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Apoptosis, Necrosis

Understanding biology and disease processes is an incredible challenge. Cell-based assays focusing on signalling, function, morphology, to name but a few enable to get further insight in biology and disease. Cell-based assay is here referred to as any assay measuring or detecting effects, elements or parts of a living cell.

CellMade offers a broad range of Cytometry, functional assays using both normal and diseased human primary cell-based models. All proposed CellMade cell models, culture media, reagents and services are thoroughly tested and guarantee optimal performance. The available cell-based assays can be used in a broad variety of experimental applications.

Apoptosis is a process of programmed cell death occuring in multicellular organisms. A cascade of biochemical events leads to characteristic, morphological cell changes and finally cell death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, chromosomal DNA fragmentation and global mRNA decay.

In contrast to Necrosis (a form of traumatic cell death that results from acute cellular injury), Apoptosis is highly regulated and controlled. Apoptosis is crucial during an organism's lifecycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike Necrosis, Apoptosis produces cell fragments that phagocytic cells can digest and remove before the contents of the cell can spill out onto surrounding cells and cause damage.

Apoptosis is a highly regulated process that cannot stop once it has begun. Within the intrinsic pathway, the cell kills itself because it sensed cell stress, while in the extrinsic pathway the cell kills itself because of signals from other cells, or external stimuli. Both pathways induce cell death by activating Caspases that will kill the cell via degrading its proteins. Dying cells that undergo the final stages of Apoptosis display phagocytotic molecules on their cell surface. These molecules mark the cell for phagocytosis by macrophages. The removal of dying cells by phagocytes occurs in an orderly manner without induction of an inflammatory response.

In addition to its intrinsic biological importance, defective apoptotic processes are implicated in a wide variety of diseases. Excessive apoptosis causes Atrophy, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer. Some factors like Fas-receptors and Caspases promote apoptosis, while some members of the Bcl-2 family inhibits Apoptosis. An example of extrinsic pathways initiating Apoptosis is mediated via an increase in calcium concentration within a cell caused by drug activity. Negative regulation of Apoptosis inhibits cell death signaling pathways, helping tumors to evade cell death and developing drug resistance.

Inhibition of Apoptosis can result in a number of cancers, autoimmune diseases, inflammatory diseases, and viral infections. It was originally believed that the associated accumulation of cells was due to an increase in cellular proliferation, but it is now known generally accepted that it is also due to a decrease in cell death. Some apoptotic factors are vital during mitochondrial respiration. Pathological inactivation of Apoptosis is correlated with frequent respiratory metabolic shifts toward glycolysis.

In order to perform analysis of Apoptotic versus Necrotic (Necroptotic) cells various biochemical techniques are used analyzing cell surface markers by cytometry.

For further information on the Cell-based assays and our standard experimental set-up, please download the CellMade Cytometry Assays – Technical Information and General Instructions leaflet.

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