11 research outputs found
Vibration acceleration promotes bone formation in rodent models
<div><p>All living tissues and cells on Earth are subject to gravitational acceleration, but no reports have verified whether acceleration mode influences bone formation and healing. Therefore, this study was to compare the effects of two acceleration modes, vibration and constant (centrifugal) accelerations, on bone formation and healing in the trunk using BMP 2-induced ectopic bone formation (EBF) mouse model and a rib fracture healing (RFH) rat model. Additionally, we tried to verify the difference in mechanism of effect on bone formation by accelerations between these two models. Three groups (low- and high-magnitude vibration and control-VA groups) were evaluated in the vibration acceleration study, and two groups (centrifuge acceleration and control-CA groups) were used in the constant acceleration study. In each model, the intervention was applied for ten minutes per day from three days after surgery for eleven days (EBF model) or nine days (RFH model). All animals were sacrificed the day after the intervention ended. In the EBF model, ectopic bone was evaluated by macroscopic and histological observations, wet weight, radiography and microfocus computed tomography (micro-CT). In the RFH model, whole fracture-repaired ribs were excised with removal of soft tissue, and evaluated radiologically and histologically. Ectopic bones in the low-magnitude group (EBF model) had significantly greater wet weight and were significantly larger (macroscopically and radiographically) than those in the other two groups, whereas the size and wet weight of ectopic bones in the centrifuge acceleration group showed no significant difference compared those in control-CA group. All ectopic bones showed calcified trabeculae and maturated bone marrow. Micro-CT showed that bone volume (BV) in the low-magnitude group of EBF model was significantly higher than those in the other two groups (3.1±1.2mm<sup>3</sup> v.s. 1.8±1.2mm<sup>3</sup> in high-magnitude group and 1.3±0.9mm<sup>3</sup> in control-VA group), but BV in the centrifuge acceleration group had no significant difference compared those in control-CA group. Union rate and BV in the low-magnitude group of RFH model were also significantly higher than those in the other groups (Union rate: 60% v.s. 0% in the high-magnitude group and 10% in the control-VA group, BV: 0.69±0.30mm<sup>3</sup> v.s. 0.15±0.09mm<sup>3</sup> in high-magnitude group and 0.22±0.17mm<sup>3</sup> in control-VA group). BV/TV in the low-magnitude group of RFH model was significantly higher than that in control-VA group (59.4±14.9% v.s. 35.8±13.5%). On the other hand, radiographic union rate (10% in centrifuge acceleration group v.s. 20% in control-CA group) and micro-CT parameters in RFH model were not significantly different between two groups in the constant acceleration studies. Radiographic images of non-union rib fractures showed cartilage at the fracture site and poor new bone formation, whereas union samples showed only new bone. In conclusion, low-magnitude vibration acceleration promoted bone formation at the trunk in both BMP-induced ectopic bone formation and rib fracture healing models. However, the micro-CT parameters were not similar between two models, which suggested that there might be difference in the mechanism of effect by vibration between two models.</p></div
Animal body weight in rib fracture healing model.
<p>Animal body weight in rib fracture healing model.</p
Microscopic images of ectopic bone cross-sections stained with hematoxylin and eosin (H&E) at (A) 40X, scale bar = 500 μm and (B) 400X, scale bar = 100 μm.
<p>Microscopic images of ectopic bone cross-sections stained with hematoxylin and eosin (H&E) at (A) 40X, scale bar = 500 μm and (B) 400X, scale bar = 100 μm.</p
Micro-CT analysis of rib fracture sites among vibration acceleration groups and constant acceleration groups.
<p>Micro-CT analysis of rib fracture sites among vibration acceleration groups and constant acceleration groups.</p
Macroscopic (left panel) and radiographic (right panel) aspects of ectopic bones among three groups (Control-VA: Control group of vibration acceleration groups, Low: Low-magnitude group, High: High-magnitude group).
<p>Macroscopic (left panel) and radiographic (right panel) aspects of ectopic bones among three groups (Control-VA: Control group of vibration acceleration groups, Low: Low-magnitude group, High: High-magnitude group).</p
Macroscopic (left panel) and radiographic (right panel) aspects of ectopic bones between two groups (Control-CA: Control group of constant acceleration groups, Centrifuge: Centrifuge group).
<p>Macroscopic (left panel) and radiographic (right panel) aspects of ectopic bones between two groups (Control-CA: Control group of constant acceleration groups, Centrifuge: Centrifuge group).</p
Microscopic images of fracture callus stained with hematoxylin and eosin (H&E) and safranin-O.
<p>Representative images of non-union ribs are in the upper row and those of union in the lower row: micro-CT images (left column), histological images stained with H&E (middle column) and histological images stained with safranin-O (right column). Magnification = 40X, scale bar = 1 mm.</p
Animal body weight in ectopic bone formation model.
<p>Animal body weight in ectopic bone formation model.</p
Region of interest in rib fracture for evaluation by micro-CT.
<p>ROI was the space between 1-mm proximal and distal planes (white lines) from the center of the bone defect (dotted white line); these planes were perpendicular to the bone axis.</p
Micro-CT analysis of ectopic bone among vibration and constant acceleration groups.
<p>Micro-CT analysis of ectopic bone among vibration and constant acceleration groups.</p