This work was supported in part by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research (26861689 and 17K11813). The authors would like to thank Mr. Nathaniel Green for proofreading.

This protocol is designed to create human gingival tissue equivalents, gingival wound models, and gingivitis models. Human skin epidermal keratinocytes (HaCaT) were kindly provided from Professor Norbert E. Fusenig of Deutsches Krebsforschungszentrum (Heidelberg, Germany)7. Human gingival fibroblasts (HGFs) were isolated from gingival tissues according to the previously published protocols8. Informed consent was obtained beforehand, and the study was approved according to the guidelines set by the Committee of Ethics, the Nippon Dental University School of Life Dentistry at Tokyo (Authorization Number: NDU-T2012-35). Protocol steps 1&#8211;3 should be performed in a cell culture hood.
1. Preparation of 3D Human Tissue Equivalents of Gingiva (GTE) (Figure 1A)
<ol>
	<li>Mix collagen type I-A gel with 10% concentrated MEM-alpha and 10% reconstruction buffer (2.2 g of NaHCO3 and 4.47 g HEPES in 100 mL 0.05 N NaOH) in a 15 mL sterile tube by pipetting. Keep the mixed collagen solution on ice until used.</li>
	<li>Place 24-well culture inserts (pore size 3.0 &#181;m) into a 24-well plate.</li>
	<li>Remove HGFs from the culture surface using 0.25% trypsin-EDTA solution. Suspend the cells in 10 mL of culture medium A (MEM-alpha + 20% FBS + 1% GlutaMAX). Count the cells by a B&#252;rker-T&#252;rk cell counter.
	<ol>
		<li>Extract the desired quantity of cells (1-5 x105 cells/mL), then centrifuge for 4 min at 190 x g.</li>
		<li>Suspend the cells in the mixed collagen solution. Keep the mixture on ice until the next step.</li>
	</ol>
	</li>
	<li>Add 0.5 mL of the cell-collagen mixture (0.5&#8211;2.5 x 105 cells/well) into the culture insert without producing any bubbles. Incubate the mixture for 10&#8211;30 min in a humidified atmosphere with 5% CO2 at 37 &#176;C to coagulate the mixture into a gel. 
	NOTE: Add the collagen mixture into the center of the culture insert to avoid unequal formation of collagen gel.</li>
	<li>Add 1 mL of the culture medium into the well and 0.5 mL into the insert. Incubate the culture plate for 24 h or overnight in a humidified atmosphere with 5% CO2 at 37 &#176;C.</li>
	<li>Remove HaCaT cells from the culture surface using 0.25% trypsin-EDTA solution. Suspend the cells in 10 mL of medium B (DMEM + 10% FBS + 1% GlutaMAX) and count the cells. Extract the needed quantity of cells (1&#8211;5 x 105 cells/mL) with a pipette, centrifuge for 4 min at 190 x g. Suspend the cells in medium B.</li>
	<li>Remove the medium from the culture inserts, which contain the HGF-collagen mixture, by aspiration. Add 0.5 mL of HaCaT cell suspension (0.5&#8211;2.5 x 105 cells/well) on the top of the HGF-collagen mixture. Incubate the cultures for 24 h or overnight. 
	NOTE: At this time point, the medium in the culture well should be medium A, while the medium in the culture insert should be medium B.</li>
	<li>Replace the culture medium with KSR medium (co-culture medium) (MEM-alpha + 15% KnockOut Serum Replacement + 1% GlutaMAX) + 5% FBS. Add 1 mL of the culture medium into the culture well and 0.5 mL into the culture insert. Incubate the cultures for 24&#8211;48 h.</li>
	<li>Replace the culture medium with KSR medium + 1% FBS. Add 1 mL into the culture well and 0.5 mL into the culture insert. Incubate the cultures for 24 h or overnight.</li>
	<li>Replace the culture medium in the culture well with 0.7&#8211;1 mL KSR medium. Remove the medium completely from the culture insert (the culture surface should be exposed to air). Incubate the cultures for 1&#8211;2 weeks. Change the medium in the culture well two times per week. 
	NOTE: Do not let the medium level rise above the culture surface (the top layer composed of keratinocytes). Always keep the culture surface dry.</li>
</ol>
2. Preparation of Wounded GTE (Figure 1B)
<ol>
	<li>Prepare a 1&#8211;3 mm diameter tissue puncher. Sterilize it with an autoclave at 121 &#176;C for 20 min.</li>
	<li>Push the tissue puncher perpendicularly into GTE about 300 &#181;m deep, and punch a hole in the tissue to simulate a wound.</li>
	<li>At this step, use the wounded GTE for investigating wound healing and tissue regeneration. Alternatively, fix GTE using 10% formalin neutral buffer solution to perform histological analysis.</li>
</ol>
3. Preparation of Inflammatory GTE (iGTE) (Figure 1B)
<ol>
	<li>Cultivate THP-1 cells according to the previous report9.</li>
	<li>Mix collagen type I-A gel with 10% concentrated RPMI 1640, 10% reconstruction buffer (2.2 g of NaHCO3 and 4.47 g HEPES in 100 mL 0.05 N NaOH) and 10 ng/mL PMA. Keep the mixed collagen solution on ice until use.</li>
	<li>Count 1&#8211;2 x 106 THP-1 cells and centrifuge for 4 min at 190 x g. Suspend the cells in 1 mL of the mixed collagen solution. Keep the mixture on ice until the next step.</li>
	<li>Add 10&#8211;30 &#181;L THP-1-collagen mixture into the wounded area of GTE. Replace the culture medium to 0.7&#8211;1 mL KSR medium containing 10 ng/mL of PMA.</li>
	<li>Incubate the mixture in a humidified atmosphere with 5% CO2 at 37 &#176;C for 72 h.</li>
	<li>Use the model for investigating gingivitis or periodontal disease (for example, add potential anti-inflammatory medicine to iGTE to see its effects on cytokine release10). Alternatively, omit 72 h PMA-treatment, add 2 &#181;g/mL of LPS into the culture, and incubate the tissue in a humidified atmosphere with 5% CO2 at 37 &#176;C for 48 h11,12.</li>
</ol>
4. Fixation and Whole Mount Immunostaining of GTE and iGTE Cultures
<ol>
	<li>Fixation of the cultures.
	<ol>
		<li>Remove the culture medium from the 24-well plate. Wash the tissues 2 times with phosphate buffered saline (PBS).</li>
		<li>Add 1 mL of 10% formalin neutral buffer solution to the insert and 1 mL to the culture well. Leave the 24-well plate in a refrigerator at 4 &#176;C overnight.</li>
		<li>Remove the 10% formalin neutral buffer solution the following day.</li>
		<li>For whole mount immunostaining, wash the tissues 3-4 times with PBS after fixation.</li>
		<li>For hematoxylin and eosin (H&#38;E) staining and regular immunostaining, proceed with dehydration, paraffin embedding, and sectioning. 
		NOTE: For whole mount immunostaining, this step can be omitted.</li>
	</ol>
	</li>
	<li>Whole mount immunostaining 
	NOTE: This protocol was modified from the one in reference 13.
	<ol>
		<li>Wash the tissues 3x in PBS 0.5&#8211;1% Triton, 10&#8211;30 min each time.</li>
		<li>Incubate the tissues twice for 30 min in blocking buffer (PBS 1% Triton + 10% BSA), at room temperature.</li>
		<li>Wash the tissues 2&#215; in blocking buffer, 5&#8211;10 min each time.</li>
		<li>Add 50 &#181;L of primary antibody solution at the required dilution/concentration to the inserts. Use a thin plastic cling film to wrap the inserts to avoid drying out the tissue.</li>
		<li>Incubate the tissue for 1 to 2 days at 4 &#176;C.</li>
		<li>Wash the tissues 3 times, for 30 min in PBS 1% Triton + 10% BSA. Wash again 3 times, for 5 min in PBS 1% Triton.</li>
		<li>Add 50 &#181;L of secondary antibody in blocking buffer (PBS 1% Triton + 10% BSA) and 5 &#181;L of Hoechst 33342 solution (NucBlue Live Cell stain) to each insert. Use a thin plastic cling film to wrap the inserts to avoid drying out the tissue.</li>
		<li>Incubate for 1 to 2 days at 4 &#176;C. Wrap the 24-well plate in a wet paper towel, and then put it into a plastic pack to be used throughout incubation.</li>
		<li>Wash the tissues 3 times, for 10 min in PBS 1% triton</li>
		<li>Use a sharp needle to cut the membrane of the culture insert to obtain the tissue. Place the membrane onto a slide. 
		NOTE: The tissue should be on the membrane.</li>
		<li>Add 2&#8211;3 drops of fluorescence mount medium. Cover the tissue with a cover glass and store at 4 &#176;C in the dark until analysis.</li>
		<li>View tissues with a confocal laser scanning microscopy (LSM).</li>
	</ol>
	</li>
</ol>

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The authors declare no conflict of interest.

This protocol is based on methods of creating gingival tissue equivalents and subcutaneous adipose-tissue equivalents described by previous reports8,21,22. Although this is a simple and easy method, some steps require special attention. For example, the collagen mixture should be kept on ice until use to avoid gel formation in the solution. When adding the collagen mixture into the culture insert, make sure the solution was inje...

Periodontal diseases are the leading cause of tooth loss in adults. Gingivitis and periodontitis are the most common periodontal diseases. Both present biofilm-mediated acute or chronic inflammatory changes in gingiva. Gingivitis is characterized by acute inflammation, whereas periodontitis usually presents as chronic inflammation. On the histological level,bacterial components trigger the activation of immune cells, such as macrophages, lymphocytes, plasma cells, and mast cells1,2. These immune cells, especially macrophages, interact with local cells (including gingival epithelial cells, fibroblasts, endothelial cells, and osteoblasts) resulting in inflammatory lesions in periodontal tissue3,4. Experimental models of periodontal diseases have been established in various types of animals, such as rats, hamsters, rabbits, ferrets, canines, and primates. However, the physiopathology of animal models is different from that of humans, making it difficult to analyze cellular and molecular mechanisms and evaluate new medicines of periodontal diseases5. Co-cultivation of periodontal bacteria and monolayer human oral epithelial cells has been used to investigate the mechanism of periodontal infections6. Nevertheless, monolayer cultures of oral cells lack the three-dimensional (3D) cellular architecture of intact tissue; therefore, they cannot mimic the in vitro situation.
Here, 3D inflammatory human tissue equivalents of gingiva (iGTE) are established to represent periodontal diseases in vitro. This 3D model of periodontal diseases occupies an intermediate position between monolayer cell cultures and animal models. Three types of human cells, including HaCaT keratinocytes, gingival fibroblasts, and THP-1 macrophages, are co-cultivated on collagen gel, and stimulated by inflammatory initiators to build iGTE. IGTE closely simulates the in vivo conditions of cell differentiation, cell-cell interaction, and macrophage activation in gingiva. This model has many possible applications for drug screening and testing new pharmacological approaches in periodontal diseases, as well as for analyzing cellular and molecular mechanisms in wound healing, inflammation, and tissue regeneration.

<table>
	<tbody>
		<tr>
			<td>Collagen type I-A</td>
			<td>Nitta Gelatin Inc</td>
			<td></td>
			<td>For making dermis of GTE</td>
		</tr>
		<tr>
			<td>MEM-alpha</td>
			<td>Thermo Fisher Scientific</td>
			<td>11900073</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>Cell Culture Insert (for 24-well plate), pore size 3.0 &#956;m</td>
			<td>Corning, Inc.</td>
			<td>353096</td>
			<td>For tissue culture</td>
		</tr>
		<tr>
			<td>GlutaMAX</td>
			<td>Thermo Fisher Scientific</td>
			<td>35050061</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>31600034</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>KnockOut Serum Replacement</td>
			<td>Thermo Fisher Scientific</td>
			<td>10828028</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Tissue puncher</td>
			<td>Shibata system service co., LTD</td>
			<td>SP-703</td>
			<td>For punching holes in GTE</td>
		</tr>
		<tr>
			<td>RPMI 1640</td>
			<td>Thermo Fisher Scientific</td>
			<td>31800022</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Sigma-Aldrich</td>
			<td>A3294</td>
			<td>For immunostaining</td>
		</tr>
		<tr>
			<td>Hoechst 33342 (NucBlue Live Cell stain)</td>
			<td>Thermo Fisher Scientific</td>
			<td>R37605</td>
			<td>For labeling nuclei</td>
		</tr>
		<tr>
			<td>Fluorescence mount medium</td>
			<td>Dako</td>
			<td></td>
			<td>For mounting samples after immunostaining</td>
		</tr>
		<tr>
			<td>Anti-Cytokeratin 8+18 antibody [5D3]</td>
			<td>abcam</td>
			<td>ab17139</td>
			<td>For identifying epithelium</td>
		</tr>
		<tr>
			<td>Scaning electron microscope</td>
			<td>Hitachi, Ltd.</td>
			<td>HITACHI S-4000</td>
			<td>For observing samples&#39; surface topography and composition</td>
		</tr>
		<tr>
			<td>Confocal laser scanning microscopy</td>
			<td>LSM 700; Carl Zeiss Microscopy Co., Ltd.</td>
			<td>LSM 700</td>
			<td>For observing samples&#39; immunofluorescence staining</td>
		</tr>
		<tr>
			<td>Anti-Cytokeratin 19 antibody</td>
			<td>abcam</td>
			<td>ab52625</td>
			<td>For identifying epithelium</td>
		</tr>
		<tr>
			<td>Anti-vimentin antibody</td>
			<td>abcam</td>
			<td>ab92547</td>
			<td>For identifying fibroblasts and activated macrophages</td>
		</tr>
		<tr>
			<td>Anti-TE-7 antibody</td>
			<td>Millipore</td>
			<td>CBL271</td>
			<td>For identifying fibroblasts in the dermis</td>
		</tr>
		<tr>
			<td>Anti-CD68 antibody</td>
			<td>Sigma-Aldrich</td>
			<td>SAB2700244</td>
			<td>For identifying macrophages</td>
		</tr>
		<tr>
			<td>Human CD14 Antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB3832-SP</td>
			<td>For identifying macrophages</td>
		</tr>
		<tr>
			<td>Alexa Fluor 594-conjugated secondary goat anti-rabbit antibody</td>
			<td>Thermo Fisher Scientific</td>
			<td>A11012</td>
			<td>For immunofluorescence staining</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488-conjugated secondary goat anti-mouse antibody</td>
			<td>Thermo Fisher Scientific</td>
			<td>A11001</td>
			<td>For immunofluorescence staining</td>
		</tr>
		<tr>
			<td>EVOS FL Cell Imaging System</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>For observing the sample&#39;s immunofluorescence staining</td>
		</tr>
		<tr>
			<td>THP-1 cells</td>
			<td>Riken BRC cell bank</td>
			<td>RCB1189</td>
			<td>For making iGTE</td>
		</tr>
		<tr>
			<td>PMA(Phorbol 12-myristate 13-acetate)</td>
			<td>Sigma-Aldrich</td>
			<td>P8139</td>
			<td>For differentiatting THP-1 cells</td>
		</tr>
	</tbody>
</table>

three-dimensional inflammatory human tissue equivalents of gingiva

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental physiopathology of periodontal diseases. Current experimental models of periodontal diseases have been established in various types of animals. However, the physiopathology of animal models is different from that of humans, making it difficult to analyze cellular and molecular mechanisms and evaluate new medicines for periodontal diseases. Here, we present a detailed protocol for reconstructing human inflammatory tissue equivalents of gingiva (iGTE) in vitro. We first build human tissue equivalents of gingiva (GTE) by utilizing two types of human cells, including human gingival fibroblasts (HGF) and human skin epidermal keratinocytes (HaCaT), under three-dimensional conditions. We create a wound model by using a tissue puncher to punch a hole in the GTE. Next, human THP-1 monocytes mixed with collagen gel are injected into the hole in the GTE. By adimistration of 10 ng/mL phorbol 12-myristate 13-acetate (PMA) for 72 h, THP-1 cells differentiated into macrophages to form inflammatory foci in GTE (iGTE) (IGTE also can be stumilated with 2 &#181;g/mL of lipopolysaccharides (LPS) for 48 h to initiate inflammation). IGTE is the first in vitro model of inflammatory gingiva using human cells with a three-dimensional architecture. IGTE reflects major pathological changes (immunocytes activition, intracellular interactions among fibryoblasts, epithelial cells, monocytes and macrophages) in periodontal diseases. GTE, wounded GTE, and iGTE can be used as versatile tools to study wound healing, tissue regeneration, inflammation, cell-cell interaction, and screen potential medicines for periodontal diseases.

HaCaT cells displayed typical keratinocyte morphology under phase-contrast microscopic observation (Figure 2A). Scanner electron microscopic (SEM) images showed that HaCaT cell surfaces were covered by many microvilli. Intercellular connections between HaCaT cells were mediated by membrane processes (Figure 2B). HaCaT cells expressed gingival epithelium marker K8/1814, indicating that HaCaT cells are suita...

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Three-dimensional Inflammatory Human Tissue Equivalents of Gingiva

The goal of the protocol is to build an inflammatory human gingiva model in vitro. This tissue model co-cultivates three types of human cells, HaCaT keratinocytes, gingival fibroblasts, and THP-1 macrophages, under three-dimensional conditions. This model can be applied to investigating periodontal diseases, such as gingivitis and periodontitis.

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental ...

three-dimensional-inflammatory-human-tissue-equivalents-of-gingiva

Research

JoVE Journal

Developmental Biology

9.7K Views.  The Nippon Dental University. The goal of the protocol is to build an inflammatory human gingiva model in vitro. This tissue model co-cultivates three types of human cells, HaCaT keratinocytes, gingival fibroblasts, and THP-1 macrophages, under three-dimensional conditions. This model can be applied to investigating periodontal diseases, such as gingivitis and periodontitis.

Video: Three-dimensional Inflammatory Human Tissue Equivalents of Gingiva

Differentiation of a Human Neural Stem Cell Line on Three Dimensional Cultures, Analysis of MicroRNA and Putative Target Genes

Neural stem cells (NSCs) are capable of self-renewal and differentiation into neurons, astrocytes and oligodendrocytes under specific local microenvironments. In here, we present a set of methods used for three dimensional (3D) differentiation and miRNA analysis of a clonal human neural stem cell (hNSC) line, currently in clinical trials for stroke disability (NCT01151124 and NCT02117635, Clinicaltrials.gov). HNSCs were derived from an ethical approved first trimester human fetal cortex and conditionally immortalized using retroviral integration of a single copy of the c-mycERTAMconstruct. We describe how to measure axon process outgrowth of hNSCs differentiated on 3D scaffolds and how to quantify associated changes in miRNA expression using PCR array. Furthermore we exemplify computational analysis with the aim of selecting miRNA putative targets. SOX5 and NR4A3 were identified as suitable miRNA putative target of selected significantly down-regulated miRNAs in differentiated hNSC. MiRNA target validation was performed on SOX5 and NR4A3 3&#8217;UTRs by dual reporter plasmid transfection and dual luciferase assay.

With the intent of characterizing changes in miRNAs on differentiated human neural stem cells (hNSCs) we describe hNSC differentiation on a three dimensional system,the evaluation of changes in microRNA expression by miRNA PCR array, and computational analysis for miRNA target prediction and its validation by dual luciferase assay.

Neural stem cells (NSCs) are capable of self-renewal and differentiation into neurons, astrocytes and oligodendrocytes under specific local ...

Three-dimensional Quantification of Dendritic Spines from Pyramidal Neurons Derived from Human Induced Pluripotent Stem Cells

Dendritic spines are small protrusions that correspond to the post-synaptic compartments of excitatory synapses in the central nervous system. They are distributed along the dendrites. Their morphology is largely dependent on neuronal activity, and they are dynamic. Dendritic spines express glutamatergic receptors (AMPA and NMDA receptors) on their surface and at the levels of postsynaptic densities. Each spine allows the neuron to control its state and local activity independently. Spine morphologies have been extensively studied in glutamatergic pyramidal cells of the brain cortex, using both in vivo approaches and neuronal cultures obtained from rodent tissues. Neuropathological conditions can be associated to altered spine induction and maturation, as shown in rodent cultured neurons and one-dimensional quantitative analysis 1. The present study describes a protocol for the 3D quantitative analysis of spine morphologies using human cortical neurons derived from neural stem cells (late cortical progenitors). These cells were initially obtained from induced&#160;pluripotent stem cells. This protocol allows the analysis of spine morphologies at different culture periods, and with possible comparison between induced&#160;pluripotent stem cells obtained from control individuals with those obtained from patients with psychiatric diseases.

Dendritic spines of pyramidal neurons are the sites of most excitatory synapses in mammalian brain cortex. This method describes a 3D quantitative analysis of spine morphologies in human cortical pyramidal glutamatergic neurons derived from induced&#160;pluripotent stem cells.

Dendritic spines are small protrusions that correspond to the post-synaptic compartments of excitatory synapses in the central nervous system. They are ...

Isolation of Perivascular Multipotent Precursor Cell Populations from Human Cardiac Tissue

Multipotent mesenchymal stem/stromal cells (MSC) were conventionally isolated, through their plastic adherence, from primary tissue digests whilst their anatomical tissue location remained unclear. The recent discovery of defined perivascular and MSC cell marker expression by perivascular cells in multiple tissues by our group and other researchers has provided an opportunity to prospectively isolate and purify specific homogenous subpopulations of multipotent perivascular precursor cells. We have previously demonstrated the use of fluorescent activated cell sorting (FACS) to purify microvascular CD146+CD34- pericytes and vascular CD34+CD146- adventitial cells from human skeletal muscle. Herein we describe a method to simultaneously isolate these two perivascular cell subsets from human myocardium by FACS, based on the expression of a defined set of cell surface markers for positive and negative selections. This method thus makes available two specific subpopulations of multipotent cardiac MSC-like precursor cells for use in basic research and/or therapeutic investigations.

Human cardiac tissue harbours multipotent perivascular precursor cell populations that may be suitable for myocardial regeneration. The technique described here allows for the simultaneous isolation and purification of two multipotent stromal cell populations associated with native blood vessels, i.e. CD146+CD34- pericytes and CD34+CD146- adventitial cells, from the human myocardium.

Multipotent mesenchymal stem/stromal cells (MSC) were conventionally isolated, through their plastic adherence, from primary tissue digests whilst their ...

Analysis of Retinoic Acid-induced Neural Differentiation of Mouse Embryonic Stem Cells in Two and Three-dimensional Embryoid Bodies

Mouse embryonic stem cells (ESCs) isolated from the inner mass of the blastocyst (typically at day E3.5), can be used as in vitro model system for studying early embryonic development. In the absence of leukemia inhibitory factor (LIF), ESCs differentiate by default into neural precursor cells. They can be amassed into a three dimensional (3D) spherical aggregate termed embryoid body (EB) due to its similarity to the early stage embryo. EBs can be seeded on fibronectin-coated coverslips, where they expand by growing two dimensional (2D) extensions, or implanted in 3D collagen matrices where they continue growing as spheroids, and differentiate into the three germ layers: endodermal, mesodermal, and ectodermal. The 3D collagen culture mimics the in vivo environment more closely than the 2D EBs. The 2D EB culture facilitates analysis by immunofluorescence and immunoblotting to track differentiation. We have developed a two-step neural differentiation protocol. In the first step, EBs are generated by the hanging-drop technique, and, simultaneously, are induced to differentiate by exposure to retinoic acid (RA). In the second step, neural differentiation proceeds in a 2D or 3D format in the absence of RA.

We describe a technique for using murine embryonic stem cells for generating two or three dimensional embryoid bodies. We then explain how to induce neural differentiation of the embryoid body cells by retinoic acid, and how to analyze their state of differentiation by progenitor cell marker immunofluorescence and immunoblotting.

Mouse embryonic stem cells (ESCs) isolated from the inner mass of the blastocyst (typically at day E3.5), can be used as in vitro model system for ...

Live Imaging of Mouse Secondary Palate Fusion

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to cleft secondary palate, a common congenital anomaly in humans. Secondary palate fusion has been extensively studied leading to several proposed cellular mechanisms that may mediate this process. However, these studies have been mostly performed on fixed embryonic tissues at progressive timepoints during development or in fixed explant cultures analyzed at static timepoints. Static analysis is limited for the analysis of dynamic morphogenetic processes such a palate fusion and what types of dynamic cellular behaviors mediate palatal fusion is incompletely understood. Here we describe a protocol for live imaging of ex vivo secondary palate fusion in mouse embryos. To examine cellular behaviors of palate fusion, epithelial-specific Keratin14-cre was used to label palate epithelial cells in ROSA26-mTmGflox reporter embryos. To visualize filamentous actin, Lifeact-mRFPruby reporter mice were used. Live imaging of secondary palate fusion was performed by dissecting recently-adhered secondary palatal shelves of embryonic day (E) 14.5 stage embryos and culturing in agarose-containing media on a glass bottom dish to enable imaging with an inverted confocal microscope. Using this method, we have detected a variety of novel cellular behaviors during secondary palate fusion. An appreciation of how distinct cell behaviors are coordinated in space and time greatly contributes to our understanding of this dynamic morphogenetic process. This protocol can be applied to mutant mouse lines, or cultures treated with pharmacological inhibitors to further advance understanding of how secondary palate fusion is controlled.

Here, we present a protocol for live imaging of mouse secondary palate fusion using confocal microscopy. This protocol can be used in combination with a variety of fluorescent reporter mouse lines, and with pathway inhibitors for mechanistic insight. This protocol can be adapted for live imaging in other developmental systems.

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to ...

Horizontal Whole Mount: A Novel Processing and Imaging Protocol for Thick, Three-dimensional Tissue Cross-sections of Skin

Processing a tissue of interest to generate a microscopic image that supports a scientific argument can be challenging. The acquisition of high-quality microscopic images is not entirely dependent upon the quality of the microscope, but also upon the methods of tissue processing, which often involve multiple critical actions or steps. Furthermore, mesenchymal cell types in the skin and other tissues represent a new challenge for tissue preparation and imaging. Here, we present a complete process, from tissue harvest to microscopy. Our technique, called &#34;horizontal whole mount,&#34; is one that novices can quickly become proficient in and that allows for antigen preservation and detection in 60-300 &#181;m-thick sections cut with a cryostat. Sections of this thickness provide enhanced visualization of tissue microarchitecture in a three-dimensional environment. In addition, the protocol preserves mesenchymal cells in a manner that enhances image quality when compared to standard cryostat or paraffin sections, thereby increasing the efficacy and reliability of immunostaining. We believe that this protocol will benefit all laboratories that visualize skin, and possibly other tissues and organs.

This work presents a novel processing and imaging protocol for thick, three-dimensional tissue cross-section analysis that enables the full exploitation of confocal imaging modalities. This protocol preserves antigenicity and represents a robust system to analyze skin histology and potentially other tissue types.

Processing a tissue of interest to generate a microscopic image that supports a scientific argument can be challenging. The acquisition of high-quality ...

A Novel Use of Three-dimensional High-frequency Ultrasonography for Early Pregnancy Characterization in the Mouse

High-frequency ultrasonography (HFUS) is a common method to non-invasively monitor the real-time development of the human fetus in utero. The mouse is routinely used as an in vivo model to study embryo implantation and pregnancy progression. Unfortunately, such murine studies require pregnancy interruption to enable follow-up phenotypic analysis. To address this issue, we used three-dimensional (3-D) reconstruction of HFUS imaging data for early detection and characterization of murine embryo implantation sites and their individual developmental progression in utero. Combining HFUS imaging with 3-D reconstruction and modeling, we were able to accurately quantify embryo implantation site number as well as monitor developmental progression in pregnant C57BL6J/129S mice from 5.5 days post coitus (d.p.c.) through to 9.5 d.p.c. with the use of a transducer. Measurements included: number, location, and volume of implantation sites as well as inter-implantation site spacing; embryo viability was assessed by cardiac activity monitoring. In the immediate post-implantation period (5.5 to 8.5 d.p.c.), 3-D reconstruction of the gravid uterus in both mesh and solid overlay format enabled visual representation of the developing pregnancies within each uterine horn. As genetically engineered mice continue to be used to characterize female reproductive phenotypes derived from uterine dysfunction, this method offers a new approach to detect, quantify, and characterize early implantation events in vivo. This novel use of 3-D HFUS imaging demonstrates the ability to successfully detect, visualize, and characterize embryo-implantation sites during early murine pregnancy in a non-invasive manner. The technology offers a significant improvement over current methods, which rely on the interruption of pregnancies for gross tissue and histopathologic characterization. Here we use a video and text format to describe how to successfully perform ultrasounds of early murine pregnancy to generate reliable and reproducible data with reconstruction of the uterine form in mesh and solid 3-D images.

Mice are widely used to study gestational biology. However, pregnancy termination is required for such studies which precludes longitudinal investigations and necessitates the use of large numbers of animals. Therefore, we describe a non-invasive technique of high-frequency ultrasonography for early detection and monitoring of post-implantation events in the pregnant mouse.

High-frequency ultrasonography (HFUS) is a common method to non-invasively monitor the real-time development of the human fetus in utero. The mouse is ...

Three-dimensional Rendering and Analysis of Immunolabeled, Clarified Human Placental Villous Vascular Networks

Nutrient and gas exchange between mother and fetus occurs at the interface of the maternal intervillous blood and the vast villous capillary network that makes up much of the parenchyma of the human placenta. The distal villous capillary network is the terminus of the fetal blood supply after several generations of branching of vessels extending out from the umbilical cord. This network has a contiguous cellular sheath, the syncytial trophoblast barrier layer, which prevents mixing of fetal blood and the maternal blood in which it is continuously bathed. Insults to the integrity of the placental capillary network, occurring in disorders such as maternal diabetes, hypertension and obesity, have consequences that present serious health risks for the fetus, infant, and adult. To better define the structural effects of these insults, a protocol was developed for this study that captures capillary network structure on the order of 1 - 2 mm3 wherein one can investigate its topological features in its full complexity. To accomplish this, clusters of terminal villi from placenta are dissected, and the trophoblast layer and the capillary endothelia are immunolabeled. These samples are then clarified with a new tissue clearing process which makes it possible to acquire confocal image stacks to z- depths of ~1 mm. The three-dimensional renderings of these stacks are then processed and analyzed to generate basic capillary network measures such as volume, number of capillary branches, and capillary branch end points, as validation of the suitability of this approach for capillary network characterization.

This study presents a protocol for the reversible tissue clearing, immunostaining, 3D-rendering and analysis of vascular networks in human placenta villi samples on the order of 1 - 2 mm3.

Nutrient and gas exchange between mother and fetus occurs at the interface of the maternal intervillous blood and the vast villous capillary network that ...

Three-dimensional Organotypic Cultures of Vestibular and Auditory Sensory Organs

The sensory organs of the inner ear are challenging to study in mammals due to their inaccessibility to experimental manipulation and optical observation. Moreover, although existing culture techniques allow biochemical perturbations, these methods do not provide a means to study the effects of mechanical force and tissue stiffness during development of the inner ear sensory organs. Here we describe a method for three-dimensional organotypic culture of the intact murine utricle and cochlea that overcomes these limitations. The technique for adjustment of a three-dimensional matrix stiffness described here permits manipulation of the elastic force opposing tissue growth. This method can therefore be used to study the role of mechanical forces during inner ear development. Additionally, the cultures permit virus-mediated gene delivery, which can be used for gain- and loss-of-function experiments. This culture method preserves innate hair cells and supporting cells and serves as a potentially superior alternative to the traditional two-dimensional culture of vestibular and auditory sensory organs.

Three-dimensional organotypic cultures of the murine utricle and cochlea in optically clear collagen I gels preserve innate tissue morphology, allow for mechanical stimulation through adjustment of matrix stiffness, and permit virus-mediated gene delivery.

The sensory organs of the inner ear are challenging to study in mammals due to their inaccessibility to experimental manipulation and optical observation. ...

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell types include enzyme-secreting acinar cells, an arborized ductal system responsible for the transportation of enzymes to the gut, and hormone-producing endocrine cells. 
Endocrine beta-cells are the sole cell type in the body that produce insulin to lower blood glucose levels. Diabetes, a disease characterized by a loss or the dysfunction of beta-cells, is reaching epidemic proportions. Thus, it is essential to establish protocols to investigate beta-cell development that can be used for screening purposes to derive the drug and cell-based therapeutics. While the experimental investigation of mouse development is essential, in vivo studies are laborious and time-consuming. Cultured cells provide a more convenient platform for screening; however, they are unable to maintain the cellular diversity, architectural organization, and cellular interactions found in vivo. Thus, it is essential to develop new tools to investigate pancreatic organogenesis and physiology.
Pancreatic epithelial cells develop in the close association with mesenchyme from the onset of organogenesis as cells organize and differentiate into the complex, physiologically competent adult organ. The pancreatic mesenchyme provides important signals for the endocrine development, many of which are not well understood yet, thus difficult to recapitulate during the in vitro culture. Here, we describe a protocol to culture three-dimensional, cellular complex mouse organoids that retain mesenchyme, termed pancreatoids. The e10.5 murine pancreatic bud is dissected, dissociated, and cultured in a scaffold-free environment. These floating cells self-assemble with mesenchyme enveloping the developing pancreatoid and a robust number of endocrine beta-cells developing along with the acinar and the duct cells. This system can be used to study the cell fate determination, structural organization, and morphogenesis, cell-cell interactions during organogenesis, or for the drug, small molecule, or genetic screening.

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

Here, we present a protocol to generate insulin expressing 3D murine pancreatoids from free-floating e10.5 dissociated pancreatic progenitors and the associated mesenchyme.

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell ...