Metabolomics comparison of red cells stored in four additive solutions reveals differences in citrate anticoagulant permeability and metabolism.

BACKGROUND AND OBJECTIVES: Metabolomics studies have revealed transition points in metabolic signatures of red cells during storage in SAGM, whose clinical significance is unclear. We set out to investigate whether these transition points occur independent of storage media and define differences in the metabolism of red cells in additive solutions. MATERIALS AND METHODS: Red cell concentrates were stored in SAGM, AS-1, AS-3 or PAGGSM, and sampled fourteen times spanning Day 1-46. Following quality control, the samples were split into extracellular and intracellular aliquots. These were analysed with ultra-high-performance liquid chromatography coupled to mass spectrometry analysis affording quantitative metabolic profiles of both intra- and extracellular red cell metabolites. RESULTS: Differences were observed in glycolysis, purine salvage, glutathione synthesis and citrate metabolism on account of the storage solutions. Donor variability however hindered the accurate characterization of metabolic transition time-points. Intracellular citrate concentrations were increased in red cells stored in AS-3 and PAGGSM media. The metabolism of citrate in red cells in SAGM was subsequently confirmed using 13 C citrate isotope labelling and shown to originate from citrate anticoagulant. CONCLUSION: Metabolic signatures that discriminate between 'fresh' and 'old' stored red cells are dependent upon additive solutions. Specifically, the incorporation and metabolism of citrate in additive solutions with lower chloride ion concentration is altered and impacts glycolysis.

Increased expression of interleukin-13 but not interleukin-4 in CD4+ cells from patients with the hyper-IgE syndrome.

Hyper IgE syndrome (HIES) is a rare immunodeficiency disorder characterized mainly by high levels of polyclonal IgE in serum and recurrent staphylococcal abscesses of the skin and lungs. The raised IgE levels have led researchers to study the synthesis of cytokines that regulate switching of immunoglobulin production towards IgE such as interleukin-4 (IL-4), IL-12 and interferon-gamma (IFN)-gamma. However, the role of IL-13 in the disease pathogenesis has not been investigated extensively. In this study, we investigated intracellular expression of IL-4 and IL-13 in mononuclear cells and CD4+ cells isolated from patients with HIES and healthy controls. Cells were stained intracellularly with antibodies directed against IL-4 and IL-13 and analysed by flow cytometry before and after activation with PMA and calcium ionophore. The mean proportion of resting or activated IL-4 and IL-13 expressing mononuclear cells were comparable in the two groups as well as the proportion of IL-4 expressing CD4+ cells. In contrast, the mean proportion of IL-13 expressing CD4+ cells was increased significantly in patients with HIES in both the resting and the activated state compared to healthy controls. We conclude that increased expression of IL-13 in CD4+ cells from patients with HIES could account, at least partly, for raised IgE levels in those individuals.

[Mesenchymal stem cells. A review.].

The bone marrow contains various types of stem cells. Among them are hematopoietic stem cells, which are the precursors of all blood cells, and mesenchymal stem cells. Mesenchymal stem cells have recently received a lot of attention in biological research because of their capability to self renewal, to expand and transdifferentiate into many different cell types; bone cells, adipocytes, chondrocytes, tendocytes, neural cells and stromal cells of the bone marrow. Mesenchymal stem cells can be cultured in vitro although their differentiation potential is not yet fully understood. Several experiments have been conducted in animal models where mesenchymal stem cells have been transplanted in order to enhance hematopoiesis or to facilitate the repair of mesenchymal tissue. Similar experiments are being conducted in humans. Mesenchymal stem cells are believed to be able to enhance hematopoietic stem cells transplantation by rebuilding the bone marrow microenvironment which is damaged after radiation- and/or chemotherapy. Mesenchymal stem cells are promising as vehicles for gene transfer and therapy. It may prove possible to tranduce them with a gene coding for a defective protein i.e. collagen I in osteogenesis imperfecta. The cells could then be expanded ex vivo and transplanted to the patients where they home to the bone marrow, differentiate and produce the intact protein. Future medicine will probably involve mesenchymal stem cells in various treatment settings.