Background Because of its non-destructive nature, label-free imaging is an important strategy for studying biological processes. However, routine microscopic techniques like phase contrast or DIC suffer from shadow-cast artifacts making automatic segmentation challenging. The aim of this study was to compare the segmentation efficacy of published steps of segmentation work-flow (image reconstruction, foreground segmentation, cell detection (seed-point extraction) and cell (instance) segmentation) on a dataset of the same cells from multiple contrast microscopic modalities. Results We built a collection of routines aimed at image segmentation of viable adherent cells grown on the culture dish acquired by phase contrast, differential interference contrast, Hoffman modulation contrast and quantitative phase imaging, and we performed a comprehensive comparison of available segmentation methods applicable for label-free data. We demonstrated that it is crucial to perform the image reconstruction step, enabling the use of segmentation methods originally not applicable on label-free images. Further we compared foreground segmentation methods (thresholding, feature-extraction, level-set, graph-cut, learning-based), seed-point extraction methods (Laplacian of Gaussians, radial symmetry and distance transform, iterative radial voting, maximally stable extremal region and learning-based) and single cell segmentation methods. We validated suitable set of methods for each microscopy modality and published them online. Conclusions We demonstrate that image reconstruction step allows the use of segmentation methods not originally intended for label-free imaging. In addition to the comprehensive comparison of methods, raw and reconstructed annotated data and Matlab codes are provided. Electronic supplementary material The online version of this article (10.1186/s12859-019-2880-8) contains supplementary material, which is available to authorized users.

Mechanisms of cisplatin antineoplastic action are beyond DNA binding. Alternative effects of cisplatin that can support a good therapeutic response are discussed in this review.

Cell viability and cytotoxicity assays are highly important for drug screening and cytotoxicity tests of antineoplastic or other therapeutic drugs. Even though biochemical-based tests are very helpful to obtain preliminary preview, their results should be confirmed by methods based on direct cell death assessment. In this study, time-dependent changes in quantitative phase-based parameters during cell death were determined and methodology useable for rapid and label-free assessment of direct cell death was introduced. The goal of our study was distinction between apoptosis and primary lytic cell death based on morphologic features. We have distinguished the lytic and non-lytic type of cell death according to their end-point features (Dance of Death typical for apoptosis versus swelling and membrane rupture typical for all kinds of necrosis common for necroptosis, pyroptosis, ferroptosis and accidental cell death). Our method utilizes Quantitative Phase Imaging (QPI) which enables the time-lapse observation of subtle changes in cell mass distribution. According to our results, morphological and dynamical features extracted from QPI micrographs are suitable for cell death detection (76% accuracy in comparison with manual annotation). Furthermore, based on QPI data alone and machine learning, we were able to classify typical dynamical changes of cell morphology during both caspase 3,7-dependent and -independent cell death subroutines. The main parameters used for label-free detection of these cell death modalities were cell density (pg/pixel) and average intensity change of cell pixels further designated as Cell Dynamic Score (CDS). To the best of our knowledge, this is the first study introducing CDS and cell density as a parameter typical for individual cell death subroutines with prediction accuracy 75.4% for caspase 3,7-dependent and -independent cell death.

We focused on the biomechanical and morphological characteristics of prostate cancer cells and their changes resulting from the effect of docetaxel, cisplatin, and long-term zinc supplementation. Cell population surviving the treatment was characterized as follows: cell stiffness was assessed by atomic force microscopy, cell motility and invasion capacity were determined by colony forming assay, wound healing assay, coherence-controlled holographic microscopy, and real-time cell analysis. Cells of metastatic origin exhibited lower height than cells derived from the primary tumour. Cell dry mass and CAV1 gene expression followed similar trends as cell stiffness. Docetaxel- and cisplatin-surviving cells had higher stiffness, and decreased motility and invasive potential as compared to non-treated cells. This effect was not observed in zinc(II)-treated cells. We presume that cell stiffness changes may represent an important overlooked effect of cisplatin-based anti-cancer drugs. Atomic force microscopy and confocal microscopy data images used in our study are available for download in the Zenodo repository (https://zenodo.org/, Digital Object Identifiers:10.5281/zenodo.1494935).

Differences in the antioxidant system, apoptotic mechanism and in cell cycle between prostatic cell lines could partially elucidate the development of cisplatin resistance. The aim of this study was to identify the most characteristic parameter for a particular cell line and/or a particular cisplatin treatment using a general regression model and to assess whether it is possible to use measured parameters as markers of cisplatin resistance. This study integrates the results of viability, antioxidant, flow cytometric and quantitative PCR assays in order to characterize the resistance of prostate cancer to cisplatin. Cell growth using metabolic- (MTT) and impedance-based assays, the expression of key cell death signaling proteins (p53, Bax and Bcl-2), cell cycle, activity of antioxidant system-related proteins (superoxide dismutase, glutathione peroxidase, glutathione reductase and metallothionein) and free radical scavenging capacity assays [free radicals (FR), ferric reducing antioxidant power (FRAP), ABTS] were analyzed in the cell lines 22Rv1, PC-3 and PNT1A with respect to rising concentrations (0-150 µM) and different length of cisplatin treatment (12-72 h). The non-functional-p53 PC-3 cell line showed decreased BAX (p<0.05) and, in contrast to PNT1A and 22Rv1, no cisplatin-induced effects on cell cycle. All cell lines showed increasing levels of free radical scavenging activity by ABTS, FRAP and FR assays in a time- and dose-dependent manner (r>0.76 at p<0.001 for ABTS, FRAP and FR at p<0.001). PC-3 showed increased (p<0.05) levels of free radical scavenging activity by ABTS and FR methods. These findings, together with significantly elevated MT, decreased p53 and Bax indicate PC-3 to be cisplatin-resistant. The differences in the antioxidant system and apoptotic mechanisms in PC-3 cells may elucidate the development of cisplatin resistance and indicate that this cell line may be further studied as a model of cytostatic resistance.

Identification of specific cell death is of a great value for many scientists. Predominant types of cell death can be detected by flow-cytometry (FCM). Nevertheless, the absence of cellular morphology analysis leads to the misclassification of cell death type due to underestimated oncosis. However, the definition of the oncosis is important because of its potential reversibility. Therefore, FCM analysis of cell death using annexin V/propidium iodide assay was compared with holographic microscopy coupled with fluorescence detection - “Multimodal holographic microscopy (MHM)”. The aim was to highlight FCM limitations and to point out MHM advantages. It was shown that the annexin V+/PI− phenotype is not specific of early apoptotic cells, as previously believed, and that morphological criteria have to be necessarily combined with annexin V/PI for the cell death type to be ascertained precisely. MHM makes it possible to distinguish oncosis clearly from apoptosis and to stratify the progression of oncosis.

We investigate the potential of Brillouin Light Scattering (BLS) Microspectroscopy for fast non-invasive all-optical assessment of the mechanical properties of viscose fibers and bleached softwood pulp. Using an optimized Brillouin spectrometer, we demonstrate fast spatial mapping of the complex longitudinal modulus over extended areas ([ 100 lm). Our results reveal that while the softwood pulp has a relatively uniform moduli, the viscous fibers have significant spatial heterogeneous in the moduli. Specifically, the viscose fibers exhibited a regular pattern of increasing and decreasing modulus normal to the fiber axis. The potential influence of a locally changing refractive index is investigated by holographic phase microscopy and ruled out. We discuss our results in light of the anisotropic mechanical properties of the fibers and are able to estimate the relative difference between the modulus along the fiber axis and that perpendicular to it. Results are presented alongside reference measurements of the quasi-static mechanical properties transverse to the fiber axes obtained using AFM-nanoindentation which reveal a similar trend, hinting at the potential usefulness of BLS for mechanical characterization applications. However, more detailed investigations are called for to uncover all the factors influencing the measured high-frequency BLS modulus and its significance in relation to physical properties of the fiber that may be of practical interest.

Herein, we describe the in vivo effects of doxorubicin (DOX) encapsulated in ubiquitous protein apoferritin (APO) and its efficiency and safety in anti-tumor treatment. APODOX is both passively (through Enhanced Permeability and Retention effect) and actively targeted to tumors through prostate-specific membrane antigen (PSMA) via mouse antibodies conjugated to the surface of horse spleen APO. To achieve site-directed conjugation of the antibodies, a HWRGWVC heptapeptide linker was used. The prostate cancer-targeted and non-targeted nanocarriers were tested using subcutaneously implanted LNCaP cells in athymic mice models, and compared to free DOX. Prostate cancer-targeted APODOX retained the high potency of DOX in attenuation of tumors (with 55% decrease in tumor volume after 3 weeks of treatment). DOX and non-targeted APODOX treatment caused damage to liver, kidney and heart tissues. In contrast, no elevation in liver or kidney enzymes and negligible changes were revealed by histological assessment in prostate cancer-targeted APODOX-treated mice. Overall, we show that the APO nanocarrier provides an easy encapsulation protocol, reliable targeting, high therapeutic efficiency and very low off-target toxicity, and is thus a promising delivery system for translation into clinical use.