Davidson Edward H, Sultan Steven M, Butala Parag, Knobel Denis, Warren Stephen M
From the Department of Plastic Surgery, New York University Langone Medical Center, New York, New York.
J Craniofac Surg. 2013 Sep;24(5):1558-64. doi: 10.1097/SCS.0b013e31828f2060.
The mechanotransduction mechanisms linking distraction device activation to new bone formation remain unknown. We hypothesize that the tension stress of activation during distraction osteogenesis is transmitted through lacunocanalicular fluid flow to initiate the osteogenic signaling cascade. Adult Sprague-Dawley rats (N = 24) were subjected to mandibular osteotomy and application of an external distraction device. After a 3-day latency period, half the animals (n = 12) underwent device activation at 0.25 mm twice daily for 6 days (total activation, 3 mm), and the other half (n = 12) had no activation. On day 10, the animals were injected with fluorescent reactive red lacunocanalicular tracer before killing. Mandibles were harvested, embedded, and sectioned, and reactive red epifluorescence lacunocanalicular flow was measured. Protein was harvested for focal adhesion kinase 1 (FAK1), NESPRIN1, SUN1, LAMIN A/C, and SMAD1 Western blotting as well as for bone morphogenetic protein (BMP)-2 enzyme-linked immunosorbent assay and alkaline phosphatase assay. Lacunocanalicular fluid flow was significantly greater in the distracted samples (60.5 ± 14 vs 10.3 ± 4 molecules of equivalent soluble fluorochrome per megapixel, P = 0.01). Flow distribution demonstrated the highest lacunocanalicular flow near the center of the distraction gap. Increased lacunocanalicular flow resulted in increased FAK1 (P = 0.009), NESPRIN1 (P = 0.01), SUN1 (P = 0.01), and LAMIN A/C (P = 0.008) expression. Focal adhesion kinase 1 activation in the presence of BMP-2 protein expression (P = 0.001) resulted in increased intranuclear SMAD1 phosphorylation (P = 0.04) and alkaline phosphatase activity (P < 0.0001). These findings suggest that activation of the distraction osteogenesis device affects cellular response through changes in lacunocanalicular fluid flow.
将牵张装置激活与新骨形成联系起来的机械转导机制尚不清楚。我们推测，牵张成骨过程中激活时的张应力通过腔管内液流传递，以启动成骨信号级联反应。成年Sprague-Dawley大鼠（N = 24）接受下颌骨截骨术并应用外部牵张装置。经过3天的潜伏期后，一半动物（n = 12）每天两次以0.25 mm的速度进行装置激活，持续6天（总激活量为3 mm），另一半（n = 12）不进行激活。在第10天，处死动物前注射荧光活性红色腔管示踪剂。采集下颌骨，包埋并切片，测量活性红色落射荧光腔管内液流。收集蛋白质用于粘着斑激酶1（FAK1）、巢蛋白1（NESPRIN1）、SUN1、核纤层蛋白A/C和SMAD1的蛋白质印迹分析，以及骨形态发生蛋白（BMP）-2酶联免疫吸附测定和碱性磷酸酶测定。牵张样本中的腔管内液流明显更大（每兆像素60.5±14对10.3±4等效可溶性荧光染料分子，P = 0.01）。液流分布显示在牵张间隙中心附近腔管内液流最高。腔管内液流增加导致FAK1（P = 0.009）、NESPRIN1（P = 0.01）、SUN1（P = 0.01）和核纤层蛋白A/C（P = 0.008）表达增加。在BMP-2蛋白表达存在的情况下FAK1激活（P = 0.001）导致核内SMAD1磷酸化增加（P = 0.04）和碱性磷酸酶活性增加（P < 0.ooo1）。这些发现表明，牵张成骨装置的激活通过腔管内液流的变化影响细胞反应。
