The arterial wall and arterial valves are complex macromolecular structures. One of the major elements of these structures is the scaffold that provides the strength and flexibility to perform the task in hand either retaining the blood in vessels against the arterial pressure or maintaining pressure via the function of coronary valves. In the last several years it has become apparent that the actual microstructure and composition of these macromolecules could influence the progress of different disease states most notably atherosclerosis and value calcification. To gain a better understanding of this process, we have embarked on studies to understand the fine structure of the macromolecules in arterial vascular bed using a novel optical imaging technique that relies on the non-linear excitation (NLE) of collagen and elastin to provide sub-micron images of their structure in unfixed fresh samples together with direct measures of low density lipoprotein particles (LDL) binding using fluorescence microscopy and conventional histology methods. These studies have identified decorin and biglycan as the major binding sites for LDL in the valve leaflet and renal ostia. Based on the relative concentration of the interaction sites of decorin/biglycan and LDL, we have decided to target the LDL electrostatic binding sites to evaluate the interference of this interaction in the progression of atherosclerosis. Specific modification of the LDL lysine amino acid residues as well as model molecules such as Heparin sulfate has demonstrated that this strategy is feasible by significantly inhibiting LDL association with decorin in specially designed in vitro assays. One of the major issues is to find molecules with high affinity to the LDL sites with minimum off target activity. Currently we are working with industry partners to evaluate other candidate molecules for attempting to block the LDL-decorin interaction. If successful finding high affinity inhibitors, in vitro, we will initiate studies in the atherosclerotic prone transgenic mouse models. With this goal in mind, we have initiated studies in normal and atherosclerosis prone transgenic mice to correlate the development of the arterial macromolecular structures using NLE microscopy. In addition, CARS microscopy directly observing the fatty acid C-H bonds will also be used to complete the minimally invasive approach evaluation of the development of atherosclerotic disease in this animal model. This study when completed will provide an in depth analysis of the development of the macromolecular structures of the arterial wall in a mammalian model and permit the background for chronic studies with different strategies to reduce atherosclerosis.
