Monitoring airway mucus flow and ciliary activity with optical coherence tomography

Muco-ciliary transport in the human airway is a crucial defense mechanism for removing inhaled pathogens. Optical coherence tomography (OCT) is well-suited to monitor functional dynamics of cilia and mucus on the airway epithelium. Here we demonstrate several OCT-based methods upon an actively transporting in vitro bronchial epithelial model and ex vivo mouse trachea. We show quantitative flow imaging of optically turbid mucus, semi-quantitative analysis of the ciliary beat frequency, and functional imaging of the periciliary layer. These may translate to clinical methods for endoscopic monitoring of muco-ciliary transport in diseases such as cystic fibrosis and chronic obstructive pulmonary disease (COPD)

Imaging three-dimensional rotational diffusion of plasmon resonant gold nanorods using polarization-sensitive optical coherence tomography

We demonstrate depth-resolved viscosity measurements within a single object using polarized optical scattering from ensembles of freely tumbling plasmon resonant gold nanorods (GNRs) monitored with polarization-sensitive optical coherence tomography. The rotational diffusion coefficient of the GNRs is shown to correlate with viscosity in molecular fluids according to the Stokes-Einstein relation. The plasmon resonant and highly anisotropic properties of GNRs are favorable for microrheological studies of nanoscale properties

Motility-, autocorrelation-, and polarization-sensitive optical coherence tomography discriminates cells and gold nanorods within 3D tissue cultures

We propose a method for differentiating classes of light scatterers based upon their temporal and polarization properties computed from time series of polarization-sensitive optical coherence tomography (PS-OCT) images. The amplitude (motility) and time scale (autocorrelation decay time) of the speckle fluctuations are combined with the cross-polarization pixel-wise to render Motility-, autocorrelation-, and polarization-sensitive (MAPS) OCT contrast images. This combination of metrics provides high specificity for discriminating diffusive gold nano-rods and mammary epithelial cell spheroids within 3D tissue culture, based on their unique MAPS signature. This has implications toward highly specific contrast in molecular (nanoparticle-based) and functional (cellular activity) imaging using standard PS-OCT hardware

Probing biological nanotopology via diffusion of weakly constrained plasmonic nanorods with optical coherence tomography

Many diseases are characterized by nanostructural changes in connective fibers and soluble proteins, which can indicate or drive disease progression. Noninvasive methods sensitive to nanotopological changes in 3D tissue models can elucidate biophysical changes associated with disease progression. Nanoparticles probe their environment via their diffusion, which is impacted by the size and connectivity of pores into which they freely diffuse. Here, we show that optical coherence tomography provides depth-resolved imaging of gold nanorods (GNRs) to infer local biological nanotopology. We demonstrate the broad potential of this method by sensing changes in diffusion of GNRs in 3D models of mammary ECM and pulmonary mucus

Role of HGF in epithelial-stromal cell interactions during progression from benign breast disease to ductal carcinoma in situ

Abstract Introduction Basal-like and luminal breast cancers have distinct stromal–epithelial interactions, which play a role in progression to invasive cancer. However, little is known about how stromal–epithelial interactions evolve in benign and pre-invasive lesions. Methods To study epithelial–stromal interactions in basal-like breast cancer progression, we cocultured reduction mammoplasty fibroblasts with the isogenic MCF10 series of cell lines (representing benign/normal, atypical hyperplasia, and ductal carcinoma in situ). We used gene expression microarrays to identify pathways induced by coculture in premalignant cells (MCF10DCIS) compared with normal and benign cells (MCF10A and MCF10AT1). Relevant pathways were then evaluated in vivo for associations with basal-like subtype and were targeted in vitro to evaluate effects on morphogenesis. Results Our results show that premalignant MCF10DCIS cells express characteristic gene expression patterns of invasive basal-like microenvironments. Furthermore, while hepatocyte growth factor (HGF) secretion is upregulated (relative to normal, MCF10A levels) when fibroblasts are cocultured with either atypical (MCF10AT1) or premalignant (MCF10DCIS) cells, only MCF10DCIS cells upregulated the HGF receptor MET. In three-dimensional cultures, upregulation of HGF/MET in MCF10DCIS cells induced morphological changes suggestive of invasive potential, and these changes were reversed by antibody-based blocking of HGF signaling. These results are relevant to in vivo progression because high expression of a novel MCF10DCIS-derived HGF signature was correlated with the basal-like subtype, with approximately 86% of basal-like cancers highly expressing the HGF signature, and because high expression of HGF signature was associated with poor survival. Conclusions Coordinated and complementary changes in HGF/MET expression occur in epithelium and stroma during progression of pre-invasive basal-like lesions. These results suggest that targeting stroma-derived HGF signaling in early carcinogenesis may block progression of basal-like precursor lesions

BigStitcher: reconstructing high-resolution image datasets of cleared and expanded samples.

Light-sheet imaging of cleared and expanded samples creates terabyte-sized datasets that consist of many unaligned three-dimensional image tiles, which must be reconstructed before analysis. We developed the BigStitcher software to address this challenge. BigStitcher enables interactive visualization, fast and precise alignment, spatially resolved quality estimation, real-time fusion and deconvolution of dual-illumination, multitile, multiview datasets. The software also compensates for optical effects, thereby improving accuracy and enabling subsequent biological analysis

Examining the effects of chromatic aberration, object distance, and eye shape on image-formation in the mirror-based eyes of the bay scallop Argopecten irradians

The eyes of scallops form images using a concave spherical mirror and contain two separate retinas, one layered on top of the other. Behavioral and electrophysiological studies indicate that the images formed by these eyes have angular resolutions of about 2°. Based on previous ray-tracing models, it has been thought that the more distal of the two retinas lies near the focal point of the mirror and that the proximal retina, positioned closer to the mirror at the back of the eye, receives light that is out-of-focus. Here, we propose three mechanisms through which both retinas may receive focused light: (1) chromatic aberration produced by the lens may cause the focal points for longer and shorter wavelengths to fall near the distal and proximal retinas, respectively; (2) focused light from near and far objects may fall on the distal and proximal retinas, respectively; and (3) the eyes of scallops may be dynamic structures that change shape to determine which retina receives focused light. To test our hypotheses, we used optical coherence tomography (OCT), a method of near-infrared optical depth-ranging, to acquire virtual cross-sections of live, intact eyes from the bay scallop Argopecten irradians . Next, we used a custom-built ray-tracing model to estimate the qualities of the images that fall on an eye’s distal and proximal retinas as functions of the wavelengths of light entering the eye (400–700 nm), object distances (0.01–1 m), and the overall shape of the eye. When we assume 550 nm wavelength light and object distances greater than 0.01 m, our model predicts that the angular resolutions of the distal and proximal retinas are 2° and 7°, respectively. Our model also predicts that neither chromatic aberration nor differences in object distance lead to focused light falling on the distal and proximal retinas simultaneously. However, if scallops can manipulate the shapes of their eyes, perhaps through muscle contractions, we speculate that they may be able to influence the qualities of the images that fall on their proximal retinas and—to a lesser extent—those that fall on their distal retinas as well

Longitudinal Study of Mammary Epithelial and Fibroblast Co-Cultures Using Optical Coherence Tomography Reveals Morphological Hallmarks of Pre-Malignancy

<div><p>The human mammary gland is a complex and heterogeneous organ, where the interactions between mammary epithelial cells (MEC) and stromal fibroblasts are known to regulate normal biology and tumorigenesis. We aimed to longitudinally evaluate morphology and size of organoids in 3D co-cultures of normal (MCF10A) or pre-malignant (MCF10DCIS.com) MEC and hTERT-immortalized fibroblasts from reduction mammoplasty (RMF). This co-culture model, based on an isogenic panel of cell lines, can yield insights to understand breast cancer progression. However, 3D cultures pose challenges for quantitative assessment and imaging, especially when the goal is to measure the same organoid structures over time. Using optical coherence tomography (OCT) as a non-invasive method to longitudinally quantify morphological changes, we found that OCT provides excellent visualization of MEC-fibroblast co-cultures as they form ductal acini and remodel over time. Different concentrations of fibroblasts and MEC reflecting reported physiological ratios <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049148#pone.0049148-Sadlonova1">[1]</a> were evaluated, and we found that larger, hollower, and more aspherical acini were formed only by pre-malignant MEC (MCF10DCIS.com) in the presence of fibroblasts, whereas in comparable conditions, normal MEC (MCF10A) acini remained smaller and less aspherical. The ratio of fibroblast to MEC was also influential in determining organoid phenotypes, with higher concentrations of fibroblasts producing more aspherical structures in MCF10DCIS.com. These findings suggest that stromal-epithelial interactions between fibroblasts and MEC can be modeled <em>in vitro</em>, with OCT imaging as a convenient means of assaying time dependent changes, with the potential for yielding important biological insights about the differences between benign and pre-malignant cells.</p> </div

Media 2: Monitoring airway mucus flow and ciliary activity with optical coherence tomography

Originally published in Biomedical Optics Express on 01 September 2012 (boe-3-9-1978

'Insecta exotica'

Originally published in Biomedical Optics Express on 01 September 2012 (boe-3-9-1978