Effects of prostaglandin E2 and D2 on cell proliferation and osteogenic capacity of human mesenchymal stem cells

The manifestation of periodontitis-related inflammatory reaction is inevitably bound to the production of prostaglandins E-2 and D-2 which have been suggested to mediate osteoclastic and osteogenic effects within the affected tissue. We demonstrated the presence of PGE(2 )and PGD(2) receptors on hMSCs on RNA level and with immunofluorescence. For each Prostaglandin, three concentrations were studied: 0.1; 0.5 or 1.0 mu g/ml. A lower expression of EP1 and EP4 (PGE(2) receptors 1 and 4) after stimulation with PGE(2) was shown, thus a tendency to compromise osteogenic differentiation and metabolism. PGE(2) induced a higher growth-rate during the first week, while a continuous inflammatory challenge determined a decrease of the proliferation of hMSCs. PGD(2) inhibited cell growth irrespective of the duration of the stimulation. PGE(2) and PGD(2) have also negative effects on calcium deposition osteogenic, thus on differentiation of hMSCs. PGE(2) and PGD(2) seem to induce bone resorption also having indirectly a negative impact on the osteogenic differentiation of hMSCs. Thus, inhibitors of PGE(2) and PGD(2) can be used as adjunct to mechanical periodontal treatment.