Name: effect of hyaluronic acid 35 kda on an in vitro model of preterm small intestinal injury and healing using enteroid-derived monolayers
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Description: Watch this Scientific Journal Video about Effect of Hyaluronic Acid 35 kDa on an In Vitro Model of Preterm Small Intestinal Injury and Healing Using Enteroid-Derived Monolayers at JoVE.com

This content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. HC is supported by grant P20GM134973 from the National Institutes of Health. KB is supported by a Children&#39;s Hospital Foundation (CHF) and Presbyterian Health Foundation (PHF) grant. Live-cell imaging services provided by the Cancer Functional Genomics core were supported partly by the National Institute of General Medical Sciences Grant P20GM103639 and National Cancer Institute Grant P30CA225520 of the National Institutes of Health, awarded to the University of Oklahoma Health Sciences Center Stephenson Cancer Center.

All animal procedures in this study were approved by the University of Oklahoma Health Sciences Center Institutional Animal Care and Use Committee. Following institutional approval, fetal small intestine convenience samples from a preterm non-human primate (NHP, 90% gestation, olive baboon, Papio anubis) were obtained following euthanasia for a separate study (Protocol #101523-16-039-I)20.
1. Establishment of preterm non-human primate 3D intestinal entero...

<ol>
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The gastrointestinal tract of a preterm infant is under continual regenerative pressure from repeated exposures to environmental insults associated with dysbiosis, inflammatory bacterial metabolites and toxins, and intermittent hypoxia23,24. Unfortunately, the intestinal epithelium of the preterm infant is unable to rapidly establish functional integrity23, resulting in barrier dysfunction, increased intestinal permeability, and, in severe...

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies in preterm infants1. The disease is characterized by severe intestinal inflammation that can rapidly deteriorate to intestinal necrosis, sepsis, and potentially death. Although the etiology is unclear, evidence suggests NEC is multifactorial and the result of a complex interaction of feeding, abnormal bacterial colonization, and an immature intestinal epithelium2,3. Preterm infants have increased intestinal permeability, abnormal bacterial colonization, and low enterocyte regenerative capacity4,5, increasing their risk for intestinal barrier dysfunction, bacterial translocation, and NEC development. Therefore, identifying strategies or interventions to accelerate intestinal epithelial maturation and promote regeneration or healing of the intestinal epithelium is critical in preventing this deadly disease.
Studies have demonstrated that human milk (HM) is protective against NEC in preterm infants6,7,8,9,10,11. Both human and animal studies have shown that bovine-based formula increases intestinal permeability and is directly toxic to intestinal epithelial cells2,12. Although not fully elucidated, evidence suggests the protective effects of HM are mediated through bioactive components such as lactoferrin, immunoglobulin A (IgA), and HM oligosaccharides13. HM is also rich in hyaluronan (HA), a uniquely nonsulfated glycosaminoglycan with repeating D-glucuronic acid and N-acetyl-D-glucosamine disaccharides14,15. Importantly, we have shown that oral 35 kDa HA (HA35), an HM HA mimic, attenuates the severity of intestinal injury, prevents bacterial translocation, and decreases mortality in a murine NEC-like intestinal injury model16,17.
Here, the effects of HA35 on intestinal healing and regeneration in vitro are further investigated. Currently, the most widely used in vitro assay for intestinal wounding and repair is a scratch wound assay performed in colorectal cancer (CRC) cell monolayers. The physiological relevance of such a model to the preterm infant intestine is limited, as wound repair of CRC cells relies heavily upon the highly proliferative nature of cancer cells rather than stem cell-driven repair processes18. To overcome this limitation, the establishment of a 2D enteroid scratch wound model, including the procedure of isolating and maintaining primary stem cell-derived small intestinal enteroids from preterm non-human primates (NHP), is described here. Given preterm NEC is most often reported in the distal small intestine, the use of primary epithelial cell organoids in a model of intestinal damage and repair provides a more physiologically translatable in vitro model compared with existing models utilizing traditional colorectal monolayers18,19.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10 mL Serological Pipet</td>
			<td>Fisher Scientific</td>
			<td>13-675-49</td>
			<td></td>
		</tr>
		<tr>
			<td>100x21mm Dish, Nunclon Delta</td>
			<td>ThermoFisher Scientific</td>
			<td>172931</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Conical tube</td>
			<td>VWR</td>
			<td>89039-666</td>
			<td></td>
		</tr>
		<tr>
			<td>24-Well, TC-Treated, Flat Bottom Plate</td>
			<td>Corning</td>
			<td>3524</td>
			<td></td>
		</tr>
		<tr>
			<td>37 &#181;M Reversible Cell Strainer</td>
			<td>STEMCELL Technologies</td>
			<td>27215</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Conical tube</td>
			<td>VWR</td>
			<td>89039-658</td>
			<td></td>
		</tr>
		<tr>
			<td>70 &#181;m Sterile Cell Strainers</td>
			<td>Fisher Scientific</td>
			<td>FB22-363-548</td>
			<td></td>
		</tr>
		<tr>
			<td>Albumin, Bovine (BSA)</td>
			<td>VWR</td>
			<td>0332-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>CellTiter-Glo 3D Cell Viability Assay</td>
			<td>Promega</td>
			<td>G9681</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle&#39;s Medium/Nutrient Ham&#39;s Mixture F-12 (DMEM-F12) with 15 mM HEPES buffer</td>
			<td>STEMCELL Technologies</td>
			<td>36254</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentle Cell Dissociation Reagent</td>
			<td>STEMCELL Technologies</td>
			<td>100-0485</td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>NIH</td>
			<td>imagej.nih.gov/ij/</td>
			<td></td>
		</tr>
		<tr>
			<td>Incucyte S3 Live-Cell Analysis Instrument</td>
			<td>Sartorius</td>
			<td>4647</td>
			<td></td>
		</tr>
		<tr>
			<td>Incucyte Scratch Wound Analysis Software Module</td>
			<td>Sartorius</td>
			<td>9600-0012</td>
			<td></td>
		</tr>
		<tr>
			<td>IntestiCult Organoid Growth Medium (Human)</td>
			<td>STEMCELL Technologies</td>
			<td>06010</td>
			<td>This is HOGMY, but without the Y-27632 or antibiotics. Also used as base for HOGM, but then only missing the antibiotics.</td>
		</tr>
		<tr>
			<td>Lipopolysaccharides from Escherichia coli O111:B4, purified by gel filtration chromatography</td>
			<td>Millipore Sigma</td>
			<td>L3012-10MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel Growth Factor Reduced (GFR) Basement Membrane Matrix, Phenol Red-Free</td>
			<td>Corning</td>
			<td>356231</td>
			<td></td>
		</tr>
		<tr>
			<td>Nunc MicroWell 96-Well, Nunclon Delta-Treated, Flat-Bottom Microplate</td>
			<td>ThermoFisher Scientific</td>
			<td>136101</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (Phosphate-Buffered Saline), 1X [-] Calcium, Magnesium, pH 7.4</td>
			<td>Corning</td>
			<td>21-040-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>Primocin</td>
			<td>Invivogen</td>
			<td>ant-pm-1</td>
			<td>This is broad-spectrum antibiotics</td>
		</tr>
		<tr>
			<td>Sodium Hyaluronate, Research Grade, HA20K</td>
			<td>Lifecore Biomedical</td>
			<td>HA20K-1</td>
			<td></td>
		</tr>
		<tr>
			<td>TC20 Automated Cell Counter</td>
			<td>Company: Bio-Rad</td>
			<td>1450102</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA 1X, 0.25% Trypsin</td>
			<td>Fisher Scientific</td>
			<td>MT25053CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-27632</td>
			<td>STEMCELL Technologies</td>
			<td>72302</td>
			<td></td>
		</tr>
	</tbody>
</table>

effect of hyaluronic acid 35 kda on an in vitro model of preterm small intestinal injury and healing using enteroid-derived monolayers

In vitro scratch wound assays are commonly used to investigate the mechanisms and characteristics of epithelial healing in a variety of tissue types. Here, we describe a protocol to generate a two-dimensional (2D) monolayer from three-dimensional (3D) non-human primate enteroids derived from intestinal crypts of the terminal ileum. These enteroid-derived monolayers were then utilized in an in vitro scratch wound assay to test the ability of hyaluronan 35 kDa (HA35), a human milk HA mimic, to promote cell migration and proliferation along the epithelial wound edge. After the monolayers were grown to confluency, they were manually scratched and treated with HA35 (50 &#181;g/mL, 100 &#181;g/mL, 200 &#181;g/mL) or control (PBS). Cell migration and proliferation into the gap were imaged using a transmitted-light microscope equipped for live-cell imaging. Wound closure was quantified as percent wound healing using the Wound Healing Size Plugin in ImageJ.&#160;The scratch area and rate of cell migration and the percentage of wound closure were measured over 24 h. HA35 in vitro accelerates wound healing in small intestinal enteroid monolayers, likely through a combination of cell proliferation at the wound edge and migration to the wound area. These methods can potentially be used as a model to explore intestinal regeneration in the preterm human small intestine.

The effects of HA on tissue repair and wound healing in various tissues and organs are well-documented; however, the specific effects of HA with a molecular weight of 35 kDa on fetal or neonatal small intestinal healing and regeneration are currently unknown. To test the ability of HA35 to promote wound healing in a model of the fetal or neonatal small intestine, we generated 3D intestinal enteroids from NHP ileal tissue and further dissociated this tissue into single cells to create 2D enteroid-derived monolayers (<stro...

Watch this Scientific Journal Video about Effect of Hyaluronic Acid 35 kDa on an In Vitro Model of Preterm Small Intestinal Injury and Healing Using Enteroid-Derived Monolayers at JoVE.com

Effect of Hyaluronic Acid 35 kDa on an In Vitro Model of Preterm Small Intestinal Injury and Healing Using Enteroid-Derived Monolayers

This protocol describes a method to establish and perform a scratch wound assay on two-dimensional (2D) monolayers derived from three-dimensional (3D) enteroids isolated from non-human primate ileum.

Effect of Hyaluronic Acid 35 kDa on an In Vitro Model of Preterm Small Intestinal Injury and Healing Using Enteroid-Derived Monolayers

In vitro scratch wound assays are commonly used to investigate the mechanisms and characteristics of epithelial healing in a variety of tissue types. ...

This protocol extends the very common scratch wound assay used for regeneration studies with enteroid-derived monolayers representing all major cell types of the small intestine. This technique enables real-time visualization of wound closure in a preterm 2D enteroid monolayer model of intestinal regeneration. Our technique can be applied to the study of preterm mammalian gut, which is typically poorly modeled using transformed colorectal cancer cell lines.Begin by thawing 96 microliters of extracellular matrix, or ECM-based hydrogel BME, overnight on ice at two to eight degrees Celsius. Dilute the ECM-based hydrogel and ice-cold PBS without calcium or magnesium at a ratio of one to 50. Coat each well of a 24-well tissue culture plate with 200 microliters of ice-cold diluted ECM-based hydrogel and incubate the coated plate for a minimum of one hour at 37 degrees Celsius and 5%carbon dioxide.Then aspirate the media from the 24-well culture plate containing the 3D enteroids destined for monolayers and replace it with 500 microliters of cell dissociation reagent per well. Manually disrupt the ECM-based hydrogel domes by pipetting up and down eight to 12 times and transferring the contents of 12 wells to a 15-milliliter conical tube. Wash the 12 empty wells with 250 microliters of cell dissociation reagent to ensure all the enteroids have been removed and transfer the contents to 15-milliliter conical tubes.Centrifuge the conical tubes at 300g for five minutes at four degrees Celsius and discard the supernatant. Add 10 milliliters of ice-cold DMEM/F-12 wash buffer to the conical tubes and suspend the enteroid pellets by inverting the tubes. Centrifuge at 300g for five minutes at four degree Celsius and remove the supernatant.Resuspend the cell pellets in 12 milliliters of 37 degrees Celsius Trypsin-EDTA and place the tubes in a 37 degree Celsius water bath for 10 minutes or until the cells appear soluble. Add three milliliters of DMEM/F-12 wash buffer to each tube to dilute Trypsin-EDTA. Mix by inverting the tubes and place on ice.Filter the dissociated enteroids through a 37 micrometer mesh cell strainer. Collect the contents into clean 15-milliliter conical tubes and centrifuge the tubes at 300g for five minutes at four degrees Celsius. Remove the supernatant from the conical tubes and resuspend the cell pellets with six milliliters of HOMGY.Next, remove the ECM-based hydrogel coated plate from the incubator and aspirate any excess ECM-based hydrogel solution without scratching the coated surface or completely drying the plate. Add 500 microliters of the combined 12 milliliters HOMGY cell suspension into each well of the 24-well plate coated with ECM-based hydrogel. Swirl the plate with the lid on to ensure an even distribution of cells within the wells.Incubate the plate at 37 degrees Celsius and 5%carbon dioxide, exchanging HOMGY media every two days until the monolayers reach greater than 90%confluency. Once the monolayers reach greater than 90%confluency, aspirate the media to remove any cells failing to attach. Treat the cells with 500 microliters of HA35 or PBS dissolved in HOMGY for 24 hours.After that, remove the media without disrupting the surface of the monolayer. Using a 200-microliter pipette tip, make a linear scratch across the full surface diameter of the monolayer in each well, being careful not to let the monolayers dry. Wash the scratched monolayers once with 500 microliters of 1X PBS and add 500 microliters of HA35 or PBS dissolved in HOMGY.Transfer the plate to the live cell analysis instrument within a 37 degree Celsius and 5%carbon dioxide incubator. Under the Schedule icon in the live cell analysis software, click on the Launch Add New Vessel Wizard icon. Select Scan on Schedule, then click on Next.Select New under Create Vessel and click on Next, then select Whole Well under Scan Type and click Next. Choose Phase for image channels and 4x for the objective. Select the plate manufacturer and the catalog number from the provided list and click Next.Select an empty vessel location followed by the desired scan pattern. Enter plate name in Name, then select plus to create a plate layout. Select small plus to create a treatment name.Enter short name and then OK.Highlight the plate wells corresponding to that treatment and hit large plus to designate wells with that treatment. Enter compound concentration and click OK.When plate is complete, select OK, Next. Select Defer analysis until later followed by Create new schedule with scans at intervals of four hours.Stop scanning at one days, zero hours. Ensure that the summary is correct and then add to schedule. In live cell analysis software, select View at the top of the screen.From the Vessel Name menu, navigate to your completed 24 hour scan and double-click the vessel name. Select Export images and movies icon on left followed by As Displayed option. Highlight the wells of interest, and then select time points of interest and Series of Images as Displayed.Ensure the sequence type and the scans are correct. Select desired target folder location. Choose JPEG from the dropdown menu and then Export.Open ImageJ software and upload the scratch wound assay image. Select Image, then type 8-bit to change the image from 24-bit RGB. Select Plugins, Macros, Install, Wound_healing_size plugin to install the Wound Healing Size Plugin.After that, set the variance window radius to 20, threshold value to 100, percentage of saturated pixels to 0.001. Yes for Set Scale global and then click on OK.Verify that the outlined area is the wound area and repeat for additional scratches. Finally, calculate the percentage of the scratch area wound healing of migrating or proliferating cells over 24 hours using the equation shown on the screen.Here, T0 is the area at time zero hours, and TC is the area at zero hours, four hours, 12 hours, or 24 hours. Enteroid generation and enteroid-derived monolayer wound healing assay procedure are shown in these images. A culture of three-dimensional, non-human primate intestinal enteroids is used to dissociate into two-dimensional monolayers.Monolayers were grown to greater than 90%confluence in a 24-well plate and then treated with HA35 or PBS for 24 hours. Monolayers were then scratched with a P200 pipette tip. Shown here are the representative images of HA35 in control treatments of nonhuman primate enteroid monolayers.Images were obtained at zero hours, four hours, 12 hours, and 24 hours after performing a scratch with a P200 pipette tip. The effect of HA35 on wound healing andoid monolayers is shown here. The change in wound healing over time in enteroid monolayers is dependent on HA35 treatment concentration.HA35 significantly increased wound healing after four hours and 12 hours at 100 micrograms per milliliter and 200 micrograms per milliliter when compared to control, but healing rates converged among treatments by 24 hours. One of the most important things to remember with this procedure is that intestinal enteroid monolayers are short-lived. So, once they're 90%confluid, investigators should look to use them quickly.This technique has become our go-to model for preterm intestinal regeneration in vitro, especially if we are interested in more mechanical rather than inflammatory injury.

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Research

JoVE Journal

Medicine

A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor.
Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5&deg; (animals rotated at 22.5&deg;), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing.
The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in functional deficits of the forelimb that are significant and sustained in the weeks following injury. The cervical unilateral injury model presented here may be a resource to researchers who wish to evaluate potentially promising therapies prior to human translation.

A reliable and repeatable way to produce a cervical unilateral spinal cord injury using the Infinite Horizon impactor is described. The method takes advantage of a custom designed frame and clamp to stabilize the spine. The standardized procedure and biomechanical injury parameters result in sufficient and sustained injuries.

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of ...

Development of an Algorithm to Perform a Comprehensive Study of Autonomic Dysreflexia in Animals with High Spinal Cord Injury Using a Telemetry Device

Spinal cord injury (SCI) is a debilitating neurological condition characterized by somatic and autonomic dysfunctions. In particular, SCI above the mid-thoracic level can lead to a potentially life-threatening hypertensive condition called autonomic dysreflexia (AD) that is often triggered by noxious or non-noxious somatic or visceral stimuli below the level of injury. One of the most common triggers of AD is the distension of pelvic viscera, such as during bladder and bowel distension or evacuation. This protocol presents a novel pattern recognition algorithm developed for a JAVA platform software to study the fluctuations of cardiovascular parameters as well as the number, severity and duration of spontaneously occurring AD events. The software is able to apply a pattern recognition algorithm on hemodynamic data such as systolic blood pressure (SBP) and heart rate (HR) extracted from telemetry recordings of conscious and unrestrained animals before and after thoracic (T3) complete transection. With this software, hemodynamic parameters and episodes of AD are able to be detected and analyzed with minimal experimenter bias.

The catheter of a telemetry device is implanted into the abdominal aorta in order to continuously collect beat-by-beat hemodynamic data from animals pre and post-high thoracic spinal cord transection. A novel JAVA software was employed to analyze hemodynamic parameters as well as frequency and intensity of spontaneous episodes of autonomic dysreflexia.

Spinal cord injury (SCI) is a debilitating neurological condition characterized by somatic and autonomic dysfunctions. In particular, SCI above the ...

Murine Model of Intestinal Ischemia-reperfusion Injury

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, hypotension, necrotizing enterocolitis, bowel transplantation, trauma and chronic inflammation. Intestinal ischemia-reperfusion (IR) injury is a consequence of acute mesenteric ischemia, caused by inadequate blood flow through the mesenteric vessels, resulting in intestinal damage. Reperfusion following ischemia can further exacerbate damage of the intestine. The mechanisms of IR injury are complex and poorly understood. Therefore, experimental small animal models are critical for understanding the pathophysiology of IR injury and the development of novel therapies.
Here we describe a mouse model of acute intestinal IR injury that provides reproducible injury of the small intestine without mortality. This is achieved by inducing ischemia in the region of the distal ileum by temporally occluding the peripheral and terminal collateral branches of the superior mesenteric artery for 60 min using microvascular clips. Reperfusion for 1 hr, or 2 hr after injury results in reproducible injury of the intestine examined by histological analysis. Proper position of the microvascular clips is critical for the procedure. Therefore the video clip provides a detailed visual step-by-step description of this technique. This model of intestinal IR injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Here we describe the detailed procedure of intestinal ischemia-reperfusion in mice which results in reproducible injury without mortality to encourage the standardization of this technique across the field. This model of intestinal ischemia-reperfusion injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, ...

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies.
Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important.
The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

This protocol induces acute lung injury in a mouse that has close fidelity to the pathogenesis of acid pneumonitis observed in humans. We generate a maximal acute nonlethal low pH lung injury and account for differences in rodent-human anatomic respiratory structure using an open tracheostomy coupled with circumferential pressure release.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute ...

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) models based on pBECs in mono-culture (MC), MC with astrocyte-conditioned medium (ACM), and non-contact co-culture (NCC) with astrocytes of porcine or rat origin. pBECs were isolated and cultured from fragments of capillaries from the brain cortices of domestic pigs 5-6 months old. These fragments were purified by careful removal of meninges, isolation and homogenization of grey matter, filtration, enzymatic digestion, and centrifugation. To further eliminate contaminating cells, the capillary fragments were cultured with puromycin-containing medium. When 60-95% confluent, pBECs growing from the capillary fragments were passaged to permeable membrane filter inserts and established in the models. To increase barrier tightness and BBB characteristic phenotype of pBECs, the cells were treated with the following differentiation factors: membrane permeant 8-CPT-cAMP (here abbreviated cAMP), hydrocortisone, and a phosphodiesterase inhibitor, RO-20-1724 (RO). The procedure was carried out over a period of 9-11 days, and when establishing the NCC model, the astrocytes were cultured 2-8 weeks in advance. Adherence to the described procedures in the protocol has allowed the establishment of endothelial layers with highly restricted paracellular permeability, with the NCC model showing an average transendothelial electrical resistance (TEER) of 1249 &#177; 80 &#937; cm2, and paracellular permeability (Papp) for Lucifer Yellow of 0.90 10-6 &#177; 0.13 10-6 cm sec-1 (mean &#177; SEM, n=55). Further evaluation of this pBEC phenotype showed good expression of the tight junctional proteins claudin 5, ZO-1, occludin and adherens junction protein p120 catenin. The model presented can be used for a range of studies of the BBB in health and disease and, with the highly restrictive paracellular permeability, this model is suitable for studies of transport and intracellular trafficking.

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of the protocol is to present an optimized procedure for the establishment of an in vitro blood-brain barrier (BBB) model based on primary porcine brain endothelial cells (pBECs). The model shows high reproducibility, high tightness, and is suitable for studies of transport and intracellular trafficking in drug discovery.

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...

Intestinal Stem Cell Isolation and Culture in a Porcine Model of Segmental Small Intestinal Ischemia

Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ischemia, when the blood supply and therefore oxygen is decreased to the intestine. This leads to intestinal barrier loss and damage to the underlying tissue. Intestinal stem cells reside at the base of the crypts of Lieberk&#252;hn and are responsible for intestinal renewal during homeostasis and following injury. Ex vivo cell culture techniques have allowed for the successful study of epithelial stem cell interactions by establishing culture conditions that support the growth of three-dimensional epithelial organ-like systems (termed "enteroids" and "colonoids" from the small and large intestine, respectively). These enteroids are composed of crypt and villus-like domains and mature to contain all of the cell types found within the epithelium. Historically, murine models have been utilized to study intestinal injury. However, a porcine model offers several advantages including similarity of size as well as gastrointestinal anatomy and physiology to that of humans. By utilizing a porcine model, we establish a protocol in which segmental loops of intestinal ischemia can be created within a single animal, enabling the study of differing time points of ischemic injury and repair in vivo. Additionally, we describe a method to isolate and culture the intestinal stem cells from the ischemic loops of intestine, allowing for the continued study of epithelial repair, modulated by stem cells, ex vivo.

This protocol will enable readers to successfully establish a porcine model of segmental intestinal ischemia and subsequently isolate and culture intestinal stem cells for the study of epithelial repair following injury.

Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

An Epithelial Abrasion Model for Studying Corneal Wound Healing

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its transparency. However, due to its external position, the cornea is highly susceptible to a wide variety of injuries that can lead to the loss of corneal transparency and eventual blindness. Efficient corneal wound healing in response to these injuries is pivotal for maintaining corneal homeostasis and preservation of corneal transparency and refractive capabilities. In events of compromised corneal wound healing, the cornea becomes vulnerable to infections, ulcerations, and scarring. Given the fundamental importance of corneal wound healing to the preservation of corneal transparency and vision, a better understanding of the normal corneal wound healing process is a prerequisite to understanding impaired corneal wound healing associated with infection and disease. Toward this goal, murine models of corneal wounding have proven useful in furthering our understanding of the corneal wound healing mechanisms operating under normal physiological conditions. Here, a protocol for creating a central corneal epithelial abrasion in mouse using a trephine and a blunt golf club spud is described. In this model, a 2 mm diameter circular trephine, centered over the cornea, is used to demarcate the wound area. The golf club spud is used with care to debride the epithelium and create a circular wound without damaging the corneal epithelial basement membrane. The resulting inflammatory response proceeds as a well-characterized cascade of cellular and molecular events that are critical for efficient wound healing. This simple corneal wound healing model is highly reproducible and well-published and is now being used to evaluate compromised corneal wound healing in the context of disease.

Here, a protocol for creating a central corneal epithelial abrasion wound in the mouse using a trephine and a blunt golf club spud is described. This corneal wound healing model is highly reproducible and is now being used to evaluate compromised corneal wound healing in the context of diseases.

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its ...

Mongolian Gerbils as an Animal Model of Wound Healing

Corneal wound healing studies have been conducted for a long time and have helped to reduce suffering and develop treatments that contribute to improving patients' eye health. Historically, corneal healing has been studied in rodents such as mice and rats, but these models might not completely mimic human disorders. However, information on other rodents such as Mongolian gerbils (Meriones unguiculatus) is scant in corneal research.
Here, we describe a technique to develop a novel animal model for studying corneal healing after photorefractive keratectomy. Due to the limited literature available on the cornea of M. unguiculatus, we also describe a histological analysis of the normal cornea. These research techniques can also be employed in the study of eye diseases because of the similarity between the corneas of Mongolian gerbils and humans in terms of genetics, anatomy, and physiology.

This article describes a new animal model developed to study the anatomy and histology of the cornea and its healing processes. This new animal model uses the Mongolian gerbil, which has a cornea with many similarities to the human cornea.

Corneal wound healing studies have been conducted for a long time and have helped to reduce suffering and develop treatments that contribute to improving ...