Name: a multi-hole cryovial eliminates freezing artifacts when muscle tissues are directly immersed in liquid nitrogen
Uploaded: 2017-04-06T14:00:00
Description: Watch this Scientific Journal Video about A Multi-hole Cryovial Eliminates Freezing Artifacts when Muscle Tissues are Directly Immersed in Liquid Nitrogen at JoVE.com

This project was supported by the National Natural Science Foundation of China (NSFC):&#160;31301950 and 31671288.

The current method has been established and validated to harvest and store more than 1,000 muscle samples for histological staining in our laboratory. All procedures involving animal care and use followed the guidelines established by the Ministry of Agriculture of China.
1. Equipment for Sample Collection
<ol>
	<li>Label the sample identity on each cryogenic vial. 
	Note: The cryogenic vial is specially designed to freeze fresh tissue samples for the cryosection procedure (Figure 1A). The ...

<ol>
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Here, we describe a new, multi-hole cryovial for freezing and storing muscle tissues to perform histological assessments of muscle function. The critical modified step in this protocol is that the sample in the multi-hole cryovial is directly immersed in liquid nitrogen. To our knowledge, this is the simplest and rapidest way to obtain excellent frozen samples for muscle cryosectioning among the existing freezing methods (see the representative results).
The technical challenge faced by muscle...

Skeletal muscle is the most valuable component of a meat-producing animal from the nutritional and processing point of view. In the meat industry, there are two especially critical aspects: the efficiency of muscle growth and the quality of the resulting meat. As a main component of the muscle, muscle fibers are directly related to growth performance and fresh meat quality in animals1. For example, the Total number of Fibers (TNF) and the Cross-sectional area of Fibers (CSAF) mostly determine muscle mass and meat quality; also, Fiber Type Composition (FTC) strongly affects fresh meat quality2. Therefore, the manipulation of muscle fiber characteristics in animals is a highly effective method to increase the core profitability and competitiveness of farms1.
To date, several intrinsic and extrinsic factors have been identified to manipulate muscle fiber characteristics1. This manipulation can be achieved through the targeted selection of animals with specific genes, such as the Myostatin gene in cattle3, the Callipyge gene in sheep4, and the RYR1 and IGF2 genes in pigs5. Also, diet control and treatments with specific hormones play an important role in muscle fiber characteristics6. Thus, an approach that combines genetic and nutritional factors might be able to improve lean meat content and meat quality. However, studies on muscle fibers are limited in the meat industry because the elucidation of the structure of muscle fibers still is a challenge.
Muscle fiber properties are identified using histochemical methods, such as the myosin adenosine triphosphatase (ATPase) assay. This method relies on the fact that enzymes located in thin (6-8 &#181;m) frozen sections of muscle fibers can be chemically reacted with certain products. However, the water content of muscles is greater than 75% in pigs, rabbits, mice, and humans, regardless of the position (i.e., back, abdomen, or hindlimb)7. Such high moisture content in muscles causes a commonly encountered issue &#8211; freezing artifacts &#8211; during the preparation of cryosections, as previously described8,9. In most cases, it is almost impossible to appropriately freeze muscle tissues in a slaughterhouse production line, according to our experience.
The protocol presented here describes a simple and efficient method used in our laboratory to freeze muscle tissues for cryosectioning in a high-throughput manner. The highlight of this method is a new cryovial that is designed for flash-freezing muscle tissues in liquid nitrogen. The current workflow can concurrently facilitate tissue freezing and processing for an excellent muscle cryosection, with a clearly visible cytoplasmic compartment and the tight apposition of myofibers to the surrounding tissue. In addition, this protocol can be applied to a wide array of options for tissue analysis because liquid nitrogen does not mix with tissues.

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			<td height="21" style="height:21px;width:140px;">Cryostat Microtome</td>
			<td style="width:111px;">&#160;Leica</td>
			<td style="width:111px;">Leica CM1950</td>
			<td style="width:148px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital Microscope&#160;</td>
			<td>Nikon</td>
			<td>Nikon DS-U3</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:140px;">&#160;Cryogenic Vial&#160;&#160; Plastic film</td>
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			<td></td>
			<td>Designed by ourself</td>
		</tr>
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			<td height="21" style="height:21px;">Liquid Nitrogen</td>
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			<td></td>
			<td>Commomly-used</td>
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			<td height="21" style="height:21px;">Scalpel</td>
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			<td>Commomly-used</td>
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			<td height="21" style="height:21px;">10cm-forcep</td>
			<td></td>
			<td></td>
			<td>Commomly-used</td>
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		<tr height="21">
			<td height="21" style="height:21px;">25cm-tweezer</td>
			<td></td>
			<td></td>
			<td>Commomly-used</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Safety glass</td>
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			<td></td>
			<td>Commomly-used</td>
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			<td height="20" style="height:20px;">Freezer gloves</td>
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			<td></td>
			<td>Commomly-used</td>
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a multi-hole cryovial eliminates freezing artifacts when muscle tissues are directly immersed in liquid nitrogen

Studies on skeletal muscle physiology face the technical challenge of appropriately processing the specimens to obtain sections with clearly visible cytoplasmic compartments. Another hurdle is the tight apposition of myofibers to the surrounding tissues. Because the process of tissue fixation and paraffin embedding leads to the shrinkage of muscle fibers, freezing is an optimal means of hardening muscle tissue for sectioning. However, a commonly encountered issue, the formation of ice crystals, occurs during the preparation of frozen sections because of the high water content of muscle. The protocol presented here first describes a simple and efficient method for properly freezing muscle tissues by immersing them in liquid nitrogen. The problem with using liquid nitrogen alone is that it causes the formation of a nitrogen gas barrier next to the tissue, which acts as an insulator and inhibits the cooling of the tissues. To avoid this "vapor blanket" effect, a new cryovial was designed to increase the speed of liquid flow around the tissue surface. This was achieved by punching a total of 14 inlet holes in the wall of the vial. According to bubble dynamics, a higher rate of liquid flow results in smaller bubbles and fewer chances to form a gas barrier. When liquid nitrogen flows into the cryovial through the inlet holes, the flow velocity around the tissue is fast enough to eliminate the gas barrier. Compared to the method of freezing muscle tissues using pre-chilled isopentane, this protocol is simpler and more efficient and can be used to freeze muscle in a throughput manner. Furthermore, this method is optimal for institutions that do not have access to isopentane, which is extremely flammable at room temperature.

The cryovial illustration and the common laboratory equipment for freezing muscles during the preparation of frozen sections are shown in Figure 1. The cryovials are made of polypropylene in a mold factory. Each vial has a total of 14 inlet holes: one is on the cap; another is at the bottom; and the remaining 12 form four parallel lines, each with four holes at 90&#176; to one another. These inlet holes can speed up the flow velocity of liquid nitrogen next to the tissue ...

Watch this Scientific Journal Video about A Multi-hole Cryovial Eliminates Freezing Artifacts when Muscle Tissues are Directly Immersed in Liquid Nitrogen at JoVE.com

A Multi-hole Cryovial Eliminates Freezing Artifacts when Muscle Tissues are Directly Immersed in Liquid Nitrogen

This protocol describes a procedure to freeze muscle tissues by plunging them directly into liquid nitrogen. This protocol also highlights a new cryovial that can avoid the &#34;blanket effect&#34; of nitrogen gas when liquid nitrogen contacts the tissue surface of a specimen.

Studies on skeletal muscle physiology face the technical challenge of appropriately processing the specimens to obtain sections with clearly visible ...

The overall goal of this procedure is to freeze muscle tissues, by plunging them directly into liquid nitrogen while eliminating freezing artifacts. Maozhang He, a student from my laboratory will demonstrate this procedure with Yizhong Huang. To begin, label the sample identity on each cryogenic vial.Then, organize the following equipment:a tank of liquid nitrogen, safety glasses or a face shield, freezer gloves, 10 centimeter forceps, and 25 centimeter tweezers. Also, organize a styrofoam cooler, plastic film, a scalpel, and A4 PVC binding covers. To prepare muscle samples, begin by filling the cooler with liquid nitrogen.Within five minutes of obtaining a specimen, gently place the sample on a piece of A4 PVC binding cover, and observe the direction of the muscle fibers. Next, use a scalpel to make two parallel incisions through the specimen in the direction of the muscle fibers, approximately 3 centimeters in length, and 0.6 centimeters apart. Trim the incised muscle into a rectangle approximately 0.6 centimeters wide, by 0.6 centimeters high, by 1.5 centimeters long.Then, using ten centimeter forceps, gently put the sample on a piece of plastic film with the longitudinal axis of the incised muscle parallel to the long edge of the film. Place the muscle tissue into the lower middle of a labeled cryogenic vial, just between the inlet holes, and tightly cap the vial. To freeze the tissue sample, use 25 centimeter tweezers to quickly submerge the whole cryogenic vial in liquid nitrogen, in the pre-cooled styrofoam cooler, waiting until the liquid nitrogen no longer boils.The liquid nitrogen should be adequate to immerse the whole cryovial, and the cryogenic vial should be entirely below the liquid level. Transfer the muscle samples to a liquid nitrogen storage tank, or a 80 degree celsius freezer for long-term storage. It is important to avoid accidental contact between the frozen muscles and the room temperature containers or instruments.To prepare slides, pre-cool a cryostat to between 20 degrees celsius, and 22 degrees celsius. Remove and discard the old microtone blade, and wipe down the knife holder, and anti-roll plate in the cryostat. Then, install a new microtone blade in the cryostat, and set the cutting thickness to eight micrometers.Remove the cryogenic vial with the muscle sample from the liquid nitrogen storage tank, or 80 degree celsius freezer, and place it in the liquid nitrogen, or on dry ice. Then, transfer the sample to the cryostat, and wait 30 minutes for the specimen to equilibrate with the temperature of the cryostat. After using OCT to embed the sample, mount the sample in the specimen holder.Then, cut eight micrometer sections. Mount the sections towards the center of a room temperature micro slide. Immediately place the slide into a slide box.Then, place the box of slides in a 80 degree celsius freezer. Do not allow the slide to dry at room temperature. As seen here, ice crystals formed when a sample of longissimus dorsi muscle from pigs was placed directly in a 80 degree celsius freezer, and caused a well known Swiss cheese effect on the muscle cryo-section.Ice crystals also formed when the muscle tissue was immersed directly in liquid nitrogen. Using another method, many needle-like ice crystals formed in the cytoplasmic compartment of myofibers when the tissue was dipped in OCT mounting medium in the proper orientation, and then rapidly frozen in a slurry of isopentane. Freezing the tissue into the multi-hole cryovial achieves excellent specimen integrity, with a clearly visible cytoplasmic compartment and the tight apposition of myofibers to the surrounding tissue.Using this method, ATPase activity was analyzed in fast-contracting, and slow-contracting muscle fibers. When given equivalent times, fast-contracting fibers appear light, with two degrees, and slow-contracting fibers appear black. In a standard freezing method shown here, muscle tissue was submerged in a slurry of isopentane without direct contact with OCT mounting medium, however a solid liquid slurry state of isopentane is difficult to maintain for more than one hour, and isopentane is not always available.

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Research

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Biology

Freezing Human ES Cells

Here we demonstrate how our lab freezes HuES human embryonic stem cell lines.  A healthy, exponentially expanding culture is washed with PBS to remove residual media that could otherwise quench the Trypsin reaction.  Warmed 0.05% Trypsin-EDTA is then added to cover the cells, and the plate allowed to incubate for up to 5 mins at room temperature.  During this time cells can be observed rounding, and colonies lifting off the plate surface.  Gentle repeated pipetting will remove cells and colonies from the plate surface.  Trypsinized cells are placed in a standard conical tube containing pre-warmed hES cell media to quench remaining trypsin, and then spun.  Cells are resuspended growth media at a concentration of approximately one million cells in one mL of media, a concentration such that one frozen aliquot is sufficient to resurrect a culture on a 10cm plate.  After cells are adequately resuspended, ice cold freezing media is added at equal volume.  Cell suspensions are mixed thoroughly, aliquoted into freezing vials, and allowed to slowly freeze to -80C over 24 hours.  Frozen cells can then moved to the vapor phase of liquid nitrogen for long term storage, or remain at -80 for approximately six months.

Here we demonstrate how our lab freezes HuES human embryonic stem cell lines.

Here we demonstrate how our lab freezes HuES human embryonic stem cell lines.  A healthy, exponentially expanding culture is washed with PBS to remove ...

Culturing of Human Nasal Epithelial Cells at the Air Liquid Interface

In vitro models using human primary epithelial cells are essential in understanding key functions of the respiratory epithelium in the context of microbial infections or inhaled agents. Direct comparisons of cells obtained from diseased populations allow us to characterize different phenotypes and dissect the underlying mechanisms mediating changes in epithelial cell function. Culturing epithelial cells from the human tracheobronchial region has been well documented, but is limited by the availability of human lung tissue or invasiveness associated with obtaining the bronchial brushes biopsies. Nasal epithelial cells are obtained through much less invasive superficial nasal scrape biopsies and subjects can be biopsied multiple times with no significant side effects. Additionally, the nose is the entry point to the respiratory system and therefore one of the first sites to be exposed to any kind of air-borne stressor, such as microbial agents, pollutants, or allergens. 
Briefly, nasal epithelial cells obtained from human volunteers are expanded on coated tissue culture plates, and then transferred onto cell culture inserts. Upon reaching confluency, cells continue to be cultured at the air-liquid interface (ALI), for several weeks, which creates more physiologically relevant conditions. The ALI culture condition uses defined media leading to a differentiated epithelium that exhibits morphological and functional characteristics similar to the human nasal epithelium, with both ciliated and mucus producing cells. Tissue culture inserts with differentiated nasal epithelial cells can be manipulated in a variety of ways depending on the research questions (treatment with pharmacological agents, transduction with lentiviral vectors, exposure to gases, or infection with microbial agents) and analyzed for numerous different endpoints ranging from cellular and molecular pathways, functional changes, morphology, etc. 
In vitro models of differentiated human nasal epithelial cells will enable investigators to address novel and important research questions by using organotypic experimental models that largely mimic the nasal epithelium in vivo.

Nasal epithelial cells, obtained through superficial scrape biopsy of human volunteers, are expanded and transferred onto tissue culture inserts. Upon reaching confluency, cells are grown at air liquid interface, yielding cultures of ciliated and non-ciliated cells. Differentiated nasal epithelial cell cultures provide viable experimental models for studying the respiratory mucosa.

In vitro models using human primary  epithelial cells are essential in understanding key functions of the respiratory  epithelium in the context of ...

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Mutations in actin cause a range of human diseases due to specific molecular changes that often alter cytoskeletal function. In this study, imaging of fluorescently tagged proteins using total internal fluorescence (TIRF) microscopy is used to visualize and quantify changes in cytoskeletal dynamics. TIRF microscopy and the use of fluorescent tags also allows for quantification of the changes in cytoskeletal dynamics caused by mutations in actin. Using this technique, quantification of cytoskeletal function in live cells valuably complements in vitro studies of protein function. As an example, missense mutations affecting the actin residue R256 have been identified in three human actin isoforms suggesting this amino acid plays an important role in regulatory interactions. The effects of the actin mutation R256H on cytoskeletal movements were studied using the yeast model. The protein, Aip1, which is known to assist cofilin in actin depolymerization, was tagged with green fluorescent protein (GFP) at the N-terminus and tracked in vivo using TIRF microscopy. The rate of Aip1p movement in both wild type and mutant strains was quantified. In cells expressing R256H mutant actin, Aip1p motion is restricted and the rate of movement is nearly half the speed measured in wild type cells (0.88 &#177; 0.30 &#956;m/sec in R256H cells compared to 1.60 &#177; 0.42 &#956;m/sec in wild type cells, p &#60; 0.005).

Disease-causing mutations in actin can alter cytoskeletal function. Cytoskeletal dynamics are quantified through imaging of fluorescently tagged proteins using total internal fluorescence microscopy. As an example, the cytoskeletal protein, Aip1p, has altered localization and movement in cells expressing the mutant actin isoform, R256H.

Mutations in actin cause a range of human diseases due to specific molecular changes that often alter cytoskeletal function. In this study, imaging of ...

Tissue Triage and Freezing for Models of Skeletal Muscle Disease

Skeletal muscle is a unique tissue because of its structure and function, which requires specific protocols for tissue collection to obtain optimal results from functional, cellular, molecular, and pathological evaluations. Due to the subtlety of some pathological abnormalities seen in congenital muscle disorders and the potential for fixation to interfere with the recognition of these features, pathological evaluation of frozen muscle is preferable to fixed muscle when evaluating skeletal muscle for congenital muscle disease. Additionally, the potential to produce severe freezing artifacts in muscle requires specific precautions when freezing skeletal muscle for histological examination that are not commonly used when freezing other tissues. This manuscript describes a protocol for rapid freezing of skeletal muscle using isopentane (2-methylbutane) cooled with liquid nitrogen to preserve optimal skeletal muscle morphology. This procedure is also effective for freezing tissue intended for genetic or protein expression studies. Furthermore, we have integrated our freezing protocol into a broader procedure that also describes preferred methods for the short term triage of tissue for (1) single fiber functional studies and (2) myoblast cell culture, with a focus on the minimum effort necessary to collect tissue and transport it to specialized research or reference labs to complete these studies. Overall, this manuscript provides an outline of how fresh tissue can be effectively distributed for a variety of phenotypic studies and thereby provides standard operating procedures (SOPs) for pathological studies related to congenital muscle disease.

The analysis of skeletal muscle tissues to determine structural, functional, and biochemical properties is greatly facilitated by appropriate preparation. This protocol describes appropriate methods to prepare skeletal muscle tissue for a broad range of phenotyping studies.

Skeletal muscle is a unique tissue because of its structure and function, which requires specific protocols for tissue collection to obtain optimal ...

Tandem High-pressure Freezing and Quick Freeze Substitution of Plant Tissues for Transmission Electron Microscopy

Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, because of laborious and time-consuming protocols that also demand experience in preparation of artifact-free samples, TEM is not considered a user-friendly technique. Traditional sample preparation for TEM used chemical fixatives to preserve cellular structures. High-pressure freezing is the cryofixation of biological samples under high pressures to produce very fast cooling rates, thereby restricting ice formation, which is detrimental to the integrity of cellular ultrastructure. High-pressure freezing and freeze substitution are currently the methods of choice for producing the highest quality morphology in resin sections for TEM. These methods minimize the artifacts normally associated with conventional processing for TEM of thin sections. After cryofixation the frozen water in the sample is replaced with liquid organic solvent at low temperatures, a process called freeze substitution. Freeze substitution is typically carried out over several days in dedicated, costly equipment. A recent innovation allows the process to be completed in three hours, instead of the usual two days. This is typically followed by several more days of sample preparation that includes infiltration and embedding in epoxy resins before sectioning. Here we present a protocol combining high-pressure freezing and quick freeze substitution that enables plant sample fixation to be accomplished within hours. The protocol can readily be adapted for working with other tissues or organisms. Plant tissues are of special concern because of the presence of aerated spaces and water-filled vacuoles that impede ice-free freezing of water. In addition, the process of chemical fixation is especially long in plants due to cell walls impeding the penetration of the chemicals to deep within the tissues. Plant tissues are therefore particularly challenging, but this protocol is reliable and produces samples of the highest quality.

Obtaining high-quality transmission electron microscopy images is challenging, especially in the case of plant cells, which have abundant large water-filled vacuoles and aerated spaces. Tandem high-pressure freezing and quick freeze substitution greatly reduce preparation time of plant samples for TEM while producing samples with excellent ultrastructural preservation.

Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, ...

The Ingestion of Fluorescent, Magnetic Nanoparticles for Determining Fluid-uptake Abilities in Insects

Fluid-feeding insects ingest a variety of liquids, which are present in the environment as pools, films, or confined to small pores. Studies of liquid acquisition require assessing mouthpart structure and function relationships; however, fluid uptake mechanisms are historically inferred from observations of structural architecture, sometimes unaccompanied with experimental evidence. Here, we report a novel method for assessing fluid-uptake abilities with butterflies (Lepidoptera) and flies (Diptera) using small amounts of liquids. Insects are fed with a 20% sucrose solution mixed with fluorescent, magnetic nanoparticles from filter papers of specific pore sizes. The crop (internal structure used for storing fluids) is removed from the insect and placed on a confocal microscope. A magnet is waved by the crop to determine the presence of nanoparticles, which indicate if the insects are able to ingest fluids. This methodology is used to reveal a widespread feeding mechanism (capillary action and liquid bridge formation) that is potentially shared among Lepidoptera and Diptera when feeding from porous surfaces. In addition, this method can be used for studies of feeding mechanisms among a variety of fluid-feeding insects, including those important in disease transmission and biomimetics, and potentially other studies that involve nano- or micro-sized conduits where liquid transport requires verification.

Fluid-feeding insects have the ability to acquire minute quantities of liquids from porous surfaces. This protocol describes a method to directly determine the ability for insects to ingest liquids from porous surfaces using feeding solutions with fluorescent, magnetic nanoparticles.

Fluid-feeding insects ingest a variety of liquids, which are present in the environment as pools, films, or confined to small pores. Studies of liquid ...

Rapid Freezing using Sandwich Freezing Device for Good Ultrastructural Preservation of Biological Specimens in Electron Microscopy

Chemical fixation has been used for observing the ultrastructure of cells and tissues. However, this method does not adequately preserve the ultrastructure of cells; artifacts and extraction of cell contents are usually observed. Rapid freezing is a better alternative for the preservation of cell structure. Sandwich freezing of living yeast or bacteria followed by freeze-substitution has been used for observing the exquisite natural ultrastructure of cells. Recently, sandwich freezing of glutaraldehyde-fixed cultured cells or human tissues has also been used to reveal the ultrastructure of cells and tissues. 
These studies have thus far been carried out with a handmade sandwich freezing device, and applications to studies in other laboratories have been limited. A new sandwich freezing device has recently been fabricated and is now commercially available. The present paper shows how to use the sandwich freezing device for rapid freezing of biological specimens, including bacteria, yeast, cultured cells, isolated cells, animal and human tissues, and viruses. Also shown is the preparation of specimens for ultrathin sectioning after rapid freezing and procedures for freeze-substitution, resin embedding, trimming of blocks, cutting of ultrathin sections, recovering of sections, staining, and covering of grids with support films.

Here we show how to use the sandwich freezing device for rapid freezing of biological specimens, including bacteria, yeast, cultured cells, isolated cells, animal and human tissues, and viruses. We also show how to prepare specimens for ultrathin sectioning after rapid freezing.

Chemical fixation has been used for observing the ultrastructure of cells and tissues. However, this method does not adequately preserve the ...

A Simple and Inexpensive Running Wheel Model for Progressive Resistance Training in Mice

Previously developed rodent resistance-based exercise models, including synergistic ablation, electrical stimulation, weighted-ladder climbing, and most recently, weighted-sled pulling, are highly effective at providing a hypertrophic stimulus to induce skeletal muscle adaptations. While these models have proven invaluable for skeletal muscle research, they are either invasive or involuntary and labor-intensive. Fortunately, many rodent strains voluntarily run long distances when given access to a running wheel. Loaded wheel running (LWR) models in rodents are capable of inducing adaptations commonly observed with resistance training in humans, such as increased muscle mass and fiber hypertrophy, as well as stimulation of muscle protein synthesis. However, the addition of moderate wheel load either fails to deter mice from running great distances, which is more reflective of an endurance/resistance training model, or the mice discontinue running nearly entirely due to the method of load application. Therefore, a novel high-load wheel running model (HLWR) has been developed for mice where external resistance is applied and progressively increased, enabling mice to continue running with much higher loads than previously utilized. Preliminary results from this novel HLWR model suggest it provides sufficient stimulus to induce hypertrophic adaptations over the 9 week training protocol. Herein, the specific procedures to execute this simple yet inexpensive progressive resistance-based exercise training model in mice are described.

This procedure describes a translatable progressive loaded running wheel resistance training model in mice. The primary advantage of this resistance training model is that it is entirely voluntary, thus reducing stress for the animals and the burden on the researcher.

Previously developed rodent resistance-based exercise models, including synergistic ablation, electrical stimulation, weighted-ladder climbing, and most ...

Culturing, Freezing, Processing, and Imaging of Entire Organoids and Spheroids While Still in a Hydrogel

Organoids and spheroids, three-dimensional growing structures in cell culture labs, are becoming increasingly recognized as superior models compared to two-dimensional culture models, since they mimic the human body better and have advantages over animal studies. However, these studies commonly face problems with reproducibility and consistency. During the long experimental processes - with transfers of organoids and spheroids between different cell culture vessels, pipetting, and centrifuging - these susceptible and fragile 3D growing structures are often damaged or lost. Ultimately, the results are significantly affected, since the 3D structures cannot maintain the same characteristics and quality. The methods described here minimize these stressful steps and ensure a safe and consistent environment for organoids and spheroids throughout the processing sequence while they are still in a hydrogel in a multipurpose device. The researchers can grow, freeze, thaw, process, stain, label, and then examine the structure of organoids or spheroids under various high-tech instruments, from confocal to electron microscopes, using a single multipurpose device. This technology improves the studies&#39; reproducibility, reliability, and validity, while maintaining a stable and protective environment for the 3D growing structures during processing. In addition, eliminating stressful steps minimizes handling errors, reduces time taken, and decreases the risk of contamination.

The present study describes methodologies for culturing, freezing, thawing, processing, staining, labeling, and examining entire spheroids and organoids under various microscopes, while they remain intact in a hydrogel within a multipurpose device.

Organoids and spheroids, three-dimensional growing structures in cell culture labs, are becoming increasingly recognized as superior models compared to ...

Quantification of Skeletal Muscle Fatty Infiltration via Decellularization

Decellularization-Based Quantification of Skeletal Muscle Fatty Infiltration

Fatty infiltration is the accumulation of adipocytes between myofibers in skeletal muscle and is a prominent feature of many myopathies, metabolic disorders, and dystrophies. Clinically in human populations, fatty infiltration is assessed using noninvasive methods, including computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US). Although some studies have used CT or MRI to quantify fatty infiltration in mouse muscle, costs and insufficient spatial resolution remain challenging. Other small animal methods utilize histology to visualize individual adipocytes; however, this methodology suffers from sampling bias in heterogeneous pathology. This protocol describes the methodology to qualitatively view and quantitatively measure fatty infiltration comprehensively throughout intact mouse muscle and at the level of individual adipocytes using decellularization. The protocol is not limited to specific muscles or specific species and can be extended to human biopsy. Additionally, gross qualitative and quantitative assessments can be made with standard laboratory equipment for little cost, making this procedure more accessible across research laboratories.

Author Spotlight: Decellularization-Based Quantification of Skeletal Muscle Fatty Infiltration  

The present study describes decellularization-based methodologies for visualizing and quantifying intramuscular adipose tissue (IMAT) deposition through intact muscle volume, as well as quantifying metrics of individual adipocytes that comprise IMAT.