In vivo detection of macrophages in a rabbit atherosclerotic model by time-resolved laser-induced fluorescence spectroscopy.

Abstract

Accumulation of numerous macrophages in the fibrous cap is a key identifying feature of plaque inflammation and vulnerability. This study investigates the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as a potential tool for detection of macrophage foam cells in the intima of atherosclerotic plaques. Experiments were conducted in vivo on 14 New Zealand rabbits (6 control, 8 hypercholesterolemic) following aortotomy to expose the intimal luminal surface of the aorta. Tissue autofluorescence was induced with a nitrogen pulse laser (337 nm, 1 ns). Lesions were histologically classified by the percent of collagen or macrophage foam cells as well as thickness of the intima. Using parameters derived from the time-resolved fluorescence emission of plaques, we determined that intima rich in macrophage foam cells can be distinguished from intima rich in collagen with high sensitivity (>85%) and specificity (>95%). This study demonstrates, for the first time, that a time-resolved fluorescence-based technique can differentiate and demark macrophage content versus collagen content in vivo. Our results suggest that TR-LIFS technique can be used in clinical applications for identification of inflammatory cells important in plaque formation and rupture.

• Authors: Laura Marcu, Qiyin Fang, Javier A Jo, Thanassis Papaioannou, Amir Dorafshar, Todd Reil, Jian-Hua Qiao, J Dennis Baker, Julie A Freischlag, Michael C Fishbein
• Journal: Atherosclerosis (Atherosclerosis) Vol. 181 Issue 2 Pg. 295-303 (Aug 2005) ISSN: 0021-9150 [Print] Ireland
• PMID: 16039283 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, P.H.S.)

Topics

• Animals
• Atherosclerosis (immunology, pathology)
• Disease Models, Animal
• Image Processing, Computer-Assisted (instrumentation, methods)
• Lasers
• Macrophages (pathology)
• Male
• Microscopy, Fluorescence (instrumentation, methods)
• Rabbits