Establishment and characterization of a clonal line of parathyroid endothelial cells.

We have isolated endothelial cells derived from bovine parathyroid tissue. These cells have been cloned and maintained by serial passage for more than 40 months without showing signs of senescence. Prolonged culture was accomplished by using a medium favoring endothelial cell growth and methods for enriching endothelial cells in primary culture. The cloned parathyroid endothelial cells contained factor VIII-related antigen, took up acetylated low-density lipoproteins and parathyroid hormone, and showed morphological features comparable to other endothelial cells. Bovine parathyroid endothelial cells replicated with a mean doubling time of 65 h. Fibroblast growth factors, platelet-derived growth factor, and calcium acted as mitogens for parathyroid endothelial cells, whereas transforming growth factor beta inhibited proliferation.