Slide-based cytometry for predicting malignancy in solid salivary gland tumors by fine needle aspirate biopsies

Efficient tumorigenesis by mutation-induced failure to terminate microRNA-mediated adaptive hyperplasia

Seven current contending cancer theories consider different sets of critical events as sufficient for tumorigenesis. These theories, most recently the microRNA dysregulation (MRD) theory, have overlapping attributes and extensive empirical support, but also some discrepancies, and some do not address both benign and malignant tumorigenesis. By definition, the most efficient tumorigenic pathways will dominate under conditions that selectively activate those pathways. The MRD theory provides a mechanistic basis to combine elements of the current theories into a new hypothesis that: (i) tumors arise most efficiently under stress that induces and sustains either protective or regenerative states of adaptive hyperplasia (AH) that normally are epigenetically maintained unless terminated; and (ii) if dysregulated by a somatic mutation that prevents normal termination, these two AH states can generate benign and malignant tumors, respectively. This hypothesis, but not multistage cancer theory, predicts that key participating AH-stem-cell populations expand markedly when triggered by stress, particularly chronic metabolic or oxidative stress, mechanical irritation, toxic exposure, wounding, inflammation, and/or infection. This hypothesis predicts that microRNA expression patterns in benign vs. malignant tumor tissue will correlate best with those governing protective vs. regenerative AH in that tissue, and that tumors arise most efficiently inmutagen-exposed stem cells that either happen to be in, or incidentally later become recruited into, an AH state.

Early detection in head and neck cancer - current state and future perspectives

Survival and quality of life in head and neck cancer are directly linked to the size of the primary tumor at first detection. In order to achieve substantial gain at these issues, both, primary prevention and secondary prevention, which is early detection of malignant lesions at a small size, have to be improved. So far, there is not only a lack in the necessary infrastructure not only in Germany, but rather worldwide, but additionally the techniques developed so far for early detection have a significance and specificity too low as to warrant safe implementation for screening programs. However, the advancements recently achieved in endoscopy and in quantitative analysis of hypocellular specimens open new perspectives for secondary prevention. Chromoendoscopy and narrow band imaging (NBI) pinpoint suspicious lesions more easily, confocal endomicroscopy and optical coherence tomography obtain optical sections through those lesions, and hyperspectral imaging classifies lesions according to characteristic spectral signatures. These techniques therefore obtain optical biopsies. Once a "bloody" biopsy has been taken, the plethora of parameters that can be quantified objectively has been increased and could be the basis for an objective and quantitative classification of epithelial lesions (multiparametric cytometry, quantitative histology). Finally, cytomics and proteomics approaches, and lab-on-the-chip technology might help to identify patients at high-risk. Sensitivity and specificity of these approaches have to be validated, yet, and some techniques have to be adapted for the specific conditions for early detection of head and neck cancer. On this background it has to be stated that it is still a long way to go until a population based screening for head and neck cancer is available. The recent results of screening for cancer of the prostate and breast highlight the difficulties implemented in such a task.

Basics of standardization and calibration in cytometry--a review

Standardization, calibration, and controls (negative and positive controls) are essential for quality assurance. Cytometers are capable of reliable and repeatable cellular analyses. However, a prerequisite is instrument calibration and standardized preanalytics. Calibration is often done by beads. Beads are available for different quality control applications, e.g. calibration of size and measuring scale, compensation, absolute cell counting, and laser alignment. Results can be standardized by converting MFI values into MESF or ABC values. Standardized data allow comparison of experiments over a long period of time and between different instruments and laboratories. Alterations in the sensitivity of the cytometer can be detected by routinely performing quality control. The process of quality assurance quantifies and helps manage the variance from the desired value. Results can thus be compared objectively with those of other laboratories. Standardization is the basis of cytometry and a prerequisite for obtaining reliable data.

Clinical applications of slide-based cytometry--an update

Slide-based cytometric approaches open the possibility to obtain quantitative and objective data from specimens that so far have not been accessible to this kind of analysis. In this review, we will highlight the specific advantages of slide-based cytometry (SBC) and show the applications that have been established for clinical samples. Focuses are cytomic analyses of oncological and hematological samples where the slide-based concept turned out to open new dimensions in understanding underlying cellular networks. We review the recent literature and point out future applications.

[Cytomics and predictive medicine for oncology]

One hundred and fifty years after Virchow introduced his fundamental concept of cellular pathology, we now have tools that allow us to unravel the mechanisms of single living cells on a previously unprecedented level of detail. By exploring the molecular cellular phenotype, multiparametric cytometry not only detects specific cellular functions in general but also offers insights into the interaction of single subunits of proteins (e.g., growth factor receptors). Several quantitative and objective techniques allow analysis of single-cell preparations as well as tissue sections to obtain data on different cellular parameters. This opens the way to quantitative and objective histology, which in the future may be possible even without blood or the need to make an incision. To use this huge amount of data for treatment decisions in an individual patient, novel bioinformatic concepts are needed in order to predict the individual course of a disease. The concept of cytomics centers on the cell as the integral unit of all life and explores diseases starting from the cell and going to subcellular units (top-down analysis).

Measurement of Signaling Pathway Activities in Solid Tumor Fine-needle Biopsies by Slide-based Cytometry

The application of molecular targeted therapies is expected to cause a modulation of cellular signaling pathway(s) that can be monitored by sequential biopsies. Fine-needle sampling (FNS) is an atraumatic and safe technique that can be repeated at numerous points during the clinical or experimental administration of a drug. However, small volume and paucicellularity of fine-needle samples may preclude a comprehensive analysis. We describe here the image-based detection of phosphorylated signaling proteins, an approach for the measurement of pathway activities and preliminary concepts for a multiplexed analysis in these specimens. Fine-needle samples were obtained from xenograft tumors and used for cell block preparations. Preanalytical parameters for the detection of phosphorylated Stat3 and nuclear factor kappaB were determined. A cytometric approach for the measurement of pathway activities was tested using 2 different slide-based analysis techniques applied to immunofluorescence and immunohistochemistry. Changes in the phosphorylation state of Stat3 and nuclear factor kappaB were observed due to delayed fixation and reproducibly quantified. Data obtained from xenografts after drug treatment suggest that slide-based cytometry gives results that are comparable to conventional analysis methods. The applicability of quantum dot nanocrystals for the detection of phosphorylated Stat3 and the combination of different labeling techniques suggest a potential for a multiplexed analysis. We propose here that FNS of solid tumors may be useful in anatomic sites where core-needle biopsies are not possible or not well tolerated. FNS can be used for biomarkers with a homogeneous distribution throughout the tumor, and slide-based analysis techniques may be applied to quantify pathway activities.

[DNA ploidy and proliferative activity in salivary gland tumours]

DNA ploidy and S-Phase fraction (SPF) of 279 salivary gland tumours were analysed using high-resolution DNA flow cytometry. All 229 benign neoplasms were diploid while 12 of 50 malignant tumours showed cell populations with aneuploid DNA content. The SPF values of diploid malignancies were significantly higher if compared with pleomorphic adenomas but did not differ from that of the zystadenolymphoma (Warthin tumour) group. While aneuploidy represents a distinct indicator of malignancy SPF values are of minor relevance for dignity assessment in salivary gland tumours.

DNA ploidy analysis in salivary gland tumours by image cytometry

AIM

To determine whether DNA ploidy by image cytometry is a good diagnostic tool to distinguish benign and malignant salivary gland tumours.

METHODS

A total of 62 salivary gland tumours were studied. Cases were histologically diagnosed [haematoxylin and eosin (H&E)]. According to the World Health Organization (WHO) classification, there were 14 mucoepidermoid carcinomas (MEC), 11 adenoid cystic carcinomas (ACC), 10 pleomorphic adenomas (PA), 10 carcinoma ex PA (CEPA), 9 acinic cell carcinomas (ACCa), 3 polymorphous low-grade adenocarcinomas (PLGA), 2 papillary cystadenocarcinomas (PC), 1 myoepithelial carcinoma (MC), 1 undifferentiated carcinoma (UC) and 1 mucinous adenocarcinoma (MA). Paraffin sections (40 microm) were micro-dissected to isolate tumour areas; cell nuclei were extracted and Feulgen-stained cytospin monolayers were analysed using a DNA image cytometry system. For each case, DNA index (DI) was calculated relative to internal controls (lymphocytes; DI=1.0). Cases were categorized as diploid or aneuploid and the proportion of cells over 5c was also calculated.

RESULTS

Fifty-three of 62 salivary gland tumours were uniformly diploid. Only nine cases were aneuploid: five CEPA, one low-grade MEC, one PC, one UC and one MA.

CONCLUSIONS

The vast majority of salivary gland tumours were diploid. High-grade malignancies may be aneuploid, and ploidy may be useful to identify malignant change in atypical PA. Further, larger studies are needed to confirm our results and to further evaluate the usefulness of the technique in high-grade lesions.

Cytomics - importance of multimodal analysis of cell function and proliferation in oncology

Cancer is a highly complex and heterogeneous disease involving a succession of genetic changes (frequently caused or accompanied by exogenous trauma), and resulting in a molecular phenotype that in turn results in a malignant specification. The development of malignancy has been described as a multistep process involving self-sufficiency in growth signals, insensitivity to antigrowth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and finally tissue invasion and metastasis. The quantitative analysis of networking molecules within the cells might be applied to understand native-state tissue signalling biology, complex drug actions and dysfunctional signalling in transformed cells, that is, in cancer cells. High-content and high-throughput single-cell analysis can lead to systems biology and cytomics. The application of cytomics in cancer research and diagnostics is very broad, ranging from the better understanding of the tumour cell biology to the identification of residual tumour cells after treatment, to drug discovery. The ultimate goal is to pinpoint in detail these processes on the molecular, cellular and tissue level. A comprehensive knowledge of these will require tissue analysis, which is multiplex and functional; thus, vast amounts of data are being collected from current genomic and proteomic platforms for integration and interpretation as well as for new varieties of updated cytomics technology. This overview will briefly highlight the most important aspects of this continuously developing field.

Slide-based cytometry for cytomics--a minireview

In the postgenomic era, to gain the most detailed quantitative data from biological specimens has become increasingly important in the emerging new fields of high-content and high-throughput single-cell analysis for systems biology and cytomics. Areas of research and diagnosis with the demand to virtually measure "anything" in the cell include immunophenotyping, rare cell detection and characterization in the case of stem cells and residual tumor cells, tissue analysis, and drug discovery. Systemic analysis is also a prerequisite for predictive medicine by genomics, proteomics, and cytomics. This issue of Cytometry Part A is dedicated to innovative concepts of system wide single cells analysis and manipulation, new technologies, data analysis and display, and, finally, quality assessment. The manuscripts to these chapters are provided by cutting edge experts in the fields. This overview will briefly highlight the most important aspects of this continuously developing field.

Systems biology and clinical cytomics: The 10th Leipziger Workshop and the 3rd International Workshop on Slide-Based Cytometry, Leipzig, Germany, April 2005

Despite very significant technical and software improvements in flow cytometry (FCM) since the 1980's, the demand for a cytometric technology combining both quantitative cell analysis and morphological documentation in Cytomics became evident. Improvements in microtechnology and computing permit nowadays similar quantitative and stoichiometric single cell-based high-throughput analyses by microscopic instruments, like Slide-Based Cytometry (SBC). SBC and related techniques offer unique tools to perform complex immunophenotyping, thereby enabling diagnostic procedures during early disease stages. Multicolor or polychromatic analysis of cells by SBC is of special importance not only as a cytomics technology platform but also because of low quantities of required reagents and biological material. The exact knowledge of the location of each cell on the slide permits repetitive restaining and reanalysis of specimens. Various separate measurements of the same specimen can be ultimately fused to one database increasing the information obtained per cell. Relocation and optical evaluation of cells as typical SBC feature, can be of integral importance for cytometric analysis, since artifacts can be excluded and morphology of measured cells can be documented. Progress in cell analytic: In the SBC, new horizons can be opened by the new techniques of structural and functional analysis with the high resolution from intracellular and membrane (confocal microscopy, nanoscopy, total internal fluorescence microscopy (TIRFM), and tissue level (tissomics), to organ and organism level (in vivo cytometry, optical whole body imaging). Predictive medicine aims at the detection of changes in patient's state prior to the manifestation of the disease or the complication. Such instances concern immune consequences of surgeries or noninfectious posttraumatic shock in intensive care patients or the pretherapeutic identification of high risk patients in cancer cytostatic therapy. Preventive anti-infectious or anti-shock therapy as well as curative chemotherapy in combination with stem cell transplantation may provide better survival chances for patient at concomitant cost containment. Predictive medicine-guided optimization of therapy could lead to individualized medicine that gives significant therapeutic effect and may lower or abrogate potential therapeutic side effects. The 10th Leipziger Workshop combined with the 3rd International Workshop on SBC aimed to offer new methods in Image- and Slide-Based Cytometry for solutions in clinical research. It moved towards practical applications in the clinics and the clinical laboratory. This development will be continued in 2006 at the upcoming Leipziger Workshop and the International Workshop on Slide-Based Cytometry.

Hyperchromatic cytometry principles for cytomics using slide based cytometry

BACKGROUND

Polychromatic analysis of biological specimens has become increasingly important because of the emerging new fields of high-content and high-throughput single cell analysis for systems biology and cytomics. Combining different technologies and staining methods, multicolor analysis can be pushed forward to measure anything stainable in a cell. We term this approach hyperchromatic cytometry and present different components suitable for achieving this task. For cell analysis, slide based cytometry (SBC) technologies are ideal as, unlike flow cytometry, they are non-consumptive, i.e. the analyzed sample is fixed on the slide and can be reanalyzed following restaining of the object.

METHODS AND RESULTS

We demonstrate various approaches for hyperchromatic analysis on a SBC instrument, the Laser Scanning Cytometer. The different components demonstrated here include (1) polychromatic cytometry (staining of the specimen with eight or more different fluorochromes simultaneously), (2) iterative restaining (using the same fluorochrome for restaining and subsequent reanalysis), (3) differential photobleaching (differentiating fluorochromes by their different photostability), (4) photoactivation (activating fluorescent nanoparticles or photocaged dyes), and (5) photodestruction (destruction of FRET dyes). Based on the ability to relocate cells that are immobilized on a microscope slide with a precision of approximately 1 microm, identical cells can be reanalyzed on the single cell level after manipulation steps.

CONCLUSION

With the intelligent combination of several different techniques, the hyperchromatic cytometry approach allows to quantify and analyze all components of relevance on the single cell level. The information gained per specimen is only limited by the number of available antibodies and sterical hindrance.

Prediction of upper aerodigestive tract cancer by slide-based cytometry

AIM

To evaluate slide-based cytometry in screening for and following up of carcinoma of the upper aerodigestive tract using swabs for a minimal-invasive approach.

METHODS

Laser scanning cytometry (LSC) was used for multiparametric analysis of cells stained for cytokeratin and DNA to determine the DNA-index (DI) of the tumor cells. Histograms with 0.95 < DI < 1.05 and 1.9 < DI < 2.1 were defined as DNA euploid and any other DI as DNA aneuploid. After subsequent HE-staining, single cells were relocalized in order to document morphology. Conventional cytology was also performed on a subset of the slides. Routine histopathology of parallel biopsies served as gold standard in all cases.

RESULTS

115 swabs from 109 patients were obtained from the entire upper aerodigestive tract. 16 swabs were classified as insufficient for LSC. In the remaining 99 specimens, 1 benign lesion was misclassified as malignant, while 61 of the 75 malignant lesions were correctly identified. This corresponds to predictive values of 98.4% and 62.2% for the detection of malignant and benign samples by LSC.

CONCLUSION

This pilot study demonstrates the validity of LSC screening for the identification of tumor malignancy in the upper aerodigestive tract from swab collected cytological material.

Cytomics, the human cytome project and systems biology: top-down resolution of the molecular biocomplexity of organisms by single cell analysis

A large amount of structural and functional information is obtained by molecular cell phenotype analysis of tissues, organs and organisms at the single cell level by image or flow cytometry in combination with bioinformatic knowledge extraction (cytomics) concerning nuclei acids, proteins and metabolites (cellular genomics, proteomics and metabolomics) as well as cell function parameters like intracellular pH, transmembrane potentials or ion gradients. In addition, differential molecular cell phenotypes between diseased and healthy cells provide molecular data patterns for (i) predictive medicine by cytomics or for (ii) drug discovery purposes using reverse engineering of the data patterns by biomedical cell systems biology. Molecular pathways can be explored in this way including the detection of suitable target molecules, without detailed a priori knowledge of specific disease mechanisms. This is useful during the analysis of complex diseases such as infections, allergies, rheumatoid diseases, diabetes or malignancies. The top-down approach reaching from single cell heterogeneity in cell systems and tissues down to the molecular level seems suitable for a human cytome project to systematically explore the molecular biocomplexity of human organisms. The analysis of already existing data from scientific studies or routine diagnostic procedures will be of immediate value in clinical medicine, for example as personalized therapy by cytomics.

[Slide-based multi-parametric cytometry in ENT. Perspectives for the clinic and research]

BACKGROUND

Flow cytometry is the standard method for the multi-parametric analysis of cells. However, for about a decade, an instrument has been available which analyses fluorescing cells immobilised on slides called a laser scanning cytometer (LSC). Its design, according to the principles of slide-based cytometry, promises many advantages, especially in the analysis of minimal sample volumes.

METHODS AND PATIENTS

To date, applications for cultured cells and animal models have been established. Its use for clinical purposes, however, remains to be critically evaluated. We analysed a variety of specimens obtained in our clinical routine.

RESULTS

First, the instrument's resolution was evaluated using standardised particles. This showed a very good sensitivity across a wide range of fluorescence intensities at various wavelengths. Next, diverse applications for tissue engineering, immunophenotyping, and ENT-oncology were tested. Considering its microanalytical capacities, LSC proved to be a convincing tool for clinical use. Additionally, complex structures such as bi-layers of cultured cells were analysed.

CONCLUSION

A broad spectrum of applications in clinical practice and research for the LSC is evident.

Preoperative detection of laryngeal cancer in mucosal swabs by slide-based cytometry

The aim of our study was to evaluate slide-based cytometry in screening for laryngeal cancer using swabs a minimally invasive approach. Laser scanning cytometry (LSC) was used for the multiparametric analysis of cells stained for cytokeratin and DNA to determine the DNA-index (DI) of the tumour cells. Histograms with DI < 0.95, 1.05 < DI < 1.9, and 2.1 < DI were defined as DNA aneuploid. After subsequent haemotoxylin-eosin (HE)-staining, single cells were re-localised and an analysis by conventional cytology was performed. Additionally, routine histopathology of parallel biopsies was obtained in all cases. Fifty one swabs from 49 lesions were analyzed. Seven and 17 swabs, were classified as insufficient for LSC and cytology, respectively. One and two benign lesions, were misclassified as malignant, respectively. Out of 34 malignant lesions, LSC detected 25 and cytology 14. LSC was superior to cytology in all of the statistical parameters tested. This pilot study demonstrates the validity of LSC for the preoperative detection of malignancy in laryngeal tumours using swabs.

Slide-based cytometry and predictive medicine: The 8th Leipziger workshop and the 1st international workshop on slide-based cytometry

Slide-based cytometry (SBC) and related techniques offer unique tools to perform complex diagnostic procedures at very early disease stages. Multicolor or polychromatic analysis of cells by SBC is of special importance, not only as a cytomics technology platform, but for patients with low blood volume such as neonates. The exact knowledge of the location of each cell on the slide allows the specimen to be restained and subsequently reanalyzed. These separate measurements can be fused to one data file (merging), increasing the information obtained per cell. Relocalization and optical evaluation of the cells, a typical feature of SBC, can be of integral importance for cytometric analysis. Predictive medicine is aimed at the detection of changes in the patient's state prior to the manifestation of deterioration or improvement. Such instances are concerned with multiorgan failure in sepsis or noninfectious posttraumatic shock in intensive care patients, or the pretherapeutic identification of high risk patients in cancer cytostatic therapy. Early anti-infectious or anti-shock therapy, as well as curative chemotherapy in combination with stem cell transplantation, may provide better survival chances for the patient as well as concomitant cost containment. Predictive medicine-guided, individualized, early reduction or cessation of therapy may lower or abrogate potential therapeutic side effects (individualized medicine). With the 8th Leipziger Workshop and the 1st International Workshop on Slide-Based Cytometry, cytomics technologies moved to more practical applications in the clinics and the clinical laboratory. This development will be continued in 2004, at the upcoming Leipziger Workshop and the International Workshop on Slide-Based Cytometry.

Eosinophilia in nasal polyposis: its objective quantification and clinical relevance

BACKGROUND

Eosinophilia within nasal polyps is often taken as a criterion for adjuvant medical treatment postoperatively such as topical steroids.

OBJECTIVE

This study was performed in order to validate a new technique for objective quantification of eosinophilia by using laser scanning cytometry (LSC), to compare these results with manual scoring and routine histopathology, and to correlate them with the history of allergy or recurrence.

METHODS

LSC was used for semi-automated analysis of single-cell preparations from representative ethmoidal polyps obtained during routine paranasal sinus surgery (n=41). This microscope-based instrument scans the cells after immobilization of cells on a glass slide and after triple staining of cytokeratin, eosinophilic granula, and DNA. The location of each cell is stored with the fluorescence data. Therefore, the morphology of every cell can be documented by re-staining with haemotoxylin and eosin and re-localization on the slide. Subsequently, slides were subjected to manual scoring. The remaining polyps were analysed by routine histopathology.

RESULTS

Data from LSC and manual scoring showed good correlation (r=0.81, P<0.001), whereas there were discrepancies with histopathology. Eosinophilia scored by LSC and histopathology was neither correlated with the history of allergy nor with recurrence as determined by Fisher's exact test independent of the definition of eosinophilia (> or =2%, > or =3%, or > or =5% of all cells).

CONCLUSION

Scoring eosinophilia by LSC in comparison with histopathology does not contribute to a more reliable basis for adjuvant medical therapy in nasal polyposis. Instead, functional parameters (cytokine production, apoptosis) may serve better.

Microscopy-based multicolor tissue cytometry at the single-cell level

Cytomics is a novel perspective from which to look at life. As with genomics and proteomics before, this discipline requires novel and innovative techniques and technologies to focus on its substrate of research--the cytome. With cytomics being the discipline that analyzes cellular systems and their interdependencies, advanced microscopy represents a key technology in cytomics research. Yet, conventional microscopy-based investigations, i.e., "look and conclude" analyses, do not meet the major cytomics criteria of 1) relating multiple parameters to each other, 2) within large populations of cells, 3) on a single-cell basis, and 4) in a quantitative and observer-independent manner. However, emerging improvements in the fields of fluorophore technology, sensitive fluorescence detection devices, and sophisticated image analysis procedures, are important and necessary steps into the cytomics era. Tissue represents an important class of cytomes, hence tissue cytometry--on the single cell level--can be expected to become an important cytomics technology. In this report, the techniques and technologies of microscopy-based multicolor tissue cytometry (MMTC) are outlined and applications are discussed, including the phenotypic characterization of tissue infiltrating leukocytes, in situ quantification of proliferation markers and tumor suppressors, and in situ quantification of apoptosis.

Cytomics in predictive medicine

Patient-specific, disease-course predictions with >95% or >99% accuracy during therapy would be highly valuable for everyday medicine. If these predictors were available, disease aggravation or progression, frequently accompanied by irreversible tissue damage or therapeutic side effects, could then potentially be avoided by early preventive therapy. The molecular analysis of heterogeneous cellular systems (cytomics) by cytometry in conjunction with pattern-oriented bioinformatic analysis of the multiparametric cytometric and other data provides a promising approach to individualized or personalized medical treatment or disease management. As a consequence, better patient care and new forms of inductive scientific hypothesis development based on the interpretation of predictive data patterns are at reach.