The air brings a plethora of chemical substances into contact with our bodies. Precisely how the skin and mucous membranes or bronchi and lungs respond to the contact with foreign matter can best be studied in cell cultures that originate from the respective tissues. "What you do is cultivate cells onto a porous plastic membrane coated on the bottom with a culture medium, and then from above you conduct air with the test substance over the cells," explains Detlef Ritter of the Fraunhofer Institute.
Yet this test procedure – which had already conceived back in the 1970s – still poses problems: "With the conventional test systems, the atmosphere above the cells frequently is not separated cleanly enough from the culture medium. That's why the test substances sometimes react directly with the solution instead of the cell surface - which adulterates the measurements," says Ritter. Another shortcoming: If you want to study cells treated with air pollutants under the microscope, then you have to apply them to a new vessel beforehand - a step that likewise influences test results.
The new test system bridges these pitfalls, the inventors say. It consists of several components. The principle element is the culture plate. It has an added exposure attachment, gas feed line and hotplate. "The culture vessel is constructed in a manner that prevents contact between the inflowing gas – and thus the test substances carried in them as well – and the culture medium. The support membrane forms a closed barrier with the adherent cells between both media," explains Detlef Ritter. This system allows researchers, he adds, to precisely define and control all the important physical parameters.
Prior to the test, researchers can strain the tissue with fluorescent dyes that indicate various growth processes, toxic and stress reactions or deleterious changes to genetic material, using illumination. The fluorescent light penetrates through the transparent base of the culture plate outward, and can be recorded and evaluated with the microscope. Through this "live imaging," the effect of certain air pollutants on the tissue being studied can be evaluated without time delay.
MEDICA.de; Source: Fraunhofer-Gesellschaft