Conditional deletion of RB1 in the Tie2 lineage leads to aortic valve regurgitation

Mechanism of Endoplasmic Reticulum Stress Pathway in the Osteogenic Phenotypic Transformation of Aortic Valve Interstitial Cells

BACKGROUND AND PURPOSE

Calcific Aortic Valve Disease (CAVD) is a crucial component of degenerative valvular disease in old age and with the increasing prevalence of the aging population. we hope that by modeling valvular osteogenesis and intervening with endoplasmic reticulum stress inhibitor TUDCA to observe the effect of endoplasmic reticulum stress on valve osteogenesis.

METHODS

In this study, rabbit heart valvular interstitial cells (VICs) were isolated and cultured. They treated with ox-LDL (Oxidized Low Density Lipoprotein) stimulation to establish a model of valvular osteogenic transformation. BMP2 (Bone Morphogenetic Protein 2), PERK (Protein kinase R-like endoplasmic reticulum kinase), CHOP (CCAAT/enhancer-binding protein homologous protein) and transcriptional regulatory factor ATF4 (Activating Transcription Factor 4 )were recorded after intervention with ER stress inhibitor TUDCA. The effects of er stress on valvular osteogenic transformation were analyzed.

RESULT

After stimulation of VICs with ox-LDL, the expression levels of BMP2, PERK, CHOP, and ATF4 increased. However, TUDCA treatment can alleviate the increased expression levels of BMP2, PERK ATF4, and CHOP under ox-LDL stimulation to a certain extent.

CONCLUSION

The endoplasmic reticulum stress signaling pathway is involved in ox-LDL-induced calcification of rabbit valve interstitial cells. Inhibition of endoplasmic reticulum stress using TUDCA can improve the progression of rabbit aortic valve calcification.

Age, sex, and regional differences in scavenger receptor CD36 in the mouse brain: Potential relevance to cerebral amyloid angiopathy and Alzheimer's disease

Scavenger receptor CD36 contributes significantly to lipid homeostasis, inflammation, and amyloid deposition, while CD36 deficiency is associated with restored cerebrovascular function in an Alzheimer's disease (AD) mouse model. Yet the distribution of CD36 has not been examined in the brain. Here, we characterized CD36 gene and protein expression in the brains of young, middle aged, aged, and elderly male and female C57BL/6J mice. Age-related increases in CD36 mRNA expression were observed in the male hippocampus and female midbrain. Additionally, male mice had greater CD36 mRNA expression than females in the striatum, hippocampus, and midbrain. CD36 protein was primarily expressed intravascularly, and this expression differed by region, age, and sex in the mouse brain. Although male mice brains demonstrated an increase in CD36 protein with age in several cortices, basal ganglia, hippocampus, and midbrain, a decrease with age was observed in female mice in the same regions. These data suggest that distinctive age, region, and sex expression of CD36 in the brain may contribute to Aβ deposition and neuroinflammation in AD.

Aortic Valve Regurgitation: Pathophysiology and Implications for Surgical Intervention in the Era of TAVR

Aortic insufficiency (AI) or regurgitation is caused by the malcoaptation of the aortic valve (AV) cusps due to intrinsic abnormalities of the valve itself, a dilatation or geometric distortion of the aortic root, or by some combination thereof. In recent years, there has been an increase in the number of studies suggesting that AI is an active disease process caused by a combination of factors including but not limited to alteration of specific molecular pathways, genetic predisposition, and changes in the mechanotransductive properties of the AV apparatus. As the surgical management of AV disease continues to evolve, increasingly sophisticated surgical and percutaneous techniques for AV repair and replacement, including transcatheter aortic valve replacement (TAVR), have become more commonplace and will likely continue to expand as new devices are introduced. However, these techniques necessitate frequent reappraisal of the biological and mechanobiological mechanisms underlying AV regurgitation to better understand the risk factors for AI development and recurrence following surgical intervention as well as expand our limited knowledge on patient selection for such procedures. The aim of this review is to describe some of the putative mechanisms implicated in the development of AI, dissect some of the cross-talk among known and possible signaling pathways leading to valve remodeling, identify association between these pathways and pharmacological approaches, and discuss the implications for surgical and percutaneous approaches to AV repair in replacement in the TAVR era.

Solvent-Free Strategy To Encapsulate Degradable, Implantable Metals in Silk Fibroin

Implantable electronics hold enormous clinical potential for diagnosis and treatment of neurodegenerative and cardiac diseases and abnormalities. Transient devices are attractive alternatives to conventional silicon electrodes, as they can provide short-term electrical stimulation/recording followed by complete device degradation, mitigating the need for removal surgeries. Packaging transient metals is inherently challenging as they degrade upon contact with aqueous conditions. Development of new transient metal packaging strategies is a critical step toward transient device development. In this fundamental work, a solvent-free compression molding approach to encapsulate magnesium, a resorbable metal, in silk fibroin protein is reported. Silk fibroin was selected because of its processing versatility, desirable mechanical properties, compatibility with biological environments, and controllable degradation behavior in aqueous environments. The silk/magnesium composites were fabricated via compression molding, followed by water annealing to modify the secondary structure of the silk protein matrix to tune physical properties. Transient composite properties as a function of water annealing time are presented, which elucidate synergies between silk physical properties and degradation kinetics of the encapsulated magnesium, information useful in the design of multifunctional, transient metal-based constructs.