Janus-like opposing roles of CD47 in autoimmune brain inflammation in humans and mice

CD47 exerts different effects on disease in distinct cell types and locations and during different stages of experimental autoimmune encephalomyelitis.

Comparison of transcriptomic and proteomic data from pathologically similar multiple sclerosis (MS) lesions reveals down-regulation of CD47 at the messenger RNA level and low abundance at the protein level. Immunohistochemical studies demonstrate that CD47 is expressed in normal myelin and in foamy macrophages and reactive astrocytes within active MS lesions. We demonstrate that CD47^−/− mice are refractory to experimental autoimmune encephalomyelitis (EAE), primarily as the result of failure of immune cell activation after immunization with myelin antigen. In contrast, blocking with a monoclonal antibody against CD47 in mice at the peak of paralysis worsens EAE severity and enhances immune activation in the peripheral immune system. In vitro assays demonstrate that blocking CD47 also promotes phagocytosis of myelin and that this effect is dependent on signal regulatory protein α (SIRP-α). Immune regulation and phagocytosis are mechanisms for CD47 signaling in autoimmune neuroinflammation. Depending on the cell type, location, and disease stage, CD47 has Janus-like roles, with opposing effects on EAE pathogenesis.

Abstract P108: Direct Evidence of Postnatal Cardiomyocyte Generation in Murine Models of Aging and Cardiac Injury

The dogma of the adult mammalian heart as a post-mitotic organ has recently come under question. Radiolabeled isotope studies have demonstrated that the human heart exhibits a low rate of renewal of cardiomyocytes throughout one’s lifespan. Furthermore, a recent study has elegantly shown that a neonatal mouse can regenerate its ventricle if the chamber is resected within the first week of birth. However, a number of questions remain unanswered about the nature of the cell type that gives rise to cardiomyocytes postnatally. The field has yet to clonally address whether cardiomyocytes divide symmetrically upon birth, or if a resident progenitor differentiates into cardiomyocytes. Rather than rely on proxies for cell division (e.g. BrdU incorporation studies), we use genetic mouse models in which cell division results in asymmetric, indelible labeling of the daughter cells (“Mosaic analysis of double markers” (MADM)) and a stochastic multi-color Cre reporter in the Rosa26 locus akin to the “Brainbow” mouse to investigate postnatal cell division clonally in order to identify which cell type(s) generate cardiomyocytes. Our studies have demonstrated limited symmetric division of cardiomyocytes during normal aging up to six weeks, with a significantly high rate of cardiomyocyte division during the first postnatal week. While we provide evidence for limited cell division in the peri-infarct region of a myocardial infarction model in the 24 hours after the infarct, the extent of cell division and proliferation over a longer time frame after the infarct remains to be explored.

In vivo molecular MRI of cell survival and teratoma formation following embryonic stem cell transplantation into the injured murine myocardium

Embryonic stem cells (ESCs) have shown the potential to restore cardiac function after myocardial injury. Superparamagnetic iron oxide nanoparticles (SPIO) have been widely employed to label ESCs for cellular MRI. However, nonspecific intracellular accumulation of SPIO limits long-term in vivo assessment of the transplanted cells. To overcome this limitation, a novel reporter gene (RG) has been developed to express antigens on the ESC surface. By employing SPIO-conjugated monoclonal antibody against these antigens (SPIO-MAb), the viability of transplanted ESCs can be detected in vivo. This study aims to develop a new molecular MRI method to assess in vivo ESC viability, proliferation, and teratoma formation. The RG is designed to express 2 antigens (hemagglutinin A and myc) and luciferase on the ESC surface. The two antigens serve as the molecular targets for SPIO-MAb. The human and mouse ESCs were transduced with the RG (ESC-RGs) and transplanted into the peri-infarct area using the murine myocardial injury model. In vivo MRI was performed following serial intravenous administration of SPIO-MAb. Significant hypointense signal was generated from the viable and proliferating ESCs and subsequent teratoma. This novel molecular MRI technique enabled in vivo detection of early ESC-derived teratoma formation in the injured murine myocardium.

Identification of the emergence of clonally multipotent hematopoietic stem and progenitor populations in the mouse embryo (153.10)

In the adult hematopoietic system, all mature blood cells derive from the hematopoietic stem cell (HSC). However, HSCs are not the first blood-forming cells to appear during embryogenesis. Rather, erythrocyte-biased progenitors can be identified in the yolk sac (YS) blood islands approximately a week after fertilization. After the establishment of circulation, fully functional HSCs can be identified within the aorta-gonad-mesonephros (AGM) and fetal liver (FL) tissues. The origin and maturation of HSCs in embryonic development remains an open and important question. To help address this issue, we sought to identify and isolate the blood-forming populations within these embryonic tissues at the stages when hematopoietic potential first appears. Using a modified OP9 stromal line that can yield 8 hematopoietic lineages (B, T, NK, DC, granulocyte, macrophage, platelet, and erythrocyte), we identified populations with multipotent potential at the clonal level in all tissues. While these embryonic multipotent cells share many of the surface markers that define adult HSCs, there are also distinct tissue-specific differences. Furthermore, these populations lack the ability to engraft into adult irradiated recipient mice, indicating their development into mature HSCs is incomplete. Our data support a model by which the ability to generate all hematopoietic lineages emerges prior to the ability to engraft.

Recent Studies of Interfacial Phenomena which Determine the Electrochemical Behavior of Lithium and Lithiated Carbon Anodes with the Emphasis on In Situ Techniques

This paper reports on some new results on the application of surface sensitive techniques for the study of the correlation of surface chemistry, morphology and electrochemical behavior of lithium and lithiated graphite as anodes for rechargeable batteries. Surface sensitive FTIR spectroscopy, atomic force microscopy (AFM), electrochemical quartz crystal microbalance (EQCM) were applied to Li and Li-graphite electrodes in a variety of electrolyte solutions of interest, in conjunction with standard electrochemical techniques. The similarity in the surface chemistry developed on Li and lithiated graphite in solutions is demonstrated and discussed. We demonstrate the strong impact of the surface chemistry on the morphology of Li deposition-dissolution processes, and the use of in situ EQCM measurements for the choice of optimal electrolyte solutions for rechargeable batteries with Li metal anodes.

An interview with Irving Weissman at the 2010 ISSCR meeting. Interview by Eva Amsen

The International Society for Stem Cell Research (ISSCR) held their annual conference in San Francisco this June. At the time, the President of the society was Irving Weissman, who is currently on the board of directors of the ISSCR as past President. He is Professor of Pathology and Developmental Biology and also the Director of the Institute of Stem Cell Biology and Regenerative Medicine at Stanford University School of Medicine, where he works on the generation of myeloid and lymphoid lineages from haematopoietic stem cells. At the ISSCR meeting, we asked Professor Weissman about his role on the board of directors of the ISSCR, and also about the meeting and the field of stem cell research in general.

Multimodality evaluation of the viability of stem cells delivered into different zones of myocardial infarction

BACKGROUND

We tested the hypothesis that multimodality imaging of mouse embryonic stem cells (mESCs) provides accurate assessment of cellular location, viability, and restorative potential after transplantation into different zones of myocardial infarction.

METHODS AND RESULTS

Mice underwent left anterior descending artery ligation followed by transplantation of dual-labeled mESCs with superparamagnetic iron oxide and luciferase via direct injection into 3 different zones of myocardial infarction: intra-infarction, peri-infarction, and normal (remote). One day after transplantation, magnetic resonance imaging enabled assessment of the precise anatomic locations of mESCs. Bioluminescence imaging allowed longitudinal analysis of cell viability through detection of luciferase activity. Subsequent evaluation of myocardial regeneration and functional restoration was performed by echocardiography and pressure-volume loop analysis. Using 16-segment analysis, we demonstrated precise localization of dual-labeled mESCs. A strong correlation between histology and magnetic resonance imaging was established (r=0.962, P=0.002). Bioluminescent imaging data demonstrated that cell viability in the remote group was significantly higher than in other groups. Echocardiography and pressure-volume loop analysis revealed improved functional restoration in animals treated with mESCs, although myocardial regeneration was not observed.

CONCLUSIONS

Multimodality evaluation of mESC engraftment in the heterogeneous tissue of myocardial infarction is possible. Magnetic resonance imaging demonstrated accurate anatomic localization of dual-labeled mESCs. Bioluminescent imaging enabled assessment of variable viability of mESCs transplanted into the infarcted myocardium. Echocardiography and pressure-volume loop analysis validated the restorative potential of mESCs. Although mESCs transplanted into the remote zone demonstrated the highest viability, precise delivery of mESCs into the peri-infarction region might be equally critical in restoring the injured myocardium.

Abstract 4998: Molecular profiling reveals heterogeneity of active self-renewal pathways in bladder cancer stem cells

The objective of the current study is to investigate the functional involvement of self-renewal related genes in patient bladder cancer stem cells. First, by fractionating primary patient bladder transitional cell carcinomas (TCCs) into subpopulations with flow cytometry, a unique tumor-initiating subpopulation expressing CD44 was identified in 5 independent TCCs, based on their enriched potential (10-200 folds) to induce xenograft tumors in immunocompromised mice. To extend this finding to a larger sample set, we analyzed a tissue array containing more than 300 bladder TCCs by immunohistochemistry. Approximately 40.4% of TCCs contain CD44+ cells; these cells usually express cytokeratin 5 (CK5) (P<0.0001) but not cytokeratin 20 (P=0.8160). In addition, cellular morphologies of CD44+ tumor cells are often small and round shape. These data suggest that CD44+ tumor cells retain cytokeratin markers and cellular morphologies resembling that of urothelial basal cells. Further, molecular profiling of oncogenic proteins implicated in the self-renewal of stem cells (i.e. Bmi1, Stat3, ß-catenin, Gli1, Oct4 and Nanog) revealed heterogeneity in bladder TCCs. Different subsets of CD44+ bladder TCCs express either one or more of different self-renewal proteins in their active forms (i.e. ~10% with nuclear Bmi1, 30% with nuclear Stat3, 5% with nuclear ß-catenin, 85% with active Gli1 and 0% with active Oct4 nor Nanog). In particular, in situ hybridization demonstrated that Gli1 mRNA was present in over 85% of bladder TCC specimens analyzed. Therefore, we examined the functional significance of the sonic hedgehog pathway in bladder tumor development. In patient bladder xenografts that originally contained active Gli1 in the cancer stem cells, preliminary experiment demonstrated that inhibition of this pathway with cyclopamine resulted in partial reduction of tumor volume (4 out of 6 xenografts). Previous reports demonstrated that genetic mutations in the pathway components (i.e. PTCH or Gli1) leading to constitutive Gli1 activation is rare in bladder TCCs. Preliminary microRNA (miRs) profiling of CD44+ bladder cancer stem cells using a real-time PCR based approach revealed a panel of differentially expressed miRs. Interestingly, in several highly elevated miRs in CD44+ bladder cancer stem cells, the negative regulators of the Gli1 pathways (i.e. PTCH and SUFU) are among the top predicted targets for these miRs. Further experiments are ongoing to validate the possible involvement of miRs in regulating the Gli1 pathways in bladder cancer stem cells. In conclusion, we demonstrated the existence of a functionally unique, CD44+ tumorigenic subpopulation in a subset of bladder TCCs. Diverse “self-renewal” proteins, including Gli1, possibly contribute to the tumorigenic properties of cancer stem cells in different subset of patient bladder TCCs.

BCL-2 and mutant NRAS interact physically and functionally in a mouse model of progressive myelodysplasia

Myelodysplastic syndromes (MDS) are clonal stem cell hematologic disorders that evolve to acute myeloid leukemia (AML) and thus model multistep leukemogenesis. Activating RAS mutations and overexpression of BCL-2 are prognostic features of MDS/AML transformation. Using NRASD12 and BCL-2, we created two distinct models of MDS and AML, where human (h)BCL-2 is conditionally or constitutively expressed. Our novel transplantable in vivo models show that expression of hBCL-2 in a primitive compartment by mouse mammary tumor virus-long terminal repeat results in a disease resembling human MDS, whereas the myeloid MRP8 promoter induces a disease with characteristics of human AML. Expanded leukemic stem cell (Lin(-)/Sca-1(+)/c-Kit(+)) populations and hBCL-2 in the increased RAS-GTP complex within the expanded Sca-1(+) compartment are described in both MDS/AML-like diseases. Furthermore, the oncogenic compartmentalizations provide the proapoptotic versus antiapoptotic mechanisms, by activating extracellular signal-regulated kinase and AKT signaling, in determination of the neoplastic phenotype. When hBCL-2 is switched off with doxycycline in the MDS mice, partial reversal of the phenotype was observed with persistence of bone marrow blasts and tissue infiltration as RAS recruits endogenous mouse (m)BCL-2 to remain active, thus demonstrating the role of the complex in the disease. This represents the first in vivo progression model of MDS/AML dependent on the formation of a BCL-2:RAS-GTP complex. The colocalization of BCL-2 and RAS in the bone marrow of MDS/AML patients offers targeting either oncogene as a therapeutic strategy.

Incorporation of bone marrow-derived Flk-1-expressing CD34+ cells in the endothelium of tumor vessels in the mouse brain

OBJECTIVE

Neoangiogenesis is a prerequisite for the full phenotypic expression and growth of a malignant tumor mass. It is believed to be triggered by tissue hypoxia and involves proliferation and sprouting of the preexisting vessels and the recruitment of endothelial progenitor cells from bone marrow.

METHODS

A chimeric mouse model was used to examine the contribution of these progenitor cells to the neovasculature of brain tumor. T-cell knockout (RAG/KO5.2) mice were irradiated lethally, and their bone marrow was repopulated with T-cell depleted green fluorescent protein (GFP)-expressing bone marrow cells. RAG/RT-2 glioma cells were implanted into the striatum of the animals. Neovascular formation at various times of tumor growth was monitored together with the extent of incorporation of GFP+ bone marrow-derived cells within the vascular tree, in particular, cells carrying the endothelial progenitor markers CD34 and Flk-1.

RESULTS

The recruitment of GFP+ cells to the growing tumor and their incorporation into the vascular network occurred during the period of increasing vascular density and preceded the expansion of the tumor. The number of marrow-derived cells with endothelial morphology and phenotype was small but significant (4% of all endothelial cells at Day 12); 54% of all tumor vessels contained at least one GFP+ cell.

CONCLUSION

Our results suggest that bone marrow cells are recruited to newly formed and remodeled tumor vessels. Their recruitment may occur in response to signals from a highly proliferating milieu, and their role is to support the neovascular complex and to promote tumor growth.

They are not stealthy in the heart: embryonic stem cells trigger cell infiltration, humoral and T-lymphocyte-based host immune response

OBJECTIVE

The in vivo immunogenicity of Embryonic Stem Cells is controversial. At present, there is only in vitro evidence of MHC I expression by this cell population but vivid speculation about their immune-privileged state. The immunology aspect of ESC transplantation deserves thorough investigation.

METHODS

We injected mouse ESC (expressing Green Fluorescent Protein, GFP) into injured myocardium of syngeneic, allogeneic and SCID recipients. Furthermore, we monitored host response for up to 4 weeks post cell transfer. We determined local response (CD 3, CD 11c expression by host cells), MHC I expression by donor cells, MHC-II expression within and around the graft, humoral response of allogeneic hosts using Flow Cytometry and evaluated the hosts' cytokine response using stimulated spleenocytes by means of ELISPOT. Cell survival was estimated by morphometry, by calculating the area of the GFP+ graft over the area of infarction at multiple sections of the harvested heart.

RESULTS

There was significant cellular infiltration into and around the graft consisting of T-lymphocytes (CD3+) and dendritic cells (CD 11c). Infiltration was detectable at 1 week and progressed through 4 weeks following cell transplantation. The humoral Ab response was moderate at 2 weeks but frank at 4 weeks. ELISPOT demonstrated a Th1 pathway of donor specific T-lymphocyte response with strong IFN-gamma and Il-2 production (figure A). MHC I expression was significant within the graft and maximal in the allogeneic groups.

CONCLUSIONS

An immune response against transplanted ESC was demonstrated and the future use of ESC will likely require the use of systemic immunosuppression.

Identification of phenotypic neural stem cells in a pediatric astroblastoma

OBJECT

The goal of this study was to illustrate the findings of a significant subpopulation of cells within a pediatric astroblastoma that have the specific cell surface phenotype found on known human neural stem cells.

METHODS

Cells with a cell surface marker profile characteristic of human neural stem cells were isolated using fluorescence-activated cell sorting from a mostly nonmitotic astroblastoma removed from the brain of an 11-year-old girl. An unusually high proportion (24%) of the cells were CD133 positive and CD24, CD34, and CD45 negative (CD133(+)CD24(-)CD34(-)CD45(-) cells), the phenotypic antigenic pattern associated with neural stem cells; very few CD133-positive cells were not also CD24, CD34, and CD45 negative. Some cells (12%) were CD34 positive, indicating the presence within the tumor of hematopoietic stem cells. Cells formed cytospheres that resembled neurospheres when seeded into stem cell media and coexpressed beta-tubulin and glial fibrillary acidic protein (GFAP) but did not express the oligodendrocyte marker O4. Cell proliferation was demonstrated by incorporation of bromodeoxyuridine. The cells lost their capacity for self-renewal in vitro after four to six passages, although they continued to coexpress beta-tubulin and GFAP. The cells did not differentiate into neurons or astrocytes when placed in differentiation medium.

CONCLUSIONS

Although this astroblastoma contained a high proportion of phenotypic neural stemlike cells, the cells had limited proliferative capacity and multipotency. Their role in astroblastoma formation and growth is unknown.

Stem cell research: paths to cancer therapies and regenerative medicine

Most tissues in complex metazoans contain a rare subset of cells that, at the single-cell level, can self-renew and also give rise to mature daughter cells. Such stem cells likely in development build tissues and are retained in adult life to regenerate them. Cancers and leukemias are apparently not an exception: rare leukemia stem cells and cancer stem cells have been isolated that contain all of the tumorigenicity of the whole tumor, and it is their properties that will guide future therapies. None of this was apparent just 20 years ago, yet this kind of stem cell thinking already provides new perspectives in medical science and could usher in new therapies. Today, political, religious, and ethical issues surround embryonic stem cell and patient-specific pluripotent stem cell research and are center stage in the attempts by governments to ban these fields for discovery and potential therapies. These interventions require physicians and physician-scientists to determine for themselves whether patient welfare or personal ethics will dominate in their practices, and whether all aspects of stem cell research can be pursued in a safe and regulated fashion.

Loss of expression of the Hoxa-9 homeobox gene impairs the proliferation and repopulating ability of hematopoietic stem cells

The homeobox gene Hoxa-9 is normally expressed in primitive bone marrow cells, and overexpression of Hoxa-9 markedly expands hematopoietic stem cells, suggesting a function in early hematopoiesis. We present evidence for major functional defects in Hoxa-9-/- hematopoietic stem cells. Hoxa-9-/- marrow cells have normal numbers of immunophenotypic stem cells (Lin(-)c-kit(+)flk-2(-)Sca-1+ [KLFS] cells). However, sublethally irradiated Hoxa-9-/- mice develop persistent pancytopenia, indicating unusual sensitivity to ionizing irradiation. In competitive transplantation assays, Hoxa-9-/- cells showed an 8-fold reduction in multilineage long-term repopulating ability, a defect not seen in marrow cells deficient for the adjacent Hoxa-10 gene. Single-cell cultures of KLFS cells showed a 4-fold reduction in large high-proliferation potential colonies. In liquid cultures, Hoxa-9-deficient Lin(-)Sca-1(+) cells showed slowed proliferation (a 5-fold reduction in cell numbers at day 8) and delayed emergence of committed progenitors (a 5-fold decrease in colony-forming cells). Slowing of proliferation was accompanied by a delay in myeloid maturation, with a decrease in Gr-1hiMac-1hi cells at the end of the culture. Retroviral transduction with a Hoxa-9 expression vector dramatically enhanced the cytokine-driven proliferation and in vivo engraftment of Hoxa-9-/- marrow cells. Hoxa-9 appears to be specifically required for normal hematopoietic stem cell function both in vitro and in vivo.

Varicella-zoster virus infection of human neural cells in vivo

Varicella-zoster virus (VZV) establishes latency in sensory ganglia and causes herpes zoster upon reactivation. These investigations in a nonobese diabetic severe combined immunodeficient mouse-human neural cell model showed that VZV infected both neurons and glial cells and spread efficiently from cell to cell in vivo. Neural cell morphology and protein synthesis were preserved, in contrast to destruction of epithelial cells by VZV. Expression of VZV genes in neural cells was characterized by nuclear retention of the major viral transactivating protein and a block in synthesis of the predominant envelope glycoprotein. The attenuated VZV vaccine strain retained infectivity for neurons and glial cells in vivo. VZV gene expression in differentiated human neural cells in vivo differs from neural infection by herpes simplex virus, which is characterized by latency-associated transcripts, and from lytic VZV replication in skin. The chimeric nonobese diabetic severe combined immunodeficient mouse model may be useful for investigating other neurotropic human viruses.

Therapeutic implications of cancer stem cells

Most cancers comprise a heterogenous population of cells with marked differences in their proliferative potential as well as the ability to reconstitute the tumor upon transplantation. Cancer stem cells are a minor population of tumor cells that possess the stem cell property of self-renewal. In addition, dysregulation of stem cell self-renewal is a likely requirement for the development of cancer. This new model for cancer will have significant ramifications for the way we study and treat cancer. In addition, through targeting the cancer stem cell and its dysregulated self-renewal, our therapies for treating cancer are likely to improve.

Incorporation of Naïve Bone Marrow Derived Cells into the Vascular Architecture of Brain Tumor

OBJECTIVE

Neovascularization is essential for tumor growth and invasion. Mounting evidence suggests that tumor cells recruit circulating endothelial progenitor cells to promote vasculogenesis to compliment tumor angiogenesis. This study examines the constitutive role of bone marrow-derived cells in this process.

METHODS

Rat glioma cells were implanted into brains of T-cell-depleted knockout mice. At various timepoints after tumor implantation, naïve bone marrow cells from ubiquitous transgenic mice expressing green fluorescent protein (GFP) were infused into these animals. The incorporation of GFP-positive cells into the vascular architecture was visualized by fluorescence confocal microscopy in conjunction with the transcription profiles of vascular endothelial growth factor (VEGF) and angiopoietin-1 and -2 (Ang-1 and Ang-2).

RESULTS

Of the cells infused, 8 days after tumor implantation, 0.49% were found exclusively sequestered in the vicinity of tumor vessels. This coincided with a decline in the expression of Ang-1 and a rise in the expression of VEGF and Ang-2. A few of these cells (0.66 of the 0.49%) localized onto the vascular wall. They resembled endothelial cells and expressed vWF.

CONCLUSION

The incorporation of bone marrow-derived unpurified endothelial cells into the tumor vascular bed is both time-limited and infrequent. These cells may play a supportive rather than a constitutive role in tumor neovascularization.

Over-expression of Bcl-2 provides protection in septic mice by a trans effect

Transgenic mice that over-express B cell leukemia/lymphomas (Bcl)-2 in myeloid cells under control of the human MRP8 promoter (hMRP8-Bcl-2) or in T lymphocytes under the E micro promoter (E micro -Bcl-2) were compared with C57BL/6 control mice following cecal ligation and puncture (CLP). There was a significant difference in outcome between the hMRP8-Bcl-2 and control mice with 100% survival in the hMRP8-Bcl-2 mice vs 25% survival in the control mice. In separate experiments there was a significant difference between E micro -Bcl-2 and control mice with 87.5 and 22.2% survival, respectively. Adoptive transfer of CD11b-positive bone marrow cells from hMRP8-Bcl-2 or C57BL/6 mice to C57BL/6 mice subjected to CLP resulted in 100 and 0% survival, respectively. Adoptive transfer of CD11b-positive cells from either hMRP8-Bcl-2 or C57BL/6 mice to Rag-1(-/-) mice (no mature T or B cells) subjected to CLP resulted in survival of 87.5 and 12.5%, respectively. The hMRP8-Bcl-2 mice had significantly more neutrophils and fewer bacteria in the peritoneum compared with C57BL/6 mice 24 h after CLP. These experiments show that Bcl-2 over-expression is protective in CLP and that protection is independent of lymphocytes. We propose that over-expression of Bcl-2 in T cells or myeloid cells induce release of a molecule(s) that protects against death following CLP.

Engraftment of sorted/expanded human central nervous system stem cells from fetal brain

Direct isolation of human central nervous system stem cells (CNS-SC) based on cell surface markers yields a highly purified stem cell population that can extensively expand in vitro and exhibit multilineage differentiation potential both in vitro and in vivo. The CNS-SC were isolated from fetal brain tissue using the cell surface markers CD133(+), CD34(-), CD45(-), and CD24(-/lo) (CD133(+) cells). Fluorescence-activated cell sorted (FACS) CD133(+) cells continue to expand exponentially as neurospheres while retaining multipotential differentiation capacity for >10 passages. CD133(-), CD34(-), and CD45(-) sorted cells (approximately 95% of total fetal brain tissue) fail to initiate neurospheres. Neurosphere cells transplanted into neonatal immunodeficient NOD-SCID mice proliferated, migrated, and differentiated in a site-specific manner. However, it has been difficult to evaluate human cell engraftment, because many of the available monoclonal antibodies against neural cells (beta-tubulin III and glial fibrillary acidic protein) are not species specific. To trace the progeny of human cells after transplantation, CD133(+)-derived neurosphere cells were transduced with lentiviral vectors containing enhanced green fluorescent protein (eGFP) expressed downstream of the phosphoglycerate kinase promoter. After transduction, GFP(+) cells were enriched by FACS, expanded, and transplanted into the lateral ventricular space of neonatal immunodeficient NOD-SCID brain. The progeny of transplanted cells were detected by either GFP fluorescence or antibody against GFP. GFP(+) cells were present in the subventricular zone-rostral migrating stream, olfactory bulb, and hippocampus as well as nonneurogenic sites, such as cerebellum, cerebral cortex, and striatum. Antibody against GFP revealed that some of the cells displayed differentiating dendrites and processes with neurons or glia cells. Thus, marking human CNS-SC with reporter genes introduced by lentiviral vectors is a useful tool with which to characterize migration and differentiation of human cells in this mouse transplantation model.

"Fluorescent timer": protein that changes color with time

We generated a mutant of the red fluorescent protein drFP583. The mutant (E5) changes its fluorescence from green to red over time. The rate of color conversion is independent of protein concentration and therefore can be used to trace time-dependent expression. We used in vivo labeling with E5 to measure expression from the heat shock-dependent promoter in Caenorhabditis elegans and from the Otx-2 promoter in developing Xenopus embryos. Thus, E5 is a "fluorescent timer" that can be used to monitor both activation and down-regulation of target promoters on the whole-organism scale.

Interaction between erythropoietin and peripheral polymorphonuclear leukocytes in hemodialysis patients

The effect of erythropoietin (EPO) on the oxidative stress and inflammation caused by polymorphonuclear leukocytes (PMNLs) in chronic hemodialysis (HD) patients was investigated in vivo and in vitro. The studies were performed on isolated PMNLs from peripheral blood of healthy controls and HD patients before and following 6 weeks of EPO treatment. The oxidative stress was expressed by the rate of superoxide release from phorbol 12-myristate 13-acetate stimulated PMNLs, and the inflammatory state was evaluated by in vitro PMNL survival, in addition to white blood cell and PMNL counts of the enrolled subjects. Following 6 weeks of EPO treatment, in HD patients, the rate of superoxide release from PMNLs as well as WBC and PMNL counts fell significantly when compared with the pretreatment values. PMNLs from HD patients and healthy controls incubated in vitro with increasing amounts of EPO displayed a significant reduction in their rates of superoxide release and a significant improvement in survival. We have concluded that EPO interacts with PMNLs, attenuating their primed state in HD patients, thus reducing oxidative stress and the extent of inflammation. To the best of our knowledge, this attenuation of the primed state of PMNLs by EPO is a new finding.

Treatment decisions in paediatric dialysis: children's versus parental rights

Treatment decisions in Paediatric Dialysis are often fraught with ethical questions about how to serve the best interests of children on dialysis, especially when parents refuse recommended treatment and opt for non-optimal interventions. This paper reviews the issues of children's rights, as guaranteed in the United Nations Covenant on Children's Rights and the Israel's Patients' Rights Law, and presents several case vignettes where conflict between children's rights for optimal treatment and parental desires arose. The paper concludes with policy recommendations to assure that children's expressed desires and medical needs are met, including the establishment of multidisciplinary committees to address the needs of children on dialysis and their families.

The PEBP2betaMYH11 fusion created by Inv(16)(p13;q22) in myeloid leukemia impairs neutrophil maturation and contributes to granulocytic dysplasia

Chromosomal translocations involving the genes encoding the alpha and beta subunits of the Pebp2/Cbf transcription factor have been associated with human acute myeloid leukemia and the preleukemic condition, myelodysplasia. Inv(16)(p13;q22) fuses the gene encoding the beta subunit of Pebp2 to the MYH11 gene encoding a smooth muscle myosin heavy chain (Smmhc). To examine the effect of the inv(16)(p13;q22) on myelopoiesis, we used the hMRP8 promoter element to generate transgenic mice expressing the Pebp2betaSmmhc chimeric fusion protein in myeloid cells. Neutrophil maturation was impaired in PEBP2betaMYH11 transgenic mice. Although the transgenic mice had normal numbers of circulating neutrophils, their bone marrow contained increased numbers of immature neutrophilic cells, which exhibited abnormal characteristics. In addition, PEBP2betaMYH11 inhibited neutrophilic differentiation in colonies derived from hematopoietic progenitors. Coexpression of both PEBP2betaMYH11 and activated NRAS induced a more severe phenotype characterized by abnormal nuclear morphology indicative of granulocytic dysplasia. These results show that PEBP2betaMYH11 can impair neutrophil development and provide evidence that alterations of Pebp2 can contribute to the genesis of myelodysplasia.

Participation of peripheral polymorphonuclear leukocytes in the oxidative stress and inflammation in patients with essential hypertension

Oxidative stress and inflammation have recently been linked to endothelial damage in essential hypertension (EH). Activated peripheral polymorphonuclear leukocytes (PMN) damage surrounding tissue by releasing reactive oxygen species (ROS) and proteolytic enzymes before self-necrosis. PMN necrosis further exacerbates inflammation and promotes chemotaxis and PMN recruitment. The number and properties of PMN from untreated EH patients is the focus of the present study. Oxidative stress was assessed by measuring the rate of superoxide anion release from separated, phorbol ester-stimulated PMN and the redox state of plasma glutathione. Inflammation was estimated indirectly by determining PMN number and their in vitro survival. PMN from EH patients (n = 37) released superoxide anion faster (P < .0001) than those of normotensives (NC, n = 37), 17.7 +/- 1.14 v 9.54 +/- 0.51 nmol/10 min/10(6) cells. The redox state of glutathione was twofold higher in EH plasma (P < .02) indicating systemic oxidative stress. PMN survival in vitro correlates linearly with the rate of superoxide release (r2 = 0.60, P < .02) and PMN count of EH patients, although in the normal range, were significantly higher (P < .0001), indicating necrosis and recruitment. Hypertensive plasma significantly reduced NC PMN viability, whereas normal plasma significantly increased EH PMN viability. What our studies show is that EH is accompanied by a primed state PMN that does not correlate with the levels of blood pressure. PMN priming in EH patients reflects an in vivo exposure to a constant stimulus ending in oxidative stress, increased self-necrosis, and cell recruitment. Oxidative stress and inflammation will result in endothelial damage and atherosclerosis in the long run.

A PMLRARalpha transgene initiates murine acute promyelocytic leukemia

The malignant cells of acute promyelocytic leukemia (APL) contain a reciprocal chromosomal translocation that fuses the promyelocytic leukemia gene (PML) with the retinoic acid receptor alpha gene (RAR alpha). To test the hypothesis that the chimera PMLRAR alpha plays a role in leukemogenesis, we expressed a PMLRAR alpha cDNA in myeloid cells of transgenic mice. PMLRAR alpha transgenic mice exhibited impaired neutrophil maturation early in life, which progressed at a low frequency over the course of several months to overt APL. Both the preleukemic state and the leukemia could be transplanted to nontransgenic mice, and the transplanted preleukemia could progress to APL. The APL recapitulated features of the human disease, including a response to retinoic acid. Retinoic acid caused the leukemic cells to differentiate in vitro and in vivo, eliciting remissions of both the preleukemic state and APL in mice. Our results demonstrate that PMLRAR alpha impairs neutrophil differentiation and initiates the development of APL. The transgenic mice described here provide an apparently accurate model for human APL that includes clear evidence of tumor progression. The model should be useful for exploring the molecular pathogenesis of APL and the mechanisms of the therapeutic response to retinoic acid, as well as for preclinical studies of therapeutic regimens.

The role of cell adhesion molecules in the development of IDDM: implications for pathogenesis and therapy

IDDM is a chronic inflammatory disease in which there is autoimmune-mediated organ-specific destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. The migration of autoreactive lymphocytes and other leukocytes from the bloodstream into the target organ is of clear importance in the etiology of many organ-specific autoimmune/inflammatory disorders, including IDDM. In IDDM, this migration results in lymphocytic invasion of the islets (formation of insulitis) and subsequent destruction of beta-cells. Migration of lymphocytes from the bloodstream into tissues is a complex process involving sequential adhesion and activation events. This migration is controlled in part by selective expression and functional regulation of cell adhesion molecules (CAMs) on the surface of lymphocytes and vascular endothelial cells or in the extracellular matrix. Understanding the mechanisms that regulate lymphocyte migration to the pancreatic islets will lead to further understanding of the pathogenesis of IDDM. In this article, we summarize the recent advances regarding the function of CAMs in the development of IDDM in animal models and in humans and discuss the potential for developing CAM-based therapies for IDDM.

Detection of permanent damage in kidneys with vesicoureteral reflux by quantitative single photon emission computerized tomography (SPECT) uptake of 99mtechnetium labeled dimercaptosuccinic acid

PURPOSE

We determined the level of functional damage to the kidney which inhibits further growth.

MATERIALS AND METHODS

Renal functional volume and percent uptake of 34 kidneys with reflux were studied by performing sequential quantitative single photon emission computerized tomography 2 times at a mean interval of 3.2 years.

RESULTS

Change in volume between the initial and repeat studies was 27.2 +/- 28.4% in all 34 kidneys. Change in volume was less than 7% in 8 kidneys and greater than 14% in 26. Receiver operating characteristic curve analysis indicated that 15.6% kidney uptake was associated with 75% sensitivity, 100% specificity and 94% accuracy in distinguishing kidneys with more than 7% from those with less than 7% change in volume. The value of kidney uptake of less than 15.6% was 100% in predicting less than 7% change in volume (positive predictive value) and the value of kidney uptake greater than 15.6% was 93% in predicting more than 7% change in volume (negative predictive value).

CONCLUSIONS

Kidney uptake of less than 15.6% represents irreversible impairment of renal growth and indicates permanent damage in kidneys with vesicoureteral reflux.

Short-term effect of erythropoietin on T-cell mitogenic proliferation in chronic renal failure patients

Uremic patients undergoing hemodialysis (HD) are known to be highly susceptible to infections. Recent data indicate that in addition to its well-known stimulating effects on red cell production, erythropoietin (EPO) may also have immunomodulating properties. The aim of this study was to examine the effect of EPO on lectin-induced T-lymphocyte transformation in uremic patients, as part of its effect on the immune response. Sixteen HD patients and 20 age- and sex-matched healthy controls were compared before and after 6 and 20 weeks of EPO treatment. T lymphocytes were analyzed for their mitogenic activity following treatment with phytohemagglutinin (PHA), concanavalin A (CON A) and anti-CD3 by measuring 3H-thymidine incorporation. HD patients showed reduced mitogenic responses to all mitogens tested, compared to healthy controls. During the 6 weeks of EPO administration, a significant increase in T-lymphocyte activity could be demonstrated following exposure to all three mitogens (PHA, from 32 +/- 2 to 45 +/- 8; CON A, from 11 +/- 3 to 25 +/- 9; anti-CD3, from 11 +/- 3 to 22 +/- 5, means +/- SD). This increase was augmented after 5 months of EPO treatment. We conclude therefore that EPO improves in vitro T-cell mitogenic proliferation, even after short periods of treatment.

Expression of granzyme A in salivary gland biopsies from patients with primary Sjögren's syndrome

OBJECTIVE

To determine whether the destruction of salivary gland epithelial cells in Sjögren's syndrome (SS) could be mediated by granzyme A, a serine protease that is contained in the granules of activated lymphocytes.

METHODS

We used in situ hybridization and polymerase chain reaction amplification to determine the expression of granzyme A messenger RNA (mRNA) in salivary gland biopsy samples.

RESULTS

Granzyme A mRNA expression was detected in salivary glands from SS patients, but not in those from normal controls. Granzyme A mRNA content was significantly correlated (P < 0.001) with the size of lymphocytic infiltrates in the salivary glands and with the clinical activity of the disease.

CONCLUSION

Cells that express granzyme A mRNA may play a role in the destruction of the target organ (i.e., the salivary gland) in patients with SS. The strong association of granzyme A mRNA expression and larger lymphoid infiltrates in the patients' salivary glands suggests that granzyme A mRNA is expressed at a relatively late stage of the local inflammatory process. Therapies designed to modulate or block granzyme A induction and action should be investigated in SS patients.

An analysis of the expression of cyclophilin C reveals tissue restriction and an intriguing pattern in the mouse kidney

Cyclophilin C (cyp C) is a cyclosporin A (CsA) binding protein originally isolated from a mouse bone marrow stromal cell line. We have compared the expression patterns of the mammalian cyclophilins A, B, and C in mouse tissues using in situ hybridization. These studies reveal that cyp C is expressed in a restricted subset of tissues including mouse ovary, testis, bone marrow, and kidney. Within the kidney, cyp C is highly expressed in a narrow zone in the outer medulla. Using monoclonal antibodies reactive against cyp C, we find that the kidney cells expressing cyp C correspond to the S3 segment of the nephron. The S3 segment has been shown to sustain histopathological damage from high dosages of CsA, raising the possibility that cyp C may be involved in mediating this damage.

Isolation of CD3-, CD4-, CD8-, IL-2R+ thymocyte precursors by panning

We present a panning method for isolation of thymocytes that are CD3-, CD4-, CD8- and IL-2R+. These cells have been isolated by positive selection on dishes coated with 7D4 antibody followed by treatment with biotinylated 145-2C11, GK1.5, and 53-6.7 antibodies and negative selection on avidin coated dishes.

Crystal structure of murine cyclophilin C complexed with immunosuppressive drug cyclosporin A

Cyclophilin is a cellular receptor for the immunosuppressive drug cyclosporin A (CsA). Cyclophilin C (CyPC) is highly expressed in murine kidney, making it a potential mediator of the nephrotoxic effects of CsA. The structure of murine CyPC complexed with CsA has been solved and refined to an R factor of 0.197 at a 1.64-A resolution. Superposition of the CyPC-CsA structure with the unligated cyclophilin A (CyPA) revealed significant migration of three loops: Gln-179 to Thr-189, Asp-47 to Lys-49, and Met-170 to Ile-176. The proximity of the loop Gln-179 to Thr-189 to the CsA binding site may account for the unique binding of a 77-kDa glycoprotein, CyPC binding protein (CyCAP), to CyPC. The binding of CsA to CyPC is similar to that of CsA to human T-cell cyclophilin A (CyPA). However, the conformation of CsA when bound to CyPC is significantly different from that when bound to CyPA. These differences may reflect conformational variation of CsA when bound to different proteins. Alternatively, the previous CyPA-CsA structure at low resolution may not provide sufficient details for a comparison with the CyPC-CsA structure.