The authors would like to thank Adriane Mosley and Libuse Jerabek (Stanford) for assistance with the surgical technique.

All animal studies were performed according to the guidelines of UCLA&#39;s animal care and use committee and the National Institutes of Health Guide for the Care and Use of Laboratory Animals. The duration of the procedure described below is approximately 45-60 min from beginning to end.
1. Preparation of Surgical Field
<ol>
	<li>Perform procedure in a clean animal surgery room.</li>
	<li>Equipment: isoflurane Vaporizer, Gaymer T Pump with heating pad.</li>
	<li>Sterile tools: two curved forceps, fine scissors, needle holder.</li>
	<li>Sterile gloves must be used during the entire procedure.</li>
</ol>
2. Preparation of Animals
<ol>
	<li>Place two male or female mice, from same genetic background, of similar weight and size in the same cage and monitor for at least two weeks to ensure harmonious cohabitation. Female mice are preferred due to their less aggressive behavior.</li>
	<li>Anesthetize animals by using an isoflurane vaporizer. Place mice in a Posi-Seal Induction Chamber connected to the isoflurane vaporizer (4-5% v/v). Once anesthesia is induced, transfer the animal to the fur shaving area and maintain the anesthesia throughout the procedure through a nose cone connected to isoflurane (1.5-2% v/v). Apply ophthalmic ointment with a Q-tip to prevent dry eyes.</li>
	<li>Place the animal on the supine position. Thoroughly shave the left side of the mouse placed on the left and the right side of the mouse placed on the right starting at approximately 1 cm above the elbow to 1 cm below the knee.</li>
	<li>Aseptically prepare the shaved areas by thoroughly wiping (2-3x) with Betadine-soaked wipes followed by alcohol wipes. Place the mice on a heated pad covered by a sterile pad.</li>
	<li>For analgesia, administer Carprofen and Buprenorphine intraperitoneally or subcutaneously at a dose of 10 mg/kg and 0.1 mg/kg respectively.</li>
	<li>Place animals on their side, back to back, with adjacent shaved areas facing up. To avoid any contamination of the surgical area, cover the mice with a sterile drape exposing only the operation area. Create a small drape opening to stay sterile when performing the surgery. We made the drape window large to have a better viewing during videotaping.</li>
</ol>
3. Parabiosis
<ol>
	<li>Using a sharp scissor, perform longitudinal skin incisions to the shaved sides of each animal starting at 0.5 cm above the elbow all the way to 0.5 cm below the knee joint (Figure 1). Following the incision, gently detach the skin from the subcutaneous fascia by holding the skin up with a pair of curved forceps and separate the fascia with a second pair to create 0.5 cm of free skin. Perform this separation along the entire incision.</li>
	<li>Begin the joining by attaching the left olecranon of one animal to the right olecranon of the other. Both olecranons and knee joints are clearly distinguishable following the skin incision. To facilitate the joining, bend the elbow of the first mouse and pass the needle of the non-absorbable 3-0 suture under the olecranon. Similarly, bend the elbow of the second mouse and pass the same suture under it. Attach joints tightly by a double surgical knot.</li>
	<li>Connect the knee joints following the same procedure.</li>
	<li>Following the attachment of the joints, connect the skin of the two animals with a continuous absorbable 5-0 Vicryl suture starting ventrally from the elbow towards the knee. To prevent skin rupture and separation perform a tight suture closure of the skin in the area around the elbows and knees. Once the ventral skin attachment has been completed, perform a double surgical knot. Place the mice in the prone position and continue the suture dorsally ending with a double surgical knot. Verify the continuity of the suture and confirm the lack of openings.</li>
	<li>Administer 0.5 ml of 0.9% NaCl subcutaneously to each mouse to prevent dehydration.</li>
</ol>
4. Postoperative Recovery
<ol>
	<li>Keep animals on heated pad until recovery.</li>
	<li>Following recovery, provide analgesics carprofen and buprenorphine. Repeat intraperitoneally or subcutaneously every 24 and 12 hr, respectively, for 48 hr at the same doses described above (step 2.5). Monitor animals for signs of pain and distress such as shaking, lethargy, chewing of tail, arched back, lack of grooming, etc. daily for two weeks.</li>
	<li>Prophylactically, treat mice with Sulfamethoxazole /Trimethoprim oral suspension in their water bottle 2 mg sulfa/ml +0.4 mg trim/ml for 10 days to prevent bacterial infections.</li>
	<li>House each parabiotic pair in a clean cage with monolithic bedding material (e.g. paper towel or absorbent sterile pad) to prevent aspiration of bedding material. Return the animals to a bedding filled cage when they are able to maintain sternal recumbency with their head up. To minimize the strain of reaching for food while adjusting to parabiotic existence, place the moistened food pellets on the cage floor. Provide nesting material. In 1-2 weeks parabiotic mice have the ability to ambulate normally on surgically paired fore-and hind-limbs.</li>
	<li>Blood chimerism occurs 10-14 days following the surgery.</li>
</ol>
5. Confirmation and Reverse Procedure
<ol>
	<li>After two weeks draw blood from the tail veins of each mouse for flow-cytometric analysis to confirm blood chimerism (Figure 3).</li>
	<li>Blood processing for flow cytometric analysis: dilute 2-3 drops of blood in 500 &#956;l of 10 mM EDTA. Add 500 &#956;l of 2% dextran (diluted in PBS), mix thoroughly and incubate at 37 &#176;C for 30 min. Transfer the supernatant in a new tube, spin at 1,200 rpm for 5 min and resuspend the pelleted cells in PBS (or other buffer) for flow cytometric analysis.</li>
	<li>Depending on experimental design, the parabiotic pair can be separated at later time points. In our experience, we have maintained parabiosed pairs for up to 9 months without any complications.</li>
	<li>Perform reverse procedure on a sterile surgical surface. Anesthetize mice by placing them in an induction chamber connected to an isoflurane vaporizer (4-5%) and maintain anesthesia with 1.5-2% isoflurane, as described above (step 2.2).</li>
	<li>Remove hair from the area surrounding the initial suture and aseptically prepare the shaved areas as described above (steps 2.3, 2.4).</li>
	<li>For analgesia, administer Carprofen and Buprenorphine intraperitoneally or subcutaneously at a dose of 10 mg/kg and 0.1 mg/kg, respectively.</li>
	<li>Cover surgical area with a sterile drape as described above (step 2.6).</li>
	<li>Using sharp scissors, separate the mice through a longitudinal incision along the lateral suture and gently detach the newly formed fascia between the two mice with a pair of curved forceps. To separate the joints, cut the knots of the suture connecting them. Trim off the skin along the incision to achieve smooth edges and reattach skin with an absorbable continuous 5-0 coated Vicryl suture.</li>
	<li>To prevent dehydration, administer 0.5 ml of 0.9% NaCl subcutaneously to each mouse. Keep animals on heated pad until recovery.</li>
	<li>After recovery, repeat analgesic administration, carprofen (10 mg/kg) every 24 hr and buprenorphine (0.1 mg/kg) every 12 hr for 48 hr.</li>
	<li>To prevent bacterial infections treat mice with Sulfamethoxazole /Trimethoprim oral suspension (2 mg sulfa/ml +0.4 mg trim/ml) in their water bottle for 10 days.</li>
</ol>

<ol><li>Bert, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Exp%C3%A9riences+et+consid%C3%A9rations+sur+la+greffe+animale%5BTitle%5D)+AND+%22Journal+de+l%27Anatomie+et+de+la+Physiologie%22%5BJournal%5D)">Expériences et considérations sur la greffe animale.</a> Journal de l'Anatomie et de la Physiologie. 1, 69-87 Forthcoming.</li>
<li>Bunster, E., Meyer, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Improved+methods+of+parabiosis%5BTitle%5D)+AND+%22Anat.+Rec%22%5BJournal%5D)">Improved methods of parabiosis.</a> Anat. Rec. 57, 339-380 (1933).</li>
<li>Waskow, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Generation+of+parabiotic+mice+for+the+study+of+DC+and+DC+precursor+circulation%5BTitle%5D)+AND+%22Methods+Mol.+Biol%22%5BJournal%5D)">Generation of parabiotic mice for the study of DC and DC precursor circulation.</a> Methods Mol. Biol. 595, 413-428 (2010).</li>
<li>Finerty, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Parabiosis+in+physiological+studies%5BTitle%5D)+AND+%22Physiol.+Rev%22%5BJournal%5D)">Parabiosis in physiological studies.</a> Physiol. Rev. 32, 277-302 (1952).</li>
<li>Aicher, A., Heeschen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nonbone+marrow-derived+endothelial+progenitor+cells%3A+what+is+their+exact+location%5BTitle%5D)+AND+%22Circ.+Res%22%5BJournal%5D)">Nonbone marrow-derived endothelial progenitor cells: what is their exact location.</a> Circ. Res. 101, e102(2007).</li>
<li>Abe, S., Boyer, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cells+derived+from+the+circulation+contribute+to+the+repair+of+lung+injury%5BTitle%5D)+AND+%22Am.+J.+Respir.+Crit.+Care+Med%22%5BJournal%5D)">Cells derived from the circulation contribute to the repair of lung injury.</a> Am. J. Respir. Crit. Care Med. 170, 1158-1163 (2004).</li>
<li>Donskoy, E., Goldschneider, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Thymocytopoiesis+is+maintained+by+blood-borne+precursors+throughout+postnatal+life.+A+study+in+parabiotic+mice%5BTitle%5D)+AND+%22J.+Immunol%22%5BJournal%5D)">Thymocytopoiesis is maintained by blood-borne precursors throughout postnatal life. A study in parabiotic mice.</a> J. Immunol. 148, 1604-1612 (1992).</li>
<li>Powell, A. E., Anderson, E. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fusion+between+Intestinal+epithelial+cells+and+macrophages+in+a+cancer+context+results+in+nuclear+reprogramming%5BTitle%5D)+AND+%22Cancer+Res%22%5BJournal%5D)">Fusion between Intestinal epithelial cells and macrophages in a cancer context results in nuclear reprogramming.</a> Cancer Res. 71, 1497-1505 (2011).</li>
<li>Duyverman, A. M., Kohno, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+transient+parabiosis+skin+transplantation+model+in+mice%5BTitle%5D)+AND+%22Nat.+Protoc%22%5BJournal%5D)">A transient parabiosis skin transplantation model in mice.</a> Nat. Protoc. 7, 763-770 (2012).</li>
<li>Ajami, B., Bennett, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Local+self-renewal+can+sustain+CNS+microglia+maintenance+and+function+throughout+adult+life%5BTitle%5D)+AND+%22Nat.+Neurosci%22%5BJournal%5D)">Local self-renewal can sustain CNS microglia maintenance and function throughout adult life.</a> Nat. Neurosci. 10, 1538-1543 (2007).</li>
<li>Weissman, I. L., Jerabek, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Tolerance+and+the+H-Y+antigen%3A+Requirement+for+male+T+cells%2C+but+not+B+cells%2C+to+induce+tolerance+in+neonatal+female+mice%5BTitle%5D)+AND+%22Transplantation%22%5BJournal%5D)">Tolerance and the H-Y antigen: Requirement for male T cells, but not B cells, to induce tolerance in neonatal female mice.</a> Transplantation. 37, 3-6 (1984).</li>
</ol>

The authors have no competing financial interests.

The parabiosis method discussed here presents minimal technical difficulties and results in low mortality rates. The attachment of knee and elbow joints is a significant improvement of the Bunster and Meyer technique. However, the procedure remains invasive thus maintenance of sterile conditions throughout the surgery is imperative. To further prevent infection of the surgical site, it is important that the parabiosed animals receive a combination of antibiotics and be monitored regularly. To ensure firm support and prev...

Parabiosis, the surgical joining of two organisms, was first described in 1864 by Paul Bert as a way to develop a model to study shared circulatory systems and consisted of the joining of the skin and muscular walls of two rats1. Parabiosis promotes formation of microvasculature at the site of inflammation3 and has had several applications in physiological studies, such as the hormonal communication between the pituitary gland and gonads as well as the role of the kidney in hypertension4. It has been further employed to investigate the recruitment and integration of progenitor cells in neovascularization5, migration of hematopoietic stem cells6, and lymphocyte trafficking7, as well as the role and kinetics of circulating inflammatory or stem cells in tumor metastasis8,9, and neurodegenerative disease10.
One significant advantage of parabiosis lies in that the partnered animals share common circulating antigens, allowing cell migration and neovascularization without triggering an immunological reaction. Importantly, Weissman et al. have shown that parabiosis between male and female mice does not lead to formation of anti H-Y antibodies11.
In the original protocol described by Paul Bert the two animals were joined together through connection of the skin and muscle walls1. This method however, caused significant strain to the animals and resulted in high mortality due to infection of the wound. Since then the parabiosis technique has been revised by several groups with the most predominant being the protocol proposed by Bunster and Meyer in 19332. Their method included joining of the scapula joints, body cavities, and skin, permitting better support and less pain for the animals. At the same time, the new method resulted in minimal post-operative care and significantly decreased mortality rates. The protocol described herein is a modification of the Bunster and Meyer technique that is less invasive and allows firmer joining. Namely, mice are connected through the elbow and knee joints as well as the skin. This joining prevents extension of the skin and therefore causes less pain and complications. Here we describe the joining of a wild type (WT) adult mouse to a constitutive GFP expressing mouse. We show that two weeks following surgery we can achieve 50% of blood chimerism demonstrating the efficacy of this surgical procedure to create a shared circulatory system.

<table><tbody><tr><td>Isoflurane-Phoenix</td><td>Clipper</td><td>NDC 57319-559-06</td><td></td></tr><tr><td>Posi-Seal Induction Chamber</td><td>Molecular Imaging Products</td><td>AS-01-0530-SM</td><td></td></tr><tr><td>Portable Anesthesia System</td><td>Molecular Imaging Products</td><td>AS-01-0007</td><td></td></tr><tr><td>Gaymer T Pump</td><td>Gaymar Industries, Inc</td><td>TP650</td><td></td></tr><tr><td>Warming Blanket (Heating pad)</td><td>Kent Scientific Corp</td><td>TP-22G</td><td></td></tr><tr><td>Curved forceps</td><td>Roboz</td><td>RS-5101</td><td></td></tr><tr><td>Scissors</td><td>Fine Science Tools (FST)</td><td>FST 14063-09</td><td></td></tr><tr><td>Needle holder</td><td>FST</td><td>FST 12501-13</td><td></td></tr><tr><td>Electrical shaver</td><td>Oster</td><td>Golden A5</td><td></td></tr></tbody></table>

parabiosis in mice: a detailed protocol

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 18641, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival2. In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.

The anticipated outcome of parabiosis of two organisms is the equal contribution of each animal's circulatory system to a common blood circulation (Figure 2). One can easily verify the successful equilibration of the blood of the parabiosed WT and GFP positive mice by flow cytometric analysis. Here, venous blood was obtained from the tails of both parabionts at 2 weeks after the surgery and was fractionated for peripheral blood cells (to exclude erythrocytes). The fractionated hematopoietic-derived cell ...

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Parabiosis in Mice: A Detailed Protocol

Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of ...

Research

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Medicine

74.3K Views.  University of California, Los Angeles. Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Video: Parabiosis in Mice: A Detailed Protocol

Generation of Parabiotic Zebrafish Embryos by Surgical Fusion of Developing Blastulae

Surgical parabiosis of two animals of different genetic backgrounds creates a unique scenario to study cell-intrinsic versus cell-extrinsic roles for candidate genes of interest, migratory behaviors of cells, and secreted signals in distinct genetic settings. Because parabiotic animals share a common circulation, any blood or blood-borne factor from one animal will be exchanged with its partner and vice versa. Thus, cells and molecular factors derived from one genetic background can be studied in the context of a second genetic background. Parabiosis of adult mice has been &#160;used extensively to research aging, cancer, diabetes, obesity, and brain development. More recently, parabiosis of zebrafish embryos has been used to study the developmental biology of hematopoiesis. In contrast to mice, the transparent nature of zebrafish embryos permits the direct visualization of cells in the parabiotic context, making it a uniquely powerful method for investigating fundamental cellular and molecular mechanisms. The utility of this technique, however, is limited by a steep learning curve for generating the parabiotic zebrafish embryos. This protocol provides a step-by-step method on how to surgically fuse the blastulae of two zebrafish embryos of different genetic backgrounds to investigate the role of candidate genes of interest. In addition, the parabiotic zebrafish embryos are tolerant to heat shock, making temporal control of gene expression possible. This method does not require a sophisticated set-up and has broad applications for studying cell migration, fate specification, and differentiation in vivo during embryonic development.

This protocol provides step-by-step instruction on how to generate parabiotic zebrafish embryos of different genetic backgrounds. When combined with the unparalleled imaging capabilities of the zebrafish embryo, this method provides a uniquely powerful means to investigate cell-autonomous versus non-cell-autonomous functions for candidate genes of interest.

Surgical parabiosis of two animals of different genetic backgrounds creates a unique scenario to study cell-intrinsic versus cell-extrinsic roles for ...

Developmental Biology

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.

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 ...

Biochemistry

Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization and for minimizing organ damage resulting from prolonged extracorporal circulation. The goal of this paper was to demonstrate a fully functional and clinically relevant model of cardiopulmonary bypass in a mouse. We report on the device design, perfusion circuit optimization, and microsurgical techniques. This model is an acute model, which is not compatible with survival due to the need for multiple blood drawings. Because of the range of tools available for mice (e.g., markers, knockouts, etc.), this model will facilitate investigation into the molecular mechanisms of organ damage and the effect of cardiopulmonary bypass in relation to other comorbidities.

This paper describes how to perform cardiopulmonary bypass in mice. This novel model will facilitate the investigation of the molecular mechanisms involved in organ damage.

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization ...

A Mouse Model of Orthopedic Surgery to Study Postoperative Cognitive Dysfunction and Tissue Regeneration

Surgery is commonly used to improve and maintain quality of life. Unfortunately, in vulnerable patients such as the elderly, complications may occur and significantly diminish the outcome. Indeed, after routine orthopedic surgery to repair a fracture, as many as 50% of elderly patients suffer from neurologic complications like delirium. Also, the capacity to heal and regenerate tissue after surgery decreases with age, and can impact the quality of fracture repair and even osseous integration of implants. Thus, a better understanding of mechanisms that drive these age-dependent changes could provide strategic targets to minimize risk for such complications and optimize outcomes. Here, we introduce a clinically relevant mouse model of tibial fracture. The postoperative changes in these mice mimic some of the cognitive impairments commonly observed after routine orthopedic surgery in humans. Briefly, an incision is performed in the right hind limb under strictly aseptic conditions. Muscles are disassociated, and a 0.38-mm stainless steel pin is inserted into the upper crest of the tibia, inside the intramedullary canal. Osteotomy is then performed, and the wound is stapled. We have used this model to investigate the effects of surgical trauma on postoperative neuroinflammation and behavioral changes. By applying this fracture model in combination with parabiosis, a surgical model in which 2 mice are anastomosed, we have studied cells and secreted factors that systemically rejuvenate organ function and tissue regeneration after injury. By following our step-by-step protocol, these models can be reproduced with high fidelity, and can be adapted to interrogate many biologic pathways that are altered by surgical trauma.

This protocol describes a mouse model of orthopedic surgery that has been used to study mechanisms of postoperative neuroinflammation and behavioral changes, and when combined with parabiosis, to study tissue regeneration during aging.

Surgery is commonly used to improve and maintain quality of life. Unfortunately, in vulnerable patients such as the elderly, complications may occur and ...

Bone Marrow Transplantation Procedures in Mice to Study Clonal Hematopoiesis

Clonal hematopoiesis is a prevalent age-associated condition that results from the accumulation of somatic mutations in hematopoietic stem and progenitor cells (HSPCs). Mutations in driver genes, that confer cellular fitness, can lead to the development of expanding HSPC clones that increasingly give rise to progeny leukocytes harboring the somatic mutation. Because clonal hematopoiesis has been associated with heart disease, stroke, and mortality, the development of experimental systems that model these processes is key to understanding the mechanisms that underly this new risk factor. Bone marrow transplantation procedures involving myeloablative conditioning in mice, such as total-body irradiation (TBI), are commonly employed to study the role of immune cells in cardiovascular diseases. However, simultaneous damage to the bone marrow niche and other sites of interest, such as the heart and brain, is unavoidable with these procedures. Thus, our lab has developed two alternative methods to minimize or avoid possible side effects caused by TBI: 1) bone marrow transplantation with irradiation shielding and 2) adoptive BMT to non-conditioned mice. In shielded organs, the local environment is preserved allowing for the analysis of clonal hematopoiesis while the function of resident immune cells is unperturbed. In contrast, the adoptive BMT to non-conditioned mice has the additional advantage that both the local environments of the organs and the hematopoietic niche are preserved. Here, we compare three different hematopoietic cell reconstitution approaches and discuss their strengths and limitations for studies of clonal hematopoiesis in cardiovascular disease.

We describe three methods of bone marrow transplantation (BMT): BMT with total-body irradiation, BMT with shielded irradiation, and BMT method with no pre-conditioning (adoptive BMT) for the study of clonal hematopoiesis in mouse models.

Clonal hematopoiesis is a prevalent age-associated condition that results from the accumulation of somatic mutations in hematopoietic stem and progenitor ...

Immunology and Infection

Mouse Heterotopic Cervical Cardiac Transplantation Utilizing Vascular Cuffs

Murine models of cardiac transplantation are frequently utilized to study ischemia-reperfusion injury, innate and adaptive immune responses after transplantation, and the impact of immunomodulatory therapies on graft rejection. Heterotopic cervical heart transplantation in mice was first described in 1991 using sutured anastomoses and subsequently modified to include cuff techniques. This modification allowed for improved success rates, and since then, there have been multiple reports that have proposed further technical improvements. However, translation into more widespread utilization remains limited due to the technical difficulty associated with graft anastomoses, which requires precision to achieve adequate length and caliber of the cuffs to avoid vascular anastomotic twisting or excessive tension, which can result in damage to the graft. The present protocol describes a modified technique for performing heterotopic cervical cardiac transplantation in mice which involves cuff placement on the recipient's common carotid artery and the donor's pulmonary artery in alignment with the direction of the blood flow.

Mouse cardiac transplantation models represent valuable research tools for studying transplantation immunology. The present protocol details mouse heterotopic cervical cardiac transplantation that involves the placement of cuffs on the recipient's common carotid artery and the donor's pulmonary artery trunk to allow for laminar blood flow.

Murine models of cardiac transplantation are frequently utilized to study ischemia-reperfusion injury, innate and adaptive immune responses after ...

A Modified Murine Heterotopic Heart Transplant Protocol Matching Contemporary Standards of Aseptic Technique, Anesthesia, and Analgesia

The development of experimental models of cardiac transplantation in animals has contributed to many advances in the fields of immunology and solid organ transplantation. While the heterotopic vascularized murine cardiac transplantation model was initially utilized in studies of graft rejection using combinations of mismatched inbred mouse strains, access to genetically modified strains and therapeutic modalities can provide powerful new preclinical insights. Fundamentally, the surgical methodology for this technique has not changed since its development, especially with respect to important factors such as aseptic technique, anesthesia, and analgesia, which make material impacts on postsurgical morbidity and mortality. Additionally, improvements in perioperative management are expected to provide improvements in both animal welfare and experimental outcomes. This paper reports upon a protocol developed in collaboration with a subject matter expert in veterinary anesthesia and describes the surgical technique with an emphasis on perioperative management. Additionally, we discuss the implications of these refinements and provide details on troubleshooting critical surgical steps for this procedure.

The present paper describes a modified technique for heterotopic vascularized cardiac transplantation with updated aseptic technique, analgesia, and anesthesia.

The development of experimental models of cardiac transplantation in animals has contributed to many advances in the fields of immunology and solid organ ...

Blood Circuit Reconstruction in an Abdominal Mouse Heart Transplantation Model

The surgical technique of heterotopic abdominal heart transplantation in mice is a standard model for research in transplantation immunology. Here, the established technique for a modified blood circuit reconstruction in a heterotopic abdominal heart transplantation model is presented. This method uses the intrathoracic inferior vena cava (IIVC) instead of the pulmonary artery of the donor heart for the anastomosis to the inferior vena cava of the recipient. It is facilitating and improving success rates for abdominal heart transplantation in mice.

A novel technique for blood circuit reconstruction in a heterotopic abdominal mouse heart transplantation model is demonstrated.

The surgical technique of heterotopic abdominal heart transplantation in mice is a standard model for research in transplantation immunology. Here, the ...

Isolation of Mouse Coronary Endothelial Cells

Endothelial cells line the inner wall of blood vessels and play an important role in the regulation of vascular tone, vascular permeability, and new vascular formation. Endothelial cell dysfunction is implicated in the development and progression of many cardiovascular diseases including ischemic heart disease. To examine the function and characterization of coronary endothelial cells, cell isolation is the first step and it requires high purity and quantity to conduct subsequent experiments. This protocol describes an efficient method to isolate adult mouse coronary endothelial cells. The mouse heart is dissected and minced into small pieces. After the digestion of the heart using dispase and collagenase II, cells are washed&#160;and incubated with magnetic beads which are conjugated with anti-CD31 antibody. The beads with endothelial cells are washed several times and are ready to use in various applications, including imaging and molecular biological experiments. Efficient isolation yields approximately 104 cells per one heart with over 90% purity.

This protocol is prepared to share our method of isolating mouse coronary endothelial cells for the purpose of imaging or to conduct molecular biological experiments.

Endothelial cells line the inner wall of blood vessels and play an important role in the regulation of vascular tone, vascular permeability, and new ...

Biology

Liver Transplantation in Mouse and Analyzing Allograft Patency

Successful Orthotopic Liver Transplantation in Mice Utilizing Microcomputed Tomography Angiography

Microcomputed tomography (microCT) angiography is an invaluable resource to researchers. New advances in this technology have allowed for high-quality images to be obtained of micro-vasculature and are high-fidelity tools in the field of organ transplantation. In this model of orthotopic liver transplantation (OLT) in mice, microCT affords the opportunity to evaluate allograft anastomosis in real time and has the added benefit of not having to sacrifice study animals. The choice of contrast, as well as image acquisition settings, create a high-definition image, which gives researchers invaluable information. This allows for evaluation of the technical aspects of the procedure as well as potentially evaluating different therapeutics over an extended duration of time. In this protocol, we detail an OLT model in mice in a stepwise fashion and finally describe a microCT protocol that can give high-quality images, which aid researchers in in-depth analysis of solid organ transplantation. We provide a step-by-step guide for liver transplantation in a mouse, as well as briefly discuss a protocol for evaluating the patency of the graft through microCT angiography.

Author Spotlight: Enhancing Transplantation Research Through MicroCT Angiography in Murine Models 

In this protocol, we discuss the implementation of a model of successful orthotopic liver transplantation (OLT) in mice. Additionally, adjuvants to further analyze allograft patency after successful OLT in a mouse are discussed as well, specifically utilizing microcomputed tomography (microCT) scans.

Microcomputed tomography (microCT) angiography is an invaluable resource to researchers. New advances in this technology have allowed for high-quality ...