Production Enhancement of Human Adipose-Derived Mesenchymal Stem Cells By Low-Intensity Ultrasound Stimulation

Background: Low-intensity ultrasound (LIUS) has been used to increase the proliferation rate of various stem cells including human adipose-derived mesenchymal stem cells (hAdMSCs). hAdMSCs is now commercially produced for various therapeutic applications. The purpose of this study was to show feasibility of enhancing the productivity of cell culture during 16-day cell culturing and increasing proliferation rate of hAdMSCs by LIUS stimulation with appropriate ultrasound parameters. Methods: Beam patterns of 5 and 10 MHz ultrasound transducers were measured to confirm the area of stimulation. The intensity of sound waves transmitted through a Petri-dish was measured in situ for quantitative evaluation. Bromodeoxyuridine (BrdU) incorporation assay was performed to search for appropriate parameters for LIUS stimulation of hAdMSCs. Cell culture medium supplemented with 8% fetal bovine serum (FBS) in a 35 mm Petri-dish was used for 16 days with subculture from 2 to 6 passage. Results: A frequency of 5 MHz, an intensity of 300 , a duration of 10 minutes per day, and continuous waves with 100% duty cycle were the best parameters according to the BrdU assay of proliferation rate of hAdMSCs. LIUS stimulation group had about 3.25-fold greater number of cells from passage 2 to 6 compared with the control group. Doubling time was decreased to 4.44 hours in average. Cell viability was the same between the control and LIUS stimulation groups.Conclusions: This study of enchanced proliferation rate and cell culture productivity of hAdMSCs by LIUS stimulation may lay the foundation for the application of LIUS stimulation in cell therapeutic industry by reducing the production cost and time required for cell therapy.