Low-Intensity Amplitude Modulated Ultrasound Increases Osteoblastic Mineralization

Abstract

The purpose of this study was to assess the effect of pulsed amplitude modulated ultrasound (pAMUS) on the level of mineralization in osteoblast cell in comparison to cells stimulated with low-intensity pulsed ultrasound (LIPUS). To make the ultrasound effects more enhanced and targeted at region of interest, this study uses a novel approach of applying pulsed amplitude modulated ultrasound to osteoblast cells. The pAMUS signal was generated using two signal generators. Pulsed signal was amplified through a power amplifier and drove two identical focused ultrasound probes, focusing at the same point in the culture dish. The effects of pAMUS were evaluated using a pAMUS signal of 45 kHz and 100 kHz with 20% duty cycle. The hydrophone verified the formation of a focal point at equal distances (16 mm) from the surface of both transducers. Intensity profile using computer controlled 2D scanner showed circular focal point with a diameter of approximately 10 mm. The effect of the signal was studied using MC3T3-E1 cells cultured in osteogenic medium at time points Day 7, 12 and 18. The cells were analyzed for ALP activity and calcium mineralization. The pAMUS significantly increased the ALP activity and matrix calcification in comparison with LIPUS stimulated cultures.

Chondro-protective effects of low intensity pulsed ultrasound

“…LIPUS stimulation also significantly reduced IL-1β induced expression of Cox-2 in mandibular condylar chondrocytes through inhibition of IL-1β activated ERK1/2 phosphorylation 39 . LIPUS at an intensity of 30mW/cm 2 for 20 min/day has been shown to significantly increase osteogenic differentiation, osteoblast proliferation, and bone healing in both in-vitro and in vivo models 26,40 .…”

Reversal of the Detrimental Effects of Simulated Microgravity on Human Osteoblasts by Modified Low Intensity Pulsed Ultrasound

“…Specifically, low-intensity pulsed ultrasound (LIPUS) was applied in vivo and showed reversal of osteopenia and enhancement of bone fractures (Boyd et al 2002; Carvalho and Cliquet Junior 2004; Ferreri et al 2011). LIPUS has shown increased anabolic events in bone cells (Binderman et al 1984; Binderman et al 1988; Rubin et al 1997; Uddin et al 2011), including enhanced cytokine release (Li et al 2003), increased mRNA expression of RUNX2, ALP, Osterix and collagen 1 (Yang et al 1996), calcium mineralization of ECM (Nolte et al 2001), activation of Akt pathway (Takeuchi et al 2008a), and increase of potassium influx (Chapman et al 1980), angiogenesis (Kaneko et al 2002), adenyl cyclase activity and TGF-β synthesis resulting in increased osteogenesis of bone stroma cells (Naruse et al 2003). Despite these effects, the exact mechanism through which LIPUS enhances bone cell properties and increases the rate of bone formation remains unknown.…”

Hybrid use of combined and sequential delivery of growth factors and ultrasound stimulation in porous multilayer composite scaffolds to promote both vascularization and bone formation in bone tissue engineering

“…52 Uddin et al reported that LIPUS increased the expression of relative osteogenic genes along with increasing ALP activity and expression. 53 Hu et al also found the similar results in hPDLCs which possess stem cell properties and demonstrated that LIPUS stimula-tion facilitates osteogenic differentiation of hPDLCs by activating integrin b1-dependent signaling transduction and up regulation of Runx2 expression. 54 Moreover, LIPUS has been shown to enhance cell adhesion and increase proliferation of MSCs.…”

“…Jiang et al investigated the osteogenic in vitro effect of LIPUS on SD rat adipose‐derived stem cells (ADSCs) and found that LIPUS‐treated ADSCs presented higher mRNA expression levels of runt‐related transcription factor 2 (Runx2), osteocalcin (OCN), ALP and bone sialoprotein (BSP) genes and higher protein levels of Runx2 and BSP than the controls . Uddin et al reported that LIPUS increased the expression of relative osteogenic genes along with increasing ALP activity and expression . Hu et al also found the similar results in hPDLCs which possess stem cell properties and demonstrated that LIPUS stimulation facilitates osteogenic differentiation of hPDLCs by activating integrin b1‐dependent signaling transduction and up regulation of Runx2 expression …”