Biology subjects

Bizheva, K.

Publications and source records attributed to Bizheva, K..

3 recordsLinked to original sources

bioRxiv2025

Comparison of volumetric dynamic optical coherence tomography with biological methods for evaluation of radiation effects in prostate tumor spheroids

Significance3D tumor spheroids are more physiologically representative of in vivo patient tumors compared to 2D monolayer culture. However, their 3D nature challenges the use of conventional biological techniques like proliferation assays, fluorescence microscopy, and the clonogenic assay, which is the gold standard method for assessing cell survival following radiation. However, clonogenic assay requires spheroid disaggregation. AimNon-invasive volumetric imaging with dynamic optical coherence tomography (dOCT) enables cellular activity to be visualized with spatial resolution within 3D tumor spheroids. Cellular activity observed via dOCT in irradiated prostate tumor spheroids was quantified for comparison with conventional biological techniques. ApproachA Varian TrueBeam linear accelerator was used to irradiate spheroid and monolayer cultures with a 6 MV beam. Cellular activity was estimated from dOCT images generated via frequency banding and compared to clonogenic assay, proliferation assay, fluorescence microscopy, and 3D cell simulation. ResultsProstate cancer cells cultured as spheroids demonstrated improved radio-resistance via clonogenic assay compared to monolayer culture. The dOCT method demonstrated quantitative and qualitative agreement with proliferation assay and fluorescence microscopy, respectively. ConclusionsA longer duration of repeated dOCT measurement in tumor spheroids following radiation treatment could offer a non-invasive alternative to the clonogenic assay.

cancer biology↗

bioRxiv2025

Longitudinal investigation of prostate tumor spheroid proliferation with dynamic line-field optical coherence tomography

Recently, it has become widely recognized that culturing cancer cells in vitro in small, 3D aggregates known as tumor spheroids provides a more physiologically relevant model of in vivo tumor behavior compared to 2D monolayer cultures. Dynamic optical coherence tomography (dOCT) is a non-invasive imaging modality that, by analyzing temporal fluctuations in the light scattered from biological tissue, does not require exogenous contrast agents to visualize and quantify cellular activity within 3D cell cultures. However, recent volumetric dOCT studies have encountered challenges due to low acquisition speeds. In this study, we present morphological and dynamic analyses of prostate tumor spheroid growth over a two-week longitudinal period, utilizing volumetric imaging with a line-field dOCT platform. Our method clearly differentiated between active cellular metabolism in live spheroids and the lack of activity in spheroids fixed with formaldehyde. Quantitative validation of the dynamic signal was conducted using the Alamar Blue proliferation assay, while qualitative validation was provided by live/dead fluorescence microscopy.

cancer biology↗

bioRxiv2025

Combined optical coherence tomography and electroretinography (OCT+ERG) system for imaging neurovascular coupling in the human retina

SignificanceDuring their early stages of development, neurological and neurodegenerative diseases cause changes to the biological tissues morphology, physiology and metabolism at cellular level, and acute, transient changes in the local blood flow. Development of novel optical methods for quantitative imaging of such changes non-invasively and simultaneously would allow for probing of neurovascular coupling in neural tissues and therefore can have a profound effect on furthering our understanding of neurodegeneration. AimTo develop an optical imaging platform based on optical coherence tomography (OCT) for imaging and characterization of neurovascular coupling in the human retina with high spatial and temporal resolution. ApproachA fast, ultrahigh resolution OCT system was developed and combined with a clinical electroretinography (ERG) system for in-vivo, simultaneous structural, functional and vascular imaging of the human retina in response to visual stimulation. Novel image processing algorithms were developed to quantify visually-evoked physiological and blood flow changes from the OCT images and explore neurovascular coupling in the healthy human retina. ResultsVisual stimulation of the human retina with singe flashes (white light, 4ms duration) caused transient changes in the optical reflectivity and thickness (optical pathlength difference) of major retinal layers, as well as the blood flow in local retinal blood vessels. The time courses of the neuronal and blood flow changes were correlated, and their magnitude was dependent on the intensity of the visual stimulus. ConclusionsWe have developed an optical imaging modality for non-invasive probing of neurovascular coupling in the living human retina and demonstrated its utility and clinical potential in a pilot study on healthy subjects. This imaging platform could serve as a useful clinical research tool for investigation of potentially blinding retinal diseases, as well as neurodegenerative brain diseases that are expressed in the retina such as Alzheimers and Parkinsons.

bioengineering↗