Du Zhaojie, Wang Lei, Zhao Yinghua, Cao Jian, Wang Tao, Liu Peng, Zhang Yabo, Yang Xinjie, Cheng Xiaobing, Liu Baolin, Lei Delin
State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, the Fourth Military Medical University, Xi'an, China; Department of Oral and Maxillofacial Surgery, No. 425 Hospital of PLA, Sanya, China.
State Key Laboratory of Military Stomatology, Department of Oral and Maxillofacial Surgery, School of Stomatology, the Fourth Military Medical University, Xi'an, China.
PLoS One. 2014 Aug 21;9(8):e105976. doi: 10.1371/journal.pone.0105976. eCollection 2014.
The sympathetic nervous system regulates bone formation and resorption under physiological conditions. However, it is still unclear how the sympathetic nerves affect stem cell migration and differentiation in bone regeneration. Distraction osteogenesis is an ideal model of bone regeneration due to its special nature as a self-engineering tissue. In this study, a rat model of mandibular distraction osteogenesis with transection of cervical sympathetic trunk was used to demonstrate that sympathetic denervation can deplete norepinephrine (NE) in distraction-induced bone callus, down-regulate β3-adrenergic receptor (adrb3) in bone marrow mesenchymal stem cells (MSCs), and promote MSC migration from perivascular regions to bone-forming units. An in vitro Transwell assay was here used to demonstrate that NE can inhibit stroma-derived factor-1 (SDF-1)-induced MSC migration and expression of the migration-related gene matrix metalloproteinase-2 (MMP-2) and downregulate that of the anti-migration gene tissue inhibitor of metalloproteinase-3 (TIMP-3). Knockdown of adrb3 using siRNA abolishes inhibition of MSC migration. An in vitro osteogenic assay was used to show that NE can inhibit the formation of MSC bone nodules and expression of the osteogenic marker genes alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor-2 (RUNX2), but knockdown of adrb3 by siRNA can abolish such inhibition of the osteogenic differentiation of MSCs. It is here concluded that sympathetic denervation-induced MSC mobilization in rat mandibular distraction osteogenesis is associated with inhibition of MSC migration and osteogenic differentiation by NE/adrb3 in vitro. These findings may facilitate understanding of the relationship of MSC mobilization and sympathetic nervous system across a wide spectrum of tissue regeneration processes.
交感神经系统在生理条件下调节骨形成和骨吸收。然而，交感神经如何影响骨再生过程中干细胞的迁移和分化仍不清楚。牵张成骨因其作为一种自我构建组织的特殊性质，是骨再生的理想模型。在本研究中，采用切断颈交感干的大鼠下颌骨牵张成骨模型，以证明去交感神经支配可使牵张诱导的骨痂中去甲肾上腺素（NE）耗竭，下调骨髓间充质干细胞（MSC）中的β3-肾上腺素能受体（adrb3），并促进MSC从血管周围区域向骨形成单位迁移。在此使用体外Transwell实验证明，NE可抑制基质细胞衍生因子-1（SDF-1）诱导的MSC迁移以及迁移相关基因基质金属蛋白酶-2（MMP-2）的表达，并下调抗迁移基因金属蛋白酶组织抑制剂-3（TIMP-3）的表达。使用小干扰RNA（siRNA）敲低adrb3可消除对MSC迁移的抑制作用。体外成骨实验表明，NE可抑制MSC骨结节的形成以及成骨标志物基因碱性磷酸酶（ALP）、骨钙素（OCN）和 runt相关转录因子2（RUNX2）的表达，但通过siRNA敲低adrb3可消除对MSC成骨分化的这种抑制作用。由此得出结论，在大鼠下颌骨牵张成骨中，去交感神经支配诱导的MSC动员与体外NE/adrb3对MSC迁移和成骨分化的抑制有关。这些发现可能有助于理解在广泛的组织再生过程中MSC动员与交感神经系统之间的关系。
