Ultrasound Evaluation of Anti-Vascular Endothelial Growth Factor–Induced Changes in Vascular Response Following Tendon Injury

While vascular ingrowth is necessary for tendon healing, hypervascularization following tendon injury is not always believed to be beneficial, and there is now evidence showing beneficial results of anti-angiogenic treatments in the context of tendon healing. However, the dose-dependency of anti-angiogenic–altered vascular response, as well as methods for evaluating these changes in vivo, has not been fully investigated. Therefore, the objective of this study was to evaluate if in vivo ultrasound imaging can detect dose-dependent, anti-angiogenic treatment–induced changes in vascularity in rat Achilles tendon after injury. Color Doppler ultrasound revealed an increase in vascularity in a low-dosage group, while photoacoustic imaging demonstrated a decrease in vascularity in mid- and high-dosage groups. Histologic staining supported the decrease in vascularity observed in the mid-dosage group. This study demonstrates dose-dependent vascular alterations from the delivery of an anti-angiogenic factor after tendon injury that can be detected through ultrasound imaging methods.