Adhesion of subsets of human blood mononuclear cells to porcine endothelial cells

Human leukocytes regulate ganglioside expression in cultured micro-pig aortic endothelial cells

Gangliosides are ubiquitous components of the membranes of mammalian cells that are thought to play important roles in various cell functions such as cell-cell interaction, cell adhesion, cell differentiation, growth control, and signaling. However, the role that gangliosides play in the immune rejection response after xenotransplantation is not yet clearly understood. In this study, the regulatory effects of human leukocytes on ganglioside expression in primary cultured micro-pig aortic endothelial cells (PAECs) were investigated. To determine the impact of human leukocytes on the expression of gangliosides in PAECs, we performed high-performance thin layer chromatography (HPTLC) in PAECs incubated with FBS, FBS containing human leukocytes, human serum containing human leukocytes, and FBS containing TNF-α. Both HPTLC and immunohistochemistry analyses revealed that PAECs incubated with FBS predominantly express the gangliosides GM3, GM1, and GD3. However, the expression of GM1 significantly decreased in PAECs incubated for 5 h with TNF-α (10 ng/mL), 10% human serum containing human leukocytes, and 10% FBS containing human leukocytes. Taken together, these results suggest that human leukocytes induced changes in the expression profile of ganglioside GM1 similar to those seen upon treatment of PAECs with TNF-α. This finding may be relevant for designing future therapeutic strategies intended to prolong xenograft survival.

Determination of potassium in red blood cells using unmeasured volumes of whole blood and combined sodium/potassium-selective membrane electrode measurements

Recent studies suggest that the measurement of intracellular potassium concentrations in red blood cells (RBC-K) can be a marker for assessing the risk, development, and treatment of hypertension. In this work, the combined use of miniature potassium- and sodium-selective membrane electrodes is evaluated as a simple means to determine RBC-K. The proposed method requires two separate sets of electrode measurements: (i) potassium and sodium concentrations in the plasma phase of an unmeasured volume of a whole blood sample, and (ii) determination of potassium and sodium concentrations in the same sample of blood after complete hemolysis by ultrasonic disruption of the RBC membranes. The dilution of sodium concentration after hemolysis can be used to determine hematocrit (Hct) (volume of red cells per unit volume of blood) of the blood. The concentration of potassium within the red blood cells (RBCs) is then calculated using the measured change in potassium levels before and after RBCs lysis and the hematocrit level determined from the sodium electrode measurements and/or a conventional centrifugation method. Good correlation for RBC-K between the proposed method and traditional flame photometry is observed for animal blood samples that possess the range of potassium levels found within human RBCs (80-120 mM). However, when potassium is much lower than that found in human RBCs (known to occur for certain animal species), the Hct measured by the sodium electrode method is falsely low, compared to traditional spun hematocrit values, because of an increased level of sodium within the RBCs, necessitating use of spun Hct levels to assess RBC-K accurately. It is envisioned that this new approach could be further miniaturized into a single-use disposable cartridge type electrode system that would enable rapid point-of-care screening of RBC-K levels in human subjects.