Zhang Hua, Lin Xin, Wan Hong, Li Jun-Hua, Li Jia-Mou
Department of Orthopaedics, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
Microsurgery. 2009;29(6):479-85. doi: 10.1002/micr.20644.
It is generally known that low-intensity pulsed ultrasound (LIPUS) accelerates peripheral nerve tissue regeneration. However, the precise cellular mechanism involved is still unclear. The purpose of this study was to determine how the Schwann cells respond directly to LIPUS stimuli. Thus, we investigated the effect of LIPUS on cell proliferation, neurotrophin-3 (NT-3), and brain-derived neurotrophic factor (BDNF) mRNA expression in rat Schwann cells. Schwann cells were enzymatically isolated from postnatal 1-3 day rat sciatic nerve tissue and cultured in the six-well plate. The ultrasound was applied at a frequency of 1 MHz and an intensity of 100 mW/cm(2) spatial average temporal average for 5 minutes/day. The control group was cultured in the same way but without the administration of ultrasound. Immunohistochemistry demonstrated that more than 98% of the experimental and control cells were positive for S-100, NT-3, and BDNF. With 5-bromo-2'-deoxyuridine (BrdU) assay, the stimulated cells also exhibited an increase in the rate of cell proliferation on days 4, 7, 10, and 14. Further investigation found that mRNA expression of NT-3 was significantly upregulated in experimental groups compared with the control 14 days after the LIPUS stimulation (the ratio of NT-3/beta-actin was 0.56 +/- 0.13 vs. 0.41 +/- 0.09, P < 0.01), whereas the mRNA expression of BDNF was significantly downregulated in experimental groups compared with the control (the ratio of BDNF/beta-actin was 0.51 +/- 0.05 vs. 0.60 +/- 0.08, P < 0.05). These results demonstrated that the application of LIPUS promotes cell proliferation and NT-3 gene expression in Schwann cells, and involved in the alteration of BDNF gene expression.
众所周知，低强度脉冲超声（LIPUS）可加速周围神经组织再生。然而，其中确切的细胞机制仍不清楚。本研究的目的是确定雪旺细胞如何直接响应LIPUS刺激。因此，我们研究了LIPUS对大鼠雪旺细胞增殖、神经营养因子-3（NT-3）和脑源性神经营养因子（BDNF）mRNA表达的影响。从出生后1 - 3天的大鼠坐骨神经组织中酶法分离出雪旺细胞，并培养于六孔板中。以1 MHz的频率、100 mW/cm²的空间平均时间平均强度施加超声，每天5分钟。对照组以相同方式培养，但不施加超声。免疫组织化学显示，超过98%的实验组和对照组细胞S-100、NT-3和BDNF呈阳性。通过5-溴-2'-脱氧尿苷（BrdU）检测，受刺激的细胞在第4、7、10和14天的细胞增殖率也有所增加。进一步研究发现，LIPUS刺激14天后，实验组中NT-3的mRNA表达与对照组相比显著上调（NT-3/β-肌动蛋白的比值为0.56±0.13 vs. 0.41±0.09，P<0.01），而实验组中BDNF的mRNA表达与对照组相比显著下调（BDNF/β-肌动蛋白的比值为0.51±0.05 vs. 0.60±0.08，P<0.05）。这些结果表明，LIPUS的应用促进了雪旺细胞的增殖和NT-3基因表达，并参与了BDNF基因表达的改变。
