Rubin J, McLeod K J, Titus L, Nanes M S, Catherwood B D, Rubin C T
Department of Medicine, Veterans Affairs Medical Center, Atlanta, Georgia, 30033, USA.
J Orthop Res. 1996 Jan;14(1):7-15. doi: 10.1002/jor.1100140104.
With use of a solenoid to generate uniform time-varying electric fields, the effect of extremely low frequency electric fields on osteoclast-like cell formation stimulated by 1,25(OH)2D3 was studied in primary murine marrow culture. Recruitment of osteoclast-like cells was assessed by counting multinuclear, tartrate-resistant acid phosphatase positive cells on day 8 of culture. A solenoid was used to impose uniform time-varying electric fields on cells; sham exposures were performed with an identical solenoid with a null net electric field. During the experiments, both solenoids heated interiorly to approximately 1.5 degrees C above ambient incubator temperature. As a result of the heating, cultures in the sham solenoid formed more osteoclast-like cells than those on the incubator shelf (132 +/- 12%). For this reason, cells exposed to the sham solenoid were used for comparison with cultures exposed to the active coil. Marrow cells were plated at 1.4 x 10(6)/cm2 in square chamber dishes and exposed to 60 Hz electric fields at 9.6 muV/cm from days 1 to 8. Field exposure inhibited osteoclast-like cell recruitment by 17 +/- 3% as compared with sham exposure (p < 0.0001). Several variables, including initial cell plating density, addition of prostaglandin E2 to enhance osteoclast-like cell recruitment, and field parameters, were also assessed. In this secondary series, extremely low frequency fields inhibited osteoclast-like cell formation by 24 +/- 4% (p < 0.0001), with their inhibitory effect consistent throughout all variations in protocol. These experiments demonstrate that extremely low intensity, low frequency sinusoidal electric fields suppress the formation of osteoclast-like cells in marrow culture. The in vitro results support in vivo findings that demonstrate that electric fields inhibit the onset of osteopenia and the progression of osteonecrosis; this suggests that extremely low frequency fields may inhibit osteoclast recruitment in vivo.
利用螺线管产生均匀的时变电场，在原代小鼠骨髓培养中研究了极低频电场对1,25(OH)₂D₃刺激的破骨细胞样细胞形成的影响。通过在培养第8天计数多核、抗酒石酸酸性磷酸酶阳性细胞来评估破骨细胞样细胞的募集情况。使用螺线管对细胞施加均匀的时变电场；假暴露则使用净电场为零的相同螺线管进行。在实验过程中，两个螺线管内部温度均比培养箱环境温度高出约1.5摄氏度。由于加热，假螺线管中的培养物比培养箱架子上的培养物形成了更多的破骨细胞样细胞（多132±12%）。因此，将暴露于假螺线管的细胞用于与暴露于有源线圈的培养物进行比较。将骨髓细胞以1.4×10⁶/cm²的密度接种在方形培养皿中，并在第1天至第8天暴露于9.6 μV/cm的60 Hz电场中。与假暴露相比，电场暴露使破骨细胞样细胞的募集减少了17±3%（p<0.0001）。还评估了几个变量，包括初始细胞接种密度、添加前列腺素E₂以增强破骨细胞样细胞的募集以及场参数。在这个二次实验系列中，极低频场使破骨细胞样细胞的形成减少了24±4%（p<0.0001），其抑制作用在所有实验方案的变化中均保持一致。这些实验表明，极低强度、低频正弦电场可抑制骨髓培养中破骨细胞样细胞的形成。体外结果支持体内研究结果，即电场可抑制骨质减少的发生和骨坏死的进展；这表明极低频场可能在体内抑制破骨细胞的募集。
