PGRN Inhibits Osteogenic Differentiation of Aortic Valve Interstitial Cells Induced by Osteogenic Induction Medium

The aim of this study was to investigate the effect and mechanism of PGRN (progranulin) on osteogenic differentiation of porcine aortic VICs (valve interstitial cells), which could provide theoretical basis for early intervention and treatment of CAVD (calcific aortic valve disease). The expression levels of Runx2 and OPN in the Normal group and CAVD group were tested by immunohistochemistry. The expression levels of PGRN, fibrosis markers (α-SMA)/calcification markers (Runx2, OPN) and p-AKT were detected by Western blot. VICs were isolated by continuous collagenase digestion, their morphological characteristics were observed and the phenotypes were identified by immunofluorescence staining. VICs were treated by increasing concentration of PGRN. ALP (alkaline phosphatase) staining, Alizarin red S staining, qPCR, Western blot were used to evaluate the cell early and late osteogenic differentiation abilities. The protein level of p-AKT was determined by Western blot. SC-79, an activator of the AKT, was used for reverse verification. The results showed that fibrosis/calcification markers in CAVD group were significantly higher than that in Normal group. However, the expression of PGRN remarkably decreased. VICs were successfully isolated, the staining of α-SMA and vimentin were positive, the staining of vWF was negative. The ALP activity and deposition of calcium salts of VICs were significantly decreased by PGRN. The mRNA and protein levels of fibrosis/calcification markers were reduced. Meanwhile, the phosphorylation level of AKT was down-regulated. The down-regulation of PGRN on fibrosis/calcification markers was attenuated by SC-79. We concluded that PGRN could inhibit the conversion of quiescent VICs to activated myofibroblast-like VICs and even osteogenesis-like VICs. The AKT signaling pathways may play an important role in these processes.

CSTR: 32200.14.cjcb.2020.01.0006