Stem cells
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Human embryonic stem cells (hESCs) promise to revolutionize reparative medicine through their potential in developing cell replacement therapies for diseases like diabetes and parkinsonism. Most of the existing hESC lines available for research, including all National Institutes of Health-registered lines, have been derived and maintained on mouse embryonic fibroblast feeders in the presence of xenoproteins. For future clinical application, many more hESC lines derived and grown in current good manufacturing practice, good tissue culture practice, and xeno-free conditions need to be developed. ⋯ We describe a safe, xeno-free cryopreservation protocol for hESCs involving vitrification in closed sealed straws using human serum albumin as opposed to fetal calf serum as the main protein source in the cryoprotectant and long-term storage in the vapor phase of liquid nitrogen. After thaw, hESCs exhibited high thaw-survival rates and low differentiation rates, remained pluripotent, and maintained normal diploid karyotypes throughout extended passage. The cryopreservation technique we describe here should complement xeno-free culture conditions for hESCs already in refinement and will prove very useful for the setting up of hESC banks throughout the world.
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Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) are functionally related hematopoietins with overlapping but distinct hematopoietic effects. GM-CSF supports more myeloid progenitor cells, whereas IL-3 promotes more erythroid, megakaryocytic and multipotential progenitor cells. Their complementary in vivo biological effects and cross competition for receptor binding prompted the development of PIXY321, a synthetic hybrid protein of GM-CSF and IL-3. ⋯ Based on these preclinical observations, clinical trials have been initiated examining the therapeutic potential of this agent in ameliorating treatment- or disease-related hematopoietic suppression. The early results indicate that PIXY321 can stimulate multilineage hematopoiesis in vivo and enhance neutrophil and platelet recovery following chemotherapy and bone marrow transplantation (BMT). These results suggest that PIXY321 elicits the biological effects of both its component cytokines and represents a novel means of delivering two independent but interactive cytokines in combination.
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Peripheral blood stem cells (PBSC) have been studied for their use after high-dose chemotherapy. The combination of a standard-dose chemotherapy [VIP: VP16 (etoposide), ifosfamide, cisplatin] in combination with hematopoietic growth factors was shown to provide effective anti-cancer activity as well as to enable sufficient stem cell mobilization for clinical use. Different growth factor regimens [granulocyte-colony-stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, interleukin (IL)-3/GM-CSF] resulted in a differential induction of high levels of circulating PBSC after VIP chemotherapy, with the sequential combination of IL-3 and GM-CSF inducing maximal numbers of CD34+ cells as well as clonogenic progenitors. ⋯ Positive selection of CD34+ cells by immunoadsorption that leads to an approximately three-log depletion of contaminating tumor cells therefore was investigated with regard to feasibility and capability as a source for PBSC transplantation. Twenty-one patients with advanced malignancies received autologous CD34+ cell transplantation after high-dose chemotherapy. Hematological recovery was as rapid as recorded for unseparated PBSC preparations, indicating that CD34+ cells can be safely used for autologous PBSC transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)