Name: longitudinal morphological and physiological monitoring of three-dimensional tumor spheroids using optical coherence tomography
Uploaded: 2019-02-09T13:00:00
Description: Watch this Scientific Journal Video about Longitudinal Morphological and Physiological Monitoring of Three-dimensional Tumor Spheroids Using Optical Coherence Tomography at JoVE.com

This work was supported by NSF grants IDBR (DBI-1455613), PFI:AIR-TT (IIP-1640707), NIH grants R21EY026380, R15EB019704 and R01EB025209, and Lehigh University startup fund.

1. Preparation of Cells
<ol>
	<li>Obtain cell lines from a qualified supplier. 
	NOTE: Verify that cells from the cell lines of interest can form spheroid in the culture media or with the help of a substrate (basement membrane matrix like Matrigel). Look into the literature9 or perform one round of a pre-experiment for a check.</li>
	<li>Thaw the frozen cells following the specific procedure provided by the cell-line supplier. A general procedure can be found elsewhere43</...

Tumor activity is highly relevant to its morphological structure. Similar to monitoring characteristic growth curve for 2D cell cultures, tracking the growth curve for 3D tumor spheroids is also a conventional approach to characterize the long-term spheroid growth behavior for different cell lines. Notably, we can characterize the drug response by analyzing tumor degradation or tumor regrowth directly reflected in the growth curve. Therefore, quantitative assessment of 3D tumor spheroids, including the size and volume, t...

Cancer is the second leading cause of death in the world1. Developing drugs targeting cancer is of crucial importance for patients. However, it is estimated that more than 90% of new anti-cancer drugs fail in the development phase because of a lack of efficacy and unexpected toxicity in clinical trials2. Part of the reason can be attributed to the use of simple two-dimensional (2D) cell culture models for compound screening, which provide results with limited predictive values of compound efficacy and toxicity for the following stages of drug discovery2,3,4. Recently, three-dimensional (3D) tumor spheroid models have been developed to provide clinically relevant physiological and pharmacological data for anti-cancer drug discovery3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25. Since these spheroids can mimic tissue-specific properties of tumors in vivo, such as nutrient and oxygen gradient, hypoxic core as well as drug resistance19, the use of these models can potentially shorten drug discovery timelines, reduce costs of investment, and bring new medicines to patients more effectively. One critical approach to evaluating compound efficacy in 3D tumor spheroid development is to monitor the spheroid growth and recurrence under treatments9,26. To do this, quantitative characterizations of the tumor morphology, involving its diameter and volume, with high-resolution imaging modalities, are imperative. 
Conventional imaging modalities, such as bright-field, phase contrast7,9,22,24, and fluorescence microscopy8,9,16,18,22 can provide a measurement of the spheroid's diameter but cannot resolve the overall structure of the spheroid in 3D space. Many factors contribute to these limitations, including penetration of the probing light in the spheroid; diffusion of the fluorescent dyes into the spheroid; emitting fluorescent signals from excited fluorescent dyes inside or on the opposite surface of the spheroid due to strong absorption and scattering; and depth-resolvability of these imaging modalities. This often leads to an inaccurate volume measurement. Development of the necrotic core in spheroids mimics necrosis in in vivo tumors6,10,15,19,25. This pathological feature is unlikely reproduced in 2D cell cultures19,25,27,28. With a spheroid size larger than 500 &#181;m in diameter, a three-layer concentric structure, including an outer layer of proliferating cells, a middle layer of quiescent cells, and a necrotic core, can be observed in the spheroid6,10,15,19,25, due to lack of oxygen and nutrients. Live and dead cell fluorescence imaging is the standard approach to label the boundary of the necrotic core. However, again, penetrations of both these fluorescent dyes and visible light hinder the potential to probe into the necrotic core to monitor its development in its actual shape.
An alternative 3D imaging modality, optical coherence tomography (OCT) is introduced to characterize the tumor spheroids. OCT is a biomedical imaging technique that is capable of acquiring label-free, non-destructive 3D data from up to 1-2 mm depths in biological tissues29,30,31,32,33,34. OCT employs low-coherence interferometry to detect back-scattered signals from different depths of the sample and provides reconstructed depth-resolved images at micron-level spatial resolutions in both lateral and vertical directions. OCT has been widely adopted in ophthalmology35,36,37 and angiography38,39. Previous studies have used OCT to observe the morphology of in vitro tumor spheroids in basement membrane matrix (e.g., Matrigel) and evaluate their responses to photodynamic therapy40,41. Recently, our group established a high-throughput OCT imaging platform to systematically monitor and quantify the growth kinetics of 3D tumor spheroids in multi-well plates42. Precise volumetric quantification of 3D tumor spheroids using a voxel counting approach and label-free necrotic tissue detection in the spheroids based on intrinsic optical attenuation contrast were demonstrated. This paper describes the details of how the OCT imaging platform was constructed and employed to obtain high-resolution 3D images of tumor spheroids. The step-by-step quantitative analyses of the growth kinetics of 3D tumor spheroids, including accurate measurements of spheroid diameter and volumes, is described. Also, the method of the non-destructive detection of necrotic tissue regions using OCT, based on the intrinsic optical attenuation contrast is presented.

<table>
	<tbody>
		<tr>
			<td>Custom Spectral Domain OCT imaging system</td>
			<td></td>
			<td></td>
			<td>Developed in our lab</td>
		</tr>
		<tr>
			<td>Superluminescent Diode (SLD)</td>
			<td>Thorlabs</td>
			<td>SLD1325</td>
			<td>light source</td>
		</tr>
		<tr>
			<td>2&#215;2 single mode fused fiber coupler, 50:50 splitting ratio</td>
			<td>AC Photonics</td>
			<td>WP13500202B201</td>
			<td></td>
		</tr>
		<tr>
			<td>Reference Arm</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lens Tube</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adapter</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Collimating Lens</td>
			<td>Thorlabs</td>
			<td>AC080-020-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Focusing Lens</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Kinematic Mirror Mount</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mirror</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1D Translational Stage</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Continuous neutral density filter</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pedestrial Post</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Clamping Fork</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sample Arm</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lens Tube</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adapter</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Collimating Lens</td>
			<td>Thorlabs</td>
			<td>AC080-020-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Galvanometer</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Relay Lens</td>
			<td>Thorlabs</td>
			<td>AC254-100-C</td>
			<td>two Relay lens to make a telescope setup</td>
		</tr>
		<tr>
			<td>Triangle Mirror Mount</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mirror</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Objective</td>
			<td>Mitutoyo</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pedestrial Post</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Clamping Fork</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polarization Controller</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>30mm Cage Mount</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cage Rod</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stage</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3D motorized translation stage</td>
			<td>Beijing Mao Feng Optoelectronics Technology Co., Ltd.</td>
			<td>JTH360XY</td>
			<td></td>
		</tr>
		<tr>
			<td>2D Tilting Stage</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Rotation Stage</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plate Holder</td>
			<td></td>
			<td></td>
			<td>3D printed</td>
		</tr>
		<tr>
			<td>Spectrometer</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lens Tube</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adapter</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Collimating Lens</td>
			<td>Thorlabs</td>
			<td>AC080-020-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Grating</td>
			<td>Wasatch</td>
			<td></td>
			<td>G = 1145 lpmm</td>
		</tr>
		<tr>
			<td>F-theta Lens</td>
			<td>Thorlabs</td>
			<td>FTH-1064-100</td>
			<td></td>
		</tr>
		<tr>
			<td>InGaAs Line-scan Camera</td>
			<td>Sensor Unlimited</td>
			<td>SU1024-LDH2</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Cell Culture Component</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HCT 116 Cell line</td>
			<td>ATCC</td>
			<td>CCL-247</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Culture Flask</td>
			<td>SPL Life Sciences</td>
			<td>70025</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Fisherbrand</td>
			<td>14388100</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips</td>
			<td>Sorenson Bioscience</td>
			<td>10340</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco GlutaMax DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>10569044</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum, certified, US origin</td>
			<td>Thermo Fisher Scientific</td>
			<td>16000044</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic (100X)</td>
			<td>Thermo Fisher Scientific</td>
			<td>15240062</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning 96-well Clear Round Bottom Ultra-Low Attachment Microplate</td>
			<td>Corning</td>
			<td>7007</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco PBS, pH 7.4</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010023</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Trypsin-EDTA (0.5%)</td>
			<td>Thermo Fisher Scientific</td>
			<td>15400054</td>
			<td></td>
		</tr>
		<tr>
			<td>Forma Series II 3110 Water-Jacketed CO2 Incubators</td>
			<td>Thermo Fisher Scientific</td>
			<td>3120</td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>VWR</td>
			<td>89428-750</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Sigma-Aldrich</td>
			<td>P7793</td>
			<td></td>
		</tr>
		<tr>
			<td>Transfer pipets</td>
			<td>Globe Scientific</td>
			<td>138080</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5702 R</td>
			<td>To centrifuge the 15 mL tube</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>NUAIRE</td>
			<td>AWEL CF 48-R</td>
			<td>To centrifuge the 96-well plate</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Histology &#38; IHC</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Digital slide scanner</td>
			<td>Leica</td>
			<td>Aperio AT2</td>
			<td>Obtain high-resolution histological images</td>
		</tr>
		<tr>
			<td>Histology Service</td>
			<td>Histowiz</td>
			<td></td>
			<td>Request service for histological and immunohistological staining of tumor spheroid</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>List of Commerical OCTs</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SD-OCT system</td>
			<td>Thorlabs</td>
			<td>Telesto Series</td>
			<td></td>
		</tr>
		<tr>
			<td>SD-OCT system</td>
			<td>Wasatch Photonics</td>
			<td>WP OCT 1300 nm</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Software for Data Analyses</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Basic Image Analysis</td>
			<td>NIH</td>
			<td>ImageJ</td>
			<td>Fiji also works.</td>
		</tr>
		<tr>
			<td>3D Rendering</td>
			<td>Thermo Fisher Scientific</td>
			<td>Amira</td>
			<td>Commercial software. Option 1</td>
		</tr>
		<tr>
			<td>3D Rendering</td>
			<td>Bitplane</td>
			<td>Imaris</td>
			<td>Commercial software. Option 2. Used in the protocol</td>
		</tr>
		<tr>
			<td>OCT acquisition software</td>
			<td></td>
			<td></td>
			<td>custom developed in C++.</td>
		</tr>
		<tr>
			<td>Stage Control</td>
			<td>Beijing Mao Feng Optoelectronics Technology Co., Ltd.</td>
			<td>MRC_3</td>
			<td>Incorporated into the custom OCT acquisition code</td>
		</tr>
		<tr>
			<td>OCT processing software</td>
			<td></td>
			<td></td>
			<td>custom developed in C++. Utilize GPU. Incorporated into the custom OCT acquisition code.</td>
		</tr>
		<tr>
			<td>Morphological and Physiological Analysis</td>
			<td></td>
			<td></td>
			<td>custom developed in MATLAB</td>
		</tr>
	</tbody>
</table>

longitudinal morphological and physiological monitoring of three-dimensional tumor spheroids using optical coherence tomography

Tumor spheroids have been developed as a three-dimensional (3D) cell culture model in cancer research and anti-cancer drug discovery. However, currently, high-throughput imaging modalities utilizing bright field or fluorescence detection, are unable to resolve the overall 3D structure of the tumor spheroid due to limited light penetration, diffusion of fluorescent dyes and depth-resolvability. Recently, our lab demonstrated the use of optical coherence tomography (OCT), a label-free and non-destructive 3D imaging modality, to perform longitudinal characterization of multicellular tumor spheroids in a 96-well plate. OCT was capable of obtaining 3D morphological and physiological information of tumor spheroids growing up to about 600 &#181;m in height. In this article, we demonstrate a high-throughput OCT (HT-OCT) imaging system that scans the whole multi-well plate and obtains 3D OCT data of tumor spheroids automatically. We describe the details of the HT-OCT system and construction guidelines in the protocol. From the 3D OCT data, one can visualize the overall structure of the spheroid with 3D rendered and orthogonal slices, characterize the longitudinal growth curve of the tumor spheroid based on the morphological information of size and volume, and monitor the growth of the dead-cell regions in the tumor spheroid based on optical intrinsic attenuation contrast. We show that HT-OCT can be used as a high-throughput imaging modality for drug screening as well as characterizing biofabricated samples.

High Throughput Optical Coherence Tomography Imaging of Spheroids in a 96-well Plate
Figure 3 exhibits the result of HT-OCT scanning of a 96-well plate with HCT 116 tumor spheroids on Day 3. The sequential scan of the whole plate starts from the bottom-right well (H12). Figure 3B shows the flow chart of the software implementation of the HT-OCT system. After one spheroid d...

Watch this Scientific Journal Video about Longitudinal Morphological and Physiological Monitoring of Three-dimensional Tumor Spheroids Using Optical Coherence Tomography at JoVE.com

Longitudinal Morphological and Physiological Monitoring of Three-dimensional Tumor Spheroids Using Optical Coherence Tomography

Optical coherence tomography (OCT), a three-dimensional imaging technology, was used to monitor and characterize the growth kinetics of multicellular tumor spheroids. Precise volumetric quantification of tumor spheroids using a voxel counting approach, and label-free dead tissue detection in the spheroids based on intrinsic optical attenuation contrast, were demonstrated.

Tumor spheroids have been developed as a three-dimensional (3D) cell culture model in cancer research and anti-cancer drug discovery. However, currently, ...

Three-dimensional tumor spheroids can mimic tissue-specific properties of tumors in vivo, providing more clinically-relevant data for anti-cancer drug discovery than simple 2D cell culture. Our imaging technique, optical coherence tomography, can easily visualize the 3D structure of a single tumorous nerves, with a size of several hundred microns, and provide more accurate characterization of its morphology and job infest, often within a few seconds. Using 3D spherical model we can potentially shorten the drug discovery timeline, reduce cost and bring new medicine to patients more effectively.Forming the spherical shape of tumor cluster is one critical step in our experiment. It is important to choose the right ultra-low attachment plate with the round bottom, and the proper centrifugation speed after cell seeding. Start this experiment by growing cells of interesting in a culture flask as described in the manuscript.Maintain the cells in an incubator under standard conditions, and monitor their health status every day. Refresh the media as needed. To perform 3D cell culture in multi-well plates, first remove the medium from the cell culture flask, and wash the cells with sterilized, 33 degree Celsius pre-warmed PBS.Then add one milliliter of Trypsin-EDTA to resuspend the cells and incubate for three minutes at 37 degrees Celsius. Add three milliliters of culture medium to dilute the Trypsin. Transfer this cell suspension into a 15 milliliter centrifuge tube, and centrifuge at 500G and room temperature for five minutes.Then remove the supernatant and resuspend the cell pellet with four milliliters of pre-warmed culture medium. To determine cell concentration, hypat one drop of sample onto a hemocytometer, and count the cells. Dilute to desired seeding concentration.Seed 200 microliters of cell suspension into each well of an ultra-low attachment, round-bottom multi-well plate, at a concentration of 3, 000 cells per milliliter, to achieve about 600 cells per well. Immediately after seeding, centrifuge the whole plate at the lowest speed available, at room temperature, for seven minutes. Place the plate in the incubator at 37 degrees Celsius and 5%Co2, making sure to refresh the medium every three days.First, construct the reference arm and sample arm of the OCT system, following the schematics in this manuscript. Then, construct the spectrometer, including a kilometer, a grading, an F-Theta lens and a line scan camera. Use a plate adapter to hold the multi-well plate in a fixed position.Before imaging, correct the tilting and rotation of the multi-well plate using a 2D tilting stage, and a rotation stage mounted on the transition stage to minimize variation of the focal plane from different wells. Then adjust the rotation to ensure the edges of the plate are parallel with the direction of the stage movement, so that the wells remain at the same horizontal positions in the OCT images. Then adjust the tilting stage to ensure the plate is parallel to the optical table, so that the wells remain at the same vertical locations for the imaging.On the day of the tumor spheroids imaging, remove the multi-well plate from the incubator. Transfer it under the OCT imaging system, and place it on the plate adapter. To adjust the height of the plate, move it along the Z direction of the translation stage.In the custom imaging software, set a desired OCT scanning range to cover the whole tumor spheroid, depending on its developmental stages, and click save parameters to save the setting. Then show the optimized XZ and YZ OCT previews of tumor spheroids. Acquire 3D OCT images of tumor spheroids one-by-one for all the wells of the plate containing spheroids.To view the preview image, click the preview button. And to acquire the OCT image, click the acquire button. Record the overall stage moving process of OCT data acquisition.To ensure the optimal image quality for all the tumor spheroids, the plate adapter need to be tuned accurately and the median volume need to be the same. Use a custom C+processing code to process 3D OCT data sets of tumor spheroids to generate OCT structural images. Use 2D OCT images in three cross-sectional, XY, XZ, and YZ planes across the centroid of the spheroid to generate the collage of spheroid images.To obtain 3D rendering of the spheroid using a desired software, first load the SD OCT data into the software. Click the surpass panel, then add new volume, and choose the blend mode to use for 3D rendering. To adjust the viewing angle, use the mouse pointer to drag the image and proceed with quantification as described in the manuscript.A collage of unfazed OCT images of HCT116 cell line spheroids was generated from the processed data, with results comparable with images from other 2D high-throughput imaging systems. Furthermore, the collage of 2D cross-sectional spheroid images from 96 wells was generated to monitor spheroid heights, and visualize spheroid inhomogeneity in the vertical direction. A collage of 3D-rendered spheroid images can be generated from any pre-defined angle to visualize the overall 3D shape and evaluate the roundness of the spheroid.After general OCT post-processing, 3D OCT structural images of a tumor spheroid have been obtained. From the OCT data, a 3D surface post and XZ, YZ, and XY orthogonal slices were generated to visualize the structure of the tumor spheroid in any direction. Longitudinal monitoring of a single tumor spheroid was performed to characterize its diameter, height, and voxel-based volume, generating the growth curves in size and volume during the 21-day development.Here, the spheroid became disrupted on day 11, and fully collapsed on day 21. Longitudinal tracking showed the increase of dead cell areas in the tumor spheroid. 3D-rendered images of the tumor spheroid showed the appearance and growth of dead cell regions from day seven to day 14, as shown by increase of red highlighted necrotic areas.As the percentage of the necrotic areas increased, the tumor spheroid could not maintain its perfect shape, and hence collapsed. With this imaging platform we can further explore other complex tumor sphere models, such as 3D imaging model, vast creature model and co-culture models to better simulate in vivo tumors. Our high-throughput OCT imaging system can provide an alterative approach for drug screening in cancer drug discovery.This is something also characterized, 3D biofabricated samples for various biomedical applications.

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Research

JoVE Journal

Cancer Research

Generation of High-Throughput Three-Dimensional Tumor Spheroids for Drug Screening

Cancer cells have routinely been cultured in two dimensions (2D) on a plastic surface. This technique, however, lacks the true environment a tumor mass is exposed to in vivo. Solid tumors grow not as a sheet attached to plastic, but instead as a collection of clonal cells in a three-dimensional (3D) space interacting with their neighbors, and with distinct spatial properties such as the disruption of normal cellular polarity. These interactions cause 3D-cultured cells to acquire morphological and cellular characteristics which are more relevant to in vivo tumors. Additionally, a tumor mass is in direct contact with other cell types such as stromal and immune cells, as well as the extracellular matrix from all other cell types. The matrix deposited is comprised of macromolecules such as collagen and fibronectin.
In an attempt to increase the translation of research findings in oncology from bench to bedside, many groups have started to investigate the use of 3D model systems in their drug development strategies. These systems are thought to be more physiologically relevant because they attempt to recapitulate the complex and heterogeneous environment of a tumor. These systems, however, can be quite complex, and, although amenable to growth in 96-well formats, and some now even in 384, they offer few choices for large-scale growth and screening. This observed gap has led to the development of the methods described here in detail to culture tumor spheroids in a high-throughput capacity in 1536-well plates. These methods represent a compromise to the highly complex matrix-based systems, which are difficult to screen, and conventional 2D assays. A variety of cancer cell lines harboring different genetic mutations are successfully screened, examining compound efficacy by using a curated library of compounds targeting the Mitogen-Activated Protein Kinase or MAPK pathway. The spheroid culture responses are then compared to the response of cells grown in 2D, and differential activities are reported. These methods provide a unique protocol for testing compound activity in a high-throughput 3D setting.

Across a wide variety of disease indications, more physiologically relevant models are being developed and implemented into drug discovery programs. The new model system described here demonstrates how three-dimensional tumor spheroids can be cultured and screened in a high-throughput 1536-well plate-based system to search for new oncology drugs.

Cancer cells have routinely been cultured in two dimensions (2D) on a plastic surface. This technique, however, lacks the true environment a tumor mass is ...

Three-Dimensional Bone Extracellular Matrix Model for Osteosarcoma

Osteosarcoma (OS) is the most common and a highly aggressive primary bone tumor. It is characterized with anatomic and histologic variations along with diagnostic or prognostic difficulties. OS comprises genotypically and phenotypically heterogeneous cancer cells. Bone microenvironment elements are proved to account for tumor heterogeneity and disease progression. Bone extracellular matrix (BEM) retains the microstructural matrices and biochemical components of native extracellular matrix. This tissue-specific niche provides a favorable and long-term scaffold for OS cell seeding and proliferation. This article provides a protocol for the preparation of BEM model and its further experimental application. OS cells can grow and differentiate into multiple phenotypes consistent with the histopathological complexity of OS clinical specimens. The model also allows visualization of diverse morphologies and their association with genetic alterations and underlying regulatory mechanisms. As homologous to human OS, this BEM-OS model can be developed and applied to the pathology and clinical research of OS.

The bone extracellular matrix (BEM) model for osteosarcoma (OS) is well established and shown here. It can be used as a suitable scaffold for mimicking primary tumor growth in vitro and providing an ideal model for studying the histologic and cytogenic heterogeneity of OS.

Osteosarcoma (OS) is the most common and a highly aggressive primary bone tumor. It is characterized with anatomic and histologic variations along with ...

Fully Human Tumor-based Matrix in Three-dimensional Spheroid Invasion Assay

Two-dimensional cell culture-based assays are commonly used in in vitro cancer research. However, they lack several basic elements that form the tumor microenvironment. To obtain more reliable in vitro results, several three-dimensional (3D) cell culture assays have been introduced. These assays allow cancer cells to interact with the extracellular matrix. This interaction affects cell behavior, such as proliferation and invasion, as well as cell morphology. Additionally, this interaction could induce or suppress the expression of several pro- and anti-tumorigenic molecules. Spheroid invasion assay was developed to provide a suitable 3D in vitro method to study cancer cell invasion. Currently, animal-derived matrices, such as mouse sarcoma-derived matrix (MSDM) and rat tail type I collagen, are mainly used in the spheroid invasion assays. Taking into consideration the differences between the human tumor microenvironment and animal-derived matrices, a human myoma-derived matrix (HMDM) was developed from benign uterus leiomyoma tissue. It has been shown that HMDM induces migration and invasion of carcinoma cells better than MSDM. This protocol provided a simple, reproducible, and reliable 3D human tumor-based spheroid invasion assay using the HMDM/fibrin matrix. It also includes detailed instructions on imaging and analysis. The spheroids grow in a U-shaped ultra-low attachment plate within the HMDM/fibrin matrix and invade through it. The invasion is daily imaged, measured, and analyzed using ilastik and Fiji ImageJ software. The assay platform was demonstrated using human laryngeal primary and metastatic squamous cell carcinoma cell lines. However, the protocol is suitable also for other solid cancer cell lines.

Tumor microenvironment is an essential part of cancer growth and invasion. To mimic carcinoma progression, a biologically relevant human matrix is needed. This protocol introduces an improvement for the in vitro three-dimensional spheroid invasion assay by applying a human leiomyoma-based matrix. The protocol also introduces a computer-based cell invasion analysis.

Two-dimensional cell culture-based assays are commonly used in in vitro cancer research. However, they lack several basic elements that form the tumor ...

Establishment and Characterization of Small Bowel Neuroendocrine Tumor Spheroids

Small bowel neuroendocrine tumors (SBNETs) are rare cancers originating from enterochromaffin cells of the gut. Research in this field has been limited because very few patient derived SBNET cell lines have been generated. Well-differentiated SBNET cells are slow growing and are hard to propagate. The few cell lines that have been established are not readily available, and after time in culture may not continue to express characteristics of NET cells. Generating new cell lines could take many years since SBNET cells have a long doubling time and many enrichment steps are needed in order to eliminate the rapidly dividing cancer-associated fibroblasts. To overcome these limitations, we have developed a protocol to culture SBNET cells from surgically removed tumors as spheroids in extracellular matrix (ECM). The ECM forms a 3-dimensional matrix that encapsulates SBNET cells and mimics the tumor micro-environment for allowing SBNET cells to grow. Here, we characterized the growth rate of SBNET spheroids and described methods to identify SBNET markers using immunofluorescence microscopy and immunohistochemistry to confirm that the spheroids are neuroendocrine tumor cells. In addition, we used SBNET spheroids for testing the cytotoxicity of rapamycin.

Neuroendocrine tumors (NETs) originate from neuroendocrine cells of the neural crest. They are slow growing and challenging to culture. We present an alternative strategy to grow NETs from the small bowel by culturing them as spheroids. These spheroids have small bowel NET markers and can be used for drug testing.

Small bowel neuroendocrine tumors (SBNETs) are rare cancers originating from enterochromaffin cells of the gut. Research in this field has been limited ...

A Three-dimensional Model of Spheroids to Study Colon Cancer Stem Cells

Colorectal cancers are characterized by heterogeneity and a hierarchical organization comprising a population of cancer stem cells (CSCs) responsible for tumor development, maintenance, and resistance to drugs. A better understanding of CSC properties for their specific targeting is, therefore, a pre-requisite for effective therapy. However, there is a paucity of suitable preclinical models for in-depth investigations. Although in vitro two-dimensional (2D) cancer cell lines provide valuable insights into tumor biology, they do not replicate the phenotypic and genetic tumor heterogeneity. In contrast, three-dimensional (3D) models address and reproduce near-physiological cancer complexity and cell heterogeneity. The aim of this work was to design a robust and reproducible 3D culture system to study CSC biology. The present methodology describes the development and optimization of conditions to generate 3D spheroids, which are homogenous in size, from Caco2 colon adenocarcinoma cells, a model that can be used for long-term culture. Importantly, within the spheroids, the cells which were organized around lumen-like structures, were characterized by differential cell proliferation patterns and by the presence of CSCs expressing a panel of markers. These results provide the first proof-of-concept for the appropriateness of this 3D approach to study cell heterogeneity and CSC biology, including the response to chemotherapy.

This protocol presents a novel, robust, and reproducible culture system to generate and grow three-dimensional spheroids from Caco2 colon adenocarcinoma cells. The results provide the first proof-of-concept for the appropriateness of this approach to study cancer stem cell biology, including the response to chemotherapy.

Colorectal cancers are characterized by heterogeneity and a hierarchical organization comprising a population of cancer stem cells (CSCs) responsible for ...

Three-Dimensional In Vitro Biomimetic Model of Neuroblastoma Using Collagen-Based Scaffolds

Neuroblastoma is the most common extracranial solid tumor in children, accounting for 15% of overall pediatric cancer deaths. The native tumor tissue is a complex three-dimensional (3D) microenvironment involving layers of cancerous and non-cancerous cells surrounded by an extracellular matrix (ECM). The ECM provides physical and biological support and contributes to disease progression, patient prognosis, and therapeutic response.
This paper describes a protocol for assembling a 3D scaffold-based system to mimic the neuroblastoma microenvironment using neuroblastoma cell lines and collagen-based scaffolds. The scaffolds are supplemented with either nanohydroxyapatite (nHA) or glycosaminoglycans (GAGs), naturally found at high concentrations in the bone and bone marrow, the most common metastatic sites of neuroblastoma. The 3D porous structure of these scaffolds allows neuroblastoma cell attachment, proliferation and migration, and the formation of cell clusters. In this 3D matrix, the cell response to therapeutics is more reflective of the in vivo situation.
The scaffold-based culture system can maintain higher cell densities than conventional two-dimensional (2D) cell culture. Therefore, optimization protocols for initial seeding cell numbers are dependent on the desired experimental timeframes. The model is monitored by assessing cell growth via DNA quantification, cell viability via metabolic assays, and cell distribution within the scaffolds via histological staining.
This model&#39;s applications include the assessment of gene and protein expression profiles as well as cytotoxicity testing using conventional drugs and miRNAs. The 3D culture system allows for the precise manipulation of cell and ECM components, creating an environment more physiologically similar to native tumor tissue. Therefore, this 3D in vitro model will advance the understanding of the disease pathogenesis and improve the correlation between results obtained in vitro, in vivo in&#160;animal models, and human subjects.

Three-Dimensional In Vitro Biomimetic Model of Neuroblastoma Using Collagen-Based Scaffolds

This paper lists the steps required to seed neuroblastoma cell lines on previously described three-dimensional collagen-based scaffolds, maintain cell growth for a predetermined timeframe, and retrieve scaffolds for several cell growth and cell behavior analyses and downstream applications, adaptable to satisfy a range of experimental aims.

Neuroblastoma is the most common extracranial solid tumor in children, accounting for 15% of overall pediatric cancer deaths. The native tumor tissue is a ...

A Three-Dimensional Spheroid Model to Investigate the Tumor-Stromal Interaction in Hepatocellular Carcinoma

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver cancer, rationalize its rank as the second most common cause of cancer-related death. Preclinical models need to be adapted to recapitulate the human conditions to select the best therapeutic candidates for clinical development and aid the delivery of personalized medicine. Three-dimensional (3D) cellular spheroid models show promise as an emerging in vitro alternative to two-dimensional (2D) monolayer cultures. Here, we describe a 3D tumor spheroid&#160;model which exploits the ability of individual cells to aggregate when maintained in hanging droplets, and is more representative of an in vivo environment than standard monolayers. Furthermore, 3D spheroids can be produced by combining homotypic or heterotypic cells, more reflective of the cellular heterogeneity in vivo, potentially enabling the study of environmental interactions that can influence progression and treatment responses. The current research optimized the cell density to form 3D homotypic and heterotypic tumor spheroids by immobilizing cell suspensions on the lids of standard 10 cm3 Petri dishes. Longitudinal analysis was performed to generate growth curves for homotypic versus heterotypic tumor/fibroblasts spheroids. Finally, the proliferative impact of fibroblasts (COS7 cells) and liver myofibroblasts (LX2) on homotypic tumor (Hep3B) spheroids was investigated. A seeding density of 3,000 cells (in 20 &#181;L media) successfully yielded Huh7/COS7 heterotypic spheroids, which displayed a steady increase in size up to culture day 8, followed by growth retardation. This finding was corroborated using Hep3B homotypic spheroids cultured in LX2 (human hepatic stellate cell line) conditioned medium (CM). LX2 CM triggered the proliferation of Hep3B spheroids compared to control tumor spheroids. In conclusion, this protocol has shown that 3D tumor spheroids can be used as a simple, economical, and prescreen in vitro tool to study tumor-stromal interactions more comprehensively.

Comprehensive in vitro models that faithfully recapitulate the relevant human disease are lacking. The current study presents three-dimensional (3D) tumor spheroid creation and culture, a reliable in vitro tool to study the tumor-stromal interaction in human hepatocellular carcinoma.

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver ...

Maintaining Human Glioblastoma Cellular Diversity Ex vivo using Three-Dimensional Organoid Culture

Glioblastoma (GBM) is the most commonly occurring primary malignant brain cancer with an extremely poor prognosis. Intra-tumoral cellular and molecular diversity, as well as complex interactions between tumor microenvironments, can make finding effective treatments a challenge. Traditional adherent or sphere culture methods can mask such complexities, whereas three-dimensional organoid culture can recapitulate regional microenvironmental gradients. Organoids are a method of three-dimensional GBM culture that better mimics patient tumor architecture, contains phenotypically diverse cell populations, and can be used for medium-throughput experiments. Although three-dimensional organoid culture is more laborious and time-consuming compared to traditional culture, it offers unique benefits and can serve to bridge the gap between current in vitro and in vivo systems. Organoids have established themselves as invaluable tools in the arsenal of cancer biologists to better understand tumor behavior and mechanisms of resistance, and their applications only continue to grow. Here, details are provided about methods for generating and maintaining GBM organoids. Instructions of how to perform organoid sample embedding and sectioning using both frozen and paraffin-embedding techniques, as well as recommendations for immunohistochemistry and immunofluorescence protocols on organoid sections, and measurement of total organoid cell viability, are all also described.

Maintaining Human Glioblastoma Cellular Diversity Ex vivo using Three-Dimensional Organoid Culture

Here, we describe a method of generating glioblastoma (GBM) organoids from primary patient specimens or patient-derived cell cultures and maintaining them to maturity. These GBM organoids contain phenotypically diverse cell populations and recreate tumor microenvironments ex vivo.

Glioblastoma (GBM) is the most commonly occurring primary malignant brain cancer with an extremely poor prognosis. Intra-tumoral cellular and molecular ...

Combining Reflectance Confocal Microscopy with Optical Coherence Tomography for Noninvasive Diagnosis of Skin Cancers via Image Acquisition

Skin cancer is one of the most common cancers worldwide. Diagnosis relies on visual inspection and dermoscopy followed by biopsy for histopathological confirmation. While the sensitivity of dermoscopy is high, the lower specificity results in 70%-80% of the biopsies being diagnosed as benign lesions on histopathology (false positives on dermoscopy).
Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) imaging can noninvasively guide the diagnosis of skin cancers. RCM visualizes cellular morphology in en-face layers. It has doubled the diagnostic specificity for melanoma and pigmented keratinocytic skin cancers over dermoscopy, halving the number of biopsies of benign lesions. RCM acquired billing codes in the USA and is now being integrated into clinics.
However, limitations such as the shallow depth (~200 &#181;m) of imaging, poor contrast for nonpigmented skin lesions, and imaging in en-face layers result in relatively lower specificity for the detection of nonpigmented basal cell carcinoma (BCCs) &#8212; superficial BCCs contiguous with the basal cell layer and deeper infiltrative BCCs. In contrast, OCT lacks cellular resolution but images tissue in vertical planes down to a depth of ~1 mm, which allows the detection of both superficial and deeper subtypes of BCCs. Thus, both techniques are essentially complementary.
A &#34;multi-modal,&#34; combined RCM-OCT device simultaneously images skin lesions in both en-face and vertical modes. It is useful for the diagnosis and management of BCCs (nonsurgical treatment for superficial BCCs vs. surgical treatment for deeper lesions). A marked improvement in specificity is obtained for detecting small, nonpigmented BCCs over RCM alone. RCM and RCM-OCT devices are bringing a major paradigm shift in the diagnosis and management of skin cancers; however, their use is currently limited to academic tertiary care centers and some private clinics. This paper familiarizes clinicians with these devices and their applications, addressing translational barriers into routine clinical workflow.

Here, we describe protocols for acquiring good-quality images using novel, noninvasive imaging devices of reflectance confocal microscopy (RCM) and combined RCM and optical coherence tomography (OCT). We also familiarize clinicians with their clinical applications so that they can integrate the techniques into regular clinical workflows to improve patient care.

Skin cancer is one of the most common cancers worldwide. Diagnosis relies on visual inspection and dermoscopy followed by biopsy for histopathological ...

Rapid Optical Clearing for Semi-High-Throughput Analysis of Tumor Spheroids

Tumor spheroids are fast becoming commonplace in basic cancer research and drug development. Obtaining data regarding protein expression within the spheroid at the cellular level is important for analysis, yet existing techniques are often expensive, laborious, use non-standard equipment, cause significant size distortion, or are limited to relatively small spheroids. This protocol presents a new method of mounting and clearing spheroids that address these issues while allowing for confocal analysis of the inner structure of spheroids. In contrast to existing approaches, this protocol provides for rapid mounting and clearing of a large number of spheroids using standard equipment and laboratory supplies. Mounting spheroids in a pH-neutral agarose-PBS gel solution before introducing a refractive-index-matched clearing solution minimizes size distortion common to other similar techniques. This allows for detailed quantitative and statistical analysis where the accuracy of size measurements is paramount. Furthermore, compared to liquid clearing solutions, the agarose gel technique keeps spheroids fixed in place, allowing for the collection of three-dimensional (3D) confocal images. The present article elaborates how the method yields high-quality two- and 3D images that provide information about inter-cell variability and inner spheroid structure.

Tumor spheroids are becoming increasingly utilized to assess tumor cell-microenvironment interactions and therapy response. The present protocol describes a robust but simple method for semi-high-throughput imaging of 3D tumor spheroids using rapid optical clearing.

Tumor spheroids are fast becoming commonplace in basic cancer research and drug development. Obtaining data regarding protein expression within the ...