In vitro systems and cultured cells as specimens for X-ray microanalysis

In vitro systems and cultured cells are recognized as useful systems in many areas of biomedical research, including X-ray microanalysis. To be reliable, in an vitro system should have an elemental composition close to that of the tissue in situ, react in the same way to stimuli, and retain the in situ regulation of ion transport. In the present paper, four of the most commonly used in vitro systems will be reviewed: incubated tissue slices (liver and pancreas), isolated glands (submandibular gland acini, sweat glands), primary cell cultures (sweat glands, endometrium), and cell lines (the colon cancer cell line T84, immortalized sweat gland cells). Incubation of tissue slices of liver in Krebs-Ringers buffer caused a significant increase in Na and Cl and a decrease in K. Initially, these changes were also observed in the pancreas, but here the values gradually returned to normal. Isolated submandibular gland acini, and isolated sweat gland ducts and coils react in a similar way to stimulation as their in situ counterparts. In primary cultures of coil cells, however, part of the cell population acquires different ion transport characteristics. Technically simplest is the use of cell lines originating from cancer cells (e.g., the T84 cell line) and immortalized cell lines. X-ray microanalysis not only confirms data on ion transport obtained with other techniques, but adds the possibility to investigate the presence of subpopulations within a culture.