Microphysiometry is the ''
in vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...
'' measurement of the functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved on a very small (micrometer) scale. The term microphysiometry emerged in the scientific literature at the end of the 1980s.
The primary parameters assessed in microphysiometry comprise
pH and the concentration of
dissolved oxygen
Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It can ...
,
glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...
, and
lactic acid
Lactic acid is an organic acid. It has the molecular formula C3H6O3. It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as wel ...
, with an emphasis on the first two. Measuring these parameters experimentally in combination with a fluidic system for cell culture maintenance and a defined application of drugs or toxins provides the quantitative output parameters extracellular acidification rates (EAR), oxygen uptake rates (OUR), and rates of glucose consumption or lactate release to characterize the metabolic situation.
Due to the label-free nature of sensor-based measurements, dynamic monitoring of cells or tissues for several days or even longer is feasible. On an extended timescale, a dynamic analysis of a cell's metabolic response to an experimental treatment can distinguish acute effects (e.g., one hour after a treatment), early effects (e.g., at 24 hours), and delayed, chronic responses (e.g., at 96 hours). As stated by Alajoki et al., "The concept is that it is possible to detect receptor activation and other physiological changes in
living cells
The cell is the basic structural and functional unit of all life, forms of life. Every cell consists of cytoplasm enclosed within a Cell membrane, membrane; many cells contain organelles, each with a specific function. The term comes from the ...
by monitoring the activity of energy metabolism".
[Alajoki ML, Bayter GT, Bemiss WR, Blau D, Bousse LJ, Chan SDH, Dawes TD, Hahnenberger KM, Hamilton JM, Lam P, McReynolds RJ, Modlin DN, Owicki C, Parce JW, Redington D, Stevenson K, Wada HG, Williams J (1997). "High-performance microphysiometry in drug discovery", Devlin JP (ed) ''High Throughput Screening: The Discovery of Bioactive Substances''. Marcel Dekker, New York, 427–442.]
See also
*
Organ-on-a-chip
An organ-on-a-chip (OOC) is a multi-channel 3D microfluidic cell culture, integrated circuit (chip) that simulates the activities, mechanics and physiological response of an entire organ or an organ system. It constitutes the subject matter of si ...
References
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Biotechnology
Research methods
Laboratory techniques