Role of human valve interstitial cells in valve calcification and their response to atorvastatin.
BACKGROUND
Calcific aortic valve stenosis is a common disease in the elderly and is characterized by progressive calcification and fibrous thickening of the valve, but the cellular and molecular mechanisms are not fully understood. We hypothesized that human valve interstitial cells (ICs) are able to differentiate into osteoblast-like cells through the influence of defined mediators and that this process can be modulated pharmacologically.


RESULTS
To test this hypothesis, we treated primary cultures of human aortic valve ICs with osteogenic media, bone morphogenic proteins ([BMPs] BMP-2, BMP-4, and BMP-7), and tissue growth factor-beta ([TGF-beta] TGF-beta1 and TGF-beta3) for 21 days. These mediators induced osteoblast differentiation of valve ICs by significantly increasing the activity and expression of alkaline phosphatase ([ALP] P<0.001). A cytokine protein array revealed that atorvastatin treatment (100 micromol/L) of human valve ICs caused a downregulation in levels of expression of BMP-2, BMP-6, TGF-beta1, and TGF-beta3 after 24 hours. In addition, human valve ICs treated with atorvastatin in the presence of osteogenic media showed a significant reduction in ALP activity in comparison to cells treated with osteogenic media only (P=<0.001). This was further confirmed with immunocytochemical staining of valve ICs, whereby atorvastatin markedly reduced the expression of ALP and osteocalcin induced by osteogenic media in comparison to untreated cells.


CONCLUSIONS
These findings suggest that human valve ICs are capable of osteoblastic differentiation, by potential mediators which can be pharmacologically targeted by atorvastatin.
Osman
Lana
L
Heart Science Centre, Royal Brompton and Harefield National Health Service Trust, Harefield, Middlesex, United Kingdom.
Yacoub
Magdi H
MH
Latif
Najma
N
Amrani
Mohamed
M
Chester
Adrian H
AH
D000368:Aged; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D001021:Aortic Valve / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000188:drug therapy / Q000473:pathology*; D000069059:Atorvastatin; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002114:Calcinosis / Q000188:drug therapy / Q000473:pathology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D003239:Connective Tissue Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology; D005355:Fibrosis; D006538:Heptanoic Acids / Q000494:pharmacology*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D008875:Middle Aged; D010006:Osteoblasts / Q000166:cytology; D015675:Osteocalcin / Q000096:biosynthesis; D011758:Pyrroles / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D053782:Transforming Growth Factor beta3
C525718:BMP2 protein, human; C525809:BMP4 protein, human; C525819:BMP7 protein, human; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D003470:Culture Media; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011758:Pyrroles; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D053782:Transforming Growth Factor beta3; D015675:Osteocalcin; D000069059:Atorvastatin; D000469:Alkaline Phosphatase