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This Article Full Text Full Text (PDF) All Versions of this Article: 93/5/564    most recent expphysiol.2007.040204v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Zulli, A. Articles by Hare, D. L. PubMed PubMed Citation Articles by Zulli, A. Articles by Hare, D. L. Related Collections Vascular

¹ Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Melbourne, Victoria, Australia ² Departments of Cardiology³ Cardiac Surgery, Austin Health, Heidelberg, Melbourne, Victoria, Australia

Angiotensin-converting enzyme 2 (ACE2) is a novel enzyme with possible implications in the treatment of blood pressure disorders. Recent evidence suggests that an upregulation of ACE2 can be stimulated by all-trans retinoic acid (at-RA); however, at-RA also affects regulation of the stem-cell marker octomer-4 (Oct-4) and thus cellular differentiation. We have previously shown that smooth muscle cells and macrophages present within rabbit atherosclerotic plaques are positive for ACE2, Oct-4 and the haematopoietic stem-cell marker CD34. Thus, to provide evidence that possible at-RA treatment could affect both plaque cellular biology (via effects on cellular differentiation) and blood pressure (via ACE2), it is vital to show that cells with atherosclerotic plaques co-express all three markers. Thus, we sought to provide evidence that a subset of cells within atherosclerotic plaques is positive for ACE2, Oct-4 and CD34. We used New Zealand White rabbits that were fed a control diet supplemented with 0.5% cholesterol plus 1% methionine for 4 weeks and then allowed to consume a normal diet for 10 weeks. Immunohistochemistry was performed by standard techniques. We report that ACE2, Oct-4 and CD34 were all present within atherosclerotic plaques. Although macrophages were positive for all three markers, spindle-shaped cells in the media did not show all three markers. The endothelium overlying normal arterial wall showed positive Oct-4 and ACE2 immunoreactivity, but CD34 immunoreactivity was patchy, indicating that such cells might not have fully differentiated. It is concluded that cells in atherosclerotic plaques express co-express ACE2, Oct-4 and CD34. Further studies aimed at establishing the effects of all-trans retinoic acid on blood pressure and atherosclerotic cell differentiation are warranted.

(Received 14 November 2007; accepted after revision 8 January 2008; first published online 11 January 2008)
Corresponding author A. Zulli: Vascular Biology Laboratory, Department of Cardiology, Austin Health, Heidelberg, Melbourne, Victoria 3084, Australia. Email: azulli{at}unimelb.edu.au

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				M. K. Raizada and J. F. R. Paton Recent advances in the renin-angiotensin system: angiotensin-converting enzyme 2 and (pro)renin receptor Exp Physiol, May 1, 2008; 93(5): 517 - 518. [Full Text] [PDF]