Analysis of lipids and endothelial and smooth muscle cells of umbilical cord in familial homozygous hypercholesterolemia.

Umbilical cord lipids from a familial hypercholesterolemia homozygote were extracted and quantitated. Free cholesterol was increased 26% and esterified cholesterol was increased 379% compared to normal, whereas phospholipid content was not altered. Analysis of homozygote umbilical artery revealed no excess cholesterol and the vessels were histologically normal. Thus, in the homozygote cord, accumulation of cholesterol occurs first in Wharton's jelly, the hypocellular glycosaminoglycan-enriched cord matrix. Skin fibroblasts, umbilical vein endothelial cells, and umbilical vein smooth muscle cells were cultured from the homozygote. Low density lipoprotein receptor activity was reduced to 9%-38% of normal in all cell types from the homozygote, demonstrating that vessel cells express the LDL, receptor defect seen in skin fibroblasts.