EXTRACTION OF LIPOPROTEIN(A), APO-B, AND APO-E FROM FRESH HUMAN ARTERIAL-WALL AND ATHEROSCLEROTIC PLAQUES

Several studies have analysed apo(a) quantitatively in arterial wall t issue derived from post mortem samples. The purpose of this study was a qualitatative analysis of Lp(a) in fresh human arterial wall tissue. It was evaluated whether Lp(a) exists as an intact lipoprotein or whe ther it is degraded. Additionally it was analysed whether there are di fferences in the apolipoprotein composition between lesion-free and di seased human arterial wall tissue. Serum and intimal tissue samples ta ken from the abdominal aorta and the inferior caval vein of 18 organ d onors were analysed for lipids, Lp(a), and apolipoproteins apo B and a po E. Serum and tissue parameters were correlated. In the aortic tissu e, higher Lp(a) and apolipoprotein levels were observed in the disease d samples, The total amount of Lp(a) recovered during three different extraction procedures was 5 mu g/g wet weight in tissue free of plaque and 11.8 mu g/g wet weight in atherosclerotic tissue, The correspondi ng values for apo B and apo E were 4.3 and 6.1 mu g/g wet weight vs. 5 .0 and 9.1 mu g/g wet weight. After density gradient centrifugation of the aortic tissue extracts, it was shown that the major parts of apo( a) and apo B detected in the lesion-free vessel wall were present as L p(a)-like particles, In the diseased tissue Lp(a) was partly dissociat ed into LDL-like particles and free apo(a). With this study we confirm that Lp(a) accumulates in the arterial wall, preferentially in diseas ed tissue, and that Lp(a) particles, deposited in atherosclerotic plaq ues, are partly degraded to LDL-like particles and free apo(a) in athe rosclerotic plaques.