Progenitor cells confer plasticity to cardiac valve endothelium

Protective Effects of Mesenchymal Stem Cells with Transient Overexpression of Hmgb1 on Balloon-Induced Carotid Artery Injury

Mesenchymal stem cells (MSC) play a crucial role in endothelial repair after artery injury. The high mobility group box 1 (HMGB1) is a key modulator of the homing of MSC to impaired artery and endothelialization. This study was aimed to determine whether balloon-induced carotid artery injury could be improved by transplantation with MSC modified by HMGB1. MSC were infected by adenoviral serotype 5 encoding recombinant green fluorescent protein (GFP) gene and HMGB1 (ad5GFP-HMGB1). The expression of HMGB1, vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) was detected in MSC using Real-time PCR, Western blot and semi-quantitative immunohistochemical assays. In vivo, reendothelialization was examined in rats subjected to carotid artery injury. The homing of MSC was observed under fluorescence microscopy, and the levels of serum tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) was assessed by ELISA assay. As a result, compared with the MSC group, the expression of HMGB1, VEGF and PCNA was markedly increased, vascular reendothelialization was accelerated, and the levels of serum TNF-α and CRP were decreased in group ad5GFP and ad5GFP-HMGB1. Transplantation of MSC infected with adGFP-HMGB1 strengthened the MSC effect. Taken together, modification of HMGB1 can enhance the protective effects of MSC on balloon-induced carotid artery injury through up-regulation of VEGF and PCNA expression and inhibition of the inflammatory response. HMGB1 in MSC may represent a novel therapeutic target for the treatment of endothelial repair.

Decreased and inactivated nuclear factor kappa B 1 (p50) in human degenerative calcified aortic valve

BACKGROUND

Degenerative aortic valve calcification is an important factor in aortic stenosis and incompetence, but the pathogenesis is unclear. The purpose of the present study was to observe the expression of p50 in degenerative calcified aortic valves, which may provide a potential therapeutic target.

METHODS

Fifteen cases of degenerative calcified aortic valve constituted the experimental group, and 10 aortic valves from patients who had undergone the Bentall operation constituted the control group.

RESULTS

Immunostaining demonstrated that α-smooth muscle actin was highly expressed in valvular interstitial cells in the experimental group and that the percentage of CD68-positive cells was significantly higher in degenerative calcified aortic valves. Using bone gamma-carboxyglutamate protein as a marker of calcification showed that osteoblasts were significantly increased in the experimental valves. Western blot showed that p50 was more highly expressed and activated in the control group compared with the experimental group. Immunohistochemistry confirmed this finding and showed that p50 was principally localized to the endothelial cells of uncalcified valves, suggesting that it might play an important role in maintaining valve function.

CONCLUSIONS

Inhibition of p50 activity in endothelial cells might lead to calcification in degenerative calcified aortic valves.

Differentiating the aging of the mitral valve from human and canine myxomatous degeneration

During the course of both canine and human aging, the mitral valve remodels in generally predictable ways. The connection between these aging changes and the morbidity and mortality that accompany pathologic conditions has not been made clear. By exploring work that has investigated the specific valvular changes in both age and disease, with respect to the cells and the extracellular matrix found within the mitral valve, heretofore unexplored connections between age and myxomatous valve disease can be found. This review addresses several studies that have been conducted to explore such age and disease related changes in extracellular matrix, valvular endothelial and interstitial cells, and valve innervation, and also reviews attempts to correlate aging and myxomatous disease. Such connections can highlight avenues for future research and help provide insight as to when an individual diverts from an aging pattern into a diseased pathway. Recognizing these patterns and opportunities could result in earlier intervention and the hope of reduced morbidity and mortality for patients.