Petra M. Bareiss

Expansion and differentiation of neural progenitors derived from the human adult enteric nervous system.

BACKGROUND & AIMS Neural stem and progenitor cells from the enteric nervous system have been proposed for use in cell-based therapies against specific neurogastrointestinal disorders. Recently, enteric neural progenitors were generated from human neonatal and early postnatal (until 5 years after birth) gastrointestinal tract tissues. We investigated the proliferation and differentiation of enteric nervous system progenitors isolated from human adult gastrointestinal tract. METHODS Human enteric spheroids were generated from adult small and large intestine tissues and then expanded and differentiated, depending on the applied cell culture conditions. For implantation studies, spheres were grafted into fetal slice cultures and embryonic aganglionic hindgut explants from mice. Differentiating enteric neural progenitors were characterized by 5-bromo-2-deoxyuridine labeling, in situ hybridization, immunocytochemistry, quantitative real-time polymerase chain reaction, and electrophysiological studies. RESULTS The yield of human neurosphere-like bodies was increased by culture in conditional medium derived from fetal mouse enteric progenitors. We were able to generate proliferating enterospheres from adult human small or large intestine tissues; these enterospheres could be subcultured and maintained for several weeks in vitro. Spheroid-derived cells could be differentiated into a variety of neuronal subtypes and glial cells with characteristics of the enteric nervous system. Experiments involving implantation into organotypic intestinal cultures showed the differentiation capacity of neural progenitors in a 3-dimensional environment. CONCLUSIONS It is feasible to isolate and expand enteric progenitor cells from human adult tissue. These findings offer new strategies for enteric stem cell research and future cell-based therapies.

Isolation of functionally distinct mesenchymal stem cell subsets using antibodies against CD56, CD271, and mesenchymal stem cell antigen-1

Mesenchymal stem cells are self-renewing cells with the ability to differentiate into osteocytes, chondrocytes and adipocytes. This article describes a subset of mesenchymal stem cells with distinct phenotypic and functional properties. Background Conventionally, mesenchymal stem cells are functionally isolated from primary tissue based on their capacity to adhere to a plastic surface. This isolation procedure is hampered by the unpredictable influence of co-cultured hematopoietic and/or other unrelated cells and/or by the elimination of a late adhering mesenchymal stem cells subset during removal of undesired cells. To circumvent these limitations, several antibodies have been developed to facilitate the prospective isolation of mesenchymal stem cells. Recently, we described a panel of monoclonal antibodies with superior selectivity for mesenchymal stem cells, including the monoclonal antibodies W8B2 against human mesenchymal stem cell antigen-1 (MSCA-1) and 39D5 against a CD56 epitope, which is not expressed on natural killer cells. Design and Methods Bone marrow derived mesenchymal stem cells from healthy donors were analyzed and isolated by flow cytometry using a large panel of antibodies against surface antigens including CD271, MSCA-1, and CD56. The growth of mesenchymal stem cells was monitored by colony formation unit fibroblast (CFU-F) assays. The differentiation of mesenchymal stem cells into defined lineages was induced by culture in appropriate media and verified by immunostaining. Results Multicolor cell sorting and CFU-F assays showed that mesenchymal stem cells were ~90-fold enriched in the MSCA-1+CD56− fraction and ~180-fold in the MSCA-1+CD56+ fraction. Phenotype analysis revealed that the expression of CD10, CD26, CD106, and CD146 was restricted to the MSCA-1+CD56− mesenchymal stem cells subset and CD166 to MSCA-1+CD56± mesenchymal stem cells. Further differentiation of these subsets showed that chondrocytes and pancreatic-like islets were predominantly derived from MSCA-1+CD56± cells whereas adipocytes emerged exclusively from MSCA-1+CD56− cells. The culture of single sorted MSCA-1+CD56+ cells resulted in the appearance of phenotypically heterogeneous clones with distinct proliferation and differentiation capacities. Conclusions Novel mesenchymal stem cells subsets with distinct phenotypic and functional properties were identified. Our data suggest that the MSCA-1+CD56+ subset is an attractive starting population for autologous chondrocyte transplantation.

Expression of the embryonic stem cell marker SOX2 in early-stage breast carcinoma

BackgroundThe SRY-related HMG-box family of transcription factors member SOX2 has been mainly studied in embryonic stem cells as well as early foregut and neural development. More recently, SOX2 was shown to participate in reprogramming of adult somatic cells to a pluripotent stem cell state and implicated in tumorigenesis in various organs. In breast cancer, SOX2 expression was reported as a feature of basal-like tumors. In this study, we assessed SOX2 expression in 95 primary tumors of postmenopausal breast cancer patients.MethodsSamples from 95 patients diagnosed and treated at the University of Tuebingen Institute of Pathology and Womens Hospital were analyzed by immunohistochemistry for SOX2 expression in the primary tumor samples and in corresponding lymph node metastasis, where present. Furthermore, SOX2 amplification status was assessed by FISH in representative samples. In addition, eighteen fresh frozen samples were analyzed for SOX2, NANOG and OCT4 gene expression by real-time PCR.ResultsSOX2 expression was detected in 28% of invasive breast carcinoma as well as in 44% of ductal carcinoma in situ (DCIS) lesions. A score of SOX2 expression (score 0 to 3) was defined in order to distinguish SOX2 negative (score 0) from SOX2 positive samples (score 1-3) and among latter the subgroup of SOX2 high expressors (score 3 > 50% positive cells). Overall, the incidence of SOX2 expression (score 1-3) was higher than previously reported in a cohort of lymph node negative patients (28% versus 16.7%). SOX2 expression was detected across different breast cancer subtypes and did not correlate with tumor grading. However, high SOX2 expression (score 3) was associated with larger tumor size (p = 0.047) and positive lymph node status (0.018). Corresponding metastatic lymph nodes showed higher SOX2 expression and were significantly more often SOX2 positive than primary tumors (p = 0.0432).ConclusionsIn this report, we show that the embryonic stem cell factor SOX2 is expressed in a variety of early stage postmenopausal breast carcinomas and metastatic lymph nodes. Our data suggest that SOX2 plays an early role in breast carcinogenesis and high expression may promote metastatic potential. Further studies are needed to explore whether SOX2 can predict metastatic potential at an early tumor stage.

SOX2 Expression Associates with Stem Cell State in Human Ovarian Carcinoma

The SRY-related HMG-box family of transcription factors member SOX2 regulates stemness and pluripotency in embryonic stem cells and plays important roles during early embryogenesis. More recently, SOX2 expression was documented in several tumor types including ovarian carcinoma, suggesting an involvement of SOX2 in regulation of cancer stem cells (CSC). Intriguingly, however, studies exploring the predictive value of SOX2 protein expression with respect to histopathologic and clinical parameters report contradictory results in individual tumors, indicating that SOX2 may play tumor-specific roles. In this report, we analyze the functional relevance of SOX2 expression in human ovarian carcinoma. We report that in human serous ovarian carcinoma (SOC) cells, SOX2 expression increases the expression of CSC markers, the potential to form tumor spheres, and the in vivo tumor-initiating capacity, while leaving cellular proliferation unaltered. Moreover, SOX2-expressing cells display enhanced apoptosis resistance in response to conventional chemotherapies and TRAIL. Hence, our data show that SOX2 associates with stem cell state in ovarian carcinoma and induction of SOX2 imposes CSC properties on SOC cells. We propose the existence of SOX2-expressing ovarian CSCs as a mechanism of tumor aggressiveness and therapy resistance in human SOC.

Selection of radioresistant tumor cells and presence of ALDH1 activity in vitro.

BACKGROUND Tumor resistance to radiotherapy has been hypothesized to be mediated by a tumor subpopulation, called cancer stem cells (CSCs). Based on the proposed function of CSCs in radioresistance, we explored the cancer stem cell properties of cells selected for radioresistance phenotype. MATERIALS AND METHODS A549 and SK-BR-3 cells were radioselected with four single doses of 4 or 3 Gy in intervals of 10-12 days and used for colony formation assay and γ-H2AX foci formation assay. Expression of putative stem cell markers, i.e. Sox2, Oct4, ALDH1, and CD133 were analyzed using Western blotting. A549 and SK-BR-3 cells sorted based on their ALDH1 activity were analyzed in clonogenic survival assays. RESULTS Radioselected A549 and SK-BR-3 cells (A549-R, SK-BR-3-R) showed increased radioresistance and A549-R cells presented enhanced repair of DNA-double strand breaks. PI3K inhibition significantly reduced radioresistance of A549-R cells. Cell line specific differences in the expression of the putative CSC markers Sox2 and Oct4 were observed when parental and radioselected cells were compared but could not be directly correlated to the radioresistant phenotype. However, enzyme activity of the putative stem cell marker ALDH1 showed a correlation to radioresistance. CONCLUSIONS Subpopulations of pooled radioresistant colonies, selected by various radiation exposures were analyzed for the presence of putative stem cell markers. Although the pattern of Sox2, Oct4, and CD133 expression was not generally associated with radioresistance, presence of ALDH1 seems to be indicative for subpopulations with increased radioresistance.

Expression and role of the embryonic protein SOX2 in head and neck squamous cell carcinoma

Recently, SOX2 has been identified as a potential lineage-specific oncogene in lung squamous cell carcinomas. Since head and neck squamous cell carcinomas (HNSCC) are morphologically and clinically highly related to lung squamous cell carcinomas, we hypothesized that SOX2 also plays an oncogenic role in this tumor entity. We assembled a cohort of 496 patients with HNSCC, including 253 metastases and 135 recurrences. SOX2 amplification (FISH) and SOX2 protein expression (immunohistochemistry) were correlated with molecular and clinicopathological parameters. In order to investigate the functional role of SOX2 in human HNSCC, SOX2 knockdown and overexpression in SCC-25 cells were generated by lentiviral constructs and subjected to cell cycle analysis, proliferation and apoptosis assays. Furthermore, SOX2 expression was correlated with the expression of proliferation and apoptosis-related proteins in primary HNSCC samples. SOX2 amplification was detected in 21% of primary HNSCC and mostly observed in a concordant manner between primary tumors and corresponding metastatic tissues. Overall, SOX2 amplification resulted in protein overexpression and was mutually exclusive with human papillomavirus infection. SOX2 protein overexpression was associated with clinicopathological parameters of worse outcome. Functionally, SOX2 induced the expression of the antiapoptotic protein BCL-2 and enhanced resistance to apoptosis-inducing agents including cisplatin, indicating SOX2 as a mediator of therapy resistance in human HNSCC. Targeting SOX2 and related molecular downstream pathways such as BCL-2 may enhance therapy efficacy in SOX2-expressing HNSCC.

SGK1-sensitive renal tubular glucose reabsorption in diabetes.

The hyperglycemia of diabetes mellitus increases the filtered glucose load beyond the maximal tubular transport rate and thus leads to glucosuria. Sustained hyperglycemia, however, may gradually increase the maximal renal tubular transport rate and thereby blunt the increase of urinary glucose excretion. The mechanisms accounting for the increase of renal tubular glucose transport have remained ill-defined. A candidate is the serum- and glucocorticoid-inducible kinase SGK1. The kinase has been shown to stimulate Na(+)-coupled glucose transport in vitro and mediate the stimulation of electrogenic intestinal glucose transport by glucocorticoids in vivo. SGK1 expression is confined to glomerula and distal nephron in intact kidneys but may extend to the proximal tubule in diabetic nephropathy. To explore whether SGK1 modifies glucose transport in diabetic kidneys, Akita mice (akita(+/-)), which develop spontaneous diabetes, have been crossbred with gene-targeted mice lacking SGK1 on one allele (sgk1(+/-)) to eventually generate either akita(+/-)/sgk1(-/-) or akita(+/-)/sgk1(+/+) mice. Both akita(+/-)/sgk1(-/-) and akita(+/-)/sgk1(+/+) mice developed profound hyperglycemia (>20 mM) within approximately 6 wk. Body weight and plasma glucose concentrations were not significantly different between these two genotypes. However, urinary excretion of glucose and urinary excretion of fluid, Na(+), and K(+), as well as plasma aldosterone concentrations, were significantly higher in akita(+/-)/sgk1(-/-) than in akita(+/-)/sgk1(+/+) mice. Studies in isolated perfused proximal tubules revealed that the electrogenic glucose transport was significantly lower in akita(+/-)/sgk1(-/-) than in akita(+/-)/sgk1(+/+) mice. The data provide the first evidence that SGK1 participates in the stimulation of renal tubular glucose transport in diabetic kidneys.

Isolation of three stem cell lines from human sacrococcygeal teratomas.

Sacrococcygeal teratomas (SCTs) are benign tumours of the newborn with absolute indication for surgery directly after birth. We recently described the presence of stem cells positive for the stem cell markers nanog and Oct4 in SCTs. Here we report the isolation of three stem cell lines from three different SCTs. Cells were propagated in mesenchymal or in embryonic stem cell medium. Non‐clonal homogeneous stem cell lines were obtained after two to three passages and characterized in vitro by immunocytochemistry, RT‐PCR, western blot, FACS analysis, and metaphase spreads. The differentiation potential was tested in vitro and in vivo. The isolated cell lines, which we refer to as human sacrococcygeal teratoma stem cells (hSctSCs), express nanog, Oct4 and stella, and are negative for malignancy markers alpha‐fetoprotein and carcinoembryonic antigen. They can be induced in vitro to express neuronal, osteogenic, and chondrogenic traits. After grafting in vivo, spontaneous integration into the neural crest of the chick embryo and teratoma formation in the nude mouse were obtained. Our results indicate that SCTs are derived from remnants of the epiblast‐derived primitive streak, which in the human embryo normally regresses but forms teratomas in children affected with SCT. The hSctSCs therefore may be comparable to mouse epiblast‐derived stem cells (EpiSCs) and share characteristic features with human embryonic stem (hES) cells. Thus, SCT tissue obtained after surgery appears to be a novel source for the generation of human stem cells without the ethical implications associated with hES cells. Copyright

Three-dimensional slice cultures from murine fetal gut for investigations of the enteric nervous system.

Three‐dimensional intestinal cultures offer new possibilities for the examination of growth potential, analysis of time specific gene expression, and spatial cellular arrangement of enteric nervous system in an organotypical environment. We present an easy to produce in vitro model of the enteric nervous system for analysis and manipulation of cellular differentiation processes. Slice cultures of murine fetal colon were cultured on membrane inserts for up to 2 weeks without loss of autonomous contractility. After slice preparation, cultured tissue reorganized within the first days in vitro. Afterward, the culture possessed more than 35 cell layers, including high prismatic epithelial cells, smooth muscle cells, glial cells, and neurons analyzed by immunohistochemistry. The contraction frequency of intestinal slice culture could be modulated by the neurotransmitter serotonin and the sodium channel blocker tetrodotoxin. Coculture experiments with cultured neurospheres isolated from enhanced green fluorescent protein (eGFP) transgenic mice demonstrated that differentiating eGFP‐positive neurons were integrated into the intestinal tissue culture. This slice culture model of enteric nervous system proved to be useful for studying cell–cell interactions, cellular signaling, and cell differentiation processes in a three‐dimensional cell arrangement. Developmental Dynamics 236:128–133, 2007.

Expression of the Wnt Receptor Frizzled-4 in the Human Enteric Nervous System of Infants

The Wnt signalling pathway plays a crucial role in the development of the nervous system. This signalling cascade is initiated upon binding of the secreted Wnt ligand to a member of the family of frizzled receptors. In the present study, we analysed the presence of frizzled-4 in the enteric nervous system of human infants. Frizzled-4 could be identified by immunohistochemistry in a subpopulation of enteric neuronal and glial cells in the small and large intestine. Detection of frizzled-4 in the tunica muscularis by RT-PCR confirmed this receptors expression on the mRNA level. Interestingly, we observed distinct cell populations that co-expressed frizzled-4 with the intermediate filament protein nestin and the neurotrophin receptor p75NTR, which have been reported to be expressed in neural progenitor cells. Flow cytometry analysis revealed that 60% of p75NTR positive cells of the tunica muscularis were positive for frizzled-4. Additionally, in pathological samples of Hirschsprungs disease, the expression of this Wnt receptor correlated with the number of myenteric ganglion cells and decreased from normoganglionic to aganglionic areas of large intestine. The expression pattern of frizzled-4 indicates that this Wnt receptor could be involved in postnatal development and/or function of the enteric nervous system.