Hansen-Algenstaedt N, Schaefer C, Wolfram L, Joscheck C, Schroeder M, Algenstaedt P, Rüther W
Department of Orthopaedic Surgery, University Hospital Hamburg-Eppendorf, 20246 Hamburg, Germany.
J Orthop Res. 2005 Sep;23(5):1073-82. doi: 10.1016/j.orthres.2005.02.013.
The processes of osteogenesis, bone remodelling, fracture repair and metastasis to bone are determined by complex sequential interactions involving cellular and microcirculatory parameters. Consequently studies targeting the analysis of microcirculatory parameters on such processes should mostly respect these complex conditions. However these conditions could not yet be achieved in vitro and therefore techniques that allow a long-term observation of functional and structural parameters of microcirculation in bone in vivo at a high spatial resolution are needed to monitor dynamic events, such as fracture healing, bone remodelling and tumor metastasis.
We developed a bone chamber implant (femur window) for long-term intravital microscopy of pre-existing bone and its microcirculation at an orthotopic site in mice preserving the mechanical properties of bone. After bone chamber implantation vascular density, vessel diameter, vessel perfusion, vascular permeability and leukocyte-endothelial interactions (LEIs) in femoral bone tissue of c57-black mice (n=11) were measured quantitatively over 12 days using intravital fluorescence microscopy. Furthermore a model for bone defect healing and bone metastasis in the femur window was tested.
Microvascular permeability and LEIs showed initially high values after chamber implantation followed by a significant decrease to a steady state at day 6 and 12, whereas structural parameters remained unaltered. Bone defect healing and tumor growth was observed over 12 and 90 days respectively.
The new femur window design allows a long-term analysis of structural and functional properties of bone and its microcirculation quantitatively at a high spatial resolution. Altered functional parameters of microcirculation after surgical procedures and their time dependent return to a steady state underline the necessity of long-term observations to achieve unaltered microcirculatory parameters. Dissection of the complex interactions between bone and microcirculation enables us to evaluate physiological and pathological processes of bone and may give new insights especially in dynamic events e.g. fracture healing, bone remodeling and tumor metastasis.
骨生成、骨重塑、骨折修复以及骨转移过程由涉及细胞和微循环参数的复杂顺序性相互作用所决定。因此，针对这些过程中微循环参数分析的研究应充分考虑这些复杂情况。然而，这些条件在体外尚未实现，因此需要能够在体内以高空间分辨率对骨微循环的功能和结构参数进行长期观察的技术，以监测诸如骨折愈合、骨重塑和肿瘤转移等动态事件。
我们开发了一种骨腔植入物（股骨窗口），用于在小鼠原位对既有骨及其微循环进行长期活体显微镜观察，同时保留骨的力学性能。在植入骨腔后，使用活体荧光显微镜在12天内对C57 - 黑小鼠（n = 11）股骨组织中的血管密度、血管直径、血管灌注、血管通透性和白细胞 - 内皮细胞相互作用（LEIs）进行定量测量。此外，还测试了股骨窗口中骨缺损愈合和骨转移的模型。
植入腔室后，微血管通透性和LEIs最初显示出较高值，随后在第6天和第12天显著下降至稳定状态，而结构参数保持不变。分别在12天和90天观察到骨缺损愈合和肿瘤生长。
新的股骨窗口设计允许在高空间分辨率下对骨及其微循环的结构和功能特性进行长期定量分析。手术操作后微循环功能参数的改变及其随时间恢复到稳定状态强调了长期观察以获得未改变的微循环参数的必要性。剖析骨与微循环之间的复杂相互作用使我们能够评估骨的生理和病理过程，尤其可能为动态事件（如骨折愈合、骨重塑和肿瘤转移）提供新的见解。
