Expression of CD133, PAX2, ESA, and GPR30 in invasive ductal breast carcinomas

BACKGROUND

Biomarkers in breast neoplasms provide invaluable information regarding prognosis and help determining the optimal treatment. We have examined the possible correlation between cancer stem cell (CSC)-like markers (CD133, paired box gene 2 protein (PAX2), epithelial specific antigen (ESA)), and a new membrane estrogen receptor (G-protein coupled receptor 30 (GPR30)) in invasive ductal breast carcinomas with known clinicopathological parameters, tumor recurrence, and expression of some known biomarkers.

METHODS

In 74 invasive ductal breast carcinomas, we investigated the protein expression of these molecular markers by immunohistochemistry, and their associations with known clinicopathological parameters, tumor recurrence, and expression of some known biomarkers. We studied the interrelationship between the expressions of these proteins.

RESULTS

CD133, a putative CSC marker, was positively related to tumor size, tumor stage, and lymph node metastasis. PAX2 was negatively correlated with tumor recurrence. ESA, one of the breast CSC markers, was an indicator of tumor recurrence. GPR30 was associated with hormone receptors. Despite the correlation between GPR30 and the nuclear estrogen receptor, the expression was dependent. Positive staining of GPR30 in tumors displayed a significant association with high C-erbB2 expression and a tendency for tumor recurrence. A positive relationship between GPR30 and CD133 existed.

CONCLUSION

Detecting the expression of CD133, PAX2, ESA, and GPR30 in invasive ductal breast carcinomas may be of help in more accurately predicting the aggressive properties of breast cancer and determining the optimal treatment.

COMPARE-AMI trial: comparison of intracoronary injection of CD133+ bone marrow stem cells to placebo in patients after acute myocardial infarction and left ventricular dysfunction: study rationale and design

Stem cell therapy has emerged as a promising approach to improve healing of the infarcted myocardium, to treat or prevent cardiac failure, and to restore lost cardiac function. Despite initial excitement, recent clinical trials using nonhomogenous human stem cells preparations showed variable results, raising concerns about the best cell type to transplant. Selected CD133(+) hematopoietic stem cells are promising candidate cells with great potential. COMPARE-acute myocardial infarction (AMI) study is a phase II, randomized, double-blind, placebo-controlled trial evaluating the safety and effectiveness of intracoronary CD133(+)-enriched hematopoietic bone marrow stem cells in patients with acute myocardial infarction and persistent left ventricular dysfunction. Patients who underwent successful percutaneous coronary intervention and present a persistent left ventricular ejection fraction <50% will be eligible to have bone marrow aspiration and randomized for intracoronary injection of selected CD 133(+) bone marrow cells vs placebo. The primary end point is a composite of a safety and efficacy end points evaluating the change at 4 months in the coronary atherosclerotic burden progression proximal and distal to the coronary stent in the infarct related artery; and the change in global left ventricular ejection fraction at 4 months relative to baseline as measured by magnetic resonance imaging. The secondary end point will be the occurrence of a major adverse cardiac event. To date, 14 patients were successfully randomized and treated without any protocol-related complication. COMPARE-AMI trial will help identify the effect of a selected population of the bone marrow stem cells on cardiac recovery of infarcted myocardium.

GSK3beta regulates differentiation and growth arrest in glioblastoma

Cancers are driven by a population of cells with the stem cell properties of self-renewal and unlimited growth. As a subpopulation within the tumor mass, these cells are believed to constitute a tumor cell reservoir. Pathways controlling the renewal of normal stem cells are deregulated in cancer. The polycomb group gene Bmi1, which is required for neural stem cell self-renewal and also controls anti-oxidant defense in neurons, is upregulated in several cancers, including medulloblastoma. We have found that Bmi1 is consistently and highly expressed in GBM. Downregulation of Bmi1 by shRNAs induced a differentiation phenotype and reduced expression of the stem cell markers Sox2 and Nestin. Interestingly, expression of glycogen synthase kinase 3 beta (GSK3β), which was found to be consistently expressed in primary GBM, also declined. This suggests a functional link between Bmi1 and GSK3β. Interference with GSK3β activity by siRNA, the specific inhibitor SB216763, or lithium chloride (LiCl) induced tumor cell differentiation. In addition, tumor cell apoptosis was enhanced, the formation of neurospheres was impaired, and clonogenicity reduced in a dose-dependent manner. GBM cell lines consist mainly of CD133-negative (CD133-) cells. Interestingly, ex vivo cells from primary tumor biopsies allowed the identification of a CD133- subpopulation of cells that express stem cell markers and are depleted by inactivation of GSK3β. Drugs that inhibit GSK3, including the psychiatric drug LiCl, may deplete the GBM stem cell reservoir independently of CD133 status.

Stem cell therapy with overexpressed VEGF and PDGF genes improves cardiac function in a rat infarct model

Background

Therapeutic potential was evaluated in a rat model of myocardial infarction using nanofiber-expanded human cord blood derived hematopoietic stem cells (CD133+/CD34+) genetically modified with VEGF plus PDGF genes (VIP).

Methods and Findings

Myocardial function was monitored every two weeks up to six weeks after therapy. Echocardiography revealed time dependent improvement of left ventricular function evaluated by M-mode, fractional shortening, anterior wall tissue velocity, wall motion score index, strain and strain rate in animals treated with VEGF plus PDGF overexpressed stem cells (VIP) compared to nanofiber expanded cells (Exp), freshly isolated cells (FCB) or media control (Media). Improvement observed was as follows: VIP>Exp> FCB>media. Similar trend was noticed in the exercise capacity of rats on a treadmill. These findings correlated with significantly increased neovascularization in ischemic tissue and markedly reduced infarct area in animals in the VIP group. Stem cells in addition to their usual homing sites such as lung, spleen, bone marrow and liver, also migrated to sites of myocardial ischemia. The improvement of cardiac function correlated with expression of heart tissue connexin 43, a gap junctional protein, and heart tissue angiogenesis related protein molecules like VEGF, pNOS3, NOS2 and GSK3. There was no evidence of upregulation in the molecules of oncogenic potential in genetically modified or other stem cell therapy groups.

Conclusion

Regenerative therapy using nanofiber-expanded hematopoietic stem cells with overexpression of VEGF and PDGF has a favorable impact on the improvement of rat myocardial function accompanied by upregulation of tissue connexin 43 and pro-angiogenic molecules after infarction.

Cancer/testis antigens can be immunological targets in clonogenic CD133+ melanoma cells

"Cancer stem cells" that resist conventional treatments may be a cause of therapeutic failure in melanoma. We report a subpopulation of clonogenic melanoma cells that are characterized by high prominin-1/CD133 expression in melanoma and melanoma cell lines. These cells have enhanced clonogenicity and self-renewal in vitro, and serve as a limited in vitro model for melanoma stem cells. In some cases clonogenic CD133(+) melanoma cells show increased expression of some cancer/testis (CT) antigens. The expression of NY-ESO-1 in an HLA-A2 expressing cell line allowed CD133(+) clonogenic melanoma cells to be targeted for killing in vitro by NY-ESO-1-specific CD8(+) T-lymphocytes. Our in vitro findings raise the hypothesis that if melanoma stem cells express CT antigens in vivo that immune targeting of these antigens may be a viable clinical strategy for the adjuvant treatment of melanoma.

Low levels of endothelial progenitor cells correlate with disease duration and activity in patients with Behçet's disease

OBJECTIVES

We tested whether Behçet's disease (BD) is characterized by alterations of circulating endothelial progenitor cells (EPCs),which are involved in vascular homeostasis and repair.

METHODS

We enrolled 30 BD patients and 27 matched healthy controls. EPCs were defined and measured by flow cytometry according to the expression of CD34, CD133 and KDR.

RESULTS

We show that BD patients had significantly lower levels of CD34+KDR+ and CD34+CD133+KDR+ EPCs than controls. We found significant negative correlations between EPC phenotypes and BD duration, while there were positive correlations between CD34+KDR+ EPCs and both BD activity scores and C-reactive protein. The lower EPC levels with increasing disease duration was shown in univariate analysis and in multivariable analysis adjusted for possible confounders.

CONCLUSION

This is the first report that BD is associated with progressive EPC decline. Reduction of EPCs may represent a mechanism of induction and/or progression of vascular injury in these patients.

Levels of circulating endothelial progenitor cells are related to uremic toxins and vascular injury in hemodialysis patients

BACKGROUND

Patients suffering from chronic kidney diseases (CKD) exhibit cardiovascular diseases and profound endothelial dysfunction. CKD patients have reduced numbers of endothelial progenitor cells, but little is known about the factors influencing these numbers.

OBJECTIVES

Among these factors, we hypothesized that uremic toxins and vascular injury affect endothelial progenitor cells.

PATIENTS/METHODS

Thirty-eight hemodialysis patients were investigated and compared with 21 healthy controls. CD34+CD133+ immature progenitors, CD34+KDR+ endothelial progenitors cells (EPC) and myeloid EPC (mEPC) were counted in peripheral blood. Levels of uremic toxins beta(2)-microglobulin, indole-3 acetic acid, indoxylsulfate, p-cresylsulfate and homocysteine were measured. Vascular injury was assessed in hemodialysis (HD) patients by measuring aortic pulse wave velocity and plasma levels of endothelial microparticles. In vitro experiments were performed to study the effect of uremic toxins on apoptosis of progenitor cells.

RESULTS AND CONCLUSIONS

CD34+CD133+ immature progenitor cell number was negatively correlated with the levels of uremic toxins beta(2)-microglobulin and indole-3 acetic acid. In vitro, indole-3 acetic acid induced apoptosis of CD133+ cells. These data indicate uremic toxins have a deleterious role on progenitor cells, early in the differentiation process. Moreover, mEPC number was positively correlated with markers of vascular injury-pulse wave velocity and endothelial microparticle levels. This suggests that vascular lesions could stimulate progenitor cell mobilization, even in a context of reduced EPC induced by CKD. In conclusion, uremic toxins and vascular injury appear to affect endothelial progenitor cell biology in CKD.

[Comparison of immunomagnetic beads and hespan precipitation for isolation of mononuclear cells from umbilical cord blood]

OBJECTIVE

To compare the characteristics of immunomagnetic beads and hespan precipitation for isolation of mononuclear cells (MNCs) from umbilical cord blood and try to find a better isolation method for MNCs.

METHODS

Fifteen umbilical cord blood samples from healthy parturiens were collected between December 2007 and March 2008. MNCs were isolated using hespan precipitation and CD133 immunomagnetic beads, respectively. MNCs were identified using the surface marker CD34 by flow cytometry on the 30th of primary culture. Growth conditions and morphologic changes of primary cells were observed by an inverted microscope.

RESULTS

The number of MNCs from umbilical cord blood isolated by hespan precipitation (15.23 +/- 4.30 x 10(6)/mL) was significantly greater than that by CD133 immunomagnetic beads (0.066 +/- 0.027 x 10(6)/mL) (p<0.05). The MNCs isolated by hespan precipitation suspended at the culture medium and their growth was slow after passage. The growth of MNCs isolated by CD133 immunomagnetic beads was kept in a good condition. The CD34 positive rate of MNCs isolated by hespan precipitation and immunomagnetic beads was 10.1% and 0.5%, respectively.

CONCLUSIONS

The hespan precipitation is an effective method for MNCs isolation from human umbilical cord blood, but with a cell growth condition below the mark. The MNCs isolated by CD133 immunomagnetic beads are in a high purity quotient.

Glioblastoma formation from cell population depleted of Prominin1-expressing cells

Prominin1 (Prom1, also known as CD133 in human) has been widely used as a marker for cancer stem cells (CSCs), which self-renew and are tumorigenic, in malignant tumors including glioblastoma multiforme (GBM). However, there is other evidence showing that Prom1-negative cancer cells also form tumors in vivo. Thus it remains controversial whether Prom1 is a bona fide marker for CSCs. To verify if Prom1-expressing cells are essential for tumorigenesis, we established a mouse line, whose Prom1-expressing cells can be eliminated conditionally by a Cre-inducible DTA gene on the Prom1 locus together with a tamoxifen-inducible CreER^TM, and generated glioma-initiating cells (GICs-LD) by overexpressing both the SV40 Large T antigen and an oncogenic H-Ras^L61 in neural stem cells of the mouse line. We show here that the tamoxifen-treated GICs-LD (GICs-DTA) form tumor-spheres in culture and transplantable GBM in vivo. Thus, our studies demonstrate that Prom1-expressing cells are dispensable for gliomagenesis in this mouse model.

MicroRNA miR-34 inhibits human pancreatic cancer tumor-initiating cells

BACKGROUND

MicroRNAs (miRNAs) have been implicated in cancer initiation and progression via their ability to affect expression of genes and proteins that regulate cell proliferation and/or cell death. Transcription of the three miRNA miR-34 family members was recently found to be directly regulated by p53. Among the target proteins regulated by miR-34 are Notch pathway proteins and Bcl-2, suggesting the possibility of a role for miR-34 in the maintenance and survival of cancer stem cells.

METHODOLOGY/PRINCIPAL FINDINGS

We examined the roles of miR-34 in p53-mutant human pancreatic cancer cell lines MiaPaCa2 and BxPC3, and the potential link to pancreatic cancer stem cells. Restoration of miR-34 expression in the pancreatic cancer cells by either transfection of miR-34 mimics or infection with lentiviral miR-34-MIF downregulated Bcl-2 and Notch1/2. miR-34 restoration significantly inhibited clonogenic cell growth and invasion, induced apoptosis and G1 and G2/M arrest in cell cycle, and sensitized the cells to chemotherapy and radiation. We identified that CD44+/CD133+ MiaPaCa2 cells are enriched with tumorsphere-forming and tumor-initiating cells or cancer stem/progenitor cells with high levels of Notch/Bcl-2 and loss of miR-34. More significantly, miR-34 restoration led to an 87% reduction of the tumor-initiating cell population, accompanied by significant inhibition of tumorsphere growth in vitro and tumor formation in vivo.

CONCLUSIONS/SIGNIFICANCE

Our results demonstrate that miR-34 may restore, at least in part, the tumor suppressing function of the p53 in p53-deficient human pancreatic cancer cells. Our data support the view that miR-34 may be involved in pancreatic cancer stem cell self-renewal, potentially via the direct modulation of downstream targets Bcl-2 and Notch, implying that miR-34 may play an important role in pancreatic cancer stem cell self-renewal and/or cell fate determination. Restoration of miR-34 may hold significant promise as a novel molecular therapy for human pancreatic cancer with loss of p53-miR34, potentially via inhibiting pancreatic cancer stem cells.

CD133+ glioblastoma stem-like cells are radiosensitive with a defective DNA damage response compared with established cell lines

PURPOSE

CD133+ glioblastoma tumor stem-like cells (TSC) have been defined as radioresistant. However, although previously classified relative to CD133- cells, the radiosensitivity of CD133+ TSCs with respect to the standard glioblastoma model, established glioma cell lines, has not been determined. Therefore, to better understand the radioresponse of this cancer stem cell, we have used established cell lines as a framework for defining their in vitro radioresponse.

EXPERIMENTAL DESIGN

The intrinsic radiosensitivity of CD133+ TSC cultures and established glioma cell lines was determined by clonogenic assay. The TSCs and established cell lines were also compared in terms of DNA double-strand break (DSB) repair capacity and cell cycle checkpoint activation.

RESULTS

Based on clonogenic analysis, each of the six TSC cultures evaluated was more sensitive to radiation than the established glioma cell lines. Consistent with increased radiosensitivity, the DSB repair capacity as defined by neutral comet assay and gammaH2AX and Rad51 foci was significantly reduced in TSCs compared with the cell lines. Although G2 checkpoint activation was intact, in contrast to the cell lines, DNA synthesis was not inhibited in TSCs after irradiation, indicating the absence of the intra-S-phase checkpoint.

CONCLUSIONS

These data indicate that the mechanisms through which CD133+ TSCs respond to radiation are significantly different from those of the traditional glioblastoma in vitro model, established glioma cell lines. If TSCs play a critical role in glioblastoma treatment response, then such differences are likely to be of consequence in the development and testing of radiosensitizing agents.

CD133-expressing stem cells associated with ovarian metastases establish an endothelial hierarchy and contribute to tumor vasculature

Recruitment and localization of endothelial precursors within tumors is a potential area for the development of therapeutics, because their functional contribution to tumor vasculature is realized to be important for cancer cell survival. However, the exact nature of the recruited cell type and cellular events orchestrating the entire phenomenon remains obscure. We report that human ovarian cancer is frequently associated with cells expressing the stem cell surface marker CD133. We further show that these CD133-expressing cells are nontumorigenic in nature, and they augment tumor development through their vasculogenic potential. This cell population is attracted by cancer stem cells (CSCs) and retains a direct physical association within the CSC-derived spheroids. Our study further delineates the contribution of these vasculogenic CD133(+) stem cells, termed by us as endothelial stem cells (EnSCs) to the developing tumor vasculature during disease progression. In support of their being stem cells, the EnSCs have a capability of establishing an entire endothelial cell hierarchy. We conclude that such EnSCs play a crucial role in ensuring the development of long-term tumor vasculature to complement CSC-driven tumor development and disease progression.

Expansion of CD133-expressing liver cancer stem cells in liver-specific phosphatase and tensin homolog deleted on chromosome 10-deleted mice

PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a lipid phosphatase that regulates mitogenic signaling pathways, and deficiency of PTEN results in cell proliferation, survival, and malignancy. Murine liver-specific Pten deletion models develop liver malignancy by 12 months of age. Using this model, we describe a population of CD133+ liver cancer stem cells isolated during the chronic injury phase of disease progression and before primary carcinoma formation. We performed immunohistochemistry and flow cytometry isolation using livers from 3- and 6-month-old Pten(loxP/loxP); Alb-Cre+ mice (mutants) and controls. CD133+CD45- nonparenchymal (NP) cells were analyzed for gene expression profile and protein levels. Single CD133+CD45- oval cells were isolated for clonal expansion and tumor analysis. Cultured and freshly isolated liver CD133+CD45- and CD133-CD45- NP cells were injected into immune-deficient and immune-competent mice. In mutant mice, the NP fraction increased in CD133+CD45- cells in 3- and 6-month-old Pten-deleted animals compared with controls. Clone lines expanded from single CD133+CD45- cells demonstrated consistent liver progenitor cell phenotype, with bilineage gene expression of hepatocyte and cholangiocyte markers. CD133+ cells from expanded clone lines formed robust tumors in immune-deficient and immune-competent mice. Furthermore, freshly isolated CD133+CD45- NP liver cells from 6-month-old mutants formed tumors in vivo, and CD133-CD45- NP cells did not. Consistent with a cancer stem cell phenotype, CD133+ cells demonstrate resistance to chemotherapy agents compared with CD133- cells. CD133+CD45- nonparenchymal cells from chronic injury Pten(loxP/loxP); Alb-Cre+ mice represent a bipotent liver progenitor cell population with cancer stem cell phenotype.

Biology of glioma cancer stem cells

Gliomas, much like other cancers, are composed of a heterogeneous mix of neoplastic and non-neoplastic cells that include both native and recruited cells. There is extensive diversity among the tumor cells, with differing capacity for in vitro and in vivo growth, a property intimately linked to the cell's differentiation status. Those cells that are undifferentiated, self-renewing, with the capacity for developing tumors (tumorigenic) cells are designated by some as cancer stem cells, because of the stem-like properties. These cells may be a critical therapeutic target. However the exact identity and cell(s) of origin of the so-called glioma cancer stem cell remain elusive. Here we review the current understanding of glioma cancer stem cell biology.

Impaired preadipocyte differentiation in human abdominal obesity: role of Wnt, tumor necrosis factor-alpha, and inflammation

OBJECTIVE

We examined preadipocyte differentiation in obese and nonobese individuals and the effect of cytokines and wingless-type MMTV (mouse mammary tumor virus) integration site family, member 3A (Wnt3a) protein on preadipocyte differentiation and phenotype.

RESEARCH DESIGN AND METHODS

Abdominal subcutaneous adipose tissue biopsies were obtained from a total of 51 donors with varying BMI. After isolation of the adipose and stromalvascular cells, inflammatory cells (CD14- and CD45-positive cells) were removed by immune magnetic separation. CD133-positive cells, containing early progenitor cells, were also isolated and quantified. The CD14- and CD45-negative preadipocytes were cultured with tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, resistin, or Wnt3a with or without a differentiation cocktail.

RESULTS

The number of preadipocytes able to differentiate to adipose cells was negatively correlated with both BMI and adipocyte cell size of the donors, whereas the number of CD133-positive cells was positively correlated with BMI, suggesting an impaired differentiation of preadipocytes in obesity. Cultured preadipocytes, like freshly isolated mature adipocytes, from obese individuals had an increased expression of mitogen-activated protein 4 kinase 4 (MAP4K4), which is known to inhibit peroxisome proliferator-activated receptor-gamma induction. TNF-alpha, but not IL-6 or resistin, increased Wnt10b, completely inhibited the normal differentiation of the preadipocytes, and instead induced a proinflammatory and macrophage-like phenotype of the cells.

CONCLUSIONS

The apparent number of preadipocytes in the abdominal subcutaneous tissue that can undergo differentiation is reduced in obesity with enlarged fat cells, possibly because of increased MAP4K4 levels. TNF-alpha promoted a macrophage-like phenotype of the preadipocytes, including several macrophage markers. These results document the plasticity of human preadipocytes and the inverse relationship between lipid storage and proinflammatory capacity.

Isolation and partial characterization of a new human glioblastoma cell line

Although significant progresses were made in the field of molecular biology of malignant cerebral gliomas, the prognostic of these tumors continues to be reserved. One of the therapeutic failure reasons is the incomplete knowledge regarding the origin of these tumors and cells features, which in fact represent an obstacle in developing a cell and molecular therapy guided against malignant cells responsible for the tumor development and for the therapeutic resistance. Initiation and characterization of glioblastoma cell lines represents an essential step in order to obtain a better in vitro and in vivo experimental model for glioblastoma. We describe here a new glioblastoma line, named T11, which was successfully isolated in our laboratories starting with a tumor sample obtained intraoperative from a 58 years-old female patient. The histopathological evaluation showed a grad IV WHO glioma (glioblastoma). The sample was prepared by manual fragmentation, followed by enzymatic digestions using different concentration of trypsin. The cell line has been cultivated for more than 150 passages. The characterization of the glioblastoma line consisted in the evaluation of cells proliferation capacity (growth curve), morphological features, karyotyping and identification of specific markers. We found that T11 expressed specific markers for glial progenitors and astrocytes (glial fibrillary acidic protein-GFAP); oligodendrocites (A2B5; O4), and microglia (CD45, CD 11b). Cells were negative for neuronal lineage markers like beta3-tubulin and NCAM. In order to evaluate the differentiation grade of T11 cell line, the presence of stem cell markers (nestin, CD133) was explored. T11l cells expressed higher level of nestin and lower level of CD133 comparing with standard glioblastoma cell line U87. T11 cell line expressed VEGF and Bcl-2, but not EGFR and Mdrl and Bax. This new line has distinct and unique characteristics when compared with standard glioblastoma cell line (e.g., U87) and may become a new and useful in vitro model for glioblastoma.

CD133 gene overexpression is frequently observed in early colorectal carcinoma

BACKGROUND/AIMS

Recently, it has been proved that colorectal carcinoma is created and propagated by a small number of undifferentiated tumorigenic CD133+ cells. The present study examined the CD133 gene expression in colorectal carcinomas we surgically removed.

METHODOLOGY

The CD133 gene expression in primary tumors and corresponding normal tissues derived from 30 patients with colorectal carcinoma was examined using a quantitative reverse-transcription PCR (QRT-PCR) and evaluated the correlation between the CD133 gene expression levels and the clinicopathological findings.

RESULTS

An increase in CD133 expression scores was observed in Dukes A's colorectal carcinomas (1.70 +/- 2.28) compared to Dukes B and C's colorectal carcinomas (0.76 +/- 0.71) (p = 0.0860). An increase in CD133 expression scores was also observed in female colorectal carcinomas (1.29 +/- 1.56) compared to male colorectal carcinomas (0.61 +/- 0.57) (p = 0.125).

CONCLUSIONS

CD133 gene overexpression in early colorectal cancer patients was more frequently observed than in advanced cases.

Cryopreservation of neurospheres derived from human glioblastoma multiforme

Cancer stem cells have been shown to initiate and sustain tumor growth. In many instances, clinical material is limited, compounded by a lack of methods to preserve such cells at convenient time points. Although brain tumor-initiating cells grown in a spheroid manner have been shown to maintain their integrity through serial transplantation in immune-compromised animals, practically, it is not always possible to have access to animals of suitable ages to continuously maintain these cells. We therefore explored vitrification as a cryopreservation technique for brain tumor-initiating cells. Tumor neurospheres were derived from five patients with glioblastoma multiforme (GBM). Cryopreservation in 90% serum and 10% dimethyl sulfoxide yielded greatest viability and could be explored in future studies. Vitrification yielded cells that maintained self-renewal and multipotentiality properties. Karyotypic analyses confirmed the presence of GBM hallmarks. Upon implantation into NOD/SCID mice, our vitrified cells reformed glioma masses that could be serially transplanted. Transcriptome analysis showed that the vitrified and nonvitrified samples in either the stem-like or differentiated states clustered together, providing evidence that vitrification does not change the genotype of frozen cells. Upon induction of differentiation, the transcriptomes of vitrified cells associated with the original primary tumors, indicating that tumor stem-like cells are a genetically distinct population from the differentiated mass, underscoring the importance of working with the relevant tumor-initiating population. Our results demonstrate that vitrification of brain tumor-initiating cells preserves the biological phenotype and genetic profiles of the cells. This should facilitate the establishment of a repository of tumor-initiating cells for subsequent experimental designs.

Engineered herpes simplex viruses efficiently infect and kill CD133+ human glioma xenograft cells that express CD111

Oncolytic herpes simplex viruses (HSV) hold promise for therapy of glioblastoma multiforme (GBM) resistant to traditional therapies. We examined the ability of genetically engineered HSV to infect and kill cells that express CD133, a putative marker of glioma progenitor cells (GPC), to determine if GPC have an inherent therapeutic resistance to HSV. Expression of CD133 and CD111 (nectin-1), the major entry molecule for HSV, was variable in six human glioma xenografts, at initial disaggregation and after tissue culture. Importantly, both CD133+ and CD133- populations of glioma cells expressed CD111 in similar relative proportions in five xenografts, and CD133+ and CD133- glioma cell subpopulations were equally sensitive to killing in vitro by graded dilutions of wild-type HSV-1(F) or several different gamma(1)34.5-deleted viruses. GPC did not display an inherent resistance to HSV. While CD111 expression was an important factor for determining sensitivity of glioma cells to HSV oncolysis, it was not the only factor. Our findings support the notion that HSV will not be able to effectively enter, infect, and kill cells in tumors that have low CD111 expression (<20%). However, virotherapy with HSV may be very effective against CD111+ GPC resistant to traditional therapies.

Optimization and validation of FePro cell labeling method

Current method to magnetically label cells using ferumoxides (Fe)-protamine (Pro) sulfate (FePro) is based on generating FePro complexes in a serum free media that are then incubated overnight with cells for the efficient labeling. However, this labeling technique requires long (>12-16 hours) incubation time and uses relatively high dose of Pro (5-6 microg/ml) that makes large extracellular FePro complexes. These complexes can be difficult to clean with simple cell washes and may create low signal intensity on T2* weighted MRI that is not desirable. The purpose of this study was to revise the current labeling method by using low dose of Pro and adding Fe and Pro directly to the cells before generating any FePro complexes. Human tumor glioma (U251) and human monocytic leukemia cell (THP-1) lines were used as model systems for attached and suspension cell types, respectively and dose dependent (Fe 25 to 100 microg/ml and Pro 0.75 to 3 microg/ml) and time dependent (2 to 48 h) labeling experiments were performed. Labeling efficiency and cell viability of these cells were assessed. Prussian blue staining revealed that more than 95% of cells were labeled. Intracellular iron concentration in U251 cells reached approximately 30-35 pg-iron/cell at 24 h when labeled with 100 microg/ml of Fe and 3 microg/ml of Pro. However, comparable labeling was observed after 4 h across the described FePro concentrations. Similarly, THP-1 cells achieved approximately 10 pg-iron/cell at 48 h when labeled with 100 microg/ml of Fe and 3 microg/ml of Pro. Again, comparable labeling was observed after 4 h for the described FePro concentrations. FePro labeling did not significantly affect cell viability. There was almost no extracellular FePro complexes observed after simple cell washes. To validate and to determine the effectiveness of the revised technique, human T-cells, human hematopoietic stem cells (hHSC), human bone marrow stromal cells (hMSC) and mouse neuronal stem cells (mNSC C17.2) were labeled. Labeling for 4 hours using 100 microg/ml of Fe and 3 microg/ml of Pro resulted in very efficient labeling of these cells, without impairing their viability and functional capability. The new technique with short incubation time using 100 microg/ml of Fe and 3 microg/ml of Pro is effective in labeling cells for cellular MRI.

Detection of cancer stem cells from the C6 glioma cell line

Various malignant cancers have been found to contain a sub-population of stem cell-like tumour cells, or cancer stem cells (CSCs), however, culture methods for CSCs and the size of the fraction of CSCs in C6, which is a commonly used glioma cell line, remain controversial. In this study, we demonstrated that the C6 cell line contains a fraction of tumour cells that can form tumour spheres in a simplified serum-free neural stem cell medium and express CD133 and nestin, which are widely-used markers for brain CSCs. Immunohistochemistry and immunofluorescence confirmed the existence of CSCs both in the C6 cell line and C6 xenografts. Flow cytometry demonstrated that 4.02% of cells in the C6 cell line and 4.21% in the C6 xenografts presented as CSCs. These results confirm the fraction of CSCs in the C6 cell line and provide a simple and effective method for isolation of CSCs to study the initiation and progression of human glioma and, possibly, other malignant tumours.