Department of Biomedical Engineering, Stony Brook University, Bioengineering Building Stony Brook, NY 11794, USA.
J Orthop Surg Res. 2010 Mar 11;5:18. doi: 10.1186/1749-799X-5-18.
Interstitial fluid flow induced by loading has demonstrated to be an important mediator for regulating bone mass and morphology. It is shown that the fluid movement generated by the intramedullary pressure (ImP) provides a source for pressure gradient in bone. Such dynamic ImP may alter the blood flow within nutrient vessel adjacent to bone and directly connected to the marrow cavity, further initiating nutrient vessel adaptation. It is hypothesized that oscillatory ImP can mediate the blood flow in the skeletal nutrient vessels and trigger vasculature remodeling. The objective of this study was then to evaluate the vasculature remodeling induced by dynamic ImP stimulation as a function of ImP frequency.
Using an avian model, dynamics physiological fluid ImP (70 mmHg, peak-peak) was applied in the marrow cavity of the left ulna at either 3 Hz or 30 Hz, 10 minutes/day, 5 days/week for 3 or 4 weeks. The histomorphometric measurements of the principal nutrient arteries were done to quantify the arterial wall area, lumen area, wall thickness, and smooth muscle cell layer numbers for comparison.
The preliminary results indicated that the acute cyclic ImP stimuli can significantly enlarge the nutrient arterial wall area up to 50%, wall thickness up to 20%, and smooth muscle cell layer numbers up to 37%. In addition, 3-week of acute stimulation was sufficient to alter the arterial structural properties, i.e., increase of arterial wall area, whereas 4-week of loading showed only minimal changes regardless of the loading frequency.
These data indicate a potential mechanism in the interrelationship between vasculature adaptation and applied ImP alteration. Acute ImP could possibly initiate the remodeling in the bone nutrient vasculature, which may ultimately alter blood supply to bone.
负荷引起的间质液流动已被证明是调节骨量和形态的重要介质。研究表明，骨髓内压（ImP）产生的流体运动为骨内压力梯度提供了来源。这种动态 ImP 可能改变邻近骨骼和直接与骨髓腔相连的营养血管内的血流，从而直接引发营养血管适应性改变。研究假设，振荡 ImP 可以调节骨骼营养血管中的血流，并触发脉管系统重塑。因此，本研究旨在评估动态 ImP 刺激引起的脉管系统重塑与 ImP 频率的关系。
使用禽类模型，在左侧尺骨骨髓腔内施加生理流体动力学 ImP（70mmHg，峰峰值），频率分别为 3Hz 或 30Hz，每天 10 分钟，每周 5 天，持续 3 或 4 周。对主要营养动脉进行组织形态计量学测量，以量化动脉壁面积、管腔面积、壁厚度和平滑肌细胞层数量，进行比较。
初步结果表明，急性循环 ImP 刺激可使营养性动脉壁面积显著增加 50%，壁厚度增加 20%，平滑肌细胞层数量增加 37%。此外，3 周的急性刺激足以改变动脉的结构特性，即增加动脉壁面积，而 4 周的加载无论加载频率如何，仅显示最小的变化。
这些数据表明了血管适应性与施加的 ImP 改变之间的潜在相互关系的机制。急性 ImP 可能启动骨骼营养血管的重塑，这可能最终改变骨骼的血液供应。
