Name: efficient vascularization of kidney organoids through intracelomic transplantation in chicken embryos
Uploaded: 2023-02-17T13:10:00
Description: Watch this Scientific Journal Video about Efficient Vascularization of Kidney Organoids through Intracelomic Transplantation in Chicken Embryos at JoVE.com

We thank George Galaris (LUMC, Leiden, the Netherlands) for his help with chicken embryo injection. We acknowledge the support of Saskia van der Wal-Maas (Department of Anatomy &#38; Embryology, LUMC, Leiden, the Netherlands), Conny van Munsteren (Department of Anatomy &#38; Embryology, LUMC, Leiden, the Netherlands), Manon Zuurmond (LUMC, Leiden, the Netherlands), and Annemarie de Graaf (LUMC, Leiden, the Netherlands). M. Koning is supported by &#39;Nephrosearch Stichting tot steun van het wetenschappelijk onderzoek van de afdeling Nierziekten van het LUMC&#39;. This work was in part supported by the Leiden University Fund &#34;Prof. Jaap de Graeff-Lingling Wiyadhanrma Fund&#34; GWF2019-02. This work is supported by the partners of Regenerative Medicine Crossing Borders (RegMedXB) and Health Holland, Top Sector Life Sciences &#38; Health. C.W. van den Berg and T.J. Rabelink are supported by The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), The Novo Nordisk Foundation Center for Stem Cell Medicine is supported by Novo Nordisk Foundation grants (NNF21CC0073729).

In accordance with Dutch law, approval by the animal welfare committee was not required for this research.
1. Preparing hiPSC-derived kidney organoids for transplantation
<ol>
	<li>Differentiate hiPSCs to kidney organoids using the protocol developed by Takasato et al.4,18,31. Culture the organoids following this protocol on polyester cell culture inserts with 0.4 &#181;m pores (cel...

<ol>
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In this manuscript, a protocol for intracelomic transplantation of hiPSC-derived kidney organoids in chicken embryos is demonstrated. Upon transplantation, organoids are vascularized by perfused blood vessels that consist of a combination of human organoid-derived and chicken-derived ECs. These are spread throughout the organoid and invade the glomerular structures, enabling interaction between the ECs and podocytes. It was previously shown that this leads to enhanced maturation of the organoid glomerular and tubular str...

Human induced pluripotent stem cell (hiPSC)-derived kidney organoids have been shown to have potential for developmental studies1,2,3,4, toxicity screening5,6, and disease modeling5,7,8,9,10,11,12,13. However, their applicability for these and eventual clinical transplantation purposes is limited by the lack of a vascular network. During embryonic kidney development, podocytes, mesangial cells, and vascular endothelial cells (ECs) interact to form the intricate structure of the glomerulus. Without this interaction, the glomerular filtration barrier, consisting of podocytes, the glomerular basement membrane (GBM), and ECs, cannot develop properly14,15,16. Although kidney organoids in vitro do contain some ECs, these fail to form a proper vascular network and diminish over time17. It is therefore not surprising that the organoids remain immature. Transplantation in mice induces vascularization and maturation of the kidney organoids18,19,20,21. Unfortunately, this is a labor-intensive process that is unsuitable for the analysis of large numbers of organoids.
Chicken embryos have been used to study vascularization and development for over a century22. They are easily accessible, require low maintenance, lack a fully functional immune system, and can develop normally after opening the eggshell23,24,25,26. The transplantation of organoids on their chorioallantoic membrane (CAM) has been shown to lead to vascularization27. However, the duration of transplantation on the CAM, as well as the level of maturation of the graft, are limited by CAM formation, which takes until embryonic day 7 to complete. Therefore, a method was recently developed to efficiently vascularize and mature kidney organoids through intracelomic transplantation in chicken embryos28. The celomic cavity of chicken embryos has been known since the 1930s to be a favorable environment for the differentiation of embryonic tissues29,30. It can be accessed early in embryonic development and allows for relatively unlimited expansion of the graft in all directions.
This paper outlines a protocol for the transplantation of hiPSC-derived kidney organoids in the celomic cavity of day 4 chicken embryos. This method induces vascularization and enhanced maturation of the organoids within 8 days. Injection of fluorescently labeled lens culinaris agglutinin (LCA) prior to sacrificing the embryos enables visualization of perfused blood vessels within the organoids through confocal microscopy.

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	<tbody>
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			<td>0.2 &#181;m filter: Whatman Puradisc 30 syringe filter 0.2 &#181;m</td>
			<td>Whatman</td>
			<td>10462200</td>
			<td></td>
		</tr>
		<tr>
			<td>35 mm glass bottom dishes&#160;</td>
			<td>MatTek Corporation</td>
			<td>P35G-1.5-14-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Aspirator tube assemblies for calibrated microcapillary pipettes</td>
			<td>Sigma-Aldrich</td>
			<td>A5177-5EA</td>
			<td>Contains silicone tubes, mouth piece and connector</td>
		</tr>
		<tr>
			<td>Confocal microscope: Leica White Light Laser Confocal Microscope&#160;</td>
			<td>Leica</td>
			<td>TCS SP8</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting forceps, simple type. Titanium, curved, with fine sharp tips</td>
			<td>Hammacher Karl</td>
			<td>HAMMHTC091-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting forceps, simple type. Titanium, straight, with fine sharp tips</td>
			<td>Hammacher Karl</td>
			<td>HAMMHTC090-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting microscope&#160;</td>
			<td>Wild Heerbrugg</td>
			<td>355110</td>
			<td></td>
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			<td>Dissecting scissors, curved, OP-special, extra sharp/sharp</td>
			<td>Hammacher Karl</td>
			<td>HAMMHSB391-10</td>
			<td></td>
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		<tr>
			<td>Donkey serum</td>
			<td>Sigma-Aldrich</td>
			<td>D9663</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey-&#945;-mouse Alexa Fluor 488</td>
			<td>ThermoFisher Scientific</td>
			<td>A-212-02</td>
			<td>dilution 1:500</td>
		</tr>
		<tr>
			<td>Donkey-&#945;-sheep Alexa Fluor 647</td>
			<td>ThermoFisher Scientific</td>
			<td>A-21448</td>
			<td>dilution 1:500</td>
		</tr>
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			<td>Double edged stainless steel razor blades</td>
			<td>Electron Microsopy Sciences</td>
			<td>72000</td>
			<td></td>
		</tr>
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			<td>DPBS, calcium, magnesium (DPBS-/-)</td>
			<td>ThermoFisher Scientific</td>
			<td>14040133</td>
			<td></td>
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		<tr>
			<td>DPBS, no calcium, no magnesium (DPBS+/+)</td>
			<td>ThermoFisher Scientific</td>
			<td>14190094</td>
			<td></td>
		</tr>
		<tr>
			<td>Egg cartons or custom made egg holders&#160;</td>
			<td>NA</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Fertilized white leghorn eggs (Gallus Gallus Domesticus)&#160;</td>
			<td>Drost Loosdrecht B.V.</td>
			<td>NA</td>
			<td></td>
		</tr>
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			<td>Incubator</td>
			<td>Elbanton BV</td>
			<td>ET-3 combi</td>
			<td></td>
		</tr>
		<tr>
			<td>Lotus Tetragonolobus lectin (LTL) Biotinylated</td>
			<td>Vector Laboratories</td>
			<td>B-1325</td>
			<td>dilution 1:300</td>
		</tr>
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			<td>Micro scissors, straight, sharp/sharp, cutting length 10 mm</td>
			<td>Hammacher Karl</td>
			<td>HAMMHSB500-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcapillaries: Thin wall glass capillaries 1.5 mm, filament</td>
			<td>World Precision Instruments</td>
			<td>TW150F-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette puller</td>
			<td>Sutter Instrument Company</td>
			<td>Model P-97</td>
			<td>We use the following settings: Heat 533, Pull 60, Velocity 150, Time 200</td>
		</tr>
		<tr>
			<td>Microscalpel holder: Castroviejo blade and pins holder, 12 cm, round handle, conical 10 mm jaws.</td>
			<td>Euronexia</td>
			<td>L-120</td>
			<td></td>
		</tr>
		<tr>
			<td>Mounting medium: Prolong Gold Antifade Mountant&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>P36930</td>
			<td></td>
		</tr>
		<tr>
			<td>Olivecrona dura dissector 18 cm&#160;</td>
			<td>Reda</td>
			<td>41146-18</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm&#160;</td>
			<td>Heathrow Scientific</td>
			<td>HS234526B</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin 5,000 U/mL</td>
			<td>ThermoFisher Scientific</td>
			<td>15070063</td>
			<td></td>
		</tr>
		<tr>
			<td>Perforated spoon&#160;</td>
			<td>Euronexia</td>
			<td>S-20-P</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dish 60 x 15 mm&#160;</td>
			<td>CELLSTAR</td>
			<td>628160</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic transfer pipettes&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>PP89SB</td>
			<td></td>
		</tr>
		<tr>
			<td>Purified mouse anti-human CD31 antibody</td>
			<td>BD Biosciences</td>
			<td>555444</td>
			<td>dilution 1:100</td>
		</tr>
		<tr>
			<td>Rhodamine labeled Lens Culinaris Agglutinin (LCA)</td>
			<td>Vector Laboratories</td>
			<td>RL-1042</td>
			<td>This product has recently been discontinued. Vectorlabs does still produce Dylight 649 labeled LCA (DL-1048-1) and fluorescein labeled LCA (FL-1041-5)</td>
		</tr>
		<tr>
			<td>Sheep anti-human NPHS1 antibody</td>
			<td>R&#38;D systems</td>
			<td>AF4269</td>
			<td>dilution 1:100</td>
		</tr>
		<tr>
			<td>Sterile hypodermic needles, 19 G</td>
			<td>BD microlance</td>
			<td>301500</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidin Alexa Fluor 405</td>
			<td>ThermoFisher Scientific</td>
			<td>S32351</td>
			<td>dilution 1:200</td>
		</tr>
		<tr>
			<td>Syringe 5 mL</td>
			<td>BD Emerald</td>
			<td>307731</td>
			<td></td>
		</tr>
		<tr>
			<td>Transparent tape&#160;</td>
			<td>Tesa</td>
			<td>4124</td>
			<td>Available at most hardware stores</td>
		</tr>
		<tr>
			<td>Triton X</td>
			<td>Sigma-Aldrich</td>
			<td>T9284</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten wire, 0.25 mm dia&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>010404.H2</td>
			<td></td>
		</tr>
	</tbody>
</table>

efficient vascularization of kidney organoids through intracelomic transplantation in chicken embryos

Kidney organoids derived from human induced pluripotent stem cells contain nephron-like structures that resemble those in the adult kidney to a certain degree. Unfortunately, their clinical applicability is hampered by the lack of a functional vasculature and consequently limited maturation in vitro. The transplantation of kidney organoids in the celomic cavity of chicken embryos induces vascularization by perfused blood vessels, including the formation of glomerular capillaries, and enhances their maturation. This technique is very efficient, allowing for the transplantation and analysis of large numbers of organoids. This paper describes a detailed protocol for the intracelomic transplantation of kidney organoids in chicken embryos, followed by the injection of fluorescently labeled lectin to stain the perfused vasculature, and the collection of transplanted organoids for imaging analysis. This method can be used to induce and study organoid vascularization and maturation to find clues for enhancing these processes in vitro and improve disease modeling.

The method and timeline for the differentiation of hiPSCs to kidney organoids, incubation of fertilized chicken eggs, transplantation of kidney organoids, injection of LCA, and collection of the organoids are summarized in Figure 1A. It is important to coordinate the timing of organoid differentiation and chicken egg incubation, starting differentiation 15 days before incubation.&#160;The actions on day 0, 3, 4, and 12 of incubation are illustrated by photographs below the timeline. Organoid...

Watch this Scientific Journal Video about Efficient Vascularization of Kidney Organoids through Intracelomic Transplantation in Chicken Embryos at JoVE.com

Efficient Vascularization of Kidney Organoids through Intracelomic Transplantation in Chicken Embryos

Here, we present a detailed protocol for the transplantation of kidney organoids in the celomic cavity of chicken embryos. This method induces vascularization and enhanced maturation of the organoids within 8 days and can be used to study these processes in an efficient manner.

Kidney organoids derived from human induced pluripotent stem cells contain nephron-like structures that resemble those in the adult kidney to a certain ...

Kidney organoids cultured in vitro remain immature, limiting their applicability. And this method of intracoelomic transplantation induces vascularization and enhances maturation of the organoids. The procedure is very efficient, allowing for the transplantation and analysis of large number of organoids in one experiment.After preparing HIPSC-derived kidney organoids and incubating the fertilized leghorn eggs create a window in the eggshell on day three of incubation. Place a small piece of transparent tape on the pointed tip of the egg. Make a small hole in the eggshell in the middle of the transparent tape by tapping it with the sharp end of a pair of dissecting scissors.Next, insert a 19-gauge needle on a five-milliliter syringe into the hole at a 45-degree angle. Aspirate two to three milliliters of albumin from the egg to lower the embryo inside the egg. Conceal the hole with a second piece of transparent tape, then place a large piece of transparent tape on the pencil marked upward facing side of the egg.Make a hole in the eggshell in the middle of the transparent tape by tapping it with the sharp end of a pair of dissecting scissors. Cut a small circular window in the eggshell from this hole using curved dissecting scissors. Look through this window to locate the embryo.Then, enlarge the window to optimize access to the embryo. Remove any large pieces of eggshell that may have fallen on top of the embryo using forceps. Remove smaller pieces by placing a few drops of DPBS with calcium and magnesium on the embryo with a plastic transfer pipette, then aspirating the DPBS with the eggshell into the pipette.Using a plastic transfer pipette, add three drops of DPBS, supplemented with 0.5%penicillin streptomycin to the egg. Carefully seal the window with a large piece of transparent tape before placing the egg back in the incubator until day four of incubation. Cut the tape from the window with curved dissecting scissors.Place the egg under a dissecting microscope on a rubber holder or egg carton. The chicken embryo is now in Hamburger-Hamilton Stage 23 to 24 and lying on its left side with its right side facing the viewer. Locate the right wing and leg bud of the embryo as the coelom will be assessed between these two limb buds.In the area between the right wing and leg bud, create an opening consecutively in the vitelline membrane, the chorion, and the amnion by holding them with two pairs of dissecting forceps and gently pulling them in opposite directions. Check whether there's unobstructed access to the coelomic cavity. Gently take hold of the edge of the body wall between the wing and limb bud with a pair of dissecting forceps and pull it slightly toward the viewer.The coelomic cavity must be clearly visible. Carefully insert a blunt but slim instrument into the coelomic cavity. Place half an organoid inside the egg on top of the allantois using a dura dissector.Using dissecting forceps, carefully take hold of the edge of the body wall and pull it slightly toward the viewer to make the opening to the coelum visible. Gently move the organoid toward and through the opening in the body wall into the coelum with a blunt tungsten wire and a micro scalpel holder. Push the organoid slightly cranially to lodge it inside the coelum.It is now visible just behind the wing bud. Add three drops of DPBS to the egg using a plastic transfer pipette. Carefully seal the window with a large piece of transparent tape before placing the egg back in the incubator until day 12 of incubation.Cut the tape from the window with curved dissecting scissors. Place the egg under a dissecting microscope in a rubber holder. Evaluate the vasculature and locate the veins, which can be distinguished from the arteries by their slightly brighter red color.To improve access to the vasculature, carefully enlarge the window by cutting it with curved dissecting scissors. After selecting the vein, insert the tip of the micro capillary needle into the vein at a zero to 20-degree angle. Ensure the needle is in the vein by gently moving the tip from side to side.Gently and steadily blow into the injection system to inject the lens culinaris agglutinin. And place the egg back in the incubator for 10 minutes to let it circulate. Place the egg in a rubber holder on the bench.Then, cut through the membranes surrounding the embryo with curved dissecting scissors. Scoop the embryo up from the egg with a perforated spoon and immediately decapitate the embryo using scissors. Under the dissection microscope, place the body of the embryo in a Petri dish.Place the embryo on its back in the Petri dish and spread its limbs. Carefully open the abdominal wall of the embryo along the longitudinal axis using forceps. Locate the organoid inside the embryo.The organoid most frequently becomes attached to the right liver lobe, either at the coddle tip or cranially, just below the rib cage. So, it's advisable to start by looking at these locations. Once the organoid is located, remove it from the embryo by cutting around it with micro scissors.Place the organoid in the chicken tissue that is inevitably attached to it in a Petri dish under the dissecting microscope. Remove as much chicken tissue as possible with a double-edged stainless steel razor blade. Immunofluorescent images of an non-transplanted kidney organoid and a transplanted kidney organoid both contain glomerular and tubular structures.In the untransplanted organoids, some human endothelial cells are present. In the transplanted organoid, a perfused vascular network is visible throughout the organoid. Magnified images of the boxed areas demonstrate the three types of endothelial cells that can be distinguished in transplanted organoids:perfused human endothelial cells, unperfused human endothelial cells, and perfused chicken-derived endothelial cells.In untransplanted organoids, endothelial cells surround glomerular structures but do not invade them. However, in transplanted organoids, glomerular structures are vascularized by perfused capillaries. Transplanted organoids can be analyzed using different techniques depending on the aim of the experiment.Direct comparison to untransplanted controls can provide insight into the process of vascularization and maturation.

efficient-vascularization-kidney-organoids-through-intracelomic

Research

JoVE Journal

Developmental Biology

Whole Retinal Explants from Chicken Embryos for Electroporation and Chemical Reagent Treatments

The retina is a good model for the developing central nervous system. The large size of the eye and most importantly the accessibility for experimental manipulations in ovo/in vivo makes the chicken embryonic retina a versatile and very efficient experimental model. Although the chicken retina is easy to target in ovo by intraocular injections or electroporation, the effective and exact concentration of the reagents within the retina may be difficult to fully control. This may be due to variations of the exact injection site, leakage from the eye or uneven diffusion of the substances. Furthermore, the frequency of malformations and mortality after invasive manipulations such as electroporation is rather high.
This protocol describes an ex ovo technique for culturing whole retinal explants from chicken embryos and provides a method for controlled exposure of the retina to reagents. The protocol describes how to dissect, experimentally manipulate, and culture whole retinal explants from chicken embryos. The explants can be cultured for approximately 24 hr and be subjected to different manipulations such as electroporation. The major advantages are that the experiment is not dependent on the survival of the embryo and that the concentration of the introduced reagent can be varied and controlled in order to determine and optimize the effective concentration. Furthermore, the technique is rapid, cheap and together with its high experimental success rate, it ensures reproducible results. It should be emphasized that it serves as an excellent complement to experiments performed in ovo.

This protocol describes a method to dissect, experimentally manipulate and culture whole retinal explants from chicken embryos. The explant cultures are useful when high success rate, efficacy and reproducibility are needed to test the effects of plasmids for electroporation and/or reagent substances, i.e., enzymatic inhibitors.

The retina is a good model for the developing central nervous system. The large size of the eye and most importantly the accessibility for experimental ...

Technique to Target Microinjection to the Developing Xenopus Kidney

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus embryos are large, develop externally, and can be easily manipulated by microinjection or surgical procedures. In addition, fate maps have been established for early Xenopus embryos. Targeted microinjection into the individual blastomere that will eventually give rise to an organ or tissue of interest can be used to selectively overexpress or knock down gene expression within this restricted region, decreasing secondary effects in the rest of the developing embryo. In this protocol, we describe how to utilize established Xenopus fate maps to target the developing Xenopus kidney (the pronephros), through microinjection into specific blastomere of 4- and 8-cell embryos. Injection of lineage tracers allows verification of the specific targeting of the injection. After embryos have developed to stage 38 - 40, whole-mount immunostaining is used to visualize pronephric development, and the contribution by targeted cells to the pronephros can be assessed. The same technique can be adapted to target other tissue types in addition to the pronephros.

Technique to Target Microinjection to the Developing Xenopus Kidney

Here, we present a protocol to use fate maps and lineage tracers to target injections into individual blastomeres that give rise to the kidney of Xenopus laevis embryos.

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus ...

An Efficient Method to Obtain Dedifferentiated Fat Cells

Tissue engineering and cell therapy hold great promise clinically. In this regard, multipotent cells, such as mesenchymal stem cells (MSCs), may be used therapeutically, in the near future, to restore function to damaged organs. Nevertheless, several technical issues, including the highly invasive procedure of isolating MSCs and the inefficiency surrounding their amplification, currently hamper the potential clinical use of these therapeutic modalities. Herein, we introduce a highly efficient method for the generation of dedifferentiated fat cells (DFAT), MSC-like cells. Interestingly, DFAT cells can be differentiated into several cell types including adipogenic, osteogenic, and chondrogenic cells. Although other groups have previously presented various methods for generating DFAT cells from mature adipose tissue, our method allows us to produce DFAT cells more efficiently. In this regard, we demonstrate that DFAT culture medium (DCM), supplemented with 20% FBS, is more effective in generating DFAT cells than DMEM, supplemented with 20% FBS. Additionally, the DFAT cells produced by our cell culture method can be redifferentiated into several tissue types. As such, a very interesting and useful model for the study of tissue dedifferentiation is presented.

We have modified the conditions for DFAT cell generation and provide herein information regarding the use of an improved growth medium for the production of these cells.

Tissue engineering and cell therapy hold great promise clinically. In this regard, multipotent cells, such as mesenchymal stem cells (MSCs), may be used ...

In Ovo Electroporation in the Chicken Auditory Brainstem

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that the chicken embryo is an effective research model for studying basic biological functions of auditory system development. More recently, the chicken embryo has become particularly valuable in studying gene expression, regulation and function associated with hearing. In ovo electroporation can be used to target auditory brainstem regions responsible for highly specialized auditory functions. These regions include the chicken nucleus magnocellularis (NM) and nucleus laminaris (NL). NM and NL neurons arise from distinct precursors of rhombomeres 5 and 6 (R5/R6). Here, we present in ovo electroporation of plasmid-encoded genes to study gene-related properties in these regions. We show a method for spatial and temporal control of gene expression that promote either gain or loss of functional phenotypes. By targeting auditory neural progenitor regions associated with R5/R6, we show plasmid transfection in NM and NL. Temporal regulation of gene expression can be achieved by adopting a tet-on vector system. This is a drug inducible procedure that expresses the genes of interest in the presence of doxycycline (Dox). The in ovo electroporation technique &#8211; together with either biochemical, pharmacological, and or in vivo functional assays &#8211; provides an innovative approach to study auditory neuron development and associated pathophysiological phenomena.

In Ovo Electroporation in the Chicken Auditory Brainstem

Auditory brainstem neurons of avians and mammals are specialized for fast neural encoding, a fundamental process for normal hearing functions. These neurons arise from distinct precursors of embryonic hindbrain. We present techniques utilizing electroporation to express genes in the hindbrain of chicken embryos to study gene function during auditory development.

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that ...

Tracing Gene Expression Through Detection of &#946;-galactosidase Activity in Whole Mouse Embryos

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. The classical histochemical reaction is based on the hydrolysis of the substrate X-gal in combination with ferric and ferrous ions, which produces an insoluble blue precipitate that is easy to visualize. Therefore, &#946;-galactosidase activity serves as a marker for the expression pattern of the gene of interest as the development proceeds. Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the subsequent method for paraffin sectioning and counterstaining. Additionally, a procedure for clarifying whole embryos is provided to better visualize X-gal staining in deeper regions of the embryo. Consistent results are obtained by performing this procedure, although optimization of reaction conditions is needed to minimize background activity. Limitations in the assay should be also considered, particularly regarding the size of the embryo in whole mount staining. Our protocol provides a sensitive and a reliable method for &#946;-galactosidase detection during the mouse development that can be further applied to the cryostat sections as well as whole organs. Thus, the dynamic gene expression patterns throughout development can be easily analyzed by using this protocol in whole embryos, but also detailed expression at the cellular level can be assessed after paraffin sectioning.

Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the method for paraffin sectioning and counterstaining. This is an easy and quick procedure to monitor gene expression during development that can also be applied to tissue sections, organs or cultured cells.

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. ...

Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. The high transfection efficiency permits at least 4 distinct mRNAs to be co-transfected with ~87% efficiency. Most of the electroporated mRNAs are degraded during the first 2 h post-electroporation, permitting time-sensitive experiments to be carried out in the developing embryo. Finally, we describe how to dynamically image live embryos electroporated with mRNAs that encode various subcellular targeted fluorescent proteins.

We report messenger RNA (mRNA) electroporation as a method that permits fast and efficient expression of multiple proteins in the quail embryo model system. This method can be used to fluorescently label cells and record their in vivo movements by time-lapse microscopy shortly after electroporation.

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. ...

A Simplified Method for Generating Kidney Organoids from Human Pluripotent Stem Cells

Kidney organoids generated from hPSCs have provided an unlimited source of renal tissue. Human kidney organoids are an invaluable tool for studying kidney disease and injury, developing cell-based therapies, and testing new therapeutics. For such applications, large numbers of uniform organoids and highly reproducible assays are needed. We have built upon our previously published kidney organoid protocol to improve the overall health of the organoids. This simple, robust 3D protocol involves the formation of uniform embryoid bodies in minimum component medium containing lipids, insulin-transferrin-selenium-ethanolamine supplement and polyvinyl alcohol with GSK3 inhibitor (CHIR99021) for 3 days, followed by culture in knock-out serum replacement (KOSR)-containing medium. In addition, agitating assays allows for reduction in clumping of the embryoid bodies and maintaining a uniform size, which is important for reducing variability between organoids. Overall, the protocol provides a fast, efficient, and cost-effective method for generating large quantities of kidney organoids.

Here we describe a protocol to generate kidney organoids from human pluripotent stem cells (hPSCs). This protocol generates kidney organoids within two weeks. The resulting kidney organoids can be cultured in large-scale spinner flasks or multi-well magnetic stir plates for parallel drug-testing approaches.

Kidney organoids generated from hPSCs have provided an unlimited source of renal tissue. Human kidney organoids are an invaluable tool for studying kidney ...

A Simple and Effective Transplantation Device for Zebrafish Embryos

Classical embryological manipulations, such as removing cells and transplanting cells within or between embryos, are powerful techniques to study complex developmental processes. Zebrafish embryos are ideally suited for these manipulations since they are easily accessible, relatively large in size, and transparent. However, previously developed devices for cell removal and transplantation are cumbersome to use or expensive to purchase. In contrast, the transplantation device presented here is economical, easy to assemble, and simple to use. In this protocol, we first introduce the handling of the transplantation device as well as its assembly from commercially and widely available parts. We then present three applications for its use: generation of ectopic clones to study signal dispersal from localized sources, extirpation of cells to produce size-reduced embryos, and germline transplantation to generate maternal-zygotic mutants. Finally, we show that the tool can also be used for embryological manipulations in other species such as the Japanese rice fish medaka.

Embryological manipulations such as extirpation and transplantation of cells are important tools to study early development. This protocol describes a simple and effective transplantation device to perform these manipulations in zebrafish embryos.

Classical embryological manipulations, such as removing cells and transplanting cells within or between embryos, are powerful techniques to study complex ...

In Ovo Intravascular Injection in Chicken Embryos

As a classical model system of embryo biology, the chicken embryo has been used to investigate embryonic development and differentiation. Delivering exogenous materials into chicken embryos has a great advantage for studying gene function, transgenic breeding, and chimera preparation during embryonic development. Here we show the method of in ovo intravascular injection whereby exogenous materials such as plasmid vectors or modified primordial germ cells (PGCs) can be transferred into donor chicken embryos at early developmental stages. The results show that the intravascular injection through the dorsal aorta and head allows injected materials to diffuse into the whole embryo through the blood circulatory system. In the presented protocol, the efficacy of exogenous plasmid and lentiviral vector introduction, and the colonization of injected exogenous PGCs in the recipient gonad, were determined by observing fluorescence in the embryos. This article describes detailed procedures of this method, thereby providing an excellent approach to studying gene function, embryo and developmental biology, and gonad-chimeric chicken production. In conclusion, this article will allow researchers to perform in ovo intravascular injection of exogenous materials into chicken embryos with great success and reproducibility.

In Ovo Intravascular Injection in Chicken Embryos

The overall goal of this paper is to describe how to perform in ovo intracellular injection of exogenous materials into chicken embryos. This approach is very useful to study the developmental biology of chicken embryos.

As a classical model system of embryo biology, the chicken embryo has been used to investigate embryonic development and differentiation. Delivering ...

Rapid and Efficient Spatiotemporal Monitoring of Normal and Aberrant Cytosine Methylation within Intact Zebrafish Embryos

Cytosine methylation is highly conserved across vertebrate species and, as a key driver of epigenetic programming and chromatin state, plays a critical role in early embryonic development. Enzymatic modifications drive active methylation and demethylation of cytosine into 5-methylcytosine (5-mC) and subsequent oxidation of 5-mC into 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine. Epigenetic reprogramming is a critical period during in utero development, and maternal exposure to chemicals has the potential to reprogram the epigenome within offspring. This can potentially cause adverse outcomes such as immediate phenotypic consequences, long-term effects on adult disease susceptibility, and transgenerational effects of inherited epigenetic marks. Although bisulfite-based sequencing enables investigators to interrogate cytosine methylation at base-pair resolution, sequencing-based approaches are cost-prohibitive and, as such, preclude the ability to monitor cytosine methylation across developmental stages, multiple concentrations per chemical, and replicate embryos per treatment. Due to the ease of automated in vivo imaging, genetic manipulations, rapid ex utero development time, and husbandry during embryogenesis, zebrafish embryos continue to be used as a physiologically intact model for uncovering xenobiotic-mediated pathways that contribute to adverse outcomes during early embryonic development. Therefore, using commercially available 5-mC-specific antibodies, we describe a cost-effective strategy for rapid and efficient spatiotemporal monitoring of cytosine methylation within individual, intact zebrafish embryos by leveraging whole-mount immunohistochemistry, automated high-content imaging, and efficient data processing using programming language prior to statistical analysis. To current knowledge, this method is the first to successfully detect and quantify 5-mC levels in situ within zebrafish embryos during early development. The method enables the detection of DNA methylation within the cell mass and also has the ability to detect cytosine methylation of yolk-localized maternal mRNAs during the maternal-to-zygotic transition. Overall, this method will be useful for the rapid identification of chemicals that have the potential to disrupt cytosine methylation in situ during epigenetic reprogramming.

This paper describes a protocol for the rapid and efficient spatiotemporal monitoring of normal and aberrant cytosine methylation within intact zebrafish embryos.

Cytosine methylation is highly conserved across vertebrate species and, as a key driver of epigenetic programming and chromatin state, plays a critical ...