Abstract: Objective To induce calcification in aortic valvular interstitial cells (VICs) in vitro and observe the shift of cellular phenotype during the process. Methods Porcine aortic VICs were isolated and expanded by collagenase methods. Fluorescent staining was performed to identify the interstitial cells. VICs at 48 passages were used for experiments. The cells were divided into two groups: the experimental group in which cells were cultured in osteogenic media supplemented with βglycerophosphate, vitamin C and dexamethasone, and the control group in which cells were cultured in normal media. After 2 weeks, calcified nodules were quantified. Calcium deposit was stained and measured by Alizarin Red S staining and assay. Real time reverse transcription polymerase chain reaction (RTPCR) was performed to measure expression of alpha smooth muscle actin (α-SMA) and calcification related factors such as osteocalcin, osteopontin and Corebinding factor α1/Runx2 (Cbfα1/Runx2). Results VICs were successfully harvested from porcine aortic valves, identified by positive staining of α-SMA, vimentin and negative staining of Von Willebrand factor (vWF). VICs could calcify after 2 weeks of osteogenic induction with calcified nodules formed. Quantification of calcified nodules and calcification deposit were significantly higher (Plt;0.05) in the experimental group than those in the control group (156.25±17.38 vs. 2.50±1.29, 17.52±2.04 vs. 1.00±0.22). Real Time RT-PCR indicated that expression of α-SMA, as well as calcification related markers like osteocalcin, osteopontin and Cbfα1/Runx2 was much higher in the experimental group than those in the control group (Plt;0.05). Conclusion VICs are activated during the progress of calcification with phenotype shifting to contraction and ossification, which might be the pathological basis of valvular calcification.
Abstract: Objective Using Amplex red fluorometric assay to detect the lysyl oxidase (LOX) enzyme activity in tissue engineered heart valve (TEHV). Methods Porcine aortic valves were decellularized with trypsin+ethylene diaminetetraacetic acid(EDTA), TritonX-100, and RNaseⅠ＋DNaseⅠ, then they were seeded by myo-fibroblasts that harvested from rats. Then they were fed with Dulbecco’s modified Eagle medium (DMEM) which contained high glucose for 27 days, they were fed with phenol red-free and serumfree DMEM for 24 hours, and the medium was harvested and used for LOX enzyme activity assays with the Amplex red fluorometric assay. And reverse transcription-polymerase chain reaction (RT-PCR) technique was used to analyze the expression of LOXmRNA in TEHV. Results All the samples produced measurable amounts of active LOX enzyme. The fluorescence units were 45.60±1.66, and the corresponding concentration of LOX enzyme were 0.123±0.003μg/ml. At the same time, all the samples expressed LOXmRNA. The expression of LOXmRNA was corresponding to the results of the Amplex red fluorometric assay. Conclusion It is feasible to detect the LOX enzyme activity in TEHV with the Amplex red fluorometric assay. And this assay gives a way to reflect that LOX plays an important role in collagen cross-linking of extracellar matrix in TEHV.