Targeting MUC1 as a Marker for Myeloid Leukemia Stem Cells by DC/AML Fusions.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1794-1794
Author(s):  
Jacalyn Rosenblatt ◽  
Zekui Wu ◽  
Corrine Lenahan ◽  
Adam Bissonnette ◽  
Baldev Vasir ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Fold Increase ◽  
Leukemia Cells ◽  
Leukemia Stem Cells ◽  
Cell Compartment ◽  
Stem Cell Compartment

Abstract The epithelial mucin antigen (MUC1) is aberrantly expressed in many epithelial tumors and hematologic malignancies and promotes oncogenesis and tumor progression. MUC1 is recognized by the T cell repertoire and has served as a target for cellular immunotherapy. In the present study, we examined MUC1 as a marker for myeloid leukemia cells and their progenitors and its capacity to serve as a target for leukemia stem cells. Myeloid leukemia cells were isolated from bone marrow aspirates or peripheral blood in patients with high levels of circulating disease. MUC1 was not expressed on unselected leukemia samples (mean expression 3%, n=12). Similarly, low levels of MUC1 expression were seen in leukemic blasts with monocytoid differentiation (mean expression 2.7%, n=5). A subset of leukemia specimens underwent CD34 selection by magnetic bead separation. In contrast to unselected cells, 38% of CD34+ leukemia cells expressed MUC1 (n=5). The leukemia stem cell compartment was isolated by separating CD34+/CD38−/ lineage- fractions by flow cytometric sorting. Leukemia stem cells demonstrated strong expression of MUC-1 by immunohistochemical staining and FACS analysis. Similarly, we examined MUC1 expression on progenitor cells derived from chronic phase chronic myeloid leukemia and following blast transformation. MUC1 was seen in only 4% of CD34+ cells obtained from chronic phase CML samples (n=4) while uniform expression was observed in samples derived from patients with accelerated/blastic phase disease. These data suggest that MUC1 serves as a marker for early leukemia progenitors and is associated with blastic transformation. We assessed the capacity of a cancer vaccine consisting of dendritic cell (DC)/myeloid leukemia fusions to stimulate immune responses that target MUC1 and other antigens expressed by the stem cell compartment. DCs were generated from adherent mononuclear cells that were cultured with GM-CSF and IL-4 and matured with TNFa. DCs were fused with patient derived myeloid leukemia cells using polyethylene glycol as previously described. Fusion cells were quantified by determining the percentage of cells that expressed unique DC and leukemia antigens. DC/AML fusions induced the expansion of MUC1 specific T cells. Stimulation of autologous T cells with DC/AML fusions resulted in a mean 3 fold increase in CD8+ cells binding the MUC-1 tetramer (N=4). DC/AML fusions stimulated anti-tumor immune responses that targeted leukemia stem cells. Fusion stimulated T cells demonstrated increased expression of IFNγ following exposure to lysate generated from unselected leukemia cells (29 fold) and leukemia stem cells (28 fold). In contrast, exposure to renal carcinoma lysate generated only a 5 fold increase in IFNγ. In summary, these findings suggest that leukemic progenitors in AML and accelerated/blast phase CML express MUC-1. DC/tumor fusion vaccines target the MUC-1 protein and the stem cell compartment, and may be a potent immunotherapeutic strategy to eliminate the malignant stem cell clone in AML.

scholarly journals Stem Cell Biomarkers in Chronic Myeloid Leukemia

2008 ◽  
Vol 24 (4-5) ◽  
pp. 201-216 ◽  
Author(s):  
Xiaoyan Jiang ◽  
Yun Zhao ◽  
Donna Forrest ◽  
Clayton Smith ◽  
Allen Eaves ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Myeloproliferative Disease ◽  
Cell Compartment ◽  
Hematopoietic Stem ◽  
Stem Cell Compartment ◽  
Treatment Responses

Chronic myeloid leukemia (CML) is a clonal multi-step myeloproliferative disease that is initially produced and ultimately sustained by a rare subpopulation of BCR-ABL+ cells with multi-lineage stem cell properties. These BCR-ABL+ CML stem cells are phenotypically similar to normal hematopoietic stem cells which are also maintained throughout the course of the disease at varying levels in different patients. Defining the unique properties of the leukemic stem cells that produce the chronic phase of CML has therefore had to rely heavily on access to samples from rare patients in which the stem cell compartment is dominated by leukemic elements. Here we review past and ongoing approaches using such samples to identify biologically and clinically relevant biomarkers of BCR-ABL+ stem cells that explain their unusual biology and that may help to design, or at least predict, improved treatment responses in CML patients. These studies are of particular interest in light of recent evidence that chronic phase CML stem cells are not only innately resistant to imatinib mesylate and other drugs that target the BCR-ABL oncoprotein, but are also genetically unstable.

Leukemic Stem Cell Assessment in Remission Bone Marrow of Acute Myeloid Leukemia Patients Is a New Prognostic Parameter.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 399-399 ◽  
Author(s):  
Monique Terwijn ◽  
Angèle Kelder ◽  
Arjo P Rutten ◽  
Alexander N Snel ◽  
Willemijn Scholten ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Prognostic Information ◽  
Cell Compartment ◽  
Hematopoietic Stem ◽  
Stem Cell Compartment ◽  
Acute Myeloid

Abstract Abstract 399 In acute myeloid leukemia (AML), relapses originate from the outgrowth of therapy surviving leukemic blasts know as minimal residual disease (MRD). Accumulating evidence shows that leukemia initiating cells or leukemic stem cells (LSCs) are responsible for persistence and outgrowth of AML. Monitoring LSCs during and after therapy might thus offer accurate prognostic information. However, as LSCs and hematopoietic stem cells (HSCs) both reside within the immunophenotypically defined CD34+CD38- compartment, accurate discrimination between LSCs and HSCs is required. We previously showed that within the CD34+CD38- stem cell compartment, LSCs can be discriminated from HSC by aberrant expression of markers (leukemia associated phenotype, LAP), including lineage markers like CD7, CD19 and CD56 and the novel LSC marker CLL-1 (van Rhenen, Leukemia 2007, Blood 2007). In addition, we reported that flowcytometer light scatter properties add to even better detection of LSCs, allowing LSCs detection in AML cases lacking LAP (ASH abstract 1353, 2008). Using this gating strategy, we determined LSC frequency in 64 remission bone marrow samples of CD34+ AML patients. A stem cell compartment was defined as a minimum of 5 clustered CD34+CD38- events with a minimal analyzed number of 500,000 white blood cells. After first cycle of chemotherapy, high LSC frequency (>1 × 10-3) clearly predicted adverse relapse free survival (RFS, figure 1a). LSC frequency above cut-off led to a median RFS of 5 months (n=9), while patients with LSC frequency below cut-off (n=22) showed a significantly longer median RFS of >56 months (p=0.00003). In spite of the relatively low number of patients, again a high LSC frequency (>2 × 10-4) after the second cycle and after consolidation therapy predicted worse RFS: after second cycle, median RFS was 6 months (n=9) vs. >43 months for patients with LSC frequency below cut-off (p=0.004). After consolidation, these figures were 6 months (n=7) vs. >32 months (n=6, p=0.03). Although total blast MRD (leukemic blasts as % of WBC) is known to predict survival (N.Feller et al. Leukemia 2004), monitoring LSCs as compared to total blast MRD has two major advantages: the specificity is higher (van Rhenen et al. Leukemia 2007) and well-known LSC makers like CLL-1, CD96 and CD123 can in principle be used for LSC monitoring, but not for total blast MRD detection since these markers are also expressed on normal progenitor cells. On the other hand, LSCs constitute only a small fraction of all leukemic blasts and therefore monitoring total blast MRD may have the advantage of a higher sensitivity. We thus tested the hypothesis that even more accurate prognostic information could be obtained by combining LSC frequency with total blast MRD. Total blast MRD after first cycle was predictive for survival with borderline significance (p=0.08): a cut-off of 0.3% resulted in two patient groups with median RFS of 9 months vs. >56 months. Figure 1b shows the result of the combined data of LSC and MRD frequency after first cycle therapy. We used the terms LSC+ and MRD+ for cell frequencies above cut-off and LSC- and MRD- for those below cut-off. We could clearly identify that apart from LSC+/MRD+ patients, LSC+/MRD- patients too have very poor prognosis, while MRD+/LSC- patients show an adverse prognosis as compared to LSC-/MRD- patients. These results from the first study on the in vivo fate of LSCs during and after therapy, strongly support the hypothesis that in CD34+ AML the leukemia initiating capacity originates from the CD34+CD38- population and is important for tumor survival and outgrowth. These results show that LSC frequency might be superior in predicting prognosis of AML patients in CR as compared to MRD total blast frequency, while the combination of both may offer the most optimal parameter to guide future intervention therapies. This work was supported by Netherlands Cancer Foundation KWF. Disclosures: No relevant conflicts of interest to declare.

Specific Detection of Aberrant and Normal Stem Cells in Acute Myeloid Leukemia Patients Opens the Way for Defining Highly Specific Targets for Stem Cell Therapy.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1353-1353
Author(s):  
J Monique Terwi ◽  
Angèle Kelder ◽  
Arjo P Rutten ◽  
Sonja Zweegman ◽  
Gert J Ossenkoppele ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
The Other ◽  
Specific Detection ◽  
Cell Compartment ◽  
Stem Cell Compartment ◽  
Marker Expression ◽  
Acute Myeloid

Abstract In acute myeloid leukemia (AML), a small fraction of blast cells contains the tumor initiating cells, further referred to as leukemic stem cells (LSCs). LSC resemble hematopoietic stem cells (HSCs) with respect to self renewal capacity and quiescence. Therefore, LSCs are proposed to be therapy resistant. In order to optimally target LSCs and sparing HSC and to monitor therapy, discrimination between LSC is HSC is required. We showed that within the CD34+CD38− stem cell compartment, LSCs can be discriminated from HSC by aberrant expression of markers, including lineage markers like CD7, CD19 and CD56 and the novel LSC marker CLL-1 (van Rhenen et al., Leukemia 2007 and Blood 2007). Too low aberrant marker expression, however, hampers discrimination in part of the cases. Therefore, we investigated additional parameters that would allow to distinguish LSCs from HSCs in CD34 positive AML patients. In 14 out of 48 cases studied, flow cytometry revealed a double population within the CD34+CD38− compartment, characterized by a small but clear difference in forward scatter (FSC, reflecting cell size) and sideward scatter (SSC, reflecting granularity). In 7/14 cases with high marker expression, FSChighSSChigh population coincided completely with the population with aberrant marker expression. In the other cases, marker expression was too moderate to show a complete overlap. The FSClowSSClow population within the CD34+CD38− stem cell compartment is the minor population at diagnosis (median 16%, range 0.2%–92%; n=14), had no expression of aberrant markers and, moreover, closely resembled the FSC/SSC characteristics of normal BM HSCs. In addition, in these patients, the normality of the FSClowSSClow population was also supported by the fact that the CD34 and CD45 antigen density was similar to that of normal BM HSCs. Altogether, this enabled to use FSC/SSC characteristics together with aberrant CD34 and CD45 expression to discriminate between LSC and HSC in cases with low or absent aberrant marker expression (8/48). In addition, the malignant character of the FSChighSSChigh population and the normal character of the FSClowSSClow population could be proven in three AML patients with cytogenetic aberrancies. Patient 1 had a t(8;21) translocation and presented with a CD34+CD38−- population that was CD19 positive (81% of the stem cell compartment) and had FSChighSSChigh properties. FACSsorted cells contained the translocation in 90% of the cells. The CD19 negative population (19% of the stem cell compartment) had FSClowSSClow characteristics and contained 0% t(8;21) cells. In two other AML cases with a cytogenetic aberrancy (t(8;21) and t(15;17), respectively), FSC/SSC characteristics, CD34/CD45 antigen density and aberrant marker expression (CD56 in one case and CLL-1 in the other) were partly overlapping (estimated LSC contribution to the CD34+CD38− compartment was 85% in both cases). Cell sorting on the highest FSC/SSC and marker expression nevertheless resulted in enrichment of cytogenetically aberrant cells (63% and 73%, respectively), while the corresponding FSClowSSClow cells, which missed CD56 and CLL-1 expression, were enriched for cytogenetically normal HSCs (87% and 67%, respectively). The marker and scatter parameters discussed above have generated the possibility to discriminate between LSCs and HSCs and now allows specific detection of LSC in >75 % of the patients. Discrimination between LSCs and HSCs in AML might not only facilitate to establish the therapeutic window of current therapies in terms of LSC specificity, but also allow the identification of new highly AML stem cells specific therapeutic targets. This should ultimately result in more selective therapies, which would be highly effective for AML stem cells, while leaving the normal HSC intact. This work was supported by Netherlands Cancer Foundation KWF.

Expression of C-Type Lectin-Like Molecule-1 (CLL-1) on Stem Cells Might Discriminate De Novo Acute Myeloid Leukemia from Acute Myeloid Leukemia Originating from Myelodysplastic Syndromes

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2697-2697
Author(s):  
Theresia M Westers ◽  
Monique Terwijn ◽  
Canan Alhan ◽  
Yvonne FCM van der Veeken ◽  
Claudia Cali ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
High Risk ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Low Risk ◽  
Cell Compartment ◽  
Stem Cell Compartment ◽  
De Novo Aml ◽  
Acute Myeloid

Abstract It is generally accepted that myelodysplastic syndromes (MDS) most often originate in a multipotent, myelorestricted progenitor population, although primary transformation may occur at the hematopoietic stem cell level. MDS can be classified into low risk and high risk with evolution to acute myeloid leukemia (AML) predominantly in the latter cases. In AML, survival of leukemia-initiating cells, often referred to as leukemic stem cells, after chemotherapy is thought to lead to minimal residual disease and relapse. Hence, in de novo AML a larger size of the stem cell compartment is predictive for poor survival. [Van Rhenen et al.,Clin Cancer Res 2005,11] The monoclonal antibody against the cell surface antigen C-type lectin-like molecule-1, CLL-1, together with lineage infidelity markers enables discrimination of normal and malignant stem cells. [Van Rhenen et al.,Blood 2007,110; Van Rhenen et al.,Leukemia 2007,21] It could be hypothesized that CLL-1 and aberrant marker expression on MDS stem cells together with size of the stem cell compartment may predict leukemic evolution. Therefore, stem cells, defined as CD45dimCD34+CD38−, were analyzed for expression of CLL-1 and aberrant lineage markers in bone marrow samples from 88 MDS patients classified by WHO as 16 RA w/o RS, 42 RCMD w/o RS, 3 MDS-U, 5 hypoplastic MDS, 6 MDS/MPD and CMML, 15 RAEB-1 and 2, 20 AML patients with a known MDS history and 26 healthy controls. Analysis of the CD34+CD38− frequency in all MDS patients and normal controls revealed no significant differences (median 0.0061% vs. 0.0074%, respectively), whereas the frequency of CD34+CD38− cells was 17-fold higher in high risk MDS (RAEB-1 and 2, median: 0.076%) as compared to low risk MDS (median: 0.0046%, p<0.001). Similar as in AML, stem cells were significantly more prevalent within the blast cell fraction (CD45dimSSCint/low) of high risk MDS as compared to low risk MDS (median 0.77% and 0.25%, respectively), reflecting the differences in clinical course in these patients (p=0.040). Regarding CLL-1 expression, a reliable number of stem cells (>20) could be tested in 11/15 high risk RAEB-1 and 2 cases and in 16/73 of the remaining low risk MDS cases. In these cases, median CLL-1 expression on the CD34+CD38− cells was 1.6% (range 0–50) in low risk and 2.0% (range 0–27) in high risk MDS. Median CLL-1 expression on stem cells was 0.0% (range 0–4.7) in normal controls. Nevertheless, expression of lineage infidelity markers, such as CD5, CD7 and CD56, on CD34+CD38− stem cells in MDS strongly suggests that a considerable part of these stem cells is malignant (median 35% in 7/16 patients tested). Our data show that CLL-1 is virtually absent on stem cells in MDS. Remarkably, median CLL-1 expression on stem cells in AML cases that evolved from MDS (7%, range 0–53, n=9) was manifold lower than in de novo AML (median 45% when excluding non de novo AML [Van Rhenen et al.,Blood 2007,110], p=0.034). Detailed analysis of CLL-1 expression in AML had already revealed that CLL-1 expression increases with differentiation (CD34− > CD34+CD38− > CD34+CD38+). [Bakker et al.,Cancer Res 2004,64;Van Rhenen et al.,Blood 2007,110] Thus, our data suggest that the CD34+CD38− cells in high risk MDS and AML with antecedent MDS are more immature than in most de novo AML, which might explain poor prognosis of AML cases with MDS history. To conclude, our data indicate that CLL-1 is a specific marker of de novo AML, while CLL-1-negative AML may have been evolved from a MDS pre-phase that is further characterized by an increasing size of the stem cell compartment upon progression towards AML.

Longterm Serial Transplantability of BCR-ABL+ Chronic Phase CML Cells Is Predicted by a 6-Week LTC-IC Assay.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2770-2770
Author(s):  
Ivan Sloma ◽  
Philip A Beer ◽  
Kyi Min Saw ◽  
Matthiew Chan ◽  
Karen Lambie ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stromal Cells ◽  
Myeloid Cells ◽  
Chronic Phase ◽  
Cell Compartment ◽  
Qrt Pcr ◽  
Nsg Mice ◽  
Stem Cell Compartment ◽  
Cd34 Cells

Abstract Abstract 2770 Since the advent of tyrosine kinase inhibitors (TKIs) to treat CML patients, the development of methods to measure and characterize the CML stem cell compartment has stimulated increasing interest. Here we compared different methods for quantifying the relative frequency of very primitive Ph+/BCR-ABL+ in 33 chronic phase CML patients that had not been previously treated with TKIs. Materials and Methods Longterm culture-initiating cells (LTC-ICs) were assayed by coculturing immunomagnetically isolated CD34+ cells for 5-weeks in LTCs containing murine stromal cells (n=10) and/or for 6-weeks in LTCs containing murine stromal cells secreting human SCF, IL-3 and G-CSF (n=33). Genotyping of the LTC-ICs was based on genotyping individual colonies generated in methylcellulose assays of cells harvested at the end of the 5 or 6 weeks of coculture, either by karyotyping G-banded metaphases (n=16) or by qRT-PCR of extracted RNA (n=17). In vivo assays were performed on 2 samples by injecting 106 CD34+ cells (>97% and 44% Ph+ 6-week LTC-ICs) IV into primary sublethally irradiated NOD/SCID IL2Rγc−/− (NSG) mice and after 30–35 weeks further into secondary NSG mice. All mice were analyzed periodically for human hematopoietic cells by flow cytometry of marrow aspirates. CD34+CD38− cells isolated by FACS from primary CML samples (n=17) were spotted on slides and examined by FISH for the presence of the BCR-ABL gene. Results The proportion of 6-week LTC-ICs that was Ph+/BCR-ABL+ ranged from <5% to 100%. Although the CML LTC-ICs represented >80% of the LTC-ICs in 36% of the 33 cases studied, these represented <50% in 45% of these cases. Ph+/BCR-ABL+ LTC-ICs were more prevalent when measured with the 5-week LTC-IC assay (86±7% Ph+/BCR-ABL+) than with the 6-week LTC-IC assay (11±8% Ph+/BCR-ABL+, n=10). FISH analysis of the initial CD34+CD38- cells showed that >80% of these were BCR-ABL+ in 70% of the 17 cases studied. Notably, these latter values were not correlated with the proportion of leukemic 6-week LTC-ICs in the same samples (Spearman rank correlation r = 0.43, p = 0.08). Primary NSG mice transplanted with CD34+ cells from the patient with no detectable normal LTC-ICs regenerated almost exclusively differentiated human myeloid cells for up to 35 weeks and at increasing levels at the later time points (35% of total marrow cells after 35 weeks). Cells obtained 8 and 35 weeks post-transplant showed these contained readily detectable clonogenic cells which were exclusively BCR-ABL+ (84 genotyped colonies). Secondary recipients were again repopulated with exclusively BCR-ABL+ myeloid cells. Recipients of the second sample showed a transient early peak of myeloid cells followed by a peak of B lymphoid cells at 8 weeks, at which time only 20% of the human CFCs present were BCR-ABL+. At 35 weeks post-transplant, human cells were still detectable in these mice (5±3% of the marrow) and myeloid cells had again become the predominant lineage with BCR-ABL+ cells detectable by qRT-PCR but no CFCs were identified. Secondary recipients of these cells were reconstituted with myeloid cells but only transiently. Conclusion Functionally defined chronic phase CML stem cells represent a very minor subset of the CD34+CD38- compartment and assessment of these cells, like assessment of the most commonly used 5-week LTC-IC assay, overestimates the BCR-ABL+ stem cell compartment. Both of these endpoints also fail to provide a reliable indicator of the prevalence of BCR-ABL+ stem cells defined by more stringent functional assays. We also show for the first time that BCR-ABL+ CML stem cells are capable of serial transplantability spanning one and a half years in NSG mice and this may be anticipated by results from the 6-week LTC-IC assay. Disclosures: No relevant conflicts of interest to declare.

scholarly journals T cell–derived interferon-γ programs stem cell death in immune-mediated intestinal damage

2019 ◽  
Vol 4 (42) ◽  
pp. eaay8556 ◽  
Author(s):  
S. Takashima ◽  
M. L. Martin ◽  
S. A. Jansen ◽  
Y. Fu ◽  
J. Bos ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Paneth Cell ◽  
Interferon Γ ◽  
Cell Compartment ◽  
Stem Cell Compartment ◽  
Immune Mediated ◽  
Donor T Cells ◽  
Epithelial Cultures

Despite the importance of intestinal stem cells (ISCs) for epithelial maintenance, there is limited understanding of how immune-mediated damage affects ISCs and their niche. We found that stem cell compartment injury is a shared feature of both alloreactive and autoreactive intestinal immunopathology, reducing ISCs and impairing their recovery in T cell–mediated injury models. Although imaging revealed few T cells near the stem cell compartment in healthy mice, donor T cells infiltrating the intestinal mucosa after allogeneic bone marrow transplantation (BMT) primarily localized to the crypt region lamina propria. Further modeling with ex vivo epithelial cultures indicated ISC depletion and impaired human as well as murine organoid survival upon coculture with activated T cells, and screening of effector pathways identified interferon-γ (IFNγ) as a principal mediator of ISC compartment damage. IFNγ induced JAK1- and STAT1-dependent toxicity, initiating a proapoptotic gene expression program and stem cell death. BMT with IFNγ–deficient donor T cells, with recipients lacking the IFNγ receptor (IFNγR) specifically in the intestinal epithelium, and with pharmacologic inhibition of JAK signaling all resulted in protection of the stem cell compartment. In addition, epithelial cultures with Paneth cell–deficient organoids, IFNγR-deficient Paneth cells, IFNγR–deficient ISCs, and purified stem cell colonies all indicated direct targeting of the ISCs that was not dependent on injury to the Paneth cell niche. Dysregulated T cell activation and IFNγ production are thus potent mediators of ISC injury, and blockade of JAK/STAT signaling within target tissue stem cells can prevent this T cell–mediated pathology.

scholarly journals The Epidermal Stem Cell Compartment: Variation in Expression Levels of E–Cadherin and Catenins Within the Basal Layer of Human Epidermis

1997 ◽  
Vol 45 (6) ◽  
pp. 867-874 ◽  
Author(s):  
Jean-Pierre Molès ◽  
Fiona M. Watt
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Basal Layer ◽  
Human Epidermis ◽  
Proliferative Potential ◽  
Stem Cell Markers ◽  
Cell Compartment ◽  
Stem Cell Compartment ◽  
E Cadherin ◽  
Cell Cell

The basal layer of the epidermis contains two types of proliferating keratinocyte: stem cells, with high proliferative potential, and transit amplifying cells, which are destined to undergo terminal differentiation after a few rounds of division. It has been shown previously that two- to three-fold differences in the average staining intensity of fluorescein-conjugated antibodies to β1 integrin subunits reflect profound differences in the proliferative potential of keratinocytes, with integrin-bright populations being enriched for stem cells. In the search for additional stem cell markers, we have stained sections of normal human epidermis with antibodies to proteins involved in intercellular adhesion and quantitated the fluorescence of individual cell-cell borders. In the basal layer, patches of brightly labeled cells were detected with antibodies to E-cadherin, β-catenin, and γ-catenin, but not with antibodies to P-cadherin, α-catenin, or with pan-desmocollin and pan-desmoglein antibodies. In the body sites examined, palm and foreskin, integrinbright regions were strongly labeled for γ-catenin and weakly labeled for E-cadherin and β-catenin. Our data suggest that there are gradients of both cell-cell and cell-extracellular matrix adhesiveness within the epidermal basal layer and that the levels of E-cadherin and of β-and γ-catenin may provide markers for the stem cell compartment, stem cells expressing relatively higher levels of γ-catenin and lower levels of E-cadherin and β-catenin than other basal keratinocytes.

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