Name: a hyperandrogenic mouse model to study polycystic ovary syndrome
Uploaded: 2018-10-02T14:30:00
Description: Watch this Scientific Journal Video about A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome at JoVE.com

This work was supported by the National Institutes of Health (Grants R00-HD068130 to S.W.) and the Baltimore Diabetes Research Center: Pilots and Feasibility Grant (to S.W.).

Here, we present detailed protocols for DHT pellet preparation and insertion, and for reproductive and metabolic testing. The mice used in this study were a mixed background (C57/B6, CD1, 129Sv) and were maintained with food and water ad libitum in a 14/10 h light/dark cycle at 24 &#176;C in the Broadway Research Building animal facility at the Johns Hopkins University School of Medicine. All procedures were approved by the Johns Hopkins University Animal Care and Use Committee.
1. Crea...

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Hyperandrogenism is a key feature of PCOS. The serum DHT levels (two fold higher in DHT mice than in no-DHT mice) used in this protocol are lower than those reported by other investigators in previous studies and are calibrated to proportionally mimic women with PCOS5,19,20,21. Unlike other models, this 2-fold DHT model does not alter the body weight and whole body composition compared with no-...

Hyperandrogenism is the hallmark of polycystic ovary syndrome (PCOS) according to NIH criteria and of&#160;the Androgen Excess and PCOS (AE-PCOS) Society. Women with PCOS have difficulty getting pregnant and have increased risk of pregnancy complications1. Even if they get pregnant, their female offspring have an adverse health outcomes2,3. Animal models have been developed using various strategies4,5,6,7,8,9,10,11,12 and exhibiting many features of PCOS (anovulation, and or impaired glucose and insulin tolerance) with increased body weight and obesity associated with enlarged adipocyte size and increased adipocyte weight. There are two major strategies to produce animal models that are used to study PCOS. One is treatment with high levels of androgens directly (exogenous androgen injection/insertion) or indirectly (such as blocking androgen conversion to estrogen with aromatase inhibitor) after birth13. Another is by fetal hyperexposure of androgens during gestation14,15 to study the offspring. For example, female offspring from rhesus monkey16,17, sheep18, and rodents exposed to male levels of androgen during the intrauterine period develop PCOS-like traits later in life. These models significantly enhanced our understanding of elevated androgen effects, and fetal programing, and uterine environmental effects. However, these models have their own limitations: 1) animals develop obesity and it is therefore difficult to separate the effects of hyperandrogenemia from obesity induced reproductive and metabolic dysfunction; 2) before pregnancy, women with PCOS already exhibit high levels of androgen, thus oocytes have been exposed to androgen excess before fertilization; 3) the pharmacological doses of testosterone (T) or dihydrotestosterone (DHT) used after birth or during gestation may not reflect the androgen environment of PCOS. Testosterone and DHT levels have been measured in ovarian follicular fluid and/or serum, and testosterone and DHT levels are 1.5 to 3.9 fold higher in women with PCOS5,19,20,21,22,23 compared to unaffected women. We created an adult mouse model23,24,25 that develops reproductive and metabolic dysfunction within two weeks of the initiation of chronic DHT exposure from insertion of a pellet with 4mm length of crystal DHT powder (total length of pellet is 8mm). This model produces serum DHT levels that are about 2-fold higher (referred to as 2xDHT) than that of control mice without DHT treatment. The 2xDHT mice do not&#160;exhibit alterations of basal serum estradiol, testosterone,&#160;LH and do not&#160;develop obesity, and&#160;show similar ovarian weight, serum levels of cholesterol, free fatty acids, leptin, TNF&#945; and IL-623,24,25 relative to controls even up to 3.5 months after DHT insertion23,24,25. Additionally, by mating females that have already developed features of PCOS, we can study the impact of a hyperandrogenic maternal environment on the metabolic and reproductive health of the offspring15.
This new paradigm (relevant to NIH and AE-PCOS Society criteria) models the disease by producing relatively similar levels of androgens to those of women with PCOS 2- to 3-fold higher testosterone or DHT levels compared to unaffected women. However, this model is maintained by continual exogenous DHT and not from programmed endogenous hyperandrogenism once DHT is withdrawn. The overall goal of this article is to focus on 1) how to make the DHT pellet; 2) how to generate a lean-PCOS like mouse model; 3) strategies to evaluate female offspring from these dams. Other measurements and assessment of phenotypes are not addressed in this manuscript but can be found in5,15,23,24,25,26.

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			<td height="26" style="height:26px;width:243px;">Crystalline 5&#945;-DHT powder&#160;</td>
			<td style="width:135px;">&#160;Sigma-Aldrich</td>
			<td style="width:119px;">A8380-1G</td>
			<td style="width:412px;"></td>
		</tr>
		<tr height="28">
			<td height="28" style="height:28px;width:243px;">Dow Corning Silastic tubing</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">11-189-15D</td>
			<td>0.04in/1mm inner diameter x0.085in/2.15mm outer diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">Medical adhesive silicone</td>
			<td style="width:135px;">&#160;Factor II, InC.</td>
			<td style="width:119px;">&#160;A-100</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">Goggles, lab coats, gloves and masks.</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">&#160;10 &#181;L pipette tips without filter</td>
			<td style="width:135px;">USA Scientific</td>
			<td style="width:119px;">11113700</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">Microscope slide for smear</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">12-550-003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">Diff Quik for staining cells</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">NC9979740</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">&#160; Lancet</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">NC9416572</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">3 mL Syring&#160;</td>
			<td style="width:135px;">Becton, Dickinson and Company (BD),</td>
			<td style="width:119px;">30985</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">&#160;attached needle: 20G</td>
			<td style="width:135px;">BD</td>
			<td style="width:119px;">305176</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">&#160;Ruler: any length than 10cm with milimeter scale.&#160;</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">Xylazine&#160;</td>
			<td style="width:135px;">Vet one AnnSeA LA, MWI, Boise</td>
			<td style="width:119px;">NDC13985-704-10</td>
			<td>100mg/ml</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">Ketamine Hydrochloride</td>
			<td style="width:135px;">Hospira, Inc</td>
			<td style="width:119px;">NDC 0409-2051-05</td>
			<td>100mg/ml</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:243px;">&#160;Surgical staple</td>
			<td style="width:135px;">&#160;AutoClip&#174; System, Fine Science Tool</td>
			<td style="width:119px;">12020-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:243px;">&#160;Insulin syringe</td>
			<td style="width:135px;">BD</td>
			<td style="width:119px;">329461</td>
			<td>1/2 CC, low dose U-100 insulin syringe</td>
		</tr>
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a hyperandrogenic mouse model to study polycystic ovary syndrome

Hyperandrogenemia plays a critical role in reproductive and metabolic function in females and is the hallmark of polycystic ovary syndrome. Developing a lean PCOS-like mouse model that mimics women with PCOS is clinically meaningful. In this protocol, we describe such a model. By inserting a 4 mm length of DHT (dihydrotestosterone) crystal powder pellet (total length of pellet is 8 mm), and replacing it monthly, we are able to produce a PCOS-like mouse model with serum DHT levels 2 fold higher than mice not implanted with DHT (no-DHT). We observed reproductive and metabolic dysfunction without changing body weight and body composition. While exhibiting a high degree of infertility, a small subset of these PCOS-like female mice can get pregnant and their offspring show delayed puberty and increased testosterone as adults. This PCOS-like lean mouse model is a useful tool to study the pathophysiology of PCOS and the offspring from these PCOS-like dams.

Serum DHT levels and Glucose tolerance test
DHT levels were measured from collected serum by both ELISA and by LC-MS according to protocol 1.24&#8211;1.25, and 2.9, 3.0. The DHT absolute values are different between mass spectrometry and ELISA, however, the relative fold (around 2-fold) of DHT vs no-DHT insertion is similar from both assays and across experiments15,23,...

Watch this Scientific Journal Video about A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome at JoVE.com

A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome

We describe the development of a lean PCOS-like mouse model with&#160;dihydrotestosterone pellet to study the pathophysiology of PCOS and the offspring from these PCOS-like dams.

Hyperandrogenemia plays a critical role in reproductive and metabolic function in females and is the hallmark of polycystic ovary syndrome. Developing a ...

This method can help answer key questions in the field of reproduction. And the endocrinology. And are applicable to the study of Polycystic Ovary Syndrome or PCOS and hyperandrogenism.The advantage of this technic is that it facilitates a consistent, uniform, long-term release of hormones in a costly effective way. JHUs treating the procedure will be Ping Xue, a technician from my laboratory. For dihydrotestosterone or DHT pellet preparation, use a razor blade to cut a 15 millimeter piece of silicone tubing.And use a three milliliter syringe equipped with a blunted 20 gauge needle to inject two to five millimeters medical adhesive silicone into one end of the tube. Allow the tubing to dry overnight. And check for air bubbles on the sealed end.Wearing the appropriate personal protective equipment pour DHT powder into a plastic wayboat in the flowhood. Impress the opened end of the adhesive capped tube into the powder. Using a large straightened paperclip, tamp the powder down into the tubing, until the DHT reaches the appropriate experimental depth.Then seal the opened side of the tube with silicone overnight. The next morning, cut each sealed side to obtain a two millimeter length of silicone on both sides of the DHT and no DHT control pellets. Then store the pellets in the 50 milliliter conical tube wrapped with foil at room temperature for up to three months.For PCOS mouse model generation equilibrate up to 20 DHT or control pellets in separate 50 milliliter conical tubes containing 30 milliliters of 0.9 percent saline for 24 hours at 37 degrees Celsius. The next day, confirm lack of response to toe pinch in an anesthetized two month old female mouse and use sterile gauze to administer sequential Povidone-iodine and 70 percent ethynol scrubs to the surgical area. Next, make a five millimeter incision through the skin near the neck.And use a ten gauge trocar to make a 15 millimeter tunnel in the rostral direction. Use the trocar to insert a pellet dorsally into the tunnel and seal the incision with the surgical adhesive. Manually approximate the wound edges with forceps and use gentle brushing strokes to apply three thin film layers of liquid adhesive to one centimeter out from each side of the opposed wound edges.Then place the mouse alone in a cage on a heat pad with monitoring until full recumbency. Replacing the pellet every four weeks to maintain a constant level of androgen exposure. Three days after pellet insertion, use a p10 pipette to squirt ten microliters of sterile saline into the vaginal cavity and use the pipette tip to immediately recover the saline.Spread the vaginal cell saline sample onto a labeled slide. And allow the saline to dry at room temperature. Fix the dried slides in a container of 100 percent ethynol for at least five minutes.Then stain the slides for one minute each in buffer B and buffer C from a dif-quick staining kit. At the end of the buffer C incubation wash the slides with tap water for three seconds and dry them at room temperature. To determine the estrous cyclicity view the slides under the ten times objective of a light microscope.Count the days in each stage and divide by the total number of days to calculate percent time at each stage. To test the glucose tolerance, 20 days DHT insertion, fast the mice overnight. Weigh the mice the next morning, and use a glucometer and test strips to measure basil glucose level of tail vein blood.Inject the mice with two grams per kilogram body weight of 20 percent dextrose. Then measure the glucose level of tail vein blood samples at 15, 30, 60, 90, 120 minutes post dextrose administration. To acquire female offspring from DHT inserted dames, move the female mouse to tested in the cage with a proven fertile male at day 15, following pellet insertion.Document the dames body weight every week to determine if the mouse is pregnant. On post-natal day seven, dip a lancet tip into tattoo paste and mark each pup with a tattoo on the toe. Weigh the marked mice every seven days until 70 days of age.Between post-natal date 12 to 16, ear punch the mice to number them according to the system as illustrated in the figure. To distinguish the sex, examine the ventral side of each tagged mouse. The females will have visible nipples.To collect blood samples for various downstream analyses use a lancet to collect the approximate experimental volume of blood between nine and ten am by submandibular vein bleeding. And centrifuge the samples to allow serum collection. Then store the serums samples in 1.5 milliliter micro-centrifuge tubes at minus 80 degrees Celsius until their analysis.To assess puberty in the DHT female offspring, every day after weaning at post-natal day 21, check the vaginal opening by visual inspection. And use calibers to measure the ano-genital distance. Although the absolute values of serum DHT are different between mass spectrometry and Elisa analysis, the relative folk change of DHT versus no-DHT insertion is similar from both assays and across experiments.DHT levels are significantly increased from pre-conception through pregnancy in both DHT and no DHT mice. However, DHT levels are two-fold higher in DHT mice compared to no DHT mice at both pre-conceptional and gestational time points. Adult DHT daughters exhibit differences in reproductive function.For example, disrupted eestrous cyclicity compared to adult no DHT daughters experiencing significantly longer times in metestrus diestrus and less time in pro-esterous and esterous. While attempting this procedure it's important to remember to incubate the pellets for 24 hours before they are used for uniform release of the hormone. Following this procedure, the reproductive and metabolic consequences of DHT exposure can also be examined.After it's development, this technic paved the way for researchers in the field of endrochronology and maternal fetal interactions to study PCOS and the impact of low level hyperandrogenism in female mice. Don't forget that working with DHT can be extremely hazardous and the precautions such as wearing gloves and a mask and goggles, and working in a bio-safety hood, should always be taken while performing this procedure.

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Research

JoVE Journal

Developmental Biology

Generating CRISPR/Cas9 Mediated Monoallelic Deletions to Study Enhancer Function in Mouse Embryonic Stem Cells

Enhancers control cell identity by regulating tissue-specific gene expression in a position and orientation independent manner. These enhancers are often located distally from the regulated gene in intergenic regions or even within the body of another gene. The position independent nature of enhancer activity makes it difficult to match enhancers with the genes they regulate. Deletion of an enhancer region provides direct evidence for enhancer activity and is the gold standard to reveal an enhancer's role in endogenous gene transcription. Conventional homologous recombination based deletion methods have been surpassed by recent advances in genome editing technology which enable rapid and precisely located changes to the genomes of numerous model organisms. CRISPR/Cas9 mediated genome editing can be used to manipulate the genome in many cell types and organisms rapidly and cost effectively, due to the ease with which Cas9 can be targeted to the genome by a guide RNA from a bespoke expression plasmid. Homozygous deletion of essential gene regulatory elements might lead to lethality or alter cellular phenotype whereas monoallelic deletion of transcriptional enhancers allows for the study of cis-regulation of gene expression without this confounding issue. Presented here is a protocol for CRISPR/Cas9 mediated deletion in F1 mouse embryonic stem (ES) cells (Mus musculus129 x Mus castaneus). Monoallelic deletion, screening and expression analysis is facilitated by single nucleotide polymorphisms (SNP) between the two alleles which occur on average every 125 bp in these cells.

Experimental validation of enhancer activity is best approached by loss-of-function analysis. Presented here is an efficient protocol that uses CRISPR/Cas9 mediated deletion to study allele-specific regulation of gene transcription in F1 ES cells which contain a hybrid genome (Mus musculus129 x Mus castaneus).

Enhancers control cell identity by regulating tissue-specific gene expression in a position and orientation independent manner. These enhancers are often ...

Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for embryo collection, immunofluorescence, imaging on a confocal microscope, and image segmentation and analysis are described. This method allows quantitation of the expression of multiple nuclear markers and the spatial (XYZ) coordinates of all cells in the embryo. It takes advantage of MINS, an image segmentation software tool specifically developed for the analysis of confocal images of preimplantation embryos and embryonic stem cell (ESC) colonies. MINS carries out unsupervised nuclear segmentation across the X, Y and Z dimensions, and produces information on cell position in three-dimensional space, as well as nuclear fluorescence levels for all channels with minimal user input. While this protocol has been optimized for the analysis of images of preimplantation stage mouse embryos, it can easily be adapted to the analysis of any other samples exhibiting a good signal-to-noise ratio and where high nuclear density poses a hurdle to image segmentation (e.g., expression analysis of embryonic stem cell (ESC) colonies, differentiating cells in culture, embryos of other species or stages, etc.).

This protocol presents a method to perform quantitative, single-cell in situ analysis of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for collection of blastocysts, whole-mount immunofluorescent detection of proteins, imaging of samples on a confocal microscope, and nuclear segmentation and image analysis are described.

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse ...

Isolation and Characterization of Primary Rat Valve Interstitial Cells: A New Model to Study Aortic Valve Calcification

Calcific aortic valve disease (CAVD) is characterized by the progressive thickening of the aortic valve leaflets. It is a condition frequently found in the elderly and end-stage renal disease (ESRD) patients, who commonly suffer from hyperphosphatemia and hypercalcemia. At present, there are no medication therapies that can stop its progression. The mechanisms that underlie this pathological process remain unclear. The aortic valve leaflet is composed of a thin layer of valve endothelial cells (VECs) on the outer surfaces of the aortic cusps, with valve interstitial cells (VICs) sandwiched between the VECs. The use of a rat model enables the in vitro study of ectopic calcification based on the in vivo physiopathological serum phosphate (Pi) and calcium (Ca) levels of patients who suffer from hyperphosphatemia and hypercalcemia. The described protocol details the isolation of a pure rat VIC population as shown by the expression of VIC markers: alpha-smooth muscle actin (&#945;-SMA) vimentin and tissue growth factor beta (TGF&#946;) 1 and 2, and the absence of cluster of differentiation (CD) 31, a VEC marker. By expanding these VICs, biochemical, genetic, and imaging studies can be performed to study and unravel the key mediators underpinning CAVD.

This protocol describes the isolation, culture, and calcification of rat-derived valve interstitial cells, a highly physiological in vitro model of calcific aortic valve disease (CAVD). Exploitation of this rat model facilitates CAVD research in exploring the cell and molecular mechanisms that underlie this complex pathological process.

Calcific aortic valve disease (CAVD) is characterized by the progressive thickening of the aortic valve leaflets. It is a condition frequently found in ...

Whole-mount Confocal Microscopy for Adult Ear Skin: A Model System to Study Neuro-vascular Branching Morphogenesis and Immune Cell Distribution

Here, we present a protocol of a whole-mount adult ear skin imaging technique to study comprehensive three-dimensional neuro-vascular branching morphogenesis and patterning, as well as immune cell distribution at a cellular level. The analysis of peripheral nerve and blood vessel anatomical structures in adult tissues provides some insights into the understanding of functional neuro-vascular wiring and neuro-vascular degeneration in pathological conditions such as wound healing. As a highly informative model system, we have focused our studies on adult ear skin, which is readily accessible for dissection. Our simple and reproducible protocol provides an accurate depiction of the cellular components in the entire skin, such as peripheral nerves (sensory axons, sympathetic axons, and Schwann cells), blood vessels (endothelial cells and vascular smooth muscle cells), and inflammatory cells. We believe this protocol will pave the way to investigate morphological abnormalities in peripheral nerves and blood vessels as well as the inflammation in the adult ear skin under different pathological conditions.

Here, we describe a high resolution whole-mount imaging method in the entire adult mouse ear skin, which enables us to visualize branching morphogenesis and patterning of peripheral nerves and blood vessels, as well as immune cell distribution.

Here, we present a protocol of a whole-mount adult ear skin imaging technique to study comprehensive three-dimensional neuro-vascular branching ...

Organotypic Culture Method to Study the Development Of Embryonic Chicken Tissues

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ideal for experimentation. Currently, the study of these developmental pathways in the chicken embryo is conducted by applying inhibitors and drugs at localized sites and at low concentrations using a variety of methods. In vitro tissue&#160;culturing is a technique that enables the study of tissues separated from the host organism, while simultaneously bypassing many of the physical limitations present when working with whole embryos, such as the susceptibility of embryos to high doses of potentially lethal chemicals. Here, we present an organotypic culturing protocol for culturing the embryonic chicken half head in vitro, which presents new opportunities for the examination of developmental processes beyond the currently established methods.

Here, we present an organotypic culturing protocol to grow embryonic chicken organs in vitro. Using this method, the development of embryonic chicken tissue can be studied, while maintaining a high degree of control over the culture environment.

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ...

Ovarian Tissue Culture to Visualize Phenomena in Mouse Ovary

Mammalian females periodically ovulate an almost constant number of oocytes during each estrus cycle. To sustain such regularity and periodicity, regulation occurs at the hypothalamic-pituitary-gonadal axis level and on developing follicles in the ovary. Despite active studies, follicle development mechanisms are not clear because of the several steps involved from the dormant primordial follicle activation to ovulation, and because of the regulation complexity that differs at each follicular stage. To investigate the mechanisms of follicle development, and the dynamics of follicles throughout the estrus cycle, we developed a mouse ovarian tissue culture model that can be used to observe follicle development using a microscope. Systematic follicle development, periodical ovulation, and follicle atresia can all be reproduced in the cultured ovary model, and the culture conditions can be experimentally modulated. Here, we demonstrate the usefulness of this method in the study of the regulatory mechanisms of follicle development and other ovarian phenomena.

Ovarian tissue cultures can be used as models of follicle development, ovulation, and follicle atresia and indicate regulatory mechanisms of dynamic ovarian processes.

Mammalian females periodically ovulate an almost constant number of oocytes during each estrus cycle. To sustain such regularity and periodicity, ...

A Mouse Distraction Osteogenesis Model

Distraction osteogenesis (DO) is a surgical procedure that involves skeletal tissue regeneration without cell transplantation. A DO model consists of the following three phases: the latency phase after osteotomy and placement of the external distractor; the distraction phase, wherein the separated bone ends are gradually and continuously distracted; and the consolidation phase. This custom-made distractor used for DO is comprised of two incomplete acrylic resin rings and an expansion screw. The process was initiated by making a mold with silicone impression material and then creating the custom-made distractor. Dental resin was poured into the formwork made of silicone impression material, and it was allowed to polymerize to create the incomplete resin rings required for the custom-made distractor. These rings were fixed with an expansion screw using transparent resin. The custom-made distractor created via this approach was attached to the tibia of mice. The tibia was fixed to the device using one pair of 25 G needles proximally, one pair of 27 G needles distally, and acrylic resin. After a latency period of 5 days, distraction was initiated at a rate of 0.2 mm/12 h. The lengthening was continued for 8 days, resulting in a total gap of 3.2 mm. The mice were sacrificed 4 weeks after distraction. Bone formation in the distraction gap was confirmed using both radiography and histology.

We present a mouse tibial distraction osteogenesis model developed using a custom-made distractor. The use of a mouse as an analysis target is advantageous for advancing research.

Distraction osteogenesis (DO) is a surgical procedure that involves skeletal tissue regeneration without cell transplantation. A DO model consists of the ...

Use of Hematopoietic Stem Cell Transplantation to Assess the Origin of Myelodysplastic Syndrome

Myelodysplastic syndromes (MDS) are a diverse group of hematopoietic stem cell disorders that are defined by ineffective hematopoiesis, peripheral blood cytopenias, dysplasia, and a propensity for transformation to acute leukemia. NUP98-HOXD13 (NHD13) transgenic mice recapitulate human MDS in terms of peripheral blood cytopenias, dysplasia, and transformation to acute leukemia. We previously demonstrated that MDS could be transferred from a genetically engineered mouse with MDS to wild-type recipients by transplanting MDS bone marrow nucleated cells (BMNC). To more clearly understand the MDS cell of origin, we have developed approaches to transplant specific, immunophenotypically defined hematopoietic subsets. In this article, we describe the process of isolating and transplanting specific populations of hematopoietic stem and progenitor cells. Following transplantation, we describe approaches to assess the efficiency of transplantation and persistence of the donor MDS cells.

We describe the use of hematopoietic stem cell transplantation (HSCT) to assess the malignant potential of genetically engineered hematopoietic cells. HSCT is useful for evaluating various malignant hematopoietic cells in vivo as well as generating a large cohort of mice with myelodysplastic syndromes (MDS) or leukemia to evaluate novel therapies.

Myelodysplastic syndromes (MDS) are a diverse group of hematopoietic stem cell disorders that are defined by ineffective hematopoiesis, peripheral blood ...

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart disease. When using prosthetic materials however, these grafts are susceptible to bacterial infections and various host responses.
Identification of bacterial and host factors that play a vital role in endovascular adherence of microorganisms is of importance to better understand the pathophysiology of the onset of infections such as infective endocarditis (IE) and to develop preventive strategies. Therefore, the development of competent models to investigate bacterial adhesion under physiological shear conditions is necessary. Here, we describe the use of a newly designed in vitro perfusion chamber based on parallel plates that allows the study of bacterial adherence to different components of graft tissues such as exposed extracellular matrix, endothelial cells and inert areas. This method combined with colony-forming unit (CFU) counting is adequate to evaluate the propensity of graft materials towards bacterial adhesion under flow. Further on, the flow chamber system might be used to investigate the role of blood components in bacterial adhesion under shear conditions. We demonstrated that the source of tissue, their surface morphology and bacterial species specificity are not the major determining factors in bacterial adherence to graft tissues by using our in-house designed in vitro perfusion model.

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

We describe an in-house designed in vitro flow chamber model, which allows the investigation of bacterial adherence to graft tissues.

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart ...

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by Sertoli cell junctions at the blood-testis barrier (BTB), which is the tightest tissue barrier in the mammalian body and segregates the seminiferous epithelium into two compartments, a basal and an adluminal. The BTB creates a unique microenvironment for germ cells in meiosis I/II and for the development of postmeiotic spermatids into spermatozoa via spermiogenesis. Here, we describe a reliable assay to monitor BTB integrity of mouse testis in vivo. An intact BTB blocks the diffusion of FITC-conjugated inulin from the basal to the apical compartment of the seminiferous tubules. This technique is suitable for studying gene candidates, viruses, or environmental toxicants that may affect BTB function or integrity, with an easy procedure and a minimal requirement of surgical skills compared to alternative methods.

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Here, we present a protocol to assess the blood-testis barrier integrity by injecting inulin-FITC into testes. This is an efficient in vivo method to study blood-testis barrier integrity that can be compromised by genetic and environmental elements.

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by ...