Sex-related differences in matrix remodeling and early osteogenic markers in aortic valvular interstitial cells

Abstract

Calcific aortic valve disease (CAVD) is a major cardiovascular disorder in the developed countries. Male is a known risk factor in this disease; unfortunately, how sex contributes to CAVD is mostly unknown. The objective of this study is to determine whether valvular interstitial cells (VICs) isolated from male versus female aortic valves demonstrate difference in osteogenic differentiation and/or extracellular matrix (ECM) remodeling. VICs were isolated from male and female rat or porcine aortic valves and cultured in osteogenic media for 10, 15 and 20 days. The proliferation among male and female VICs was assessed by a cell growth assay. The matrix remodeling of the VIC samples was quantified using glycosaminoglycan (GAG), collagen type I and gelatin zymography assays. Early osteogenic marker expression was assessed using alkaline phosphatase (ALP) staining and enzyme activity assay and Alizarin Red S staining. Our result showed that proliferation of VICs was significantly greater in female than male after 12 days of culture in regular media. Additionally, male VICs showed elevated amounts of normalized GAG, collagen I, and activated matrix metallopreoteniase-2 expression compared to female. Similarly, ALP content was greater in male VICs than female at all time points. In addition, male VICs formed calcific nodules with greater size, % area and integrated density than females. The results from this research suggest that there is a sex-related difference in the events associated with osteogenic differentiation of the aortic VICs, where male VICs are more prone to calcification.

Sex-Specific Features of Calcific Aortic Valve Disease

“…High levels of ERK phosphorylation were detected in calcified and stenotic human valves [ 72 ]. In support of the hypothesis of early occurrence of sex-specific differences in CAVD pathogenesis, another study using VICs obtained from male and female rat and porcine aortic valves showed that there is a sex-related difference in the events associated with osteogenic differentiation of the aortic VICs, where male VICs are more prone to calcification than female ones [ 73 ]. Human VICs undergo osteoblastic differentiation in response to specific mediators such as BMPs and TGF-β [ 74 ].…”

Calcific Aortic Valve Disease

“…Supporting the hypothesis that sex-specific divergence of CAVD etiology may occur early on is a growing body of evidence indicating intrinsic cellular-scale differences between men and women [6] that also yield differences in the cellular response to pathological stimuli. For example, VIC culture in hormone-free osteogenic medium is associated with an increase in calcification in male VICs compared to female VICs [9]. The discovery that men and women exhibit different CAVD pathogenesis has the potential to provoke transformative changes in the approach used to investigate CAVD etiology as well as the clinical treatment of this disease.…”

Tumor necrosis factor‐α promotes and exacerbates calcification in heart valve myofibroblast populations

“…These results have led to a growing interest to better understand the regulatory role of TNF‐α in AVS. Recent studies suggest that TNF‐α induces VIC calcification through both apoptotic and osteogenic mechanisms 38‐41 . For example, VIC mineralization in human valves depends on apoptotic signaling through death receptor 4 caused by increasing expression of the TNF ligand superfamily member 10 (TNF10 or TRAIL) 42 .…”