Measuring and modulating angiogenesis during fracture healing

骨折愈合中的并发症通常是由于愈合骨的血液供应不足。为了形成骨骼，血管必须侵入组织，为组织带来适当的营养和细胞。血管的形成，称为血管生成，对骨折愈合至关重要。本项目研究大鼠股骨骨折愈合过程中血管的生长以及机械环境如何改变血管生长。在该项目中，微计算机断层扫描（microCT）和激光多普勒将用于量化和可视化骨折愈合过程中重要时间点的血管生成。在骨折愈合过程中，血管生成对于骨形成是必要的，但不是充分的。在某些机械环境下，即使有足够的血液供应，也不会发生骨生长。大鼠股骨骨折的外固定允许在愈合过程中改变力学环境。将研究三种不同载荷条件对骨折愈合的影响：（1）静态固定，（2）骨折块间加压，（3）静态拉伸。将评估三种负载条件下的血管流量、体积和结构，并进行比较。从身体中取出骨头后，将确定骨痂的硬度特性，以衡量骨痂愈合的程度。了解血管生成在骨折愈合中的作用对于确定为什么某些骨折在某些条件下不愈合是有价值的。

Complications in fracture healing often result from insufficient blood supply to the healing bone. In order for bone to form, blood vessels must invade the tissue, bringing proper nutrients and cells to the tissue. The formation of blood vessels, called angiogenesis, is critical to fracture healing. This project examines the growth of blood vessels during fracture healing in a rat femur as well as how the mechanical environment may alter blood vessel growth. In this project micro-computed tomography (microCT) and laser Doppler and will be used to quantify and visualize angiogenesis at important time points during fracture healing. Angiogenesis is necessary, but not sufficient, for bone formation during fracture healing. Under certain mechanical environments, bone growth does not occur even with an adequate blood supply. External fixation on a rat femur fracture allows one to alter the mechanical environment during the healing process. The influence of three different loading conditions on fracture healing will be investigated: (1) static fixation, (2) interfragmentary compression, and (3) static tension. Vascular flow, volume, and structure will be assessed for the three loading conditions and compared. After removing the bone from the body, the stiffness properties of the callus, which measure how well it has healed, will be determined. Understanding the role of angiogenesis in fracture healing is valuable in determining why some fractures do not heal under certain conditions.