Over the last two decades, numerous advances in our understanding of bone cell biology and bone mineral homeostasis have been achieved. As a dynamic connective and supportive tissue, bone is constantly sensing and responding to both external mechanical forces and internal systemic and local signals. A variety of intravital imaging approaches have been investigated to identify molecular and cellular processes and to decipher signaling pathways involved in the cellular communication between different types of bone cells that form bone multicellular units. Furthermore, bone multicellular units interact with cells of the immune and hematopoietic system to maintain bone homeostasis. Bone-forming osteoblasts and bone-degrading osteoclasts are situated on the endosteal surface of bone influencing the dynamic remodeling and the regeneration of bone tissue. Osteocytes are found at very unique locations in the bone, closely surrounded by bone matrix, forming a cellular network through their interconnected dendritic processes. Bone marrow cells fill the numerous large cavities inside the bones with various blood cell lineages arising from hematopoietic stem and progenitor cells. A highly complex and interconnected network of arterial vessels and sinusoidal capillaries span through the bone marrow spaces forming an interface between the blood circulation and the bone marrow which allows cell trafficking between both compartments. Live imaging of animals using multiphoton microscopy represents a powerful approach to address the cellular behaviors of bone and bone marrow cells over time and space in their natural tissue microenvironment. The in vivo environment is crucial, because the dynamic behavior of cells is critically influenced by many tissue factors including extracellular components, cytokine and growth factor gradients, and fluid forces, such as blood flow. The review article focuses upon recent advances in multiphoton imaging technologies as well as novel experimental approaches in the understanding of the dynamic molecular and cellular mechanisms underlying bone tissue homeostasis, remodeling, and regeneration under physiological and pathological conditions. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

中文翻译：

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骨和骨髓环境的活体多光子成像。

在过去的二十年里，我们对骨细胞生物学和骨矿物质稳态的理解取得了许多进展。作为一种动态的结缔组织和支持组织，骨骼不断地感知和响应外部机械力和内部系统和局部信号。已经研究了多种活体成像方法来识别分子和细胞过程，并破译参与形成骨多细胞单位的不同类型骨细胞之间的细胞通讯的信号通路。此外，骨多细胞单位与免疫和造血系统的细胞相互作用以维持骨稳态。成骨成骨细胞和骨降解破骨细胞位于骨内膜表面，影响骨组织的动态重塑和再生。骨细胞位于骨骼中非常独特的位置，被骨基质紧密包围，通过相互连接的树突状突起形成细胞网络。骨髓细胞用造血干细胞和祖细胞产生的各种血细胞谱系填充骨骼内的众多大腔。动脉血管和正弦毛细血管的高度复杂和相互连接的网络跨越骨髓空间，形成血液循环和骨髓之间的界面，允许细胞在两个隔室之间进行运输。使用多光子显微镜对动物进行实时成像代表了一种强大的方法来解决骨骼和骨髓细胞在其自然组织微环境中随时间和空间的细胞行为。体内环境至关重要，因为细胞的动态行为受到许多组织因素的严重影响，包括细胞外成分、细胞因子和生长因子梯度以及流体力，如血流。这篇综述文章重点介绍了多光子成像技术的最新进展以及在理解生理和病理条件下骨组织稳态、重塑和再生的动态分子和细胞机制方面的新实验方法。© 2019 作者。Cytometry Part A 由 Wiley Periodicals, Inc. 代表 International Society for Advancement of Cytometry 出版。这篇综述文章重点介绍了多光子成像技术的最新进展以及在理解生理和病理条件下骨组织稳态、重塑和再生的动态分子和细胞机制方面的新实验方法。© 2019 作者。Cytometry Part A 由 Wiley Periodicals, Inc. 代表 International Society for Advancement of Cytometry 出版。这篇综述文章重点介绍了多光子成像技术的最新进展以及在理解生理和病理条件下骨组织稳态、重塑和再生的动态分子和细胞机制方面的新实验方法。© 2019 作者。Cytometry Part A 由 Wiley Periodicals, Inc. 代表 International Society for Advancement of Cytometry 出版。