Time Courses of Growth and Remodeling of Porcine Aortic Media During Hypertension: A Quantitative Immunohistochemical Examination
J-J. Hu 1, A. Ambrus 1, T.W. Fossum 1, M.W. Miller 1, J.D. Humphrey 1 and E. Wilson 1*
1 Department of Biomedical Engineering (J-JH,JDH), Department of Veterinary Pathobiology (AA), and Department of Small Animal Medicine and Surgery (TWF,MWM), Texas A&M University, College Station, Texas, and Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center, College Station, Texas (EW)
* To whom correspondence should be addressed. E-mail: emilyw{at}tamu.edu.
Submitted on July 25, 2007
Accepted on 21 November 2007
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Abstract |
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Arteries undergo marked structural and functional changes in human and experimental hypertension that generally involve smooth muscle cell hypertrophy / hyperplasia as well as abnormal extracellular matrix turnover. In this study, we examined time courses of changes in smooth muscle cell activity and matrix protein content in a novel mini-pig aortic coarctation model. Cell proliferation was evaluated by immunostaining of Ki-67, apoptosis was assessed by TUNEL, and phenotypic changes were monitored by immunostaining three smooth muscle cell contractile markers (caldesmon, calponin, and smoothelin). Changes in medial collagen and elastin were examined by picrosirius red and Verhoeff-van Gieson staining, respectively. LabVIEW-based image analysis routines were developed to objectively and efficiently quantify the (immuno)histochemical results. We found that significant cell proliferation and matrix production occurred in the early stages of this coarctation model and then declined gradually; the smooth muscle cells also tended to exhibit a less contractile phenotype following these cellular and extracellular changes. Specifically, different aspects of the phenotypic changes associated with hypertension occurred at different rates: cell proliferation and collagen production occurred early and peaked by 2 weeks whereas changes in contractile protein expression continued to decrease over the entire 8 week study period. The temporal changes found in this study emphasize the importance of simultaneously tracing time courses of smooth muscle cell growth and differentiation as well as matrix protein production and content. Smooth muscle cells are multi-functional and caution must be used to not over-define phenotype. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
Key Words:
vascular smooth muscle cell, phenotypic modulation, aortic coarctation, hypertension, quantitative immunohistochemistry
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