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Mechanobiological modulation of cytoskeleton and calcium influx in osteoblastic cells by short-term focused acoustic radiation force.

Zhang S, Cheng J, Qin YX - PLoS ONE (2012)

Bottom Line: Cell viability was not affected.Application of pulsed ultrasound radiation generated only a minimal temperature rise of 0.1°C, and induced a streaming resulting fluid shear stress of 0.186 dyne/cm(2), suggesting that hyperthermia and acoustic streaming might not be the main causes of the observed cell responses.In conclusion, these data provide more insight in the interactions between acoustic mechanical stress and osteoblastic cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Mechanotransduction has demonstrated potential for regulating tissue adaptation in vivo and cellular activities in vitro. It is well documented that ultrasound can produce a wide variety of biological effects in biological systems. For example, pulsed ultrasound can be used to noninvasively accelerate the rate of bone fracture healing. Although a wide range of studies has been performed, mechanism for this therapeutic effect on bone healing is currently unknown. To elucidate the mechanism of cellular response to mechanical stimuli induced by pulsed ultrasound radiation, we developed a method to apply focused acoustic radiation force (ARF) (duration, one minute) on osteoblastic MC3T3-E1 cells and observed cellular responses to ARF using a spinning disk confocal microscope. This study demonstrates that the focused ARF induced F-actin cytoskeletal rearrangement in MC3T3-E1 cells. In addition, these cells showed an increase in intracellular calcium concentration following the application of focused ARF. Furthermore, passive bending movement was noted in primary cilium that were treated with focused ARF. Cell viability was not affected. Application of pulsed ultrasound radiation generated only a minimal temperature rise of 0.1°C, and induced a streaming resulting fluid shear stress of 0.186 dyne/cm(2), suggesting that hyperthermia and acoustic streaming might not be the main causes of the observed cell responses. In conclusion, these data provide more insight in the interactions between acoustic mechanical stress and osteoblastic cells. This experimental system could serve as basis for further exploration of the mechanosensing mechanism of osteoblasts triggered by ultrasound.

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Related in: MedlinePlus

Pulsed ultrasound radiation affects the arrangement of actin cytoskeleton in MC3T3-E1 osteoblasts.Pulsed ultrasound was applied for 1 min, cells were then rinsed three times with fresh DPBS (total time,10 min), then fixed and stained with rhodamine-phalloidin. Actin stress fibers were imaged in control cells (A) and 10 min (B) after ultrasound radiation. Actin stress fibers increased following pulsed ultrasound radiation. Scale bar, 10 µm.
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pone-0038343-g006: Pulsed ultrasound radiation affects the arrangement of actin cytoskeleton in MC3T3-E1 osteoblasts.Pulsed ultrasound was applied for 1 min, cells were then rinsed three times with fresh DPBS (total time,10 min), then fixed and stained with rhodamine-phalloidin. Actin stress fibers were imaged in control cells (A) and 10 min (B) after ultrasound radiation. Actin stress fibers increased following pulsed ultrasound radiation. Scale bar, 10 µm.

Mentions: Rhodamine-phalloidin staining was used to monitor the reorganization of actin cytoskeletons in MC3T3-E1 cells. Representative images of MC3T3-E1 cells stained with rhodamine-phalloidin are shown in Figure 6. The images showed different distributions and densities of cytoplasmic actin. In control cells, the phalloidin stained images revealed typical long and straight stress fibers, composed of actin filaments during the process of cell spreading. These fibers stretch all over the cell, provide the main skeleton structure, and are responsible for the cell shape (Figure 6A). Changes in actin cytoskeleton were obvious after one minute of pulsed ultrasound radiation (Figure 6B). Pulsed ultrasound caused a substantial rearrangement of F-actin stress fibers. Enhanced fluorescence intensity F-actin stress fibers appeared in the central area of pulsed ultrasound radiated cells, compared to control cells where brighter F-actin stress fibers were only arranged along the sides of the cells. These results indicate that pulsed ultrasound affects the rearrangement of the actin cytoskeleton.


Mechanobiological modulation of cytoskeleton and calcium influx in osteoblastic cells by short-term focused acoustic radiation force.

Zhang S, Cheng J, Qin YX - PLoS ONE (2012)

Pulsed ultrasound radiation affects the arrangement of actin cytoskeleton in MC3T3-E1 osteoblasts.Pulsed ultrasound was applied for 1 min, cells were then rinsed three times with fresh DPBS (total time,10 min), then fixed and stained with rhodamine-phalloidin. Actin stress fibers were imaged in control cells (A) and 10 min (B) after ultrasound radiation. Actin stress fibers increased following pulsed ultrasound radiation. Scale bar, 10 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368843&req=5

pone-0038343-g006: Pulsed ultrasound radiation affects the arrangement of actin cytoskeleton in MC3T3-E1 osteoblasts.Pulsed ultrasound was applied for 1 min, cells were then rinsed three times with fresh DPBS (total time,10 min), then fixed and stained with rhodamine-phalloidin. Actin stress fibers were imaged in control cells (A) and 10 min (B) after ultrasound radiation. Actin stress fibers increased following pulsed ultrasound radiation. Scale bar, 10 µm.
Mentions: Rhodamine-phalloidin staining was used to monitor the reorganization of actin cytoskeletons in MC3T3-E1 cells. Representative images of MC3T3-E1 cells stained with rhodamine-phalloidin are shown in Figure 6. The images showed different distributions and densities of cytoplasmic actin. In control cells, the phalloidin stained images revealed typical long and straight stress fibers, composed of actin filaments during the process of cell spreading. These fibers stretch all over the cell, provide the main skeleton structure, and are responsible for the cell shape (Figure 6A). Changes in actin cytoskeleton were obvious after one minute of pulsed ultrasound radiation (Figure 6B). Pulsed ultrasound caused a substantial rearrangement of F-actin stress fibers. Enhanced fluorescence intensity F-actin stress fibers appeared in the central area of pulsed ultrasound radiated cells, compared to control cells where brighter F-actin stress fibers were only arranged along the sides of the cells. These results indicate that pulsed ultrasound affects the rearrangement of the actin cytoskeleton.

Bottom Line: Cell viability was not affected.Application of pulsed ultrasound radiation generated only a minimal temperature rise of 0.1°C, and induced a streaming resulting fluid shear stress of 0.186 dyne/cm(2), suggesting that hyperthermia and acoustic streaming might not be the main causes of the observed cell responses.In conclusion, these data provide more insight in the interactions between acoustic mechanical stress and osteoblastic cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Mechanotransduction has demonstrated potential for regulating tissue adaptation in vivo and cellular activities in vitro. It is well documented that ultrasound can produce a wide variety of biological effects in biological systems. For example, pulsed ultrasound can be used to noninvasively accelerate the rate of bone fracture healing. Although a wide range of studies has been performed, mechanism for this therapeutic effect on bone healing is currently unknown. To elucidate the mechanism of cellular response to mechanical stimuli induced by pulsed ultrasound radiation, we developed a method to apply focused acoustic radiation force (ARF) (duration, one minute) on osteoblastic MC3T3-E1 cells and observed cellular responses to ARF using a spinning disk confocal microscope. This study demonstrates that the focused ARF induced F-actin cytoskeletal rearrangement in MC3T3-E1 cells. In addition, these cells showed an increase in intracellular calcium concentration following the application of focused ARF. Furthermore, passive bending movement was noted in primary cilium that were treated with focused ARF. Cell viability was not affected. Application of pulsed ultrasound radiation generated only a minimal temperature rise of 0.1°C, and induced a streaming resulting fluid shear stress of 0.186 dyne/cm(2), suggesting that hyperthermia and acoustic streaming might not be the main causes of the observed cell responses. In conclusion, these data provide more insight in the interactions between acoustic mechanical stress and osteoblastic cells. This experimental system could serve as basis for further exploration of the mechanosensing mechanism of osteoblasts triggered by ultrasound.

Show MeSH
Related in: MedlinePlus