Zhong Ziwei, Akkus Ozan
Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
Biorheology. 2011;48(2):89-97. doi: 10.3233/BIR-2011-0587.
Bone marrow is the niche for stem cells and is within close proximity to bone lining cells. Forces experienced by these cells guide their differentiation and proliferation. As these forces are dependent on the viscosity of the medium, the knowledge about the viscosity of marrow is essential to modeling the mechanical environment of bone. This study sought to examine the effects of age on the rheological properties of human yellow bone marrow. Samples were harvested from the femurs of male donors ranging from 22 to 82 years of age (N=19) and subjected to stress and frequency sweeps to determine viscosity and dynamic moduli, respectively. The viscosity of bone marrow at physiologically plausible shear rates ranged from 44 to 142 mPa·s. The coefficients of variation ranged up to 0.40 within subjects and 0.14 between subjects. Regressions of viscosity values against age did not generate a strong level of significance; therefore, earlier reported changes in the composition of marrow with age did not translate into variation in viscosity of marrow. Since age does not seem to offer a governing effect, the observed variation within and between donors may stem from other factors (genetic, nutrition, etc.). The wide range of variation in the viscosity of marrow within subject, between subjects and with age implies that the fluid shear experienced by cells resident in marrow may also vary substantially.
骨髓是干细胞的微环境，且与骨衬细胞紧密相邻。这些细胞所经历的力引导着它们的分化和增殖。由于这些力取决于介质的粘度，因此了解骨髓的粘度对于模拟骨骼的力学环境至关重要。本研究旨在探讨年龄对人黄骨髓流变学特性的影响。从年龄在22至82岁的男性供体的股骨中采集样本（N = 19），并分别进行应力扫描和频率扫描以确定粘度和动态模量。在生理上合理的剪切速率下，骨髓的粘度范围为44至142 mPa·s。受试者内变异系数高达0.40，受试者间变异系数为0.14。粘度值与年龄的回归分析未产生显著水平；因此，先前报道的随着年龄增长骨髓成分的变化并未转化为骨髓粘度的变化。由于年龄似乎没有主导作用，观察到的供体内部和供体之间的差异可能源于其他因素（遗传、营养等）。骨髓粘度在受试者内、受试者间以及随年龄的广泛变化意味着驻留在骨髓中的细胞所经历的流体剪切力也可能有很大差异。
