Abstract
Cardiovascular disease (CVD) is the leading cause of mortality globally, responsible for over 17.3 million deaths annually (~31% of all deaths). Over the next decade, this value is projected to increase, surpassing 23.6 million annual deaths by 2030. The vast majority of these deaths are caused by complications resulting from progressive thickening of the arterial wall, and the formation and growth of arterial plaques within the vessel lumen. Subsequent plaque rupture may potentially lead to blood clot (thrombus) formation. The combined effect of these processes is the reduction of vessel diameter (stenosis) and subsequent reduction in blood flow (ischemia), while complete occlusion of a vessel via thrombus formation may precipitate a heart attack or stroke. Utilizing discrete event simulation (DES) modeling, the various processes of lesion formation and growth were examined, and it was demonstrated that an increased number of raised lesions in an individual at an early age represents a reliable biomarker for increased risk of subsequent sudden cardiac death (SCD). As a result of this finding, the levels of known CVD risk factors for a group of ~3,000 young people (ages 15-34) were investigated. Using generalized linear regression modeling (GLM) the manner in which these factors contribute to lesion formation and growth was analyzed. From this analysis, a subpopulation (~13%) exhibiting an increased number of raised lesions was identified. However, no correlation between accelerated atherosclerosis and measured levels of risk factors was observed in this group, suggesting one or more “hidden” risk factors. Thus, a biosensor capable of identifying this “high-risk” group presenting a significantly increased number of lesions would be extremely beneficial. Atherosclerotic plaques possess a large number of apoptotic and necrotic cells. Based on this, a fusion protein was designed and expressed that was capable of targeting and binding to these apoptotic cells (Annexin V), as well as generating a detectable bioluminescent signal (RLuc8). This Annexin-Renilla Fusion Protein (ArFP) was subsequently characterized and applied both in vitro and in vivo, demonstrating that apoptosis detection is possible in a number of samples including vascular tissue. Plaque identification through apoptosis detection with this unique sensor provides another step towards the early identification and possible intervention of those at the highest risk of CVD-related death.