Optical imaging of experimental arthritis using allogeneic leukocytes labeled with a near-infrared fluorescent probe

The Department of Radiology, S-372, UCSF Medical Center, University of California in San Francisco, 513 Parnassus Ave, San Francisco, CA 94143, USA.
European journal of nuclear medicine and molecular imaging (Impact Factor: 5.22). 09/2006; 33(9):998-1006. DOI: 10.1007/s00259-006-0081-y
Source: PubMed

ABSTRACT The purpose of this study was to assess the feasibility of inflammation detection in an antigen-induced arthritis model using fluorescent leukocytes and optical imaging.
Antigen-mediated monoarthritis was induced in the right knee of 12 Sprague-Dawley rats. Six rats remained untreated and six rats were treated with cortisone. All rats received ex vivo fluorescent-labeled rat leukocytes. Optical images of both knees were acquired before and at 5 min, 1 h, 4 h, and 24 h after cell injection. Images were evaluated qualitatively and quantitatively by calculating signal intensity ratios between the right arthritic (A) and contralateral normal (N) knee. A/N ratios were tested for significant differences between baseline values and values after cell injection using a paired t test as well as between the untreated and cortisone-treated group using an unpaired t test. Synovial specimens were processed and evaluated for labeled cells with fluorescence microscopy.
At 4 h and 24 h p.i., the A/N ratios of untreated arthritic knees showed a significant signal increase compared with baseline values (p<0.05) and a significant difference compared with A/N ratios of cortisone-treated animals (p<0.05). Fluorescent microscopy confirmed the presence of labeled cells in the arthritic synovium.
Inflammation in antigen-induced arthritis can be detected with ex vivo labeled allogenic leukocytes and optical imaging.

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