Applications of low intensity pulsed ultrasound for functional bone tissue engineering using adult stem cells

Low intensity pulsed ultrasound (LIPUS) has been used extensively for fracture healing. Many LIPUS parameters have been studied in depth except for pulse repetition frequency (PRF). However, to examine this parameter, a custom LIPUS system needed to be designed since commercial systems have very little control over parameter modification. Specifically, the PRF of commercial systems is typically set to either 100 Hz or 1 kHz and cannot be changed. A custom system was used to explore the effects of PRF on human adipose derived adult stem cells (hASCs) and bone marrow derived mesenchymal stem cells (hMSCs). The PRF was found to significantly affect cellular response to LIPUS stimulation for both cell types. Additionally, LIPUS was shown to strongly accelerate osteogenic differentiation of hASCs based on amount of calcium accretion normalized by total DNA.