Basic and clinical aspects of calcimimetics. Effect of direct injection therapy in the expression of calcium-sensing receptor in parathyroid cell

Medical treatments including intravenous vitamin D therapy often fail to control parathyroid hormone (PTH) level in advanced secondary hyperparathyroidism (SHPT) . High level of PTH in spite of hypercalcemia rssults from poor sensitivity for calcium (Ca) of parathyroid cell (PTC) , due to low content of Ca-sensing receptor (CaSR) . It has been reported that direct vitamin D injection into parathyroid gland (PTG) efficiently decreased PTH level without significant changes of Ca level in dialysis patients as well as in uremic animals, possibly through up-regulation of CaSR and vitamin D receptor and decrease of cell number in PTC. In addition, the increase of CaSR expression in PTC induced by gene therapy using the same technique of direct injection into PTG has been also confirmed in model animals. These new therapeutic strategies for increasing CaSR expression in PTC may be promising for the the control of Ca and PTH levels in patients with advanced SHPT.