Name: instrumentation of near-term fetal sheep for multivariate chronic non-anesthetized recordings
Uploaded: 2015-10-25T14:00:00
Description: Watch this Scientific Journal Video about Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings at JoVE.com

authors gratefully acknowledge funding support from the Molly Towell Perinatal Research Foundation, Canadian Institutes of Health Research (CIHR), and Fonds de Recherche du Qu&#233;bec &#8211; Sant&#233; (FRQS) (to MGF) and CIHR-Quebec Training Network in Perinatal Research (QTNPR) (to LDD).
The authors wish to thank Esther Simard, Marco Bosa, Carl Bernard and Carmen Movila for technical assistance.

Animal care followed the guidelines of the Canadian Council on Animal Care and the approval by the Universit&#233; de Montr&#233;al Council on Animal Care (protocol #10-Rech-1560). Detailed information on materials and methods used is provided in the Table 1.
1. Anesthesia
<ol>
	<li>Insert a single-lumen catheter into a jugular vein.</li>
	<li>Sedate the ewe using acepromazine (Atravet 10 mg/mL) 2 mg intravenously approximately 30 min&#160;prior to the induction of anesthesia in order to red...

The anesthetic and surgical procedures are presented that are required for establishing an animal model for studying fetal physiology and pathophysiology: the chronically instrumented non-anesthetized fetal sheep.
Four critical steps within the protocol should be emphasized. First, passing the catheters and electrodes through the maternal flank: it is important that this is done at once to avoid any internal organ injuries. Second, securing the uterotomy operating site prior to exteriorizing t...

A variety of animal models exist for the study of both normal and compromised pregnancies, including laboratory rodents, non-human primates and domestic ruminants.1,2,3,4,5 The chronically instrumented pregnant sheep has been used extensively for 50 years as a model of human fetal development and responses to pathophysiologic stimuli such as lipopolysaccharide (LPS).6-10 The lesions following LPS exposure mimic exactly what is seen in preterm infants with periventricular leukomalacia, which is due to a similar maturational profile of both species.11, 12
Other pregnancy complications have also been studied in great detail such as the discovery that antenatal glucocorticoids promote lung development 13-15 and understanding the impact of intrauterine growth restriction (IUGR) on the fetus 16,17.
The extensive use of the fetal sheep model is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, recording of bioelectrical activity, application of electric stimulation and in vivo brain imaging.18 Telemetry is also possible, although less frequently used yet due to the higher sophistication to set up as well as the initial and maintenance cost.19
Moreover, the fetal sheep model is very versatile as many variations of instrumentation are possible depending on the measures of interest. For example, it is possible to record over days to weeks multivariate signals in real time such as fetal breathing movements, electrical brain activity, cardiovascular responses, electrocardiogram, regional blood flow to a range of organs using flow probes or microspheres, etc. Thanks to this versatility, a wide range of studies have been conducted including the development of the cardiovascular system20,21, hypothalamo-pituitary-adrenal (HPA) axis22, brain development23 and sleep states development in particular24, effects of hypoxia/asphyxia25, therapeutic hypothermia 26, inflammation6-11, combination of both27, glucocorticoids28,29, anti-depressants30, broncho-pulmonary dysplasia (BPD) 31,32, fetal programming33,34,35,36,37,38,39 or development of novel fetal monitoring modalities prior and during labor to name but a few areas of investigation. 40,41,42,43
The overall goal of the method presented is to show this versatile model&#8217;s basic implementation. It allows establishing a wide variety of acute and chronic experimental protocols studying fetal physiology and pathophysiology on the integrative, organ, cellular and molecular levels.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>ACE Light source</td>
			<td>Schott-Fostec</td>
			<td>A20500</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting scissors</td>
			<td>Fine Science Tools</td>
			<td>14060 - 11</td>
			<td></td>
		</tr>
		<tr>
			<td>Angled dissecting scissors</td>
			<td>Fine Science Tools</td>
			<td>15006 - 09</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel handle</td>
			<td>Fine Science Tools</td>
			<td>10003 - 12</td>
			<td>alternating dissecting tool</td>
		</tr>
		<tr>
			<td>Curved scalpel blades #12</td>
			<td>Fine Science Tools</td>
			<td>10012 - 00</td>
			<td>alternating dissecting tool</td>
		</tr>
		<tr>
			<td>Bone scissors</td>
			<td>Fine Science Tools</td>
			<td>16044 - 10</td>
			<td></td>
		</tr>
		<tr>
			<td>S &#38; T suture tying forceps</td>
			<td>Fine Science Tools</td>
			<td>00272 - 13</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont SS forceps - angled</td>
			<td>Fine Science Tools</td>
			<td>11203 - 25&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Braided silk suture size 6-0</td>
			<td>Teleflex Medical</td>
			<td>07 - 30&#160; - 10</td>
			<td></td>
		</tr>
		<tr>
			<td>Medical Tape</td>
			<td>transpore</td>
			<td>3M</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine hydrochloride 100 mg/ml</td>
			<td>Hospira</td>
			<td>NDC 0409 - 2051 - 05</td>
			<td>Final Does is 80 mg/kg</td>
		</tr>
		<tr>
			<td>Tranqui Ved Injection (xylazine 100 mg/ml)</td>
			<td>Vecdo</td>
			<td>NDC 50989 - 234 - 11</td>
			<td>Final Does is 10 mg/kg</td>
		</tr>
		<tr>
			<td>Reactive orange 14</td>
			<td>Sigma - Aldrich</td>
			<td>R - 8254</td>
			<td></td>
		</tr>
		<tr>
			<td>Ringers Solution Components</td>
			<td></td>
			<td></td>
			<td>Solution is gas equilibrated with 95% O2 and 5% Co2, final pH 7.4</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Sigma - Aldrich</td>
			<td>S7653</td>
			<td>Final Concentration: 118 mM</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Fisher Scientific</td>
			<td>P217 - 3</td>
			<td>Final Concentration: 4.7 mM</td>
		</tr>
		<tr>
			<td>Calcium chloride dihydrate</td>
			<td>Fisher Scientific</td>
			<td>C79 - 500</td>
			<td>Final Concentration: 2.5 mM</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic</td>
			<td>Fisher Scientific</td>
			<td>P -285</td>
			<td>Final Concentration: 1.2 mM</td>
		</tr>
		<tr>
			<td>Magnesium sulfate</td>
			<td>J.T. Baker</td>
			<td>Jan-00</td>
			<td>Final Concentration: 0.57 mM</td>
		</tr>
		<tr>
			<td>4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES)</td>
			<td>Fisher Scientific</td>
			<td>BP 310 - 500</td>
			<td>Final Concentration: 5.95 g/L</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma - Aldrich</td>
			<td>G8270</td>
			<td>Final Concentration: 5.5 mM</td>
		</tr>
		<tr>
			<td>LifeWindow</td>
			<td>Digicare Biomedical Technology</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CED bioamplifier and ADC units</td>
			<td>Cambridge Electronic Design Limited, 
			Unit 4, Science Park, 
			Milton Road, 
			Cambridge CB4 0FE 
			ENGLAND.</td>
			<td>Bioamp: 1902; ADC: micro1401; Data acquisition software: Spike 2, V7.13</td>
			<td></td>
		</tr>
		<tr>
			<td>Neurolog analog signal bioamplifier</td>
			<td>Digitimer Ltd 
			37 Hydeway 
			Welwyn Garden City 
			Hertfordshire, AL7 3BE, England</td>
			<td>NL108A</td>
			<td></td>
		</tr>
		<tr>
			<td>ABL800Flex</td>
			<td>Radiometer Canada; 200 Aberdeen Dr, London, ON N5V 4N2</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf 5804R</td>
			<td>Eppendorf Canada; 2810 Argentia Road, #2 
			Mississauga, Ontario, L5N 8L2</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Arrow Jugular Catheterization Set</td>
			<td>Arrow International, Inc., 2400 Bernville Road, Reading, PA 19605 USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Atravet</td>
			<td></td>
			<td></td>
			<td>10 mg/mL</td>
		</tr>
		<tr>
			<td>Diazepam</td>
			<td></td>
			<td></td>
			<td>5mg/mL</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Ketalar</td>
			<td></td>
			<td>100 mg/mL</td>
		</tr>
		<tr>
			<td>Propofol</td>
			<td></td>
			<td></td>
			<td>10 mg/mL</td>
		</tr>
		<tr>
			<td>SurgiVeT</td>
			<td>Endotracheal Tubes; Smiths Medical ASD, Inc. St. Paul, MN 55112, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cook Airway Exchange Catheter with RAPI-FIT Adapters</td>
			<td>Cook Critical Care 750, Bloomington IN 47402-0489 USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dispomed Ventilator</td>
			<td>Dispomed Ltd., 745 Nazaire-Laurin, Joliette, Quebec J6E 0L6</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BD Insyte-W</td>
			<td>Becton Dickinson, Infusion Therapy Systems Inc., 9450 S State St, Sandy Utah 84070 USA</td>
			<td></td>
			<td>22 to 20 G; 1 in [0.9 x 25 mm] to 1.16 in [1.1 x 30 mm]</td>
		</tr>
		<tr>
			<td>Edwards Lifesciences Ref: PX272 Pressure monitoring kit with TruWave Disposable Pressure</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>LifeWindow LW6000</td>
			<td>Digicare Biomedical Technology 107 Commerce Road, Boynton Beach, FL 33426-9365 USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gaymar</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Babcock</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polyvinyl catheters</td>
			<td>SCI (Scientific Commodities Inc.)</td>
			<td></td>
			<td>2 meters</td>
		</tr>
		<tr>
			<td>2-0 Vicryl</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Castroviejo scissors</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>electrocardiogram (ECG)</td>
			<td>LIFYY, Metrofunk Kabel-Union, Berlin, Germany</td>
			<td></td>
			<td>four copper electrodes in single sheath, 2 meters</td>
		</tr>
		<tr>
			<td>2-O Vicryl</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3-0 Vicryl</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PDS II USP</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Trimethoprim sulfadoxine</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stopcock</td>
			<td>Argon Medical, Cat&#160;041220001A</td>
			<td></td>
			<td>Double 4-way Stopcock with male luer lock</td>
		</tr>
		<tr>
			<td>Needles</td>
			<td>Tyco Healthcare 8881202389</td>
			<td></td>
			<td>Monoject aluminum hub blunt needles, 22Gx, 0.7mmx 38.1mm: for fetal arterial and venous catheters</td>
		</tr>
		<tr>
			<td>Needles</td>
			<td>Tyco Healthcare 8881202322</td>
			<td></td>
			<td>Monoject aluminum hub blunt needles, 16Gx, 1.6mmx38.1mm: for amniotic catheters</td>
		</tr>
	</tbody>
</table>

instrumentation of near-term fetal sheep for multivariate chronic non-anesthetized recordings

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as endotoxins, bacteria, umbilical cord occlusions, hypoxia and various pharmacological treatments. The life-saving clinical practices of glucocorticoid treatment in fetuses at risk of premature birth and the therapeutic hypothermia have been developed in this model. This is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation and in vivo organ imaging. Here we describe the surgical instrumentation procedure required to achieve a stable chronically instrumented non-anesthetized fetal sheep model including characterization of the post-operative recovery from blood gas, metabolic and inflammation standpoints.

38 pregnant time-dated ewes were instrumented at 128&#177;2 days of gestation (dGA, ~0.88 gestation, term 145 dGA) with arterial, venous and amniotic catheters and electrocardiogram (ECG) electrodes with sterile technique under general anesthesia (both ewe and fetus). In case of twin pregnancy the larger fetus was chosen based on palpating and estimating the intertemporal diameter; alternatively, the fetus to be instrumented may be selected randomly to avoid any potential bias or both fetuses may be instrumented. The tot...

Watch this Scientific Journal Video about Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings at JoVE.com

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings

The chronically instrumented non-anesthetized fetal sheep model is used to study human fetal development in health and disease, because it permits surgical placement and maintenance of catheters and electrodes, repetitive blood sampling, substance injection, recording of bioelectrical activity, and in vivo imaging. We describe the procedures required to establish this model.

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as ...

instrumentation-near-term-fetal-sheep-for-multivariate-chronic-non

Research

JoVE Journal

Developmental Biology

Preparation and Culture of Myogenic Precursor Cells/Primary Myoblasts from Skeletal Muscle of Adult and Aged Humans

Skeletal muscle homeostasis depends on muscle growth (hypertrophy), atrophy and regeneration. During ageing and in several diseases, muscle wasting occurs. Loss of muscle mass and function is associated with muscle fiber type atrophy, fiber type switching, defective muscle regeneration associated with dysfunction of satellite cells, muscle stem cells, and other pathophysiological processes. These changes are associated with changes in intracellular as well as local and systemic niches. In addition to most commonly used rodent models of muscle ageing, there is a need to study muscle homeostasis and wasting using human models, which due to ethical implications, consist predominantly of in vitro cultures. Despite the wide use of human Myogenic Progenitor Cells (MPCs) and primary myoblasts in myogenesis, there is limited data on using human primary myoblast and myotube cultures to study molecular mechanisms regulating different aspects of age-associated muscle wasting, aiding in the validation of mechanisms of ageing proposed in rodent muscle. The use of human MPCs, primary myoblasts and myotubes isolated from adult and aged people, provides a physiologically relevant model of molecular mechanisms of processes associated with muscle growth, atrophy and regeneration. Here we describe in detail a robust, inexpensive, reproducible and efficient protocol for the isolation and maintenance of human MPCs&#160;and their progeny&#160;&#8212; myoblasts and myotubes from human muscle samples using enzymatic digestion. Furthermore, we have determined the passage number at which primary myoblasts from adult and aged people undergo senescence in an in vitro culture. Finally, we show the ability to transfect these myoblasts and the ability to characterize their proliferative and differentiation capacity and propose their suitability for performing functional studies of molecular mechanisms of myogenesis and muscle wasting in vitro.

This protocol describes a robust, reproducible and simple method of isolation and culture of myoblast progenitor cells from the skeletal muscle of adult and aged people. The muscles used here include foot and leg muscles. This approach enables the isolation of an enriched population of primary myoblasts for functional studies.

Skeletal muscle homeostasis depends on muscle growth (hypertrophy), atrophy and regeneration. During ageing and in several diseases, muscle wasting ...

Isolation and Characterization of Mesenchymal Stromal Cells from Human Umbilical Cord and Fetal Placenta

The human umbilical cord (UC) and placenta are non-invasive, primitive and abundant sources of mesenchymal stromal cells (MSCs) that have increasingly gained attention because they do not pose any ethical or moral concerns. Current methods to isolate MSCs from UC yield low amounts of cells with variable proliferation potentials. Since UC is an anatomically-complex organ, differences in MSC properties may be due to the differences in the anatomical regions of their isolation. In this study, we first dissected the cord/placenta samples into three discrete anatomical regions: UC, cord-placenta junction (CPJ), and fetal placenta (FP). Second, two distinct zones, cord lining (CL) and Wharton&#39;s jelly (WJ), were separated. The explant culture technique was then used to isolate cells from the four sources. The time required for the primary culture of cells from the explants varied depending on the source of the tissue. Outgrowth of the cells occurred within 3 - 4 days of the CPJ explants, whereas growth was observed after 7 - 10 days and 11 - 14 days from CL/WJ and FP explants, respectively. The isolated cells were adherent to plastic and displayed fibroblastoid morphology and surface markers, such as CD29, CD44, CD73, CD90, and CD105, similarly to bone marrow (BM)-derived MSCs. However, the colony-forming efficiency of the cells varied, with CPJ-MSCs and WJ-MSCs showing higher efficiency than BM-MSCs. MSCs from all four sources differentiated into adipogenic, chondrogenic, and osteogenic lineages, indicating that they were multipotent. CPJ-MSCs differentiated more efficiently in comparison to other MSC sources. These results suggest that the CPJ is the most potent anatomical region and yields a higher number of cells, with greater proliferation and self-renewal capacities in vitro. In conclusion, the comparative analysis of the MSCs from the four sources indicated that CPJ is a more promising source of MSCs for cell therapy, regenerative medicine, and tissue engineering.

Here, we present a protocol for the dissection of human umbilical cord (UC) and fetal placenta sample into cord lining (CL), Wharton&#39;s jelly (WJ), cord-placenta junction (CPJ), and fetal placenta (FP) for the isolation and characterization of mesenchymal stromal cells (MSCs) using the explant culture technique.

The human umbilical cord (UC) and placenta are non-invasive, primitive and abundant sources of mesenchymal stromal cells (MSCs) that have increasingly ...

Whole-cell Patch-clamp Recordings of Isolated Primary Epithelial Cells from the Epididymis

The epididymis is an essential organ for sperm maturation and reproductive health. The epididymal epithelium consists of intricately connected cell types that are distinct not only in molecular and morphological features but also in physiological properties. These differences reflect their diverse functions, which together establish the necessary microenvironment for the post-testicular sperm development in the epididymal lumen. The understanding of the biophysical properties of the epididymal epithelial cells is critical for revealing their functions in sperm and reproductive health, under both physiological and pathophysiological conditions. While their functional properties have yet to be fully elucidated, the epididymal epithelial cells can be studied using the patch-clamp technique, a tool for measuring the cellular events and the membrane properties of single cells. Here, we describe the methods of cell isolation and whole-cell patch-clamp recording to measure the electrical properties of primary dissociated epithelial cells from the rat cauda epididymides.

We present a protocol that combines cell isolation and whole-cell patch-clamp recording to measure the electrical properties of the primary dissociated epithelial cells from the rat cauda epididymides. This protocol allows for investigation of the functional properties of primary epididymal epithelial cells to further elucidate the physiological role of the epididymis.

The epididymis is an essential organ for sperm maturation and reproductive health. The epididymal epithelium consists of intricately connected cell types ...

Zika Virus Infection of Cultured Human Fetal Brain Neural Stem Cells for Immunocytochemical Analysis

Human fetal brain neural stem cells are a unique non-genetically modified model system to study the impact of various stimuli on human developmental neurobiology. Rather than use an animal model or genetically modified induced pluripotent cells, human neural stem cells provide an effective in vitro system to examine the effects of treatments, screen drugs, or examine individual differences. Here, we provide the detailed protocols for methods used to expand human fetal brain neural stem cells in culture with serum-free media, to differentiate them into various neuronal subtypes and astrocytes via different priming procedures, and to freeze and recover these cells. Furthermore, we describe a procedure of using human fetal brain neural stem cells to study Zika virus infection.

This article details the methods that are used to expand human fetal brain neural stem cells in culture, as well as how to differentiate them into various neuronal subtypes and astrocytes, with an emphasis on the use of neural stem cells to study Zika virus infection.

Human fetal brain neural stem cells are a unique non-genetically modified model system to study the impact of various stimuli on human developmental ...

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound (30/45MHZ) System

Congenital heart defects (CHDs) are the most common cause of childhood morbidity and early mortality. Prenatal detection&#160;of the underlying molecular mechanisms of CHDs is&#160;crucial for inventing new preventive and therapeutic strategies. Mutant mouse models are powerful tools to discover new&#160;mechanisms&#160;and environmental stress modifiers that drive cardiac development and their potential&#160;alteration in CHDs. However, efforts to establish the causality of these putative contributors have been limited to histological&#160;and molecular studies&#160;in non-survival animal experiments, in which&#160;monitoring the key physiological and hemodynamic parameters is&#160;often absent. Live imaging technology has become an essential tool to establish the&#160;etiology of CHDs. In particular,&#160;ultrasound imaging can be used prenatally without surgically exposing the fetuses,&#160;allowing maintaining&#160;their baseline physiology while monitoring the impact of environmental stress&#160;on the hemodynamic and structural aspects of cardiac chamber development. Herein, we use the High-Frequency Ultrasound (30/45)&#160;system to examine the cardiovascular system in fetal mice at E18.5 in utero at the baseline and in response to prenatal hypoxia exposure. We demonstrate the feasibility of the system to measure cardiac chamber size, morphology, ventricular function, fetal heart rate, and umbilical artery flow indices, and their alterations in fetal mice exposed to systemic chronic hypoxia in utero in real time.

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound 30/45MHZ System

High-frequency ultrasound imaging of the fetal mouse has improved imaging resolution and can provide precise non-invasive characterization of cardiac development and structural defects. The protocol outlined herein is designed to perform real-time fetal mice echocardiography in vivo.

Congenital heart defects (CHDs) are the most common cause of childhood morbidity and early mortality. Prenatal detection&#160;of the underlying molecular ...

Intravenous and Intra-amniotic In Utero Transplantation in the Murine Model

In utero transplantation (IUT) is a unique and versatile mode of therapy that can be used to introduce stem cells, viral vectors, or any other substances early in the gestation. The rationale behind IUT for therapeutic purposes is based on the small size of the fetus, the fetal immunologic immaturity, the accessibility and proliferative nature of the fetal stem or progenitor cells, and the potential to treat a disease or the onset of symptoms prior to birth. Taking advantage of these normal developmental properties of the fetus, the delivery of hematopoietic stem cells (HSC) via an IUT has the potential to treat congenital hematologic disorders such as sickle cell disease, without the required myeloablative or immunosuppressive conditioning required for postnatal HSC transplants. Similarly, the accessibility of progenitor cells in multiple organs during development potentially allows for a more efficient targeting of stem/progenitor cells following an IUT of viral vectors for gene therapy or genome editing. Additionally, IUT can be used to study normal developmental processes including, but not limited to, the development of immunologic tolerance. The murine model provides a valuable and affordable means to understanding the potential and limitations of IUT prior to pre-clinical large animal studies and an eventual clinical application. Here, we describe a protocol for performing an IUT in the murine fetus through intravenous and intra-amniotic routes. This protocol has been used successfully to elucidate the necessary conditions and mechanisms behind in utero hematopoietic stem cell transplantation, tolerance induction, and in utero gene therapy.

Intravenous and Intra-amniotic In Utero Transplantation in the Murine Model

We describe a protocol for performing an in utero transplantation (IUT) through intravenous and intra-amniotic routes of injection in the murine model. This protocol can be used to introduce cells, viral vectors, and other substances into the unique immune-tolerant fetal environment.

In utero transplantation (IUT) is a unique and versatile mode of therapy that can be used to introduce stem cells, viral vectors, or any other substances ...

High Frequency Ultrasound for the Analysis of Fetal and Placental Development In Vivo

Ultrasound imaging is a widespread method used to detect organ anomalies and tumors in human and animal tissues. The method is non-invasive, harmless, and painless, and the application is easy, fast, and can be done anywhere, even with mobile devices. During pregnancy, ultrasound imaging is standardly used to closely monitor fetal development. The technique is important to assess intrauterine growth restriction (IUGR), a pregnancy complication with short- and long-term health consequences for both the mother and fetus. Understanding the process of IUGR is indispensable for developing effective therapeutic strategies. 
The ultrasound system used in this manuscript is an ultrasound device produced for the analysis of small animals and can be used in various research fields, including pregnancy research. Here we describe the usage of the system for in vivo analysis of fetuses from natural killer (NK) cell/mast cell (MC)-deficient mothers that give birth to growth-restricted pups. The protocol includes preparation of the system, handling of the mice before and during measurements, and the usage of the B-mode, color doppler mode, and pulse-wave doppler mode. Fetal size, placental size, and blood supply to the fetus were analyzed. We found reduced implantation sizes and smaller placentas in NK/MC-deficient mice from mid-gestation onwards. In addition, MC/NK-deficiency was associated with absent and reversed end diastolic flow in the fetal Arteria umbilicalis(UmA) and an elevated resistance index. The methods described in the protocol can easily be used for related and non-related research topics.

High Frequency Ultrasound for the Analysis of Fetal and Placental Development In Vivo

Here we describe the technique of high frequency ultrasound for in vivo analysis of fetuses in mice. This method allows the follow-up of fetuses and the analysis of placental parameters as well as maternal and fetal blood flow throughout pregnancy.

Ultrasound imaging is a widespread method used to detect organ anomalies and tumors in human and animal tissues. The method is non-invasive, harmless, and ...

Culturing and Measuring Fetal and Newborn Murine Long Bones

Long bones are complex and dynamic structures, which arise from endochondral ossification via a cartilage intermediate. The limited access to healthy human bones makes particularly valuable the use of mammalian models, such as mouse and rat, to look into different aspects of bone growth and homeostasis. Additionally, the development of sophisticated genetic tools in mice allows more complex studies of long bone growth and asks for an expansion of techniques used to study bone growth. Here, we present a detailed protocol for ex vivo murine bone culture, which allows the study of bone and cartilage in a tightly controlled manner while recapitulating most of the in vivo process. The method described allows the culture of a range of bones, including tibia, femur, and metatarsal bones, but we have focused mainly on tibial culture here. Moreover, it can be used in combination with other techniques, such as time-lapse live imaging or drug treatment.

Here, we present a method for ex vivo culture of long murine bones at both fetal and newborn stages, suitable for analyzing bone and cartilage development and homeostasis in controlled conditions while recapitulating the in vivo process.

Long bones are complex and dynamic structures, which arise from endochondral ossification via a cartilage intermediate. The limited access to healthy ...

Recapitulating Suckling-to-Weaning Transition In Vitro using Fetal Intestinal Organoids

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to digest solid food. This process is termed suckling-to-weaning transition and results in the replacement of neonatal epithelium with adult epithelium which goes hand in hand with metabolic and morphological adjustments. These complex developmental changes are the result of a genetic program that is intrinsic to the intestinal epithelial cells but can, to some extent, be modulated by extrinsic factors. Prolonged culture of mouse primary intestinal epithelial cells from late fetal period, recapitulates suckling-to-weaning transition in vitro. Here, we describe a detailed protocol for mouse fetal intestinal organoid culture best suited to model this process in vitro. We describe several useful assays designed to monitor the change of intestinal functions associated with suckling-to-weaning transition over time. Additionally, we include an example of an extrinsic factor that is capable to affect suckling-to-weaning transition in vivo, as a representation of modulating the timing of suckling-to-weaning transition in vitro. This in vitro approach can be used to study molecular mechanisms of the suckling-to-weaning transition as well as modulators of this process. Importantly, with respect to animal ethics in research, replacing in vivo models by this in vitro model contributes to refinement of animal experiments and possibly to a reduction in the use of animals to study gut maturation processes.

This protocol describes how to mimic suckling-to-weaning transition in vitro using mouse late fetal intestinal organoids cultured for 30 days.

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to ...

Transuterine Fetal Tracheal Occlusion Model in Mice

Fetal tracheal occlusion (TO), an established treatment modality, promotes fetal lung growth and survival in severe congenital diaphragmatic hernia (CDH). Following TO, retention of the secreted epithelial fluid increases luminal pressure and induces lung growth. Various animal models have been defined to understand the pathophysiology of CDH and TO. All have their own advantages and disadvantages such as the difficulty of the technique, the size of the animal, cost, high mortality rates, and the availability of genetic tools. Herein, a novel transuterine model of murine fetal TO is described. Pregnant mice were anesthetized, and the uterus exposed via a midline laparotomy. The trachea of selected fetuses were ligated with a single transuterine suture placed behind the trachea, one carotid artery, and one jugular vein. The dam was closed and allowed to recover. Fetuses were collected just before parturition. Lung to body weight ratio in TO fetuses was higher than that in control fetuses. This model provides researchers with a new tool to study the impact of both TO and increased luminal pressure on lung development.

Various animal models of congenital diaphragmatic hernia and fetal tracheal occlusion present advantages and disadvantages regarding ethical issues, cost, surgical difficulty, size, survival rates, and availability of genetic tools. This model provides a new tool to study the impact of both tracheal occlusion and increased luminal pressure on lung development.

Fetal tracheal occlusion (TO), an established treatment modality, promotes fetal lung growth and survival in severe congenital diaphragmatic hernia (CDH). ...