Objective To investigate the biological effects of low intensity of pulsed ultrasound (LIPUS) on human periosteal cells and marrow stromal cells in vitro. Methods LIPUS of 30 mW/cm2 was used to stimulate the cultured human periosteal cells and marrow stromal cells for 5 min, 10 and 20 min per day, respectively, followed by the examination of cell proliferation and differentiation potential. Results Thymidine incorporation and total protein assay indicated that LIPUS had no significant effect on DNA and protein synthesis of the periosteal and marrow stromal cells, suggesting that LIPUS did not promote proliferation of these cells. However, ALP activity and osteocalcin secretion of the human periosteal cells were dramatically increased. Conclusion The results suggested that low intensity pulsed ultrasound stimulated periosteal cell proliferation and differentiation toward osteogenic lineage, this might contribute to the curing effect of low intensity pulsed ultrasound for fracture.

The objective of this program is to investigate the biological effect of dynamic strain on human periosteal cells in vitro. Using a well-established model, the Flexercell unit, we placed mechanical stress (50,000 microstrain, 1 Hz and sine wave) on human periosteal cells grown in collagen coated flexible membrane. The time points of proliferative and differentiative properties were assessed by means of cell counting, thymidine incorporation, synthesis of alkaline phosphatase and osteocalcin, and long term of mechanical load induced calcium nodules formation was also demonstrated. The results showed that the application of highly controlled strains exerted a significant effect on human periosteal cells by up regulation of osteogenic properties rather than exercised an influence on proliferation. The results suggested that the promoting effects of dynamic strain on human periosteal cells probably contribute to the biological function of mechanical loading bearing.
Biomechanical Phenomena ; Cell Proliferation ; Cells, Cultured ; Humans ; Periosteum ; cytology ; Stress, Mechanical ; Ulna ; cytology ; Weight-Bearing