We addressed the role of hyperglycemia in leukocyte-endothelium interaction under flow conditions by exposing human umbilical vein endothelial cells for 24 h to normal (5 mM), high concentration of glucose (30 mM), advanced glycosylation end product-albumin (100 microg/ml), or hyperglycemic (174-316 mg/dl) sera from patients with diabetes and abnormal hemoglobin A1c (8.1+/-1.4%). At the end of incubation endothelial cells were perfused with total leukocyte suspension in a parallel plate flow chamber under laminar flow (1.5 dyn/cm2). Rolling and adherent cells were evaluated by digital image processing. Results showed that 30 mM glucose significantly (P < 0. 01) increased the number of adherent leukocytes to endothelial cells in respect to control (5 mM glucose; 151+/-19 versus 33+/-8 cells/mm2). A similar response was induced by endothelial stimulation with IL-1beta, here used as positive control (195+/-20 cells/mm2). The number of rolling cells on endothelial surface was not affected by high glucose level. Stable adhesion of leukocytes to glucose-treated as well as to IL-1beta-stimulated endothelial cells was preceded by short interaction of leukocytes with the endothelial surface. The distance travelled by leukocytes before arrest on 30 mM glucose, or on IL-1beta-treated endothelial cells, was significantly (P < 0.01) higher than that observed for leukocytes adhering on control endothelium (30 mM glucose: 76.7+/-3.5; IL1beta: 69.7+/-4 versus 5 mM glucose: 21.5+/-5 microm). Functional blocking of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1 on endothelial cells with the corresponding mouse mAb significantly inhibited glucose-induced increase in leukocyte adhesion (67+/-16, 83+/-12, 62+/-8 versus 144+/-21 cells/ mm2). Confocal fluorescence microscopy studies showed that 30 mM glucose induced an increase in endothelial surface expression of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1. Electrophoretic mobility shift assay of nuclear extracts of human umbilical vein endothelial cells (HUVEC) exposed for 1 h to 30 mM glucose revealed an intense NF-kB activation. Treatment of HUVEC exposed to high glucose with the NF-kB inhibitors pyrrolidinedithiocarbamate (100 microM) and tosyl-phe-chloromethylketone (25 microM) significantly reduced (P < 0.05) leukocyte adhesion in respect to HUVEC treated with glucose alone. A significant (P < 0.01) inhibitory effect on glucose-induced leukocyte adhesion was observed after blocking protein kinase C activity with staurosporine (5 nM). When HUVEC were treated with specific antisense oligodesoxynucleotides against PKCalpha and PKCepsilon isoforms before the addition of 30 mM glucose, a significant (P < 0.05) reduction in the adhesion was also seen. Advanced glycosylation end product-albumin significantly increased the number of adhering leukocytes in respect to native albumin used as control (110+/-16 versus 66+/-7, P < 0.01). Sera from diabetic patients significantly (P < 0.01) enhanced leukocyte adhesion as compared with controls, despite normal levels of IL-1beta and TNFalpha in these sera. These data indicate that high glucose concentration and hyperglycemia promote leukocyte adhesion to the endothelium through upregulation of cell surface expression of adhesive proteins, possibly depending on NF-kB activation.

For chronic kidney diseases, there is little chance that the vast majority of world's population will have access to renal replacement therapy with dialysis or transplantation. Tissue engineering would help to address this shortcoming by regeneration of damaged kidney using naturally occurring scaffolds seeded with precursor renal cells. The aims of the present study were to optimize the production of three-dimensional (3D) rat whole-kidney scaffolds by shortening the duration of organ decellularization process using detergents that avoid nonionic compounds, to investigate integrity of extracellular matrix (ECM) structure and to enhance the efficacy of scaffold cellularization using physiological perfusion method. Intact rat kidneys were successfully decellularized after 17 h perfusion with sodium dodecyl sulfate. The whole-kidney scaffolds preserved the 3D architecture of blood vessels, glomeruli, and tubuli as shown by transmission and scanning electron microscopy. Micro-computerized tomography (micro-CT) scan confirmed integrity, patency, and connection of the vascular network. Collagen IV, laminin, and fibronectin staining of decellularized scaffolds were similar to those of native kidney tissues. After infusion of whole-kidney scaffolds with murine embryonic stem (mES) cells through the renal artery, and pressure-controlled perfusion with recirculating cell medium for 24 and 72 h, seeded cells were almost completely retained into the organ and uniformly distributed in the vascular network and glomerular capillaries without major signs of apoptosis. Occasionally, mES cells reached peritubular capillary and tubular compartment. We observed the loss of cell pluripotency and the start of differentiation toward meso-endodermal lineage. Our findings indicate that, with the proposed optimized protocol, rat kidneys can be efficiently decellularized to produce renal ECM scaffolds in a relatively short time, and rapid recellularization of vascular structures and glomeruli. This experimental setup may open the possibility to obtain differentiation of stem cells with long lasting in vitro perfusion.