Synchrotron-based FTIR spectra of stained single cells. Towards a clinical application in pathology

Abstract

Over the last few years, FTIR spectroscopy has become a potential analytical method in tissue and cell studies for cancer diagnosis. This has opened a way towards clinical applications such as a tool that would scan samples to assess the presence or absence of malignant cells in biopsies, or as an aid to help pathologists to better characterise those cells that are suspicious but not diagnostic for cancer. The latter application has the problem that in order to assess these cells pathologists would have already dealt with stained samples. Therefore, it is important to understand how staining would affect the spectra of cells. To this purpose, we have conducted this study in order to clarify, first, how haematoxylin and eosin (H&E) and Papanicolau (Pap) stainings affect the spectra of single cells and, second, whether FTIR spectroscopy could differentiate between stained lung cancer cells and their normal counterparts. Furthermore, different cell preparations (cytospin, and smear) used in cytological diagnosis were assessed. Experiments performed using a bright infrared (IR) source (synchrotron) showed that both H&E and Pap staining induced marked changes in the lipid and amide-II band regions. Despite this, FTIR spectroscopy of already stained cells is capable of differentiating between lung cancer cells and their normal counterparts. The clinical applications of this methodology are discussed.

Study of gemcitabine‐sensitive/resistant cancer cells by cell cloning and synchrotron FTIR microspectroscopy

“…In summary, the work presented here is a proof of concept using a lung model based on our previously reported work on the study of lung cancer and gemcitabine using vibrational spectroscopy (10,19,25,40). The experimental setup described in this article using cell cloning opens a new door to study the effects of chemotherapy drugs on cancer cells with vibrational spectroscopy using more uniform cancer cell populations.…”

“…Therefore, we decided to study the cell nucleus recognising that although the spectral contribution of cell cytoplasm is minor when compared to the nuclear one, is not always negligible. Second, our previous work with stained CALU-1 cells studied with S-FTIR microspectroscopy allowed us to measure the nucleus (around 10 mm diameter) within the cell (whole cell size around 25 to 30 mm in diameter) (25). On this basis, we decided to use a 15 3 15 mm aperture centered on the cell's nucleus to cover the whole nucleus.…”

The effect of optical substrates on micro-FTIR analysis of single mammalian cells

“…It has been shown that synchrotron-based Fourier-transform infrared (FTIR) microspectroscopy has no cytotoxic effects on examined cells as no detectable biochemical changes between control and exposed cells have been found despite the increased power density of the SR light [4]. IR spectral differences have been reported between cancerous and normal cells [5, 6], between cells in different growth stages [7–9], or as an effect of drugs on cells [10–13]. There is no unique substrate used in all these studies, and no comparison has been reported in literature of which one is more suitable for cell growth and IR analysis.…”

Suitability of infrared microspectroscopic imaging for histopathology of the uterine cervix

“…In particular, the high number of spectra pixels, the large ROIs including very complex tissue areas and the newly introduced image co‐registration substantiate our final assessment of the method, in contrast to many studies cited in the Introduction, which received very favourable appraisals. Really promising publications in recent years indicating very high resolution and important clinical relevance, such as the detection of micrometastases in lymph node histopathology or the analysis of already stained cell preparations (cytospin and smear), are very impressive, but their methodical approach is characterized by a low number of mostly selected samples 11,15,32 …”