Samples were organized into control (nondifferentiated) and test groups which were analyzed at 3 different time points: 1, 2, and 4 weeks. Periodontal ligament MSCs were isolated and then expanded in an MSCM medium while cyclic nucleotide levels and phosphodiesterase activity were assessed.
cAMP and cGMP levels were markedly higher in the first week than in the following stages. Similarly, PDE activity increased during the first week and reached the peak in the second week.
This work validates that cAMP, cGMP, and PDE activities are important factors in the first phase of the osteogenic induction of a human stem cell.