Sample handling and stability of hepatocyte growth factor in blood samples

As regards clinical studies performed on hepatocyte growth factor (HGF) during recent years, we have aimed in the present study to investigate the eventual differences in sample handling of this cytokine that might influence the results of serum concentrations. Venous blood from patients with current infectious diseases and controls was used in different sub-studies. Compared with samples separated within one hour, no significant changes in serum HGF levels were observed when whole blood stayed 4, or 24h at 6 degrees C before or 6h in room temperature after separation but HGF levels were significantly higher (P<0.01) when whole blood was kept at room temperature 4 and 24h before separation. Serum HGF was stable up to 20 freeze-thaw cycles. The serum concentrations of HGF were significantly higher than levels in the plasma (19%; P<0.05). A significant increase in serum HGF levels (12%, P<0.05) was observed after shaking the whole blood sample to a visible haemolysis, although the HGF concentration in blood cells was around half of that in serum. HGF tolerated storage at -70 degrees C for at least 4 months. We conclude that standardized methods in sample handling are important in the study of HGF concentrations in blood samples.