Tissue culture fixation technique

Raman spectroscopy can offer a number of advantages over traditional cell or tissue analysis techniques used in the field of TE (Table 18.1). Commonly used analytical techniques in TE include the determination of a specific enzyme activity (e.g. lactate dehydrogenase, alkaline phosphatase), the expression of genes (e.g. real-time reverse transcriptase polymerase chain reaction) or proteins (e.g. immunohistochemistry, immunocytochemistry, flow cytometry) relevant to cell behaviour and tissue formation. These techniques require invasive processing steps (enzyme treatment, chemical fixation and/or the use of colorimetric or fluorescent labels) which consequently render these techniques unsuitable for studying live cell culture systems in vitro. Raman spectroscopy can, however, be performed directly on cells/tissue constructs without labels, contrast agents or other sample preparation techniques. 

A TMA can be constructed from cultured cell lines. These cell line samples can serve as control samples because they have been extensively used in the literature and their profile for the marker of interest might be well documented (10,11,12). The cell line pellets are processed in a manner similar to that for routine surgical pathology tissue. This is important because it eliminates any variability related to fixation protocols with reference to immunohistochemical reactivity and sample viability. Use of a resin-based approach has also been described (13). This technique provides excellent morphology and minimizes variability of marker expression related to fixation protocols. 

---