There is no published procedure for using the HT60 kit for cultured cells, and such usage is regarded as off-label. The Congo Red Amyloid kit was designed for tissue sections, but most histological procedures can be used on cultured adherent cells. Specific considerations are mentioned for the thickness of cells and the use of a polarized microscope. Congo Red staining has specific requirements for cells to be stated at a certain thickness. If the cells are within the 6-12 micron range, no major adjustments to the protocol are expected. However, if the cells are extremely small or large, this might be an issue. Additionally, it is advised to utilize a polarized microscope for Congo Red staining, as it can be somewhat nonspecific when using a bright field microscope or an inverted microscope. Not everything that stains red under a light microscope with Congo Red is necessarily amyloid. Apple green staining with polarized microscopy is considered specific for Congo Red. It's important to note that not everything that stains red with Congo Red can automatically be assumed to be amyloid. Adapting a bright field microscope to use the polarized filters necessary for polarized microscopy is possible, but it is uncertain if this is possible when using an inverted microscope.
Due to possible size variation, it is recommended to stain a series of slides if possible. Starting with the times stated in the pdf file is advised, and the staining time may be varied depending upon the thickness or size of the cultured cells. Trying both shortened and extended times depending upon the results obtained is also recommended.
