Osteocyte viability and regulation of osteoblast function in a 3D trabecular bone explant under dynamic hydrostatic pressure
Osteocyte viability and regulation of osteoblast function in a 3D trabecular bone explant under dynamic hydrostatic pressure
复制标题
DOI：
10.1359/jbmr.040516
复制
发表时间：
2004-09-01
影响因子：
6.2
通讯作者：
Guo, XE
中科院分区：
文献类型：
--
作者：
Takai, E;Mauck, RL;Guo, XE
采用一种新的骨小梁骨移植模型，研究了DHP载荷下骨细胞与成骨细胞的相互作用。DHP负荷增强骨细胞活力和成骨细胞功能，通过类骨形成测量。然而，活骨细胞是成骨细胞在DHP作用下形成类骨细胞所必需的，这在体外培养中直接显示了成骨细胞与骨细胞的相互作用。摘要：建立骨小梁骨外植体模型，观察骨细胞与成骨细胞相互作用和动态静水压力（DHP）负载对骨细胞活力和成骨细胞功能的影响。材料与方法：取小牛掌骨骨小梁骨芯，清洗骨髓和骨小梁表面细胞，分为6组，(1)活芯+动静水压（DHP），(2)活芯假手术，(3)活芯+成骨细胞+ DHP，(4)活芯+成骨细胞+假手术，(5)失活芯-成骨细胞DHP，(6)失活芯+成骨细胞+假手术，培养时间为2、8、15、22天，每组4天。3 ~ 6组取成骨细胞，5、6组取失活后取成骨细胞。组1、组3、组5每天进行DHP负荷。采用骨组织形态测定法，根据形态学定量骨细胞活力，并根据每骨表面的类骨表面积（Os/Bs）评估成骨细胞功能。TUNEL染色评价不同条件下骨细胞的死亡模式。结果：部分骨细胞在培养过程中保持活力。负载DHP可显著提高骨细胞的活力直至第8天，而存在种子成骨细胞可显著降低骨细胞的活力。与失活骨细胞的骨芯相比，活骨细胞的骨芯显示出更高的Os/Bs，当结合DHP加载时，在更大的时间点范围内达到显著水平。在没有活骨细胞的情况下，DHP负荷没有增加Os/Bs。无论处理或培养时间如何，凋亡细胞的百分比保持不变。结论：DHP能增强骨细胞活力，提示骨细胞体外存活需要机械刺激。此外，骨细胞在DHP负载信号的传递中发挥关键作用，以调节成骨细胞的功能。该外植体培养模型可用于长期培养的机械转导研究。
A new trabecular bone explant model was used to examine osteocyte-osteoblast interactions under DHP loading. DHP loading enhanced osteocyte viability as well as osteoblast function measured by osteoid formation. However, live osteocytes were necessary for osteoblasts to form osteoids in response to DHP, which directly show osteoblast-osteocyte interactions in this in vitro culture.Introduction: A trabecular bone explant model was characterized and used to examine the effect of osteocyte and osteoblast interactions and dynamic hydrostatic pressure (DHP) loading on osteocyte viability and osteoblast function in long-term culture.Materials and Methods: Trabecular bone cores obtained from metacarpals of calves were cleaned of bone marrow and trabecular surface cells and divided into Six groups, (1) live cores + dynamic hydrostatic pressure (DHP), (2) live cores sham, (3) live cores + osteoblast + DHP, (4) live cores + osteoblast + sham, (5) devitalized cores - osteoblast DHP, and (6) devitalized cores + osteoblast + sham, With four culture durations (2, 8, 15, and 22 days; n = 4/group). Cores from groups 3-6 were seeded with osteoblasts, and cores from groups 5 and 6 were devitalized before seedings. Groups 1, 3, and 5 were Subjected to daily DHP loading. Bone histomorphometry was performed to quantify osteocyte viability based on morphology and to assess osteoblast function based on osteoid surface per bone surface (Os/Bs). TUNEL staining was performed to evaluate the mode of osteocyte death under various conditions.Results: A portion of osteocytes remained viable for the duration of culture. DHP loading significantly enhanced osteocyte viability up to day 8, whereas the presence of seeded osteoblasts significantly decreased osteocyte viability. Cores with live osteocytes showed higher Os/Bs compared with devitalized cores, which reached significant levels over a greater range of time-points when combined with DHP loading. DHP loading did not increase Os/Bs in the absence of live osteocytes. The percentage of apoptotic cells remained the same regardless of treatment or culture duration.Conclusion: Enhanced osteocyte viability with DHP suggests the necessity of mechanical stimulation for osteocyte survival in vitro. Furthermore, osteocytes play a critical role in the transmission of signals from DHP loading to modulate ostcoblast function. This explant culture model may be used for mechanotransduction studies in long-term cultures.