It would be important to study the characteristics and the action of “dentured” or “modified” LDL in atherogenesity. We investigated whether modified LDL was formed in normal human and what effect this LDL had on human arterial smooth muscle cells in culture.
Incubation of plasma prepared from normal human was performed at 37°C for 6 hours. Thrombin was added to both of incubated plasma and also non-incubated plasma obtained from each subject in order to remove fibrin. Lipoproteins (VLDL, IDL, LDL and HDL) were ultracentrifugally isolated from each serum.
LDL obtained from incubated plasma had faster mobility than that from non-incubated plasma on agarose-gel electrophoresis. Lipids-composition (TC, TG, PL and Ch-ester) was altered in LDL after incubation. These alterations of LDL might be induced by lipid transfer protein. In this way, LDL obtained from normal human was modified.
DNA synthesis of human arterial smooth muscle cells (SMC) increased in the culture with LDL addition. This action of LDL was dose-dependent manner. DNA synthesis increased in the culture with modified LDL more than that with native LDL.
These data indicated that LDL obtained from normal human was easily modified and modified LDL influenced DNA synthesis of cultured arterial SMC.