title: Stimulation of angiogenesis by canine parathyroid tissue.
abstract: BACKGROUND
  Autotransplanted parathyroid tissue is capable of inducing neovascularization in vivo, restoring calcium homeostasis with regulatory control. The mechanisms of parathyroid-induced neovascularization remain to be determined. Using an unique three-dimensional in vitro model, we tested the ability of parathyroid tissue to stimulate angiogenesis.
  
  
  METHODS
  Healthy 1 mm3 fragments of normal canine parathyroid tissue were cocultured with freshly isolated microvessels that were embedded in a collagen I gel. After 7 days the gels were stained with Gs-1 lectin, a specific marker for rat endothelium. With image analysis the microvessel density (as the percentage of area) was determined.
  
  
  RESULTS
  A significant increase in mean microvessel density (20.90% +/- 1.28 versus 16.51% +/- 1.66%) was seen with parathyroid coculture compared with control (n = 17, p < 0.05). There was no difference in microvessel density between controls and microvessels exposed to increasing concentrations of parathyroid hormone or calcium. The density of seeded microvessels influenced the effect of parathyroid stimulation of angiogenesis. The effect was apparent only at low seeding densities.
  
  
  CONCLUSIONS
  We conclude that parathyroid tissue intrinsically stimulates angiogenesis in vitro by a secreted product, independent of calcium or parathyroid hormone.
authors.affiliation: Department of Surgery, University of Arizona Health Sciences Center, Tucson, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Carter
authors.forename: S L
authors.initials: SL
authors.lastname: Crowell
authors.forename: C A
authors.initials: CA
authors.lastname: Boswell
authors.forename: S K
authors.initials: SK
authors.lastname: Williams
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D018920:Coculture Techniques; D004285:Dogs; D005110:Extracellular Space / Q000378:metabolism; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D018919:Neovascularization, Physiologic; D009994:Osmolar Concentration; D010280:Parathyroid Glands / Q000502:physiology*; D010281:Parathyroid Hormone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium