We would like to thank Yanmin Wan, Guobin Kang, and Pallabi Kundu for their assistance in generating BLT-humanized mice. We would like to acknowledge the UNMC Genomics Core Facility who receives partial support from the Nebraska Research Network In Functional Genomics NE-INBRE P20GM103427-14, The Molecular Biology of Neurosensory Systems CoBRE P30GM110768, The Fred &#38; Pamela Buffett Cancer Center - P30CA036727, The Center for Root and Rhizobiome Innovation (CRRI) 36-5150-2085-20, and the Nebraska Research Initiative. We would like to thank University of Nebraska - Lincoln Life Sciences Annex and their staff for their assistance. This study is supported in part by the National Institutes of Health (NIH) Grants R01AI124804, R21AI122377-01, P30 MH062261-16A1 Chronic HIV Infection and Aging in NeuroAIDS (CHAIN) Center, 1R01AI111862 to Q Li.&#160; The funders had no role in study design, data collection and analysis, preparation of the manuscript or decision for publication.

All methods described here were conducted in accordance with Institutional Animal Care and Research Committee (IACUC)-approved protocols at the University of Nebraska-Lincoln (UNL). The IACUC at UNL has approved two protocols related to generating and using hu-BLT mice, including double hu-mice. Additionally, the Scientific Research Oversight Committee (SROC) at UNL has also approved the use of human embryonic stem cells and fetal tissues, which are procured from the Advanced Bioscience Resources for humanized mice studi...

<ol>
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The protocol described here is for the creation of double hu-BLT mice that feature both a functional human immune system and a stable human-like gut microbiome. This protocol can be adapted to other humanized or non-humanized mice models without the need for GF animals and gnotobiotic facilities. While the methods described here are relatively simple, there are several critical details that are important for the successful creation of double hu-BLT mice. NSG mice are extremely immunodeficient and preventing infections is...

Humanized mice (hu-mice) have transformed the study of many aspects of human health and disease including hematopoiesis, immunity, cancer, autoimmune disease, and infectious disease1,2,3,4,5,6,7,8,9. These hu-mice have the distinct advantage over other mouse models in that they have a functional human immune system and can be infected with human specific pathogens. Nevertheless, the importance of the gut microbiome has been demonstrated by its role in many human diseases such as obesity, metabolic syndrome, inflammatory diseases, and cancer10,11,12,13. The mucosal immune system and gut microbiome are reciprocally regulated to maintain gut and systemic homeostasis. The immune system is shaped by antigens presented by the gut microbiome and reciprocally the immune system plays an important regulatory role in promoting commensal gut bacteria and eliminating pathogens14,15,16. However, the gut microbiome of hu-mice has not been well characterized and the murine gut microbiome differs substantially in composition and function from humans17. This is due to evolutionary, physiological, and anatomical differences between the murine and human gut as well as other important factors such as diet, which may influence the experimental results of hu-mice disease models18. Therefore, beyond classification of murine gut microbiome of hu-mice, an animal model featuring both a human immune system and human gut microbiome is needed to study the complex interactions of human disease in vivo.
The study of human diseases directly in human subjects is often impractical or unethical. Many animal models cannot be used to study human pathogens like human immunodeficiency virus type 1 (HIV-1). Non-human primate models are genetically outbred, very expensive, and are not susceptible to many human pathogens. Mice that have been derived as germ free (GF) and reconstituted with human-like gut microbiomes have been widely used to study human health and disease19,20. However, these animals do not have a human immune system and working with GF animals requires specialized facilities, procedures, and expertise. Therefore, there is a need for improved pre-clinical models to study the complex relationship of the gut microbiome and the human immune system. Many strains of mice, such as NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG), are not commercially available as GF. GF animals also may suffer from long-lasting immune deficiencies that are not completely reversed by the engraftment of microbes21. Therefore, we created a double hu-mice featuring both a functional human immune system and stable human-like gut microbiome under specific pathogen free (SPF) conditions. To generate double hu-mice, surgery was performed on NSG mice to create bone-marrow, liver, thymus humanized mice (hu-BLT). The hu-BLT mice were then treated with broad spectrum antibiotics and then given fecal transplants with a healthy human donor sample. We characterized the bacterial gut microbiome of 173 fecal samples from 45 double hu-BLT mice and 4 human fecal donor samples. Double hu-BLT mice have unique 16S rRNA gene profiles based on the individual human donor sample that is transplanted. Importantly, the transplanted human-like microbiome was stable in the mice for the duration of the study up to 14.5 weeks post-transplant. In addition, the predicted metagenomes showed that double hu-BLT mice have different predicted functional capacity than hu-mice that is more similar to the human donor samples.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Animal Feeding Needles 18G</td>
			<td style="width:225px;">Cadence Science</td>
			<td style="width:103px;">9928B</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:337px;">Clidox-s Activator</td>
			<td style="width:225px;">Pharmacal Research Laboratories</td>
			<td style="width:103px;">95120F</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:337px;">Clidox-s Base</td>
			<td style="width:225px;">Pharmacal Research Laboratories</td>
			<td style="width:103px;">96125F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">DGM 108 cage rack</td>
			<td style="width:225px;">Techniplast</td>
			<td style="width:103px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:337px;">Flat Brown Grocery Bag 3-5/8&#34;D x 6&#34;W x 11-1/16&#34;L&#160;</td>
			<td style="width:225px;">Grainger</td>
			<td style="width:103px;">12R063</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FMT Upper Delivery Microbiota Preparations&#160;</td>
			<td style="width:225px;">OpenBiome</td>
			<td style="width:103px;">FMP30</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Grape Kool-Aid</td>
			<td style="width:225px;">Kraft Foods Inc.</td>
			<td style="width:103px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">hCD19-PE/Cy5</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">302209</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">hCD3-PE</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">300408</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">hCD4-Alexa 700</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">300526</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">hCD45-FITC</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">304006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">hCD8-APC/Cy7</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">301016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Lactate Buffered Ringer&#39;s Solution</td>
			<td style="width:225px;">Boston BioProducts Inc&#160;</td>
			<td style="width:103px;">PY-906-500&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">mCD45-APC</td>
			<td style="width:225px;">Biolegend</td>
			<td style="width:103px;">103111</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Microvette 100 K3E</td>
			<td style="width:225px;">Microvette</td>
			<td style="width:103px;">20.1278.100</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:337px;">Neosporin First Aid Antibiotic/Pain Relieving Ointment</td>
			<td style="width:225px;">Neosporin</td>
			<td style="width:103px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">NSG mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ)</td>
			<td style="width:225px;">The Jackson Laboratory</td>
			<td style="width:103px;">005557</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">PrecisionGlide 25 G Needle</td>
			<td style="width:225px;">BD</td>
			<td style="width:103px;">305127</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">RS200 X-ray irradiator</td>
			<td style="width:225px;">RAD Source Technologies</td>
			<td style="width:103px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Sealsafe Plus GM500 microisolator cages</td>
			<td style="width:225px;">Techniplast</td>
			<td style="width:103px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Sterile Non-woven Gauze</td>
			<td style="width:225px;">Fisherbrand</td>
			<td style="width:103px;">22-028-558</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:337px;">Teklad global 16% protein irradiated mouse chow</td>
			<td style="width:225px;">Teklad</td>
			<td style="width:103px;">2916</td>
			<td></td>
		</tr>
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a double humanized blt-mice model featuring a stable human-like gut microbiome and human immune system

Humanized mice (hu-mice) that feature a functional human immune system have fundamentally changed the study of human pathogens and disease. They can be used to model diseases that are otherwise difficult or impossible to study in humans or other animal models. The gut microbiome can have a profound impact on human health and disease. However, the murine gut microbiome is very different than the one found in humans. &#160;There is a need for improved pre-clinical hu-mice models that have an engrafted human gut microbiome. Therefore, we created double hu-mice that feature both a human immune system and stable human-like gut microbiome. NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice are one of the best animals for humanization due to their high level of immunodeficiency. However, germ-free NSG mice, and various other important germ-free mice models are not currently commercially available. Further, many research settings do not have access to gnotobiotic facilities, and working under gnotobiotic conditions can often be expensive and time consuming. Importantly, germ-free mice have several immune deficiencies that exist even after the engraftment of microbes. Therefore, we developed a protocol that does not require germ-free animals or gnotobiotic facilities. To generate double hu-mice, NSG mice were treated with radiation prior to surgery to create bone-marrow, liver, thymus-humanized (hu-BLT) mice. The mice were then treated with broad spectrum antibiotics to deplete the pre-existing murine gut microbiome. After antibiotic treatment, the mice were given fecal transplants with healthy human donor samples via oral gavage. Double hu-BLT mice had unique 16S rRNA gene profiles based on the individual human donor sample that was transplanted. Importantly, the transplanted human-like microbiome was stable in the double hu-BLT mice for the duration of the study up to 14.5 weeks post-transplant.

Figure 1 shows an outline of the methods used to create double hu-BLT mice and briefly describes the process of adding a functional human immune system and stable human-like gut microbiome to the NSG mice. Figure 2 shows an example of flow cytometry analysis of peripheral blood from a humanized BLT-mouse 10 weeks post-surgery. Figure 3 shows the relative abundance of the human fecal donor samples used to transfer a gut microbiome to...

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A Double Humanized BLT-mice Model Featuring a Stable Human-Like Gut Microbiome and Human Immune System

We describe a novel method for generating double humanized BLT-mice that feature a functional human immune system and a stable engrafted human-like gut microbiome. This protocol can be followed without the need for germ-free mice or gnotobiotic facilities.

Humanized mice (hu-mice) that feature a functional human immune system have fundamentally changed the study of human pathogens and disease. They can be ...

Our protocol is significant, because it can be use to reproducibly create mice with both a human gut microbiome and a human immune system. We call these mice, double humanized mice. The double humanized mouse model can be used for both basic and translational biomedical research, including the study of in vivo relationships between the human gut microbiome and human immune system.Demonstrating the procedure will be Jianshui Zhang, a postdoc, and Yilun Chang, a PhD grad student from our laboratory. To implant the liver and thymus tissues into the left kidney capsule, first, place the mouse in a hood. On the day of surgery, treat the mice with whole body sublethal irradiation at a 12 centigrays per gram of body weight dose.Shave each mouse around the left lateral and medial side after confirming an appropriate level of sedation. Apply ophthalmic ointment to the animal's eyes, and apply an ear tag as needed. Disinfect the skin with three sequential iodine and 70%isopropanol scrubs.When the skin has been prepped, use forceps to load one to one-to-six millimeter cubed human fetal liver tissue fragment into a trocar, followed by one one-to-1.6 millimeter cubed human fetal thymus tissue fragment. Use the forceps to lift the skin, and use a scalpel to make a small longitudinal cut into the skin. Extend the cut to 1.5 to two centimeters on the left side of the mouse.And use forceps to lift the muscle layer. Use scissors to open the muscle layer longitudinally, extending the cut as necessary to expose the kidney, and gently grasp the fatty tissue surrounding the kidney. Use a scalpel to make a one-to-two millimeter incision at the posterior end of the kidney capsule and slowly insert the preloaded trocar into the incision parallel to the long axis of the kidney.Release the tissues between the kidney capsule and kidney, and return the kidney and bowel to their normal positions. Then, use sutures to close the muscle layer and surgical staples to close the skin. Place the mouse into an autoclaved microisolator cage with monitoring until full recumbancy.Six hours after the surgery, place the mice under a heat lamp and disinfect the tails with 70%isopropanol. Inject 1.5 to five times 10-to-the-five CD34 positive human fetal liver tissue isolated hemopoietic stem cells in 200 microliters of PBS into one dilated tail vein per animal. Then stop any bleeding with gentle pressure and return the mice to their home cage.Nine to 12 weeks after the surgery, use an appropriately sized plastic comb restraint to isolate one leg of one humanized mouse, and spray the medial side of the isolated leg with 70%isopropanol. Spread antibiotic and pain-relieving ointment onto the collection site. Using a 25-gauge needle held at a 90 degree angle, puncture the saphenous vein to collect 50 to 100 microliters of blood into an EDTA-coated blood collection tube.When a suitable volume of blood has been obtained, apply pressure to the site with a sterile piece of gauze to stop the bleeding before returning the mouse to its cage. Then use the collected peripheral blood sample to assess the level of human immune cell reconstitution by flow cytometry using antibodies against human CD45, CD3, CD4, CD8, CD19 and mouse CD45. For fresh fecal sample collection, place individual autoclaved paper bags into a fume hood and place one mouse into each bag until each animal defecates.Then return the mice to their cage, and use sterile forceps to transfer each fecal sample into one 1.5-milliliter tube per mouse for minus 80 degrees Celsius storage. At the end of the 14-day antibiotic treatment, change the drinking water to autoclaved sterilized water, and transfer the mice into a new autoclaved cage. 24 and 48 hours after the cessation of antibiotics thaw properly prepared sources of fecal microbiota transplant material, and aliquot the samples in an anaerobic chamber under anaerobic conditions.To perform a fecal transplant, deliver 200 microliters of fecal microbiota transplant material via oral gavage to each experimental animal, and spread any remaining thawed material on the fur of humanized mice or onto the cage bedding. Here, an example of flow cytometry analysis of peripheral blood from a humanized BLT mouse 10 weeks post surgery is shown. T and B cell populations can both be identified, as well as CD4 and CD8 positive T cells subsets.In this graph the relative abundance of the human fecal donor samples used to transfer a gut microbiome to create double humanized mice can be observed. The phenotypic changes to the spleen and cecum induced by antibiotic treatment is similar to that observed in germ-free animals. This principal component analysis plot of representative 16S ribosomal RNA sequencing data reveals that double humanized mice have human-like gut microbiomes that are unique to the human donor sample.The most critical aspect of this protocol is to limit the introduction of unwanted bacteria to ensure the mice remain healthy and maintain the human gut microbiome. This model has the potential to advance personalized medicine and to allow us to look at how human disease impacts the gut microbiome while controlling for other mitigating factors.

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8.6K Views.  Nebraska Center for Virology. Our protocol is significant, because it can be use to reproducibly create mice with both a human gut microbiome and a human immune system. We call these mice, double humanized mice. The double humanized mouse model can be used for both basic and translational biomedical research, including the study of in vivo relationships between the human gut microbiome and human immune system.Demonstrating the procedure will be Jianshui Zhang, a postdoc, and Yilun Chang, a PhD grad student from our...