Investigating Age-Dependent Oxygenation and Blood Perfusion in a Mouse Model of Peripheral Artery Disease (PAD) Using Multispectral Optoacoustic Tomography (MSOT), Laser Speckle Contrast Imaging (LSCI) and Histology

Background/Objectives: Peripheral artery disease (PAD) is frequently asymptomatic, requiring non-invasive approaches for disease evaluation and therapy monitoring. This study demonstrates that multispectral optoacoustic tomography (MSOT) and laser speckle contrast imaging (LSCI) can non-invasively assess changes in tissue vascular oxygenation and perfusion, respectively, in a mouse hindlimb PAD model, enabling comparison of age-dependent vascular responses. Methods: PAD was induced by cauterization of the femoral artery in young (2 months) and old (18 months) mice, which were imaged using MSOT and LSCI at baseline (Day 0) and on Days 3, 7, and 14 post-surgery. Correlative histology including Hematoxylin and Eosin (H&E), Masson’s Trichrome for collagen, and immunofluorescence for CD31 and Ki-67 were performed. Results: Reduced tissue oxygenation was observed by MSOT in the ischemic limb shortly after surgery and faster recovery occurred in young compared to old mice. LSCI revealed time-dependent perfusion recovery in both groups, with consistently better recovery in young mice. Histological analyses confirmed ischemic damage and demonstrated enhanced angiogenesis and cellular proliferation in young muscle tissues. The observations were consistent for each methodology. Conclusions: These results indicate that both MSOT and LSCI serve as effective, non-invasive tools for longitudinal monitoring of muscle injury, capable of revealing age-dependent vascular responses without the need for exogenous contrast agents.