HIGH GLUCOSE AND HYPEROSMOLALITY STIMULATE HEPATOCYTE GROWTH-FACTOR SECRETION FROM CULTURED HUMAN MESANGIAL CELLS

Hepatocyte growth factor is a recently cloned potent mitogen to hepato cytes, but its extrahepatic roles are not completely defined. It cause s proliferation of endothelial and epithelial cells implicating potent ial action in the glomerulus. We aimed to determine whether cultured h uman mesangial cells secrete hepatocyte growth factor and the effect o f high glucose conditions. Mesangial cells were isolated from the norm al cortex of a child's kidney. After differential glomerular sieving a nd trypsin digestion of glomeruli, mesangial cells were cultured in 20 % fetal calf serum/RPMI. Glucose concentration in the medium was adju sted to 5 mmol/l, 11 mmol/l, 25 mmol/l or 5 mmol/l/20 mmol/l mannitol to correct for osmolality. After 0, 24, 48, 72 h incubation, hepatocyt e growth factor was measured in the supernatant by enzyme immune assay using recombinant hepatocyte growth factor and monoclonal antibodies to human hepatocyte growth factor. Hepatocyte growth factor was secret ed by cultured mesangial cells. High glucose and hyperosmolar conditio ns caused a 100-200 % increase in hepatocyte growth factor secretion a t 48-72 h (p = 0.001). Hepatocyte growth factor secretion at 48 h in 5 mmol/l glucose was 16.46 +/- 1.09 ng/ml (mean +/- SEM), 11 mmol/l glu cose: 32.98 +/- 4.54, 25 mmol/l glucose: 33.32 +/- 7.89, 5 mmol/l gluc ose/20 mmol/l mannitol: 34.05 +/- 3.64; at 72 h in 5 mmol/l glucose: 2 3.92 +/- 2.85 ng/ml, 11 mmol/l glucose: 28.26 +/- 2.03, 25 mmol/l gluc ose: 62.04 +/- 12.2, 5 mmol/l glucose/20 mmol/l mannitol: 45.76 +/- 6. 25. Trypan blue exclusion demonstrated membrane integrity. These findi ngs demonstrate for the first time that cultured human mesangial cells secrete hepatocyte growth factor and there is stimulation by high glu cose and hyperosmolar conditions. Hepatocyte growth factor may have a renotropic role in the pathogenesis of diabetic nephropathy.