Biology subjects

Chester, A. H.

Publications and source records attributed to Chester, A. H..

5 recordsLinked to original sources

bioRxiv2026

Biomineralization from platelet δ-granules as the origin of cardiovascular calcification in humans and other animals.

Cardiovascular calcification is present in practically all cardiac diseases, which are the top killers in the world today1, and is particularly associated with atherosclerosis2, aortic stenosis3 and rheumatic fever4. If not the direct cause of death, calcification contributes considerably to complications that can lead to heart failure5. Nonetheless, the origins and mechanisms of cardiovascular calcification are still strongly debated3,6-12. Just over a decade ago, it has been reported that nano and micron-sized calcified spherical particles, formed from a single crystal of magnesium-containing calcium phosphate, were the first calcified structure that could be detected in cardiovascular tissue13. These particles were found even before any sign of cardiac disease was present and were present in all stages of cardiac diseases13. The ubiquity of these particles suggests their importance for the origins and development of cardiovascular calcific diseases. Here, we show that these particles originate from platelet {delta}-granules and are present in mammals, birds and lizards. Based on our results, we suggest a new mechanism for the origins of these particles, complementing existing models of cardiovascular calcification7,14, and bringing a new, early, and hitherto unaccounted key event in the process of cardiovascular calcification. This new mechanism model, along with a better understanding of the early stages of cardiovascular calcification, could open the path for the development of pharmacological prevention and treatment solutions for several cardiac diseases.

pathology↗

bioRxiv2024

Density-Dependent Colour Scanning Electron Microscopy (DDC-SEM). Applications in the study of calcified tissues and visual impact.

Scanning Electron Microscopy (SEM) is widely used as a technique for materials characterization. It has also been successfully applied to the imaging of biological samples, providing invaluable insights into the topography, morphology and composition of biological structures. A particular method combining different SEM detectors, named Density-Dependent Coloured SEM (DDC-SEM), has proven to be most useful for the identification and visualization of minerals in soft tissues. The method consists of a manipulation of original greyscale SEM images to produce coloured images that provide both topography and density information for samples with components of different densities. Here we provide a discussion on how to use DDC-SEM to aid the visualization and intuitive understanding of pathological calcification. This method has become popular not only for its scientific improvement of conventional SEM greyscale images, but also for its aesthetical merits. Lay summaryScanning Electron Microscopes (SEM) are widely used tools for examining biological materials such as human tissue. Like other electron microscopes, it only produces images in greyscale. SEM has been useful, for instance, in improving our understanding of calcific diseases. These diseases involve the build-up of mineral in the bodys soft tissues, and frequently affect the heart, kidneys, or eyes. This work provides a discussion on using a SEM technique known as Density-Dependent Colour Scanning Electron Microscopy (DDC-SEM), which enhances SEM images through scanning the same area with different detectors, assigning a unique colour to each detectors output, and then overlaying these images.

scientific communication and education↗

bioRxiv2022

Alizarin Red fluorescence imaging for nano calcification

The formation of calcium phosphate (calcification) has been observed in a variety of healthy and diseased tissues and contributes to a wide range of pathologies. In physiological and pathological mechanisms, calcification begins at the nano scale and then develops into structures that range from a few micrometres to several centimetres. Fluorescence microscopy can be an efficient way to visualise such early calcification and its interaction with cells and proteins. The limited shelf life and high cost of commercial dyes for staining calcification, however, can be problematic when using this imaging method. Here, we aim to evaluate the effectiveness and stability of Alizarin Red (AR) as a fluorescent staining agent for nano and micro calcified structures. Our results show that AR staining for nano and micro calcified structures is a simple, reliable, effective, and quite inexpensive method to visualize calcification at the nano and micro scale in biological samples.

pathology↗

bioRxiv2022

Density-Dependent Color Scanning Electron Microscopy (DDC-SEM) for calcified tissue and pathological calcification.

Scanning electron microscopy (SEM) is widely used for materials characterization. It has also been successfully applied to the imaging of biological samples, providing invaluable insights into the topography, morphology and composition of biological structures, including pathological minerals, in diseases affecting cardiovascular, kidney and ocular tissues. Here we provide a comprehensive and detailed guide on how to use colored SEM to aid the visualization and characterization of pathological calcification, and identify the effects of different sample preparation protocols for the visualisation of these minerals.

pathology↗

bioRxiv2019

Electron microscopy characterization of minerals formed in vitro by human bone cells and vascular smooth muscle cells

Soft tissue mineralization has been found to be a major component of diseases such as aortic valve stenosis and rheumatic heart disease. Cardiovascular mineralization has been suggested to follow mechanisms similar to those of bone formation with several cell culture models been developed over the years to provide mechanistic insights. These cell models have been characterized by a wide range of biochemical and molecular methods, which identified the presence of osteogenic markers and bone-like cells. However, there is a surprisingly small number of studies where the mineral formed in these cell culture models has been characterized by physico-chemical methods, and even fewer studies have compared this mineral to the one produced by bone cells in cultures. Here we investigated the morphology and composition of the minerals formed in cell cultures of vascular smooth muscle cells and bone cells. Electron microscopy and traditional cell mineralization assays were applied, revealing that vascular cells are indeed able to form calcified nodules of elemental composition similar to bone, however with different morphology. Comparison of morphologies of the two minerals to that found in cardiovascular tissue shows that some of tissue calcification resembles the calcified fibers produced by bone cells in vitro. These results suggest that the characterization of the mineral is of utmost importance and its morphology and chemical properties can contribute an important piece of information in the comprehensive analysis of soft tissue mineralization mechanisms, both in in vitro cell culture as well as in clinical samples.

pathology↗