Development of Optical Imaging Methods for Evaluating the Vascular Response to Hind Limb Ischemia

Abstract

Peripheral arterial disease (PAD) affects millions of individuals and increases the risk of myocardial infarction, stroke, and mortality. Compared to the general population, diabetic patients have a four times greater risk of developing PAD, worse lower-extremity function, and a greater risk of amputation. Gaining a better understanding of the mechanisms through which diabetes impairs arteriogenesis in PAD and developing novel treatments that are less invasive and more effective than the current standard of care are areas of significant focus within basic and clinical cardiovascular research. The mouse hind limb ischemia (HLI) model is a widely used system for studying the mechanisms of arteriogenesis and for testing new PAD therapies, but there is a lack of techniques for acquiring physiologically-relevant, quantitative data intravitally in this model. In this work, non-invasive, quantitative hyperspectral imaging of hemoglobin saturation and optical coherence tomography imaging of vessel structure and function were developed and validated for the HLI model. This optical imaging platform was applied to study the effects of hyperglycemia on recovery from ischemia and identify a relevant preclinical model that incorporates a cardiovascular risk factor associated with PAD in humans. Additionally, the optical imaging techniques were applied in combination with traditional methods to evaluate reactive oxygen species-responsive, “on demand” local release of antioxidant and anti-inflammatory therapies that target molecular drivers of the impaired vascular response to ischemia in diabetic animals. Overall, this work facilitates the use of more complex and more physiologically relevant mouse models of PAD such as diabetic and aged animals through a reduction in both the number of cohorts required and the time required for acquisition of comprehensive longitudinal data. This advance in preclinical methodologies is anticipated to accelerate the development of improved therapeutic clinical treatments for PAD.