Objective:To observe the effects of different low intensity pulsed ultrasound(LIPUS) on proliferation of fibroblast and to screen out the optimum parameters of LIPUS.Methods:LIPUS of different frequency(1?1.2?1.7MHz)and different intensity was used to stimulate the cultured human fibroblast cells for 5 min

10 min

20 min and 30min

respectively

and examination of cell proliferation by MTT after 24h.Results:①Optical absorption value of cell activity in MTT assay increased significantly in the cell culture with LIPUS of different frequency(1?1.2?1.7MHz) and four intensity of each frequency treatment for 5

10 minutes

as compared with the control group(P<0.01).With a peak detected in the cell culture with LPUS treatment for 10 minutes.But optical absorption value decreased with longer treat time

optical absorption value decreased significantly in human skin fibroblasts with LIPUS stimulation for more than 30 minutes(P<0.01)

as compared with the control group.②The peak relative survival rate detected in the cell culture with LIPUS of 1MHz

0.1W/cm2 treatment for 10 minutes.Conclusion:Stimulation with LIPUS could induce cell proliferation at a shorter time and could inhibit cell growth in vitro at a longer time.1MHz

0.1W/cm2 treatment for 10 minutes is the better parameter for promote cell proliferation.