The authors want to express gratitude to the Veterinary Diagnostic Laboratory of Iowa State University employees, namely, Haley M. Lambert, Emily Rahe, Rosalyn M. Branaman, Victoria J. Green, and Jennifer M. Groeltz-Thrush, for the timely processing of the samples provided. The authors wish to acknowledge support from the Faculty Startup, ISU VPR Miller Award, ISU VPR Miller Award, and NSF SBIR sub-award to ISU # 1912948.

<ol>
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K. Allenspach is a co-founder of LifEngine Animal Health and 3D Health Solutions. She serves as a consultant for Ceva Animal Health, Bioiberica, LifeDiagnostics, Antech Diagnostics, Deerland Probiotics, and Mars. J. P. Mochel is a co-founder of LifEngine Animal Health and 3D Health Solutions. Dr. Mochel serves as a consultant for Ceva Animal Health and Ethos Animal Health. Other authors do not have any conflicts of interest to declare.

There is currently a lack of standardized protocols available for the isolation and maintenance of canine hepatic and intestinal organoids. Establishing standard operating procedures for organoid cultures is warranted for this model to be applicable in different laboratory settings. Specifically, providing standardized operating protocols for the culture of these canine organoid models is key to characterizing organoids' normal growth during culture and passaging to derive optimal timepoints for expansion and maintenance. Canine intestinal organoids cultured using the protocol have been previously characterized by Chandra et al.12.
One of the most critical steps of the protocol is the passaging of organoids. The optimal time for the first passage of hepatic spheroids was determined to be on day 7 after isolation based on the hepatic spheroid measurements. The maximum volume of spheroids was achieved by day 7, and at the same time, spheroids began to bud and formed hepatic organoids. The increase in overall organoid volume from day 2-7 after isolation was more than 365 times, suggesting the optimal passage time is longer than the canine intestinal organoid culture. After 7 days in culture, no gross signs of cellular apoptosis in the hepatic spheroid were observed, even without cleaning or passaging (Figure 7). Passaging the intestinal and hepatic organoids can be challenging as the procedure can lead to the loss of cells and altered viability. The results indicate that prolonged incubation of hepatic organoids with trypsin-like protease (up to 12 min) does not negatively influence the subculture. Incubating the organoids in trypsin-like protease for longer than 24 min can be detrimental to the subsequent subculture of the organoids.
In case of suboptimal breakage in the cell clusters with the organoid passage, mechanical dissociation instead of prolonged incubation with trypsin-like protease might be more beneficial. If problems are encountered with proper dissociation of the organoids, brief vortexing of the samples may be attempted to enhance the passage yield. On the other hand, vortexing has the potential to ruin a culture and damage cells, so it should only be used when other procedures have failed repeatedly. Breaking hepatic organoids into single cells lowers the growth rate of the organoids, while breaking them into clusters of cells can greatly improve their viability. Ten minutes was chosen as the incubation time for the organoid protocol. A 12 min incubation timepoint was deemed not cytotoxic compared to a 24 min incubation in the trypsin-like protease experiment.
The survivability experiment confirmed that canine hepatic organoids could survive for up to 19.5 days in unfavorable conditions (structural and nutritional depletion). Organoids that survived these conditions the longest were cultured with CMGF+ media. This observation might have been caused by the slower growth of hepatic organoids in media not supplemented with Rock inhibitor and GSK3&#946;. Organoid cultures with CMGF+ R/G grew faster and may have depleted their resources faster. This experiment opens possibilities of miniaturizing the canine organoid culture to achieve a high-throughput system conversion. Such a technology shows the potential to facilitate drug discovery or toxicology studies at a substantially reduced cost.
Some common problems encountered during canine organoid culture maintenance are improper sample solidification when plating, culture contamination, and establishing the proper density and size of the organoids. If solubilized ECM solidifies prematurely during plating, immediately place it on ice for 10 min. If solubilized ECM does not form dome-like structures, it is likely that not enough media was removed from the sample. If this is the case, dilute the sample with a more solubilized ECM until domes form.
When fungal or bacterial contamination is found in an entire plate (see Figure 4), the best solution is to discard the plate. Treatment with antifungal or antibiotic drugs can be attempted, but the success of such an attempt is extremely low. If a single well is contaminated in a plate, viable and unaffected wells can be cleaned (follow steps 4.1 to 4.5) to a new plate and monitored closely. If the sample has already been Emergency Frozen, it is advisable to discard the entire sample, as thawing the sample exposes the incubator to additional contamination risk.
Healthy organoid culture should be at least in the medium size and medium density category or larger. Optimal density is crucial for organoid culture growth. Lower density must be corrected by cleaning the organoids to medium density. If the situation of extreme density occurs (overcrowding), the organoids should be expanded to more wells. Gross signs of cellular apoptosis often accompany both overcrowding and low density of the organoid culture. If these issues are not corrected in time, the whole organoid culture will turn apoptotic in a matter of days. If organoids achieve extra large size or very high density, the culture should be used for an experiment, freezing, or fixation.
The organoid media currently contains 17 components, and the addition of growth factors needed for organoid maintenance and expansion can therefore be expensive. This problem can be solved by growing 2D cell cultures that synthesize the growth factors to produce conditioned CMGF+. Cell culture L-WRN produces Wnt-3a, R-Spondin-3, and Noggin growth factors37. The cell colony uses 90% DMEM/F12 and 10% FBS culture media. When the culture achieves 90 percent confluency, media is harvested every day for 1 week. The harvested media is then mixed with 2x CMGF+ (without these growth factors). While 2D cultures can produce the needed growth factors at a fraction of the cost, the added time and preparation to produce the media must be expected. Concentrations of growth factors between conditioned media batches can also differ37,38.
Canine adult stem-cell-derived organoid cultures are a unique biomedical model that can help achieve the goals of the One Health Initiative39. The organoid technology can be used in many basic and biomedical research areas, spanning from developmental biology, pathophysiology, drug discovery and testing, toxicology to the study of infectious diseases and regenerative medicine40. Translational and reverse translational research are both areas where canine organoids are applicable15. Dogs have been used for centuries in translational experimental settings, and their companion animal status has also facilitated their position as one of the most explored species in veterinary medicine.
In conclusion, this manuscript provides standardized operating protocols for isolation, maintenance, harvesting, and biobanking of canine hepatic and intestinal organoids to facilitate the application of this model in various biomedical fields. This model is uniquely suitable to promote reverse translational research as a tool of the One Health Initiative to promote the inter and intradisciplinary sharing of knowledge.

Rodents are the most commonly utilized animal model for biomedical and translational research1. They are exceptionally useful for investigating basic molecular pathogenesis of the diseases, although their clinical relevance for chronic multifactorial diseases has recently been questioned2. The canine model exhibits several advantages in comparison to rodents3,4. Dogs and humans share similarities in metabolomics and intestinal microbiome that developed due to consumption of human diet throughout various periods of their domestication5,6,7. Similarities between canine and human gastrointestinal anatomy and physiology is another of the examples8.
Additionally, dogs often share similar environments and lifestyles with their owners9. The longer lifespan of dogs in comparison to rodents allows for the natural development of numerous chronic conditions10. Inflammatory bowel disease or metabolic syndrome are examples of multifactorial chronic diseases that share important similarities between humans and dogs11,12. Canine preclinical trials that involve dogs with naturally occurring diseases can generate more reliable data than those gained from rodent models13. However, to minimize the use of live animal research and comply with the principles of the 3Rs (Reduce, Refine, Replace)14, alternatives to in vivo testing using 3D in vitro canine organoids have emerged15.
Organoids are self-assembled 3D stem cell-derived structures that recapitulate the physiology and microanatomy of their original organs16,17. This technology was first described by Sato et al. in 200917 and allowed for more translatable in vitro studies in epithelial cell lines than were previously possible using 2D cancer cell cultures18,19,20. Organoids are useful in vitro models in many biomedical disciplines such as in preclinical toxicological21,22,23, absorption, or metabolism studies24,25,26,27,28, as well as in personalized medical approaches29,30,31. The successful culture of canine intestinal organoids has been described for the first time in 201912, while hepatic organoids derived from a dog were first reported by Nantasanti et al. in 201532. Canine organoids have since been successfully used in studies investigating canine chronic enteropathies, gastrointestinal stromal tumors, colorectal adenocarcinoma12, and Wilson&#39;s Disease33,34.
While adult stem cells can be harvested via necropsies, the organoid technology does not always require sacrificing of the animals. Endoscopic and laparoscopic biopsies, or even fine-needle aspirates of organs35, are a viable source of adult stem cells for epithelial organoid isolation12. Widespread use of such non-invasive techniques in veterinary practice facilitates options for reverse translational research&#160;(translation of information from veterinary clinical practice to human clinical practice and vice versa)15. Further advancement of organoid technology can be ensured by the standardization of organoid culture and maintenance methods. The organoid protocol presented here is partially based on previously published work of Saxena et al. from 201536, and methods were adapted to fit specifics of canine intestinal and hepatic organoid culture. The overall workflow of the canine organoid protocols is depicted in Figure 1.
Canine Organoid Isolation Protocol introduces methods of obtaining samples from endoscopic, laparoscopic,and surgical biopsies, as well as necropsies. It outlines the initial pre-treatment of tissue samples and methodologies used for transport to the laboratory. Materials and reagents needed for organoid isolation are summarized in the &#39;Preparation for Isolation&#39; section. The process of adult stem cell isolation from tissue samples is further described in detail. Finally, the process of plating organoids into dome-like structures using a solubilized extracellular membrane matrix is discussed.
The second protocol, Canine Organoid Maintenance Protocol, describes methods of documenting and culturing organoids. Media changes and their frequency are discussed in this section. Furthermore, the laboratory procedures such as passaging and cleaning the cell cultures, which are essential to ensure the successful maintenance of 3D canine organoids, are described. Appropriate passaging is a critical step of the protocol, and possible adjustments and troubleshooting of this step are discussed further in the manuscript.
The last protocol is Canine Organoid Harvesting and Biobanking Protocol containing methods for preparing full-grown organoids for paraffin-embedding and RNA preservation. Methods of biobanking organoid samples in liquid nitrogen storage are also described here. Finally, the ways to thaw frozen samples and support their growth are discussed.
In conclusion, this article aims to provide consistent canine organoid culture procedures through the standardization of inter-laboratory protocols. In doing so, the manuscript aims to facilitate the reproducibility of data derived from canine organoid models to increase their relevance in translational biomedical research.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63515/63515fig01.jpg" /> 
Figure 1: Workflow of canine organoid protocols. The Canine Organoid Isolation Protocol describes the preparation of the materials needed for organoid isolation, the harvesting of a tissue sample (through the means of necropsies, endoscopic, laparoscopic, and surgical biopsies), and guidance on cell dissociation and plating of the cellular population. The Canine Organoid Maintenance Protocol discusses cleaning and passaging of the organoid culture. The Organoid Harvesting and Biobanking Protocol discusses the preparation of organoid samples for paraffin-embedding and further organoid characterization. Methods to biobank organoid cultures and reviving them from storage in liquid nitrogen are also discussed. <a href="https://www.jove.com/files/ftp_upload/63515/63515fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chelating solution</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>D-Sorbitol</td>
			<td>Fisher Chemical</td>
			<td>BP439-500</td>
			<td></td>
		</tr>
		<tr>
			<td>DTT</td>
			<td>Promega</td>
			<td>V3151</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Fisher Chemical</td>
			<td>P217-500</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Sigma</td>
			<td>P5655-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2HPO4-2H2O</td>
			<td>Sigma</td>
			<td>S5136-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Fisher Chemical</td>
			<td>S271-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Pen Strep</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Fisher Chemical</td>
			<td>S5-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Organoid media</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>[Leu15]-Gastrin I human</td>
			<td>Sigma</td>
			<td>G9145-.5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>A-83-01</td>
			<td>PeproTech</td>
			<td>9094360</td>
			<td></td>
		</tr>
		<tr>
			<td>Advanced DMEM/F12</td>
			<td>Gibco</td>
			<td>12634-010</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 supplement</td>
			<td>Gibco</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Corning</td>
			<td>35-010-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamax</td>
			<td>Gibco</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>VWR Life Science</td>
			<td>J848-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Human R-Spondin-1</td>
			<td>PeproTech</td>
			<td>120-38-500UG</td>
			<td></td>
		</tr>
		<tr>
			<td>Murine EGF</td>
			<td>PeproTech</td>
			<td>315-09-1MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Murine Noggin</td>
			<td>PeproTech</td>
			<td>250-38-250UG</td>
			<td></td>
		</tr>
		<tr>
			<td>Murine Wnt-3a</td>
			<td>PeproTech</td>
			<td>315-20-10UG</td>
			<td></td>
		</tr>
		<tr>
			<td>N2 supplement</td>
			<td>Gibco</td>
			<td>17502-048</td>
			<td></td>
		</tr>
		<tr>
			<td>N-Acetyl-L-cysteine</td>
			<td>Sigma</td>
			<td>A9165-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Nicotinamide</td>
			<td>Sigma</td>
			<td>N0636-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Primocin</td>
			<td>InvivoGen</td>
			<td>ant-pm-1</td>
			<td></td>
		</tr>
		<tr>
			<td>ROCK inhibitor (Y-27632)</td>
			<td>EMD Millipore Corp.</td>
			<td>SCM 075</td>
			<td></td>
		</tr>
		<tr>
			<td>SB202190 (P38 inhibitor)</td>
			<td>Sigma</td>
			<td>S7067-25MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Stemolecule CHIR99021 (GSK3&#946;)</td>
			<td>Reprocell</td>
			<td>04-0004-base</td>
			<td></td>
		</tr>
		
		<tr>
			<td>Trimethoprim</td>
			<td>Sigma</td>
			<td>T7883-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfamethoxazole</td>
			<td>Sigma-Aldrich</td>
			<td>S7507-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic Acid, Glacial</td>
			<td>Fisher Chemical</td>
			<td>A38-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>Fisher Chemicals</td>
			<td>D128-500</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA, pH 8.0, 0.5 M</td>
			<td>Invitrogen</td>
			<td>15575-038</td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde (37%)</td>
			<td>Fisher Chemical</td>
			<td>F79P-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutaraldehyde solution</td>
			<td>Sigma</td>
			<td>G5882</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel Matrix For Organoid Culture</td>
			<td>Corning</td>
			<td>356255</td>
			<td>Extracellular Membrane Matrix</td>
		</tr>
		<tr>
			<td>Paraformaldehyde, 97%</td>
			<td>Alfa Aesar</td>
			<td>A11313</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS, 1X (Phosphate-Buffered Saline)</td>
			<td>Corning</td>
			<td>21-040-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS, 1X (Phosphate-Buffered Saline)</td>
			<td>Corning</td>
			<td>21-040-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAlater Soln.</td>
			<td>Invitrogen</td>
			<td>AM7021</td>
			<td>RNA Storage Reagent</td>
		</tr>
		<tr>
			<td>TrypLE Express</td>
			<td>Gibco</td>
			<td>12604-021</td>
			<td>Trypsin-like Protease</td>
		</tr>
		<tr>
			<td>Other</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6 Well Cell Culture Plate</td>
			<td>Corning</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>ACD Hybez II Hybridization System</td>
			<td>ACD a biotechne brand</td>
			<td>321710</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tube, 15 mL</td>
			<td>Corning</td>
			<td>430766</td>
			<td></td>
		</tr>
		<tr>
			<td>CoolCell LX</td>
			<td>Corning</td>
			<td>BCS-405MC</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryogenic Vials</td>
			<td>Corning</td>
			<td>430488</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable Centrifuge Tube (50 mL)</td>
			<td>Fisherbrand</td>
			<td>05-539-13</td>
			<td></td>
		</tr>
		<tr>
			<td>GyroMini Nutating mixer (Rocker)</td>
			<td>Labnet</td>
			<td>S0500-230V-EU</td>
			<td></td>
		</tr>
		<tr>
			<td>Heat Bath</td>
			<td>Lab-Line Instruments</td>
			<td>3000</td>
			<td></td>
		</tr>
		<tr>
			<td>Mr. Frosty Freezing Container</td>
			<td>ThermoFisher Scientific</td>
			<td>5100-0001</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop 2000</td>
			<td>ThermoFisher Scientific</td>
			<td>ND2000CLAPTOP</td>
			<td>SpectrophotometerAnalysis</td>
		</tr>
		<tr>
			<td>Panasonic incubator</td>
			<td>Panasonic</td>
			<td>MCO-170ML-PA</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm M Wrapping Film</td>
			<td>Bemis Company Inc</td>
			<td>PM996/EMD</td>
			<td>Laboratory Flexible Film Tape</td>
		</tr>
		<tr>
			<td>Protected Disposable Scalpels</td>
			<td>Bard-Parker</td>
			<td>239844</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAscope 2.5 HD Assay &#8211; RED</td>
			<td>ACD a biotechne brand</td>
			<td>322350</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAscope H2O2 &#38; Protease Plus Reagents</td>
			<td>ACD a biotechne brand</td>
			<td>322330</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAscope Target Retrieval Reagents</td>
			<td>ACD a biotechne brand</td>
			<td>322000</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAscope Wash Buffer Reagents</td>
			<td>ACD a biotechne brand</td>
			<td>310091</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Dish</td>
			<td>Dot Scientific</td>
			<td>6676621</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Plate 24 wells</td>
			<td>Fisherbrand</td>
			<td>FB012929</td>
			<td></td>
		</tr>
	</tbody>
</table>

standardization and maintenance of 3d canine hepatic and intestinal organoid cultures for use in biomedical research

Dogs develop complex multifactorial diseases analogous to humans, including inflammatory diseases, metabolic diseases, and cancer. Therefore, they represent relevant large animal models with the translational potential to human medicine. Organoids are 3-dimensional (3D), self-assembled structures derived from stem cells that mimic the microanatomy and physiology of their organ of origin. These translational in vitro models can be used for drug permeability and discovery applications, toxicology assessment, and to provide a mechanistic understanding of the pathophysiology of multifactorial chronic diseases. Furthermore, canine organoids can enhance the lives of companion dogs, providing input in various areas of veterinary research and facilitating personalized treatment applications in veterinary medicine. A small group of donors can create a biobank of organoid samples, reducing the need for continuous tissue harvesting, as organoid cell lines can be sub-cultured indefinitely. Herein, three protocols that focus on the culture of intestinal and hepatic canine organoids derived from adult stem cells are presented. The Canine Organoid Isolation Protocol outlines methods to process tissue and embedding of the cell isolate in a supportive matrix (solubilized extracellular membrane matrix). The Canine Organoid Maintenance Protocol describes organoid growth and maintenance, including cleaning and passaging along with appropriate timing for expansion. The Organoid Harvesting and Biobanking Protocol describes ways to extract, freeze, and preserve organoids for further analysis.

Watch this Scientific Journal Video about Standardization and Maintenance of 3D Canine Hepatic and Intestinal Organoid Cultures for Use in Biomedical Research at JoVE.com

Standardization and Maintenance of 3D Canine Hepatic and Intestinal Organoid Cultures for Use in Biomedical Research

Experimental methods to harvest adult stem cells from canine intestinal and hepatic tissues to establish 3D organoid cultures are described. Furthermore, the laboratory techniques to ensure consistent growth and provide standard operating procedures to harvest, biobank, and revive canine intestinal and hepatic organoid cultures are discussed.

Dogs develop complex multifactorial diseases analogous to humans, including inflammatory diseases, metabolic diseases, and cancer. Therefore, they ...

standardization-maintenance-3d-canine-hepatic-intestinal-organoid

Research

JoVE Journal

Medicine

4.4K Views.  Iowa State University. Experimental methods to harvest adult stem cells from canine intestinal and hepatic tissues to establish 3D organoid cultures are described. Furthermore, the laboratory techniques to ensure consistent growth and provide standard operating procedures to harvest, biobank, and revive canine intestinal and hepatic organoid cultures are discussed.

Video: Standardization and Maintenance of 3D Canine Hepatic and Intestinal Organoid Cultures for Use in Biomedical Research

In Vivo Canine Muscle Function Assay

We describe a minimally-invasive and reproducible method to measure canine pelvic limb muscle strength and muscle response to repeated eccentric 
contractions. The pelvic limb of an anesthetized dog is immobilized in a stereotactic frame to align the tibia at a right angle to the femur. Adhesive wrap affixes the 
paw to a pedal mounted on the shaft of a servomotor to measure torque. Percutaneous nerve stimulation activates pelvic limb muscles of the paw to either push (extend) or 
pull (flex) against the pedal to generate isometric torque. Percutaneous tibial nerve stimulation activates tibiotarsal extensor muscles. Repeated eccentric (lengthening) 
contractions are induced in the tibiotarsal flexor muscles by percutaneous peroneal nerve stimulation. The eccentric protocol consists of an initial isometric contraction 
followed by a forced stretch imposed by the servomotor. The rotation effectively lengthens the muscle while it contracts, e.g., an eccentric contraction. During 
stimulation flexor muscles are subjected to an 800 msec isometric and 200 msec eccentric contraction. This procedure is repeated every 5 sec. To avoid fatigue, 4 min rest 
follows every 10 contractions with a total of 30 contractions performed.

In Vivo Canine Muscle Function Assay

We describe a minimally-invasive and painless method to measure canine hindlimb muscle strength and muscle response to repeated eccentric contractions.

We describe a minimally-invasive and reproducible method to measure canine pelvic limb muscle strength and muscle response to repeated eccentric 
...

Generation of Alginate Microspheres for Biomedical Applications

Alginate-based materials have received considerable attention for biomedical applications because of their hydrophilic nature, biocompatibility, and physical architecture. Applications include cell encapsulation, drug delivery, stem cell culture, and tissue engineering scaffolds. In fact, clinical trials are currently being performed in which islets are encapsulated in PLO coated alginate microbeads as a treatment of type I diabetes. However, large numbers of islets are required for efficacy due to poor survival following transplantation. The ability to locally stimulate microvascular network formation around the encapsulated cells may increase their viability through improved transport of oxygen, glucose and other vital nutrients. Fibroblast growth factor-1 (FGF-1) is a naturally occurring growth factor that is able to stimulate blood vessel formation and improve oxygen levels in ischemic tissues. The efficacy of FGF-1 is enhanced when it is delivered in a sustained fashion rather than a single large-bolus administration. The local long-term release of growth factors from islet encapsulation systems could stimulate the growth of blood vessels directly towards the transplanted cells, potentially improving functional graft outcomes. In this article, we outline procedures for the preparation of alginate microspheres for use in biomedical applications. In addition, we describe a method we developed for generating multilayered alginate microbeads. Cells can be encapsulated in the inner alginate core, and angiogenic proteins in the outer alginate layer. The release of proteins from this outer layer would stimulate the formation of local microvascular networks directly towards the transplanted islets.

In the following sections, we outline procedures for the preparation of alginate microspheres for use in biomedical applications. We specifically illustrate a technique for creating multilayered alginate microspheres for the dual purpose of cell and protein encapsulation as a potential treatment for type 1 diabetes.

Alginate-based materials have received considerable attention for biomedical applications because of their hydrophilic nature, biocompatibility, and ...

The Bovine Lung in Biomedical Research: Visually Guided Bronchoscopy, Intrabronchial Inoculation and In Vivo Sampling Techniques

There is an ongoing search for alternative animal models in research of respiratory medicine. Depending on the goal of the research, large animals as models of pulmonary disease often resemble the situation of the human lung much better than mice do. Working with large animals also offers the opportunity to sample the same animal repeatedly over a certain course of time, which allows long-term studies without sacrificing the animals.
The aim was to establish in vivo sampling methods for the use in a bovine model of a respiratory Chlamydia psittaci infection. Sampling should be performed at various time points in each animal during the study, and the samples should be suitable to study the host response, as well as the pathogen under experimental conditions.
Bronchoscopy is a valuable diagnostic tool in human and veterinary medicine. It is a safe and minimally invasive procedure. This article describes the intrabronchial inoculation of calves as well as sampling methods for the lower respiratory tract. Videoendoscopic, intrabronchial inoculation leads to very consistent clinical and pathological findings in all inoculated animals and is, therefore, well-suited for use in models of infectious lung disease. The sampling methods described are bronchoalveolar lavage, bronchial brushing and transbronchial lung biopsy. All of these are valuable diagnostic tools in human medicine and could be adapted for experimental purposes to calves aged 6-8 weeks. The samples obtained were suitable for both pathogen detection and characterization of the severity of lung inflammation in the host.

The Bovine Lung in Biomedical Research: Visually Guided Bronchoscopy, Intrabronchial Inoculation and In Vivo Sampling Techniques

This article describes bronchoscopic techniques in the bovine lung under experimental conditions, i.e. bronchoscopically guided inoculation, bronchoalveolar lavage, bronchial brushing, and transbronchial lung biopsy.

There is an ongoing search for alternative animal models in research of respiratory medicine. Depending on the goal of the research, large animals as ...

Use of a Low-flow Digital Anesthesia System for Mice and Rats

A traditional vaporizer depends on flowing gas and atmospheric pressure for passive anesthetic vaporization. Newly developed direct injection vaporizers utilize a syringe pump to directly administer volatile anesthetics into a gas stream. Unlike a traditional vaporizer, it can be used at very low flow rates, making it ideal for use on mice and rats. 
The equipment's capability to use low flow rates could result in a substantial cost savings due to the reduced need for anesthetic agents, compressed gas, and charcoal scavenging filters1. A lower flow rate means less waste of anesthetic gas and likely reduces the risk of anesthetic exposure to laboratory personnel. Thus, the high levels of precision and safety associated with direct injection vaporizers, along with a reduced need for anesthetic agents, compressed gas, and charcoal filters are beneficial for research requiring small animal anesthesia. 
The goal of this protocol is to demonstrate the use of a syringe-driven direct injection vaporizer as part of a digital, low-flow anesthesia system. The direct injection vaporizer is capable of accurately delivering anesthesia at very low flow rates compared to a traditional vaporizer, making it a promising alternative for controlled gas anesthetic delivery to rodents.

Here, we present a protocol to more safely and efficiently administer anesthetic gas to mice using a digital, low flow anesthesia system utilizing a syringe-driven direct injection vaporizer.

A traditional vaporizer depends on flowing gas and atmospheric pressure for passive anesthetic vaporization. Newly developed direct injection vaporizers ...

Forskolin-induced Swelling in Intestinal Organoids: An In Vitro Assay for Assessing Drug Response in Cystic Fibrosis Patients

Recently-developed cystic fibrosis transmembrane conductance regulator (CFTR)-modulating drugs correct surface expression and/or function of the mutant CFTR channel in subjects with cystic fibrosis (CF). Identification of subjects that may benefit from these drugs is challenging because of the extensive heterogeneity of CFTR mutations, as well as other unknown factors that contribute to individual drug efficacy. Here, we describe a simple and relatively rapid assay for measuring individual CFTR function and response to CFTR modulators in vitro. Three dimensional (3D) epithelial organoids are grown from rectal biopsies in standard organoid medium. Once established, the organoids can be bio-banked for future analysis. For the assay, 30-80 organoids are seeded in 96-well plates in basement membrane matrix and are then exposed to drugs. One day later, the organoids are stained with calcein green, and forskolin-induced swelling is monitored by confocal live cell microscopy at 37 &#176;C. Forskolin-induced swelling is fully CFTR-dependent and is sufficiently sensitive and precise to allow for discrimination between the drug responses of individuals with different and even identical CFTR mutations. In vitro swell responses correlate with the clinical response to therapy. This assay provides a cost-effective approach for the identification of drug-responsive individuals, independent of their CFTR mutations. It may also be instrumental in the development of future CFTR modulators.

Forskolin-induced Swelling in Intestinal Organoids: An In Vitro Assay for Assessing Drug Response in Cystic Fibrosis Patients

This protocol describes an assay for measuring CFTR function and CFTR modulator responses in cultured tissue from subjects with cystic fibrosis (CF). Biopsy-derived intestinal organoids swell in a cAMP-driven fashion, a response that is defective (or strongly reduced) in CF organoids and can be restored by exposure to CFTR modulators.

Recently-developed cystic fibrosis transmembrane conductance regulator (CFTR)-modulating drugs correct surface expression and/or function of the mutant ...

Improvement of a Closed Chest Porcine Myocardial Infarction Model by Standardization of Tissue and Blood Sampling Procedures

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved drug to prevent or reduce myocardial I/R injury. The study and understanding of the pathophysiological mechanisms of myocardial I/R injury is essential to develop successful treatments. Large animal experiments are an important step in translational methods. The porcine model of acute myocardial infarction has been established and described by ourselves and others. We aimed to further improve the value of the model by focusing in detail on the sampling techniques for use in future experiments. Furthermore, we emphasize small but important steps that can affect the quality of the final results. To mimic the clinical situation of myocardial I/R injury, a percutaneous coronary intervention (PCI) catheter was inserted into the left anterior descending coronary artery (LAD) of an anesthetized pig. &#176;&#176;&#176;This model mimics acute myocardial infarction and PCI treatment in humans with the possibility of accurately determining the area at risk as well as the necrotic- and viable ischemic tissue. Here the model was used to investigate the effect of a bicyclic peptide inhibitor of FXIIa. The model can also be modified to allow longer reperfusion times to study later effects of myocardial infarction.

Here we demonstrate a protocol to standardize sampling procedures of an established porcine model of acute myocardial infarction in order to increase its translational value in the understanding of the pathophysiology of myocardial ischemia/reperfusion injury and to test novel drug candidates.

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved ...

Invasive Hemodynamic Characterization of the Portal-hypertensive Syndrome in Cirrhotic Rats

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. Portal hypertension (PHT) due to cirrhosis is responsible for the most severe complications in patients with liver disease. The full picture of the portal hypertensive syndrome is characterized by increased portal pressure (PP) due to the increased intrahepatic vascular resistance (IHVR), hyperdynamic circulation, and increased splanchnic blood flow. Progressive splanchnic arterial vasodilation and increased cardiac output with elevated heart rate (HR) but low arterial pressure characterizes the portal hypertensive syndrome.
Novel therapies are currently being developed that aim to decrease PP by either targeting IHVR or increased splanchnic blood flow &#8212; but side effects on systemic hemodynamics may occur. Thus, a detailed characterization of portal venous, splanchnic, and systemic hemodynamic parameters, including measurement of PP, portal venous blood flow (PVBF), mesenteric arterial blood flow, mean arterial pressure (MAP), and HR is needed for preclinical evaluation of the efficacy of novel treatments for PHT. Our video article provides the reader with a structured protocol for performing invasive hemodynamic measurements in cirrhotic rats. In particular, we describe the catheterization of the femoral artery and the portal vein via an ileocolic vein and the measurement of portal venous and splanchnic blood flow via perivascular Doppler-ultrasound flow probes. Representative results of different rat models of PHT are shown.

Here we describe a detailed protocol for invasive measurements of hemodynamic parameters including portal pressure, splanchnic blood flow, and systemic hemodynamics in order to characterize the portal hypertensive syndrome in rats.

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. ...

Generation of Human 3D Lung Tissue Cultures (3D-LTCs) for Disease Modeling

Translation of novel discoveries to human disease is limited by the availability of human tissue-based models of disease. Precision-cut lung slices (PCLS) used as 3D lung tissue cultures (3D-LTCs) represent an elegant and biologically highly relevant 3D cell culture model, which highly resemble in situ tissue due to their complexity, biomechanics and molecular composition. Tissue slicing is widely applied in various animal models. 3D-LTCs derived from human PCLS can be used to analyze responses to novel drugs, which might further help to better understand the mechanisms and functional effects of drugs in human tissue. The preparation of PCLS from surgically resected lung tissue samples of patients, who experienced lung lobectomy, increases the accessibility of diseased and peritumoral tissue. Here, we describe a detailed protocol for the generation of human PCLS from surgically resected soft-elastic patient lung tissue. Agarose was introduced into the bronchoalveolar space of the resectates, thus preserving lung structure and increasing the tissue&#39;s stiffness, which is crucial for subsequent slicing. 500 &#181;m thick slices were prepared from the tissue block with a vibratome. Biopsy punches taken from PCLS ensure comparable tissue sample sizes and further increase the amount of tissue samples. The generated lung tissue cultures can be applied in a variety of studies in human lung biology, including the pathophysiology and mechanisms of different diseases, such as fibrotic processes at its best at (sub-)cellular levels. The highest benefit of the 3D-LTC ex vivo model is its close representation of the in situ human lung in respect of 3D tissue architecture, cell type diversity and lung anatomy as well as the potential for assessment of tissue from individual patients, which is relevant to further develop novel strategies for precision medicine.

Generation of Human 3D Lung Tissue Cultures 3D-LTCs for Disease Modeling

Here, we present a protocol for the preparation of agarose-filled human precision-cut lung slices from resected patient tissue that are suitable for generating 3D lung tissue cultures to model human lung diseases in biological and biomedical studies.

Translation of novel discoveries to human disease is limited by the availability of human tissue-based models of disease. Precision-cut lung slices (PCLS) ...

Use of 3D Robotic Ultrasound for In Vivo Analysis of Mouse Kidneys

Common modalities for in vivo imaging of rodents include positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US). Each method has limitations and advantages, including availability, ease of use, cost, size, and the use of ionizing radiation or magnetic fields. This protocol describes the use of 3D robotic US for in vivo imaging of rodent kidneys and heart, subsequent data analysis, and possible research applications. Practical applications of robotic US are the quantification of total kidney volume (TKV), as well as the measurement of cysts, tumors, and vasculature. Although the resolution is not as high as other modalities, robotic US allows for more practical high throughput data collection. Furthermore, using US M-mode imaging, cardiac function may be quantified. Since the kidneys receive 20%-25% of the cardiac output, assessing cardiac function is critical to the understanding of kidney physiology and pathophysiology.

Use of 3D Robotic Ultrasound for In Vivo Analysis of Mouse Kidneys

This protocol demonstrates robotic ultrasound (US) as a practical, cost-effective, and quick alternative to traditional non-invasive image modalities.

Common modalities for in vivo imaging of rodents include positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), ...

Standardizing the Responses to Platelet Agonist Collagen-Related Peptide

Reproducibility and Harmonization in Research Using Biological Standards: The Example of Platelet Agonist Collagen-Related Peptide

Metrology - the science of measure - is a subject few biological scientists are taught about in their training to their detriment; the application of simple standardization processes to everyday working practices provides confidence in data and reproducibility over distance and time.
This method demonstrates how to standardize a core laboratory experiment used widely in hemostasis research and clinical practice, specifically, measuring responses to the platelet collagen receptor (glycoprotein [GP]VI) agonist collagen-related peptide, cross-linked (CRP-XL) by light transmission aggregometry (LTA). Using this approach will ensure intra-lab reproducibility and inter-lab harmonization, regardless of agonist stock or supplier. Importantly, this method is applicable to other platelet agonists and, indeed, many other biological molecules and bioassays.
The process outlined below involves making a 6-8 point dilution series of the &#39;standard&#39; and the &#39;test&#39; (the material you are checking) and running them side by side in a chosen assay (in this case, LTA). CRP-XL is used at mass/volume concentrations, but not every material gives the same biological activity at a given concentration, so a dilution series is made to compare the standard and test material and determine what concentration is needed to give equivalent activity. The dilution series must span 0-100% aggregation. Data is plotted using non-linear regression, and the EC50 value of each sample (standard and test) is determined. To assign activity, divide the EC50 value of the standard by that of the test to determine how much more or less potent it is and adjust the concentration accordingly. This approach will ensure that the same biological &#39;activity&#39; is added to the assay time and time again.

Author Spotlight: Biological Standardization to Ensure Reproducibility and Harmonization in Research 

Here we present a method to standardize the platelet agonist collagen-related peptide cross-linked (CRP-XL) using light transmission aggregometry. While the protocol is targeted at platelet function, the experimental process can be applied to most biological molecules and bioassays to ensure scientific rigor and reproducibility.

Metrology - the science of measure - is a subject few biological scientists are taught about in their training to their detriment; the application of ...