Calcitonin gene related peptide enhances bone colony development in vitro

Recent evidence suggests that sensory nerve fibers of the dental pulp secrete calcitonin gene related peptide alpha exactly where secondary or tertiary dentin is mineralized. In addition, calcitonin gene related peptide raises the level of cyclic adenosine monophosphate in osteoblasts, indicating a potential effect on secretory activity in bone. Because calcitonin and calcitonin gene related peptide are formed from the same gene, the authors tested whether calcitonin gene related peptide or calcitonin has an osteogenic potential in vitro. To this end, 0.01, 0.1, and 1 microg/ml of salmon calcitonin or rat calcitonin gene related peptide in Bigger, Gwatkin, Jackson b medium was added daily to 3 x 10(6) rat light density bone marrow leukocytes that were separated with the Ficoll-Paque density gradient separation method, then seeded on a previously prepared fibroblast layer in Petri dishes. After 7 days, the number and size of bone colonies formed in the calcitonin gene related peptide (0.1 or 1 microg/ml) added group was significantly greater than that of the control group. There was no statistically significant difference between the calcitonin added and control groups. Calcitonin gene related peptide has an osteogenic stimulating effect, either by stimulating stem cell mitosis or osteoprogenitor cell differentiation (or both), whereas salmon calcitonin has no effect.