Identification of primitive human hematopoietic cells capable of repopulating NOD/SCID mouse bone marrow: implications for gene therapy.

The development of stem-cell gene therapy is hindered by the absence of repopulation assays for primitive human hematopoietic cells. Current methods of gene transfer rely on in vitro colony-forming cell (CFC) and long-term culture-initiating cell (LTC-IC) assays, as well as inference from other mammalian species. We have identified a novel human hematopoietic cell, the SCID-repopulating cell (SRC), a cell more primitive than most LTC-ICs and CFCs. The SRC, exclusively present in the CD4+CD8- fraction, is capable of multilineage repopulation of the bone marrow of nonobese diabetic mice with severe combined immunodeficiency disease (NOD/SCID mice). SRCs were rarely transduced with retroviruses, distinguishing them from most CFCs and LTC-ICs. This observation is consistent with the low level of gene marking seen in human gene therapy trials. An SRC assay may aid in the characterization of hematopoiesis, as well as the improvement of transduction methods.

Molecular characterisation of side population cells with cancer stem cell-like characteristics in small-cell lung cancer.

BACKGROUND: Side population (SP) fraction cells, identified by efflux of Hoechst dye, are present in virtually all normal and malignant tissues. The relationship between SP cells, drug resistance and cancer stem cells is poorly understood. Small-cell lung cancer (SCLC) is a highly aggressive human tumour with a 5-year survival rate of <10%. These features suggest enrichment in cancer stem cells. METHODS AND RESULTS: We examined several SCLC cell lines and found that they contain a consistent SP fraction that comprises <1% of the bulk population. Side population cells have higher proliferative capacity in vitro, efficient self-renewal and reduced cell surface expression of neuronal differentiation markers, CD56 and CD90, as compared with non-SP cells. Previous reports indicated that several thousand SP cells from non-small-cell lung cancer are required to form tumours in mice. In contrast, as few as 50 SP cells from H146 and H526 SCLC cell lines rapidly reconstituted tumours. Whereas non-SP cells formed fewer and slower-growing tumours, SP cells over-expressed many genes associated with cancer stem cell and drug resistance: ABCG2, FGF1, IGF1, MYC, SOX1/2, WNT1, as well as genes involved in angiogenesis, Notch and Hedgehog pathways. CONCLUSIONS: Side population cells from SCLC are highly enriched in tumourigenic cells and are characterised by a specific stem cell-associated gene expression signature. This gene signature may be used for development of targeted therapies for this rapidly fatal tumour.

Magnetic properties of lunar sample 10048-22.

The natural remanent magnetization (3.7 x 10(4) electromagnetic units per cubic centimeter) and the susceptibility per cubic centimeter (6.3 x 10(-13)) of an 18.5-gram breccia specimen were determined with instrumentation and techniques currently used in paleomagnetism. The relatively low magnetic stability of the rock in the earth's field and in alternating demagnetizing fields precludes considering it as a reliable carrier of paleomagnetism. A magnetic balance study yields an unusually high Curie temperature (750 degrees C) which is possibly diagnostic of metallic Fe containing less than 5 percent nickel. The estimated relative abundance of the iron in the sample is about 0.5 percent.

Increased expression of a novel leukocytic factor in patients with hemolytic anemia.

Misprimed polymerase chain reaction (PCR) products were generated from the crude leukocytic DNA extract of four of five patients with hereditary hemolytic anemia, during the course of exon 6 pyruvate kinase L gene amplification. These by-products, which originated from abundant mRNA templates, were not observed in seven healthy individuals. Two markers were cloned (GenBank accession numbers M64700 and M64701). We focused further studies on one of the human markers associated with hereditary hemolytic anemia, human DNA marker B (HUMDNAMB). HUMDNAMB is a 451-bp open reading frame that has never been described previously. The nucleic acid sequence region 303-416 is 63% homologous to a coding region of the bovine interferon alpha-A gene. Matrix analysis of the amino acid sequences reveals a structural similarity between the two proteins. The HUMDNAMB protein is expected to be larger than interferons, based on the size of its 2-kb messenger RNA detected by Northern blot in human leukocytes, fetal liver, and fetal intestine.

Recovery of the hypothalamic-pituitary-adrenal (HPA) axis in patients with rheumatic diseases receiving low-dose prednisone.

PURPOSE: To assess the status of the hypothalamic-pituitary-adrenal (HPA) axis in cortico-steroid-treated patients whose prednisone dose had been tapered to physiologic doses. PATIENTS AND METHODS: The design of the study was a retrospective chart review of 50 consecutive patients receiving 10 mg or less of prednisone daily at a university teaching hospital rheumatology clinic. Patients were given a rapid adrenocorticotropic hormone stimulation test, with cortisol levels obtained at baseline and after intravenous administration of cosyntropin. Charts were reviewed for duration of therapy, highest, current, and total cumulative steroid dose, and average daily steroid dose in each month of the preceding 2 years. RESULTS: Current steroid dose was the only significant indicator of HPA axis function. Patients receiving less than 5 mg of prednisone daily had a normal HPA axis response, whereas those receiving 5 mg or more had widely varied responses. Neither the total, the highest prednisone dose, nor the duration of therapy was a significant indicator of HPA axis recovery. CONCLUSIONS: Spontaneous recovery of the HPA axis is usual for patients who are taking prednisone at daily doses of 5 mg or less. Return of normal HPA axis function can be achieved without alternate-day therapy in patients whose disease allows tapering to daily prednisone doses of 5 mg or less.

Differential maintenance of primitive human SCID-repopulating cells, clonogenic progenitors, and long-term culture-initiating cells after incubation on human bone marrow stromal cells.

Many experimental and clinical protocols are being developed that involve ex vivo culture of human hematopoietic cells on stroma or in the presence of cytokines. However, the effect of these manipulations on primitive hematopoietic cells is not known. Our severe combined immune-deficient mouse (SCID)-repopulating cell (SRC) assay detects primitive human hematopoietic cells based on their ability to repopulate the bone marrow (BM) of immune-deficient non-obese diabetic/SCID (NOD/SCID) mice. We have examined here the maintenance of SRC, colony-forming cells (CFC), and long-term culture-initiating cells (LTC-IC) during coculture of adult human BM or umbilical cord blood (CB) cells with allogeneic human stroma. Transplantation of cultured cells in equivalent doses as fresh cells resulted in lower levels of human cell engraftment after 1 and 2 weeks of culture for BM and CB, respectively. Similar results were obtained using CD34+-enriched CB cells. By limiting dilution analysis, the frequency of SRC in BM declined sixfold after 1 week of culture. In contrast to the loss of SRC as measured by reduced repopulating capacity, the transplanted inocula of cultured cells frequently contained equal or higher numbers of CFC and LTC-IC compared with the inocula of fresh cells. The differential maintenance of CFC/LTC-IC and SRC suggests that SRC are biologically distinct from the majority of these in vitro progenitors. This report demonstrates the importance of the SRC assay in the development of ex vivo conditions that will allow maintenance of primitive human hematopoietic cells with repopulating capacity.

Engraftment of immune-deficient mice with primitive hematopoietic cells from beta-thalassemia and sickle cell anemia patients: implications for evaluating human gene therapy protocols.

Permanent correction of genetic deficiencies of the hematopoietic system requires gene transfer into stem cells and long-term lineage specific expression after autologous transplantation. However, progress to develop gene therapy protocols has been hampered by the absence of in vivo assays that detect genetically deficient human hematopoietic stem cells and their diseased differentiated progeny. The establishment of systems to transplant human cells into immune-deficient SCID mice provides such an assay. We report that primitive bone marrow cells from beta-thalassemia major and sickle cell anemia patients engraft immune-deficient mice, giving rise to high levels of human erythroid and myeloid cells in response to treatment with human cytokines. The bone marrow of transplanted mice contained the entire erythroid lineage from BFU-E to mature erythrocytes expressing human gamma, beta or beta s-globin. Moreover, human erythroid cells from mice transplanted with sickle cell anemia bone marrow showed characteristic sickling under reducing conditions in an in vitro assay. This model provides a powerful in vivo system that can be used to evaluate the efficiency of globin gene transfer into primitive human hematopoietic cells, lineage-specific expression in mature erythrocytes, and ultimately correction of the cellular defect found in the erythroid lineage.