Vitalitätsassays

Vitalitätsassays, also known as vitality assays, are laboratory tests designed to assess whether cells, tissues, or microorganisms are alive and metabolically active. They are used across cell biology, toxicology, pharmacology, microbiology, and clinical research to measure viability after treatment, exposure to compounds, or during culture.

Principles and categories: Most vitality assays rely on a readout that correlates with cellular viability, such as metabolic activity, membrane integrity, or enzymatic function. Readouts are typically colorimetric, fluorometric, or luminescent and can be endpoint or real-time.

Common assay types include: MTT, XTT, and MTS colorimetric assays, which measure mitochondrial dehydrogenase activity that reduces tetrazolium salts to colored formazans; resazurin-based assays (such as Alamar Blue) that yield a fluorescent or colorimetric signal proportional to metabolic activity; ATP-based luminescent assays (e.g., CellTiter-Glo) that detect cellular ATP as a proxy for viable cells; dye-exclusion methods like trypan blue, which exploit membrane integrity to distinguish live and dead cells; and fluorescence-based assays using calcein AM and propidium iodide or ethidium homodimer for live/dead discrimination.

Applications: Vitalitätsassays are integral to assessing drug toxicity, screening compounds, monitoring cell viability in culture, evaluating microbial survival, and supporting quality control in bioprocesses.

Considerations: The choice of assay depends on cell type, assay sensitivity, potential interference from test compounds, and whether the study requires endpoint measurements or real-time monitoring. Metabolic readouts may not reflect viability under all conditions, and results can vary between assays; proper controls and standardization are essential.