Transplantation and non-invasive longitudinal in vivo imaging of parathyroid cells

The parathyroid cell is a critical physiological regulator of extracellular Ca 2+ levels via secretion of parathyroid hormone (PTH). Regulation of PTH secretion is complex, not fully understood and represents a unique feature between extracellular Ca 2+ , intracellular Ca 2+ , and hormone secretion. One major problem in parathyroid research is the difficulty maintaining surgically procured cells ex vivo to allow detailed cellular characterization. Here, we introduce a new platform for transplantation and non-invasive in vivo imaging of parathyroid cells using the anterior chamber of the eye as a transplantation site. Parathyroid tissue pieces transplanted into the mouse eye engrafted on the iris became vascularized and retained cellular composition. Transplanted animals showed elevated PTH levels as a sign of a functional graft. In vivo confocal microscopy allowed repetitive monitoring of parathyroid graft morphology and vascularization. In summary, there is an urgent need for novel methods to characterize complex cellular processes in parathyroid cells. We show a novel method and strategy for non-invasive in vivo investigations that can be applied under physiological and pathological conditions, enabling deepening knowledge of parathyroid physiology and pathology.