Name: Murine Alveolar Bone Specimen Collection
Uploaded: 2023-07-21T12:20:00
Description: Watch this Scientific Journal Video about Murine Alveolar Bone Specimen Collection at JoVE.com

murine alveolar bone specimen collection 

分析牙槽骨重塑以探索骨骼力学生物学

It is generally known that bone is under constant reconstruction throughout life, in response to mechanical forces according to Wolff&#39;s law1,2. Appropriate mechanical stimulation, such as gravity and daily exercise, maintains bone mass and strength and prevents bone loss by stimulating both osteoblasts and osteoclasts. Osteoclasts, responsible for bone resorption3,4,5,6,7, and osteoblasts, responsible for bone formation8,9,10, maintain bone homeostasis and function jointly in the biological process of bone remodeling. In contrast, in the absence of loading stimuli, as in astronauts under long-term microgravity, bones suffer 10% bone mineral density loss, thus increasing the risk of osteoporosis11,12. Furthermore, noninvasive and convenient mechanical therapies, including orthodontics and distraction osteogenesis, have emerged as treatments for bone diseases13,14. All these have shown that mechanical force plays a critical role in maintaining bone quality and quantity. Recent studies generally analyzed bone remodeling in response to mechanical loading using time-consuming models such as running wheel and tail suspension tests, which usually took 4 weeks or more to simulate force loading or unloading15,16. Therefore, there is demand for a convenient and efficient animal model for studying bone remodeling driven by force loading.
The alveolar bone is the most active in terms of bone remodeling, with a high turnover rate17. Orthodontic tooth movement (OTM), a common treatment for malocclusion, is an artificial process of alveolar bone remodeling in response to mechanical force. However, OTM, which induces rapid bone remodeling18, is also a time-saving way to study the effects of mechanical force on bone remodeling compared with other models with a long experimental period. Therefore, OTM is an ideal model to study bone remodeling under mechanical stimuli. It is noteworthy that the mechanism of alveolar bone remodeling is often time-sensitive, and it is necessary to observe the changes in alveolar bone remodeling at certain time points after modeling. With the dual advantages of temporal and spatial control of DNA recombination and tissue specificity, an inducible conditional gene knockout mouse model is a suitable choice for OTM studies.
Conventionally, OTM-mediated alveolar bone remodeling has been divided into tension zones involving bone formation and pressure zones involving bone resorption19,20,21, which is more detailed but difficult to regulate. Furthermore, Yuri et al. reported that the time of bone formation in OTM differed on the tension and compression sides22. In addition, a previous study had demonstrated that the first molar could initiate wide remodeling of the maxillary alveolar bone under orthodontic force, which was not constrained to the tension and pressure zones23. Therefore, we selected the area located within three roots of M1 in the cross-section of the maxillary bone as the region of interest (ROI) and described methods to assess the activity of osteoblasts and osteoclasts in the same area to evaluate alveolar bone remodeling under OTM.
As a nuclear transcription factor, signal transducer and activator of transcription 3 (STAT3) has been proven critical in bone homeostasis24,25. Previous studies have reported low bone mineral density and recurrent pathological fractures in Stat3-mutant mice26,27. Our previous study demonstrated that deletion of Stat3 in Osx+ osteoblasts caused craniofacial malformation and osteoporosis, as well as spontaneous bone fracture28. Recently, we provided in vivo evidence with an inducible osteoblast-specific Stat3 deletion mouse model (Col1&#945;2CreERT2; Stat3fl/fl, hereafter called Stat3Col1&#945;2ERT2) that STAT3 is critical in mediating the effects of orthodontic force driving alveolar bone remodeling29. In this study, we provide methods and protocols for using inducible osteoblast lineage-specific Stat3 knockout mice to study bone remodeling under orthodontic force and describe methods for analyzing alveolar bone remodeling during OTM, thus shedding light on skeletal mechanical biology.

作者聚焦：比较牙槽和长骨重塑以探索 OTM 模型的潜力 

使用诱导型成骨细胞谱系特异性 Stat3 敲除小鼠研究正畸牙齿移动过程中的牙槽骨重塑

Our research focuses on the mechanism of bone remodeling under mechanical force, including alveolar bone and long bones. We try to answer how bones respond to mechanical stimuli to shed new light on skeletal mechanical biology for further clinical treatment. Currently, studies on OTM were limited to gene expression analysis in vivo or cellular function analysis in vitro.To this end, a challenge arose. How to trace and explore the function of specific genes in specific lineages during OTM in vivo? That's why we use inducible conditional knockout mice here.Orthodontic tooth movement, which induces rampant bone remodeling, is a time-saving method to study the effects of mechanical force on bone remodeling compared to other models that have a long experimental period. Our protocol also reveals dynamic alveolar bone remodeling at different time points with inducible gene-specific knockout mice. There are many important cell lineages in the alveolar bone.We aim to trace them and find out their underlying mechanisms during OTM. Furthermore, we will compare the mechanisms between alveolar bone and long bone remodeling to provide further clues for the potential of OTM model in biomechanical research.

Watch this Scientific Journal Video about Murine Alveolar Bone Specimen Collection at JoVE.com

Murine Alveolar Bone Specimen Collection   

鼠肺泡骨标本采集 

首先将皮肤垂直切开安乐死小鼠的颈部区域，将头部与身体分开，解剖头部的整个皮肤。接下来，切掉从双侧虹口到下颌骨后部区域的皮肤和颊肌。将颊肌和肌腱与喙骨完全断开，以切除下颌骨。修剪任何多余的骨头以获得完整的上颌骨。去除双侧第三磨牙后面的骨头，剥去腭粘膜。最后，断开正畸矫治器，沿腭正中缝合线切开门牙之间的骨头，得到左右牙槽骨。通过对牙槽骨进行免疫荧光染色证实了成骨细胞中 STAT3 缺失的肺泡骨重塑。立体显微镜显示，野生型小鼠的正畸牙齿移动距离在第4、7和10天增加。然而，STAT3敲除小鼠的正畸牙齿移动距离减小了。第 10 天的显微 CT 分析证实了移位减少，表明 STAT3 缺失减缓了正畸牙齿移位。

Research

JoVE Journal

Medicine

Murine Alveolar Bone Specimen Collection 

Using Inducible Osteoblastic Lineage-Specific Stat3 Knockout Mice to Study Alveolar Bone Remodeling During Orthodontic Tooth Movement

The alveolar bone, with a high turnover rate, is the most actively-remodeling bone in the body. Orthodontic tooth movement (OTM) is a common artificial ...