ECE2008 Oral Communications Bone and adrenal (9 abstracts)
A peculiar characteristic of parathyroid tissue is the ability to spontaneously induce angiogenesis, to proliferate and to secrete PTH when autotransplanted in patients undergoing total parathyroidectomy. Since stem/progenitor cells have been involved in the process of tissue regeneration, we searched for putative parathyroid progenitors from human normal and tumoral parathyroids. By immunohistochemistry, FACS analysis and cell culture we identified parathyroid cells positive for the haematopoietic/endothelial marker CD34 which expressed surface antigens typical of endothelial progenitors, such as CD146 and CXCR4, but not the haematopoietic and mesenchymal markers, such as CD45, Thy-1/CD90, CD105 and CD117/c-kit. These cells were more abundant in tumoral than in normal parathyroids (4.4±1.2 and 2.2±0.9% respectively; P=0.05), without any difference in their immunophenotype except for the expression of nestin, a neural stem cell specific marker, which was almost exclusively restricted to the tumor-derived CD34+ population. Purified CD34+ cells, but not CD34− cells, proliferated, although at a low rate, and differentiated into mature endothelial cells. Finally, parathyroid specific markers, such as glial cell missing B, PTH and calcium sensing receptor, were detected at mRNA and/or protein level in a subset of CD34+ cells. In conclusion, we identified cells which expressed both endothelial and parathyroid specific markers in human adult normal and tumoral parathyroids, providing a candidate for the putative parathyroid progenitors. Further studies are need to demonstrate the potential differentiation in multiple lineages and the self-renewal ability of these cells.