HPE cells: a clonal endothelial cell line established from human parathyroid tissue (human parathyroid cell line)

We report the culture and cloning of human endothelial cells derived from parathyroid tissue surgically removed from a patient affected by Multiple Endocrine Neoplasia Type 1 syndrome. These cells, known as HPE, have been isolated and maintained in culture by serial passages for more than 15 months. The clonal cell line grows in a medium containing serum substitutes which favour endothelial cell growth. HPE cells replicate with a mean doubling time of 120 h, showing typical functional and morphological features of endothelial cells, such as uptake of acetylated low density lipoprotein and positive reaction for Factor VIII-Related Antigen. Basic fibroblast growth factor, vascular endothelial growth factor, insulin-like growth factor type I and ascorbic acid stimulate cell proliferation, whereas transforming growth factor beta and heparin act as inhibitory factors. Prostaglandin E2, secretin and epinephrine increased cAMP production, while human parathyroid hormone, histamine and glucagon were inert. Cells were found to express pro-collagen alpha 1 (type I) mRNA. In HPE cells Restriction Fragments Length Polymorphism and PCR analysis did not show allelic loss at chromosome 11q12-13, known to be a typical feature of MEN 1 parathyroid tumors. These cells are the first example of an established normal human clonal cell line with an endothelial phenotype.