Targeting Matrix Vesicles in Vascular Calcification

Calcification of tissues is a feature of aging, and problematic in blood vessels and heart tissue. It reduces elasticity and cardiovascular tissue function, leading to eventually fatal problems. The underlying mechanisms that drive calcification likely involve the inflammatory signaling produced by senescent cells, contributing to the shift in behavior that makes cells in blood vessel walls act more like osteoblasts, attempting to build bone by depositing calcium structures in the tissue. As noted here, the roots of calcification remain much debated, and there is plenty of room for new discoveries.

Vascular calcification (VC) is a prominent clinical pathology of atherosclerosis, diabetes mellitus, hypertension, aging, and chronic kidney disease (CKD), resulting in abnormal calcium phosphate accumulation in the intimal and medial layers of the vessel wall. After vascular calcification, the stiffness of the vascular wall is increased, and the compliance is decreased, which results in myocardial ischemia, left ventricular hypertrophy, and heart failure. At present, vascular calcification is still lacks effective treatment methods, and the pathogenesis mechanism remains unclear.

The phenotype switching of vascular smooth muscle cells (VSMCs) has been regarded as the principal driver in the calcification of intimal and medial layers. VSMCs undergo the phenotypic transformation from a differentiated "contractile" into a dedifferentiated "synthetic" proliferative phenotype in the process of vascular calcification. The phenotypic switching VSMCs express higher osteoblast-like markers, and is associated with increased proliferation and migration ability. The osteoblast-like phenotype of VSMCs is regarded as the cellular characteristic factor of vascular calcification. Many factors such as oxidative stress damage, hyperphosphatemic environment, and inflammation increase the indices related to bone formation in VSMCs and promote their transformation into osteoblasts. On the other hand, a variety of biochemical factors are also involved in the phenotype switching of VSMCs.

Matrix vesicles (MVs), one kind of extracellular matrix derived extracellular vesicles (EVs), are membrane-bound microparticles released by cells, containing various cargo, including proteins, carbohydrates, lipids, DNA and small RNAs, such as microRNAs (miRNAs). The origin and composition of MVs determine their calcification potential. Recent evidence showed that extracellular MVs serve as nucleating foci to initiate microcalcification. The formation and secretion of MVs and the increase of intracellular alkaline phosphatase (ALP) activity are also involved in the osteoblast-like phenotype transformation of VSMCs.

However, the specific mechanisms and functions of MVs regulating vascular calcification have not been fully elucidated. For example, what is the originating cell that releases MVs in vascular calcification, and how do the pro-calcification MVs get into the recipient cell? This article aims to review the detailed role of MVs in the progression of VC and compare the difference with other major drivers of calcification, including aging, uremia, mechanical stress, oxidative stress, and inflammation. We will also bring attention to the novel findings in the isolation and characterization of MVs, and the therapeutic application of MVs in VC.



"The underlying mechanisms that drive calcification likely involve the inflammatory signalling produced by senescent cells, contributing to the shift in behaviour that makes cells in blood vessel walls act more like osteoblasts -"

The cellular reprogramming involving the phenotypical switching from smooth muscle to osteo's would seem to be more likely the result of mitochondrial exhaustion, itself the result of the effect of reactive oxygen species over time, rather than anything else. Mitophagy has been closely linked both to differentiation and, when it is lacking, to dedifferentiation, The key factor required is probably mitophagy. Thus what is needed, according to the de Gray classification, is Mitosens.
Much of the work done on IPSC's, dwells on the importance of mitophagy or the health of the mitochondria in obtaining the desired result, whether that result is dedifferentiation or differentiation.

Matrix vesicles/exosomes are likely to be a downstream effect of the state of the mitochondria.
Thus ,we are back to ROS and antioxidents.

Posted by: JLH at February 19th, 2022 7:41 AM

Is it that horrible tasting, as to prevent a regular routine of two tablespoons of Bragg's Apple Cider Vinegar to negate this issue? We spend all this time and effort researching an issue that should be put to rest immediately (~3 months) in the population. I spoke to a cardiac rehabilitation nurse about whether their patients are informed about this simple treatment. She said "it's out of our therapeutic lane". I'm starting to loose my empathy for those suffering from this. It only takes a few minutes of Internet research to discover this treatment.

I have a joke: An old couple, he with hearing loss, she with worsening chest pains, goes to their doctor to have her checked out. After she is examined, the doctor comes out and announces to the husband "I'm sorry Sir, your wife has acute angina". The old man, not certain he'd heard the doctor correctly says "What was that?". The doctor raises his voice and says clearly "I'm sorry, but your wife has acute angina". The old man says "I know, but what's wrong with her?"

Posted by: Thomas Mark Schaefer at February 22nd, 2022 10:03 AM
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