  
Vashe Chandrakanthan ◽  
Avani Yeola ◽  
Jair C. Kwan ◽  
Rema A. Oliver ◽  
Qiao Qiao ◽  
...  
Keyword(s):  
Stem Cells ◽  
Growth Factor ◽  
Tissue Regeneration ◽  
Somatic Cells ◽  
Dependent Manner ◽  
Cell Plasticity ◽  
Differentiation Potential ◽  
Multipotent Stem Cells ◽  
Differentiated Cells

Current approaches in tissue engineering are geared toward generating tissue-specific stem cells. Given the complexity and heterogeneity of tissues, this approach has its limitations. An alternate approach is to induce terminally differentiated cells to dedifferentiate into multipotent proliferative cells with the capacity to regenerate all components of a damaged tissue, a phenomenon used by salamanders to regenerate limbs. 5-Azacytidine (AZA) is a nucleoside analog that is used to treat preleukemic and leukemic blood disorders. AZA is also known to induce cell plasticity. We hypothesized that AZA-induced cell plasticity occurs via a transient multipotent cell state and that concomitant exposure to a receptive growth factor might result in the expansion of a plastic and proliferative population of cells. To this end, we treated lineage-committed cells with AZA and screened a number of different growth factors with known activity in mesenchyme-derived tissues. Here, we report that transient treatment with AZA in combination with platelet-derived growth factor–AB converts primary somatic cells into tissue-regenerative multipotent stem (iMS) cells. iMS cells possess a distinct transcriptome, are immunosuppressive, and demonstrate long-term self-renewal, serial clonogenicity, and multigerm layer differentiation potential. Importantly, unlike mesenchymal stem cells, iMS cells contribute directly to in vivo tissue regeneration in a context-dependent manner and, unlike embryonic or pluripotent stem cells, do not form teratomas. Taken together, this vector-free method of generating iMS cells from primary terminally differentiated cells has significant scope for application in tissue regeneration.

Sign in / Sign up

Export Citation Format

Share Document