Cell and tissue have mechanical properties that control their behavior, function, and shape. Any change in these mechanical properties can result in elongation, stretching, segregation, and folding of cell or tissue. Cell differentiation and cell proliferation are directly controlled by tissue mechanics. Changes in tissue or cell mechanics can also result in cancer formation. Therefore measurement of mechanical properties of cell and tissue is an essential process.
To measure the mechanical properties cells of tissues need to be deformed with the help of a known force or stress. Mitchison and Swann in 1954 described and used a device named “cell elastimeter” which is a microaspiration device used to pull cell surface with controlled pressure. They used this device to study the mechanical properties of the sea urchin embryo from the fertilization of gametes to the first cleavage.
Microaspiration setup works on the same principle as cell elastimeter do. With the help of microaspiration we can study the mechanical properties of isolated cells as well as cells present in a tissue. This technique is used to study and measure cell surface tension, the elasticity of embryonic tissues, and the apparent viscosity of isolated cells.
The micropipette is a powerful, cost-effective, and noninvasive technique to study and evaluate how cell shape and cell response is governed by biomass. It also evaluates the transition a cell from non-mutagenic form to cancerous cell or tumor.
Building and preparation of Micropipette aspiration setup:
Materials and equipment:
For the preparation of micropipette aspiration following materials and equipment are required:
- Micropipette flushing needle
- Glass capillaries without any type of filament
- Fetal bovine serum
- Polyethylene glycol
- PBS or cell culture medium for the cleaning solution
- Pipette storage container
- Pipette puller
- Micropipette
- Micromanipulator
- Inverted microscope
- Microfluidic pump
- Syringe
- Intermediate reservoir
The assemblage of aspiration setup:
The assemblage of aspiration setup
Figure shows the assemblage of micropipette aspiration setup. The Microaspiration setup has a micromanipulator mounted on an inverted microscope. A liquid reservoir is connected with a micropipette and both these are manipulated on a stage. The reservoir has a height h and the difference of this height with the height of culture dish containing sample provide a positive pressure . Where is the gravitational pull of the earth, liquid volumetric density and is the height of the liquid reservoir. The microfluidic pump is attached to this liquid reservoir providing a negative pressure . The net pressure on the micropipette tip is given as:
Calculation and calibration of accurate aspiration pressure is very important as the technique relays on this calibration. The micropipette is carefully attached with tubing and then microfluidic pump and reservoir are adjusted to calibrate aspiration pressure.
After setting up the aspiration assembly the sample is loaded and viewed with the help of a microscope.
