Purpose: Two-dimensional mapping of arterial tissue by MALDI-MSI for in-situ visualization of proteins, metabolites and lipids.
Methods: Human pathological arteries and healthy mammary arteries were obtained from patients subjected to carotid endarterectomy and from patients admitted for coronary artery bypass surgery, respectively. An early model of atherosclerosis was performed by feeding rabbits with regular diet (control group) and with cholesterol-rich diet (pathological group). Following histological characterization, specific methods for visualization of metabolites, proteins and lipids in their original locations inside the different arterial layers (intima, media) were set-up. Aortic tissue from both animal groups was dissected and comparatively analyzed by MALDI-MSI, using sinapinic acid, 2,5-dihidroxybenzoic acid and 9-aminoacridine as matrix for proteins, lipids and metabolites respectively. Experiments were performed in an UltrafleXtreme MALDI-ToF/ToF and a Solarix FT-ICR (BrukerDaltonik) instruments.
Results: Protein evaluation resulted in 15 m/z values defining media or intima layers. From them six are significant altered between control and pathological animals. Two of them are localized in the media layer and the other four in the intima. There are 8 m/z values of metabolites identifying lipids. All of them are localized in the intima layer and are significantly altered when comparing control and atherosclerotic tissue. Lipids analysis show 11 masses (m/z) defining intima, 8 of them specifically localized in the plaque region. A couple of them are varied with significance.
Conclusions: A novel protein MALDI-MSI protocol for human atherosclerotic lesions and healthy arteries has been developed and successfully applied. A panel of 15 m/z consisting in proteins, metabolites and lipids are here described to be significant involved in atherosclerosis and, importantly, its identification goes together with their localization, helping enormously in the study of underlying mechanism of atherosclerosis.