Mesenchymal stem cells from amniotic fluid (AF-MSC) are able to differentiate into multiple lineages and are not tumorigenic after transplantation in mice (De Coppi et al, Nat Biotechnol 2007), becoming potential good candidates for therapeutic purposes. Many evidences showed spontaneous or induced in vitro osteogenesis in AF-MSCs, assayed by cell morphology, calcium deposition or alkaline phosphatase activity.

Considering the role of physiological agents in bone homeostasis, aim of this work was to study the effects of calcitonin (Ct), a regulator of bone resorption (Inzerillo et al, J Pediatr Endocrinol Metab 2004), on AF-MSCs during osteogenic differentiation.

Cell samples were from amniocentesis (16th week pregnancy) of healthy subjects following informed consent; the Ct receptor expression assayed by immunolabelling and Western blot; and intracellular Ca²⁺ levels monitored using single cell imaging technique.

Ct receptor was expressed in AF-MSCs cultured in growth or osteogenic medium. The intracellular localization and immunoreactive band of the receptor showed an inactive form. This was supported by a very low and variable cell response to Ct on calcium variations.

These preliminary results showed that AF-MSCs could be a potential osteogenic model useful to study in vitro cell response to Ct and its receptor activation, involved in the numerous regulatory actions on osteoblasts/osteocytes and osteoclasts.