Abstract 5810: Perivascular Cells Are a Potential Source of Chondrocyte-Like Cells in Atherosclerotic Lesions of Apolipoprotein E Deficient Mice
Introduction: The presence of chondrocyte-like cells is a common phenomenon in mouse models of advanced atherosclerosis. However the source of those cells is still unclear. Since stem cell antigen-1 (Sca-1) positive cells have been found in the adventitia of apoE−/− mice and chondrogenic transformation of mesenchymal stem cell lineages has been described, we hypothesized that a possible source of the chondrocyte-like cells are perivascular Sca-1 positive cells.
Methods: Innominate arteries of 23 weeks apoE−/− mice were immunostained for Sca-1, CD 45, CD 31 and Mac-2 and analyzed by fluorescence microscopy. The thoracic aortas, aortic arches and innominate arteries of apoE−/− mice and C57BL/6 controls were harvested from 13, 23 and 34 week old mice. The adventitia and attached perivascular tissue and the remaining aorta were both enzyme digested. The isolated cells were stained for Sca-1, CD 45, CD 31, CD 34, CD11b and F4/80 and sorted by flow cytometry using positive selection for Sca-1, CD 34 and negative selection for CD 45, CD 31, CD 11b and F4/80. RNA was isolated from the sorted cells and the expression of Cbfa1/Runx2 was determined by PCR.
Results: Sca-1 positive, CD 45, CD 31 and Mac-2 negative cells were observed in the vascular wall by immunofluorescence and were located within close proximity to the chondrocyte-like cells within the atherosclerotic lesions. FACS analyses confirmed the presence of these cells within the aorta, aortic adventitia, aortic arch and the innominate artery of the apoE −/− mice and BL6 controls. Furthermore the perivascular cells also express Cbfa1/Runx2.
Conclusions: Our data suggest that perivascular derived Sca-1 positive cells exist within both atherosclerotic lesions and within arteries from wild type controls of different ages. These cells also express Cbfa1/Runx2, a transcription factor associated with osteogenesis and therefore may be a source of the chondrocyte-like cells found in adavanced lesions of apoE−/− mice.