Name: mouse heterotopic cervical cardiac transplantation utilizing vascular cuffs
Uploaded: 2022-06-23T14:40:00
Description: Watch this Scientific Journal Video about Mouse Heterotopic Cervical Cardiac Transplantation Utilizing Vascular Cuffs at JoVE.com

DK is supported by National Institutes of Health grants 1P01AI116501, R01HL094601, R01HL151078, Veterans Administration Merit Review grant 1I01BX002730, and The Foundation for Barnes-Jewish Hospital.

All animal handling procedures were conducted in compliance with the NIH Care and Use of Laboratory Animals guidelines and approved by the Animal Studies Committee at Washington University School of Medicine. Hearts from C57BL/6 (B6) and BALB/c mice (weighing 20-25 g) were transplanted into gender-matched B6 recipients (6-8 weeks of age). The mice were obtained from commercial sources (see Table of Materials). Syngeneic transplants were performed to evaluate cellular responses related to ischemia-reperfu...

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	<li>Abbott, C. P., Lindsey, E. S., Creech, O., Dewitt, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+for+heart+transplantation+in+the+rat.">A technique for heart transplantation in the rat.</a> The Archives of Surgery. 89, 645-652 (1964).</li><li>Ono, K., Lindsey, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+technique+of+heart+transplantation+in+rats.">Improved technique of heart transplantation in rats.</a> The Journal of Thoracic and Cardiovascular Surgery. 57 (2), 225-229 (1969).</li><li>Corry, R. J., Winn, H. J., Russell, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+transplantation+in+congenic+strains+of+mice.">Heart transplantation in congenic strains of mice.</a> Transplantation Proceedings. 5 (1), 733-735 (1973).</li><li>Heron, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+for+accessory+cervical+heart+transplantation+in+rabbits+and+rats.">A technique for accessory cervical heart transplantation in rabbits and rats.</a> Acta Pathologica Microbiologica Scandinavica Section A Pathology. 79 (4), 366-372 (1971).</li><li>Chen, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+of+cervical+heterotopic+heart+transplantation+in+mice.">A technique of cervical heterotopic heart transplantation in mice.</a> Transplantation. 52 (6), 1099-1101 (1991).</li><li>Matsuura, A., Abe, T., Yasuura, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplified+mouse+cervical+heart+transplantation+using+a+cuff+technique.">Simplified mouse cervical heart transplantation using a cuff technique.</a> Transplantation. 51 (4), 896-898 (1991).</li><li>Yu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cuff+anastomosis+of+both+renal+artery+and+vein+to+minimize+thrombosis:+a+novel+method+of+kidney+transplantation+in+mice.">Cuff anastomosis of both renal artery and vein to minimize thrombosis: a novel method of kidney transplantation in mice.</a> Journal of Investigative Surgery. 35 (1), 56-60 (2022).</li><li>Tomita, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+technique+of+heterotopic+cervical+heart+transplantation+in+mice.">Improved technique of heterotopic cervical heart transplantation in mice.</a> Transplantation. 64 (11), 1598-1601 (1997).</li><li>Wang, Q., Liu, Y., Li, X. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplified+technique+for+heterotopic+vascularized+cervical+heart+transplantation+in+mice.">Simplified technique for heterotopic vascularized cervical heart transplantation in mice.</a> Microsurgery. 25 (1), 76-79 (2005).</li><li>Oberhuber, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+cervical+heart+transplantation+model+using+a+modified+cuff+technique.">Murine cervical heart transplantation model using a modified cuff technique.</a> Journal of Visualized Experiments. (92), e50753 (2014).</li><li>Ratschiller, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterotopic+cervical+heart+transplantation+in+mice.">Heterotopic cervical heart transplantation in mice.</a> Journal of Visualized Experiments. (102), e52907 (2015).</li><li>Mao, X., Xian, P., You, H., Huang, G., Li, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+modified+cuff+technique+for+mouse+cervical+heterotopic+heart+transplantation+model.">A modified cuff technique for mouse cervical heterotopic heart transplantation model.</a> Journal of Visualized Experiments. (180), e63504 (2022).</li><li>Li, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravital+2-photon+imaging+of+leukocyte+trafficking+in+beating+heart.">Intravital 2-photon imaging of leukocyte trafficking in beating heart.</a> Journal of Clinical Investigation. 122 (7), 2499-2508 (2012).</li><li>Kreisel, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+two-photon+imaging+reveals+monocyte-dependent+neutrophil+extravasation+during+pulmonary+inflammation.">In vivo two-photon imaging reveals monocyte-dependent neutrophil extravasation during pulmonary inflammation.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (42), 18073-18078 (2010).</li><li>Li, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+monocytic+cells+in+regressing+atherosclerotic+plaques+by+intravital+2-photon+and+positron+emission+tomography-based+imaging-brief+report.">Visualization of monocytic cells in regressing atherosclerotic plaques by intravital 2-photon and positron emission tomography-based imaging-brief report.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 38 (5), 1030-1036 (2018).</li><li>Li, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lung+transplant+acceptance+is+facilitated+by+early+events+in+the+graft+and+is+associated+with+lymphoid+neogenesis.">Lung transplant acceptance is facilitated by early events in the graft and is associated with lymphoid neogenesis.</a> Mucosal Immunology. 5 (5), 544-554 (2012).</li><li>Faust, N., Varas, F., Kelly, L. 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(160), e61103 (2020).</li><li>Latchana, N., Peck, J. R., Whitson, B., Black, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preservation+solutions+for+cardiac+and+pulmonary+donor+grafts:+a+review+of+the+current+literature.">Preservation solutions for cardiac and pulmonary donor grafts: a review of the current literature.</a> Journal of Thoracic Disease. 6 (8), 1143-1149 (2014).</li><li>Hartley, C. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Doppler+velocity+measurements+from+large+and+small+arteries+of+mice.">Doppler velocity measurements from large and small arteries of mice.</a> American Journal of Physiology - Heart and Circulatory Physiology. 301 (2), 269-278 (2011).</li><li>Bovenkamp, P. 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Utilizing this technique, mouse heterotopic cervical cardiac transplantation can be performed in less than 40 min by an experienced microsurgeon and in approximately 60 min by an entry-level microsurgeon. While cervical heart transplantation has been studied in numerous animal models, a mouse model remains the gold standard due to multiple well-defined genetic strains, genetic alteration capabilities, and the availability of numerous reagents, including monoclonal antibodies24. The technique descr...

Abbott et al. published1 the first description of heterotopic abdominal heart transplantation in rats in 1964. These surgical techniques were refined and simplified by Ono et al. in 19692. Corry et al. first described a method for heterotopic abdominal heart transplantation in mice in 1973; similar to the previously reported rat models, this involved engraftment into the host&#39;s abdomen with revascularization by end-to-side anastomoses of the donor&#39;s pulmonary artery and ascending aorta to the recipient&#39;s inferior vena cava and abdominal aorta, respectively3. Heterotopic cervical heart transplantation in rats was described by Heron in 1971 using Teflon cuffs made from 16 G (1.6 mm outer diameter) intravenous catheters4. Chen5 and Matsuura et al.6 later reported heterotopic cervical heart transplantation in mice in 1991, whose techniques differed primarily in their method of re-anastomosis. Chen&#39;s approach involved sutured anastomoses of the donor&#39;s ascending aorta to the carotid artery of the recipient and the donor&#39;s pulmonary artery to the external jugular vein of the recipient5. Due to the advanced technical skill required for these microsurgical sutured anastomoses, a significant amount of time and experience was necessary to achieve a high success rate. Matsuura et al. described a method utilizing a non-suture cuff technique, similar to that used by Heron, which involved end-to-end anastomoses using the extra-luminal placement of cuffs. He fashioned Teflon cuffs from 22 G (0.8 mm outer diameter) and 24 G (0.67 mm outer diameter) intravenous catheters and placed them over the recipient&#39;s external jugular vein and common carotid artery, respectively6. These cuffs were then placed inside the donor&#39;s pulmonary artery and aorta and secured by tying a suture ligature around the connection. This approach translated into an improved success rate. Most importantly, it resulted in a shortening of the time required to complete both cervical anastomoses, thus reducing the warm ischemic time of the graft to less than one-third of that utilizing the abdominal suturing method. Furthermore, since the cuffs are placed around the external surface of the vessel, there is no foreign body exposed to the vessel lumen, which largely reduces the possibility of thrombosis after surgery7. Meanwhile, utilization of the cuff technique provides support around the vessels at the site of the anastomosis without requiring any suturing, which reduces the risk of bleeding after revascularization6.
Numerous revisions of this technique have been proposed. To accommodate the short length of the mouse common carotid artery (approximately 5 mm), Tomita et al.8 developed a modification of this technique with a smaller arterial cuff (0.6 mm outer diameter) while omitting holding sutures and pulling the artery directly through the cuff with fine forceps instead. Wang et al. further simplified this approach by placing 22 G and 24 G cuffs on the donor&#39;s right pulmonary artery and recipient&#39;s right common carotid artery, respectively9. Various reports have described modifications to these approaches, including the use of specialized cuffs, microsurgical clamps, vessel dilators, and cardioplegia10,11,12. Notably, all of these methods involve the retrograde circulation of blood through the heart, with blood flowing from the recipient common carotid artery to the donor aorta, the coronary arteries, the coronary sinus, then emptying into the right atrium and exiting from the pulmonary artery into the recipient external jugular vein.
Compared to engraftment in the abdomen, cervical cardiac transplantation offers multiple advantages. As previously mentioned, cervical exposure allows for quicker revascularization and shorter warm ischemic times6. The cervical method is also less invasive and is associated with shorter postoperative recovery times as it avoids a laparotomy6. Importantly, end-to-end anastomoses with cuffs can be performed instead of end-to-side anastomoses, which decreases the risk of complications such as anastomotic bleeding. The abdominal approach also poses an increased risk of developing thrombotic complications in the abdominal aorta or inferior vena cava, leading to spinal cord ischemia and hindlimb paralysis. The superficial cervical location of the transplant allows for easy access to graft viability assessment by palpation, electrocardiography, and invasive or non-invasive imaging. Although the cervical grafts resume spontaneous cardiac activity following reperfusion, they do not significantly impact the systolic and diastolic parameters of the recipient. This model provides valuable insight for studying cellular responses following transplantation, such as ischemia-reperfusion injury and graft rejection. Furthermore, this model offers an ideal approach to allow for post-transplant imaging, such as intravital two-photon microscopy or positron emission tomography (PET) imaging. To this end, our laboratory has previously reported methods to image moving tissues and organs in the mouse, including beating murine hearts and aortic arch grafts following heterotopic cervical transplantation&#160;to visualize leukocyte trafficking during ischemia-reperfusion injury and within atherosclerotic plaques, respectively13,14,15. Additionally, due to its superficial location and ease of exposure, this model is suitable for cardiac re-transplantation16.
This report describes a technique that allows for laminar blood flow with the external placement of the vascular cuffs on the vessels from which blood flow originates. This allows for a smooth transition of blood flow from one vessel to the next, avoiding the exposure of the distal vessel edge into the vascular lumen. Additionally, the technique utilizes a larger 20 G cuff, instead of previously used 22 G cuffs, for the donor pulmonary artery to ensure ample return of blood flow to the recipient.

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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.

This mouse cervical heterotopic cardiac transplantation model has been utilized to perform over 1,000 transplants in our laboratory, with a survival rate of approximately 97%. The success rate is slightly higher than previous reports using other cervical heterotopic heart transplantation techniques in mice10,11,20. This could potentially be attributed to the larger 20 G cuff placed on the donor pulmonary artery to ensure ample r...

Watch this Scientific Journal Video about Mouse Heterotopic Cervical Cardiac Transplantation Utilizing Vascular Cuffs at JoVE.com

Mouse Heterotopic Cervical Cardiac Transplantation Utilizing Vascular Cuffs

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 ...

Our vascular cuff placement allows for laminar blood flow and we utilize a larger cuff for the donor pulmonary artery to ensure ample blood return to the recipients. These modifications used in this protocol decrease the likelihood of turbulent blood flow and thrombus formation and result in improved survival rates. This method provides valuable insight for studying immune responses after transplantation such as ischemia reperfusion injury and graft rejection.Additionally, our technique allows for easier post-transplant monitoring or re-transplantation. Demonstrating this procedure will be Dr.Wen Jun Li, an expert microsurgeon in our laboratory who developed this technique. Prepare the surgical area by shaving the hair from the chest and abdomen using an electric razor.Administer 100 units of heparin intravenously into the penile vein for males or external jugular vein for males and females. Place the mice in a supine position with forelimbs overhead. Secure the forelimbs and hindlimbs with surgical tape and disinfect the skin with 0.75%iodine and 70%ethanol.Perform an incision for the median laparosternotomy from the umbilicus to sternal angle, followed by a bilateral thoracotomy along each costal margin. Fold the anterior chest wall over the neck for full exposure of the mediastinum. Excise the thymus and expose the intrathoracic inferior vena cava.For retrograde perfusion, inject 1.5 milliliters of four degrees Celsius saline into the intrathoracic inferior vena cava with the needle oriented superiorly toward the graft. Ligate the superior vena cava using an 8-0 silk suture and divide distally. Repeat the retrograde perfusion by injecting another 1.5 milliliters of four degrees Celsius saline via the inferior vena cava.Ligate the inferior vena cava using an 8-0 silk suture and divide distally. Dissect the aortic arch and pulmonary artery trunk for graft harvesting and transect both distally. Ligate the pulmonary veins on the posterior surface of the heart using a 6-0 silk suture and divide distally.Perform graft preparation by removing the donor heart from the chest cavity. Place the excised heart in a plastic container filled with four degrees Celsius heparinized saline for one to two minutes. Transfer the graft onto a sterile plastic flask filled with ice for cuff placement.Place a one millimeter long 20 gauge angiocatheter cuff over the pulmonary artery for the donor cuff. Using fine forceps, gently fold the edges of the artery back over the cuff. Secure the folded vessel to the cuff using a 10-0 nylon tie.Store the donor heart in heparinized saline or another preservation solution at four degrees Celsius. Prepare the surgical area by shaving the hair from the cervical area using an electric razor. Apply sterile non-medicated ophthalmic ointment to the eyes to prevent corneal drying.Place the animal in a supine position with forelimbs adjacent to the body and the head turned slightly to the left. Secure the forelimbs and hindlimbs with surgical tape. Disinfect the skin with 0.75%iodine and 70%ethanol.After making a midline cervical incision from the lower mandible to the sternum, transect the right sternocleidomastoid muscle. Excise the right lobe of the inframandibular gland to create space for graft implantation. Tie a slipknot over the proximal external jugular vein using a 6-0 silk suture.Ligate the distal external jugular vein and adjacent branches using an 8-0 silk suture. Suture under the vein and cover with gauze. Make a transverse incision across the anterior wall of the external jugular vein.Place a 10-0 nylon suture through the edge of the proximal external jugular vein and the underlying tissue to secure the vein during cuff insertion. Ligate the distal right common carotid artery using an 8-0 silk suture just inferior to the carotid bifurcation. Tie a slipknot over the proximal common carotid artery using a 6-0 silk suture.Transect the artery distally between the sutures. Then place a 0.6 milliliter long 24 gauge angiocatheter cuff over the recipient's right common carotid artery. Using fine forceps, gently fold the edges of the artery back over the cuff.Secure the folded vessel to the cuff using a 10-0 nylon tie. Place the donor heart superior to the right cervical area. Drip cold saline onto the heart graft every few minutes during implantation.Place a 10-0 nylon suture through the edge of the donor aorta and through a superficial bite of the underlying tissue to secure the graft in place. Flush the donor aorta with 0.5 milliliters of 0.9%heparinized saline. Insert the recipient's common carotid artery cuff into the donor aorta.Secure the anastomosis with an 8-0 silk tie. Remove the aortic anchor suture. De-air the external jugular vein by flushing the recipient's external jugular vein with 0.5 milliliters of 0.9%heparinized saline.Perform pulmonary artery anastomosis by inserting the donor pulmonary artery cuff into the recipient's external jugular vein and secure with an 8-0 silk tie. Remove the external jugular vein anchor suture and transect the remaining posterior wall of the external jugular vein to free the graft from the underlying tissue. Ensure the graft is properly oriented without kinking or twisting of the anastomosis.Release the slipknots on the recipient's external jugular vein, followed by the common carotid artery to initiate heart graft reperfusion. The technique demonstrated in this protocol showed a survival rate of approximately 97%This could potentially be attributed to the larger 20 gauge cuff placed on the donor pulmonary artery to ensure ample return of blood flow to the recipient. Additionally, the alignment of blood flow with cuff placement in the present technique minimizes the risk of thrombosis and anastomotic turbulence.The mean recipient operation time was approximately 37 minutes with an average cold ischemia time of 20 minutes. For survival studies, cardiac grafts were assessed daily by direct visualization and digital palpation of the heartbeat. Intravital two-photon imaging was performed early after transplantation to evaluate leukocyte trafficking.It is important to check that the graft is properly positioned and oriented prior to skin closure to prevent twisting. This method can be used in re-transplantation models to identify resident immune cells in transplanted grafts that mediate alloimmune responses.

mouse-heterotopic-cervical-cardiac-transplantation-utilizing-vascular

Research

JoVE Journal

Immunology and Infection

Murine Model of CD40-activation of B cells

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand (CD40L), human B cells can be expanded without difficulties from small amounts of peripheral blood within 14 days to very large amounts of highly-pure CD40-B cells (&gt;109 cells per patient) from healthy donors as well as cancer patients1-4. CD40-B cells express important lymph node homing molecules and can attract T cells in vitro5. Furthermore they efficiently take up, process and present antigens to T cells6,7. CD40-B cells were shown to not only prime na&iacute;ve, but also expand memory T cells8,9. Therefore CD40-activated B cells (CD40-B cells) have been studied as an alternative source of immuno-stimulatory antigen-presenting cells (APC) for cell-based immunotherapy1,5,10. In order to further study whether CD40-B cells induce effective T cell responses in vivo and to study the underlying mechanism we established a cell culture system for the generation of murine CD40-activated B cells. Using splenocytes or purified B cells from C57BL/6 mice for CD40-activation, optimal conditions were identified as follows: Starting from splenocytes of C57BL/6 mice (haplotype H-2b) lymphocytes are purified by density gradient centrifugation and co-cultured with HeLa cells expressing recombinant murine CD40 ligand (tmuCD40L HeLa)11. Cells are recultured every 3-4 days and key components such as CD40L, interleukin-4, -Mercaptoethanol and cyclosporin A are replenished. In this protocol we demonstrate how to obtain fully activated murine CD40-B cells (mCD40B) with similar APC-phenotype to human CD40-B cells (Fig 1a,b). CD40-stimulation leads to a rapid outgrowth and expansion of highly pure (&gt;90%) CD19+ B cells within 14 days of cell culture (Fig 1c,d). To avoid contamination with non-transfected cells, expression of the murine CD40 ligand on the transfectants has to be controlled regularly (Fig 2). Murine CD40-activated B cells can be used to study B-cell activation and differentiation as well as to investigate their potential to function as APC in vitro and in vivo. Moreover, they represent a promising tool for establishing therapeutic or preventive vaccination against tumors and will help to answer questions regarding safety and immunogenicity of this approach12.

In this video, we demonstrate the procedure of CD40-activation and expansion of murine B cells from splenocytes of C57BL/6 mice, which can be used as a model antigen-presenting cell (APC) to study induction of immunity.

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand ...

Isolation of Functional Cardiac Immune Cells

Cardiac immune cells are gaining interest for the roles they play in the pathological remodeling in many cardiac diseases.1-5 These immune cells, which include mast cells, T-cells and macrophages; store and release a variety of biologically active mediators including cytokines and proteases such as tryptase.6-8 These mediators have been shown to be key players in extracellular matrix metabolism by activating matrix metalloproteinases or causing collagen accumulation by modulating the cardiac fibroblasts' function.9-11 However, available techniques for isolating cardiac immune cells have been problematic because they use bacterial collagenase to digest the myocardial tissue. This technique causes activation of the immune cells and thus a loss of function. For example, cardiac mast cells become significantly less responsive to compounds that cause degranulation.12 Therefore, we developed a technique that allows for the isolation of functional cardiac immune cells which would lead to a better understanding of the role of these cells in cardiac disease.13, 14
This method requires a familiarity with the anatomical location of the rat's xiphoid process, axilla and falciform ligament, and pericardium of the heart. These landmarks are important to increase success of the procedure and to ensure a higher yield of cardiac immune cells. These isolated cardiac immune cells can then be used for characterization of functionality, phenotype, maturity, and co-culture experiments with other cardiac cells to gain a better understanding of their interactions.

This method for isolating functional immune cells from the heart provides an alternative to the conventional methods of collagenase digestion, which causes unwanted immune cell activation, resulting in a decreased responsiveness of these cells. Our method of isolation yields functional cardiac immune cells by avoiding problems associated with enzymatic digestion.

Cardiac immune cells are gaining interest for the roles they play in the pathological remodeling in many cardiac diseases.1-5  These immune cells, which ...

Differentiating Functional Roles of Gene Expression from Immune and Non-immune Cells in Mouse Colitis by Bone Marrow Transplantation

To understand the role of a gene in the development of colitis, we compared the responses of wild-type mice and gene-of-interest deficient knockout mice to colitis. If the gene-of-interest is expressed in both bone marrow derived cells and non-bone marrow derived cells of the host; however, it is possible to differentiate the role of a gene of interest in bone marrow derived cells and non- bone marrow derived cells by bone marrow transplantation technique. To change the bone marrow derived cell genotype of mice, the original bone marrow of recipient mice were destroyed by irradiation and then replaced by new donor bone marrow of different genotype. When wild-type mice donor bone marrow was transplanted to knockout mice, we could generate knockout mice with wild-type gene expression in bone marrow derived cells. Alternatively, when knockout mice donor bone marrow was transplanted to wild-type recipient mice, wild-type mice without gene-of-interest expressing from bone marrow derived cells were produced. However, bone marrow transplantation may not be 100% complete. Therefore, we utilized cluster of differentiation (CD) molecules (CD45.1 and CD45.2) as markers of donor and recipient cells to track the proportion of donor bone marrow derived cells in recipient mice and success of bone marrow transplantation. Wild-type mice with CD45.1 genotype and knockout mice with CD45.2 genotype were used. After irradiation of recipient mice, the donor bone marrow cells of different genotypes were infused into the recipient mice. When the new bone marrow regenerated to take over its immunity, the mice were challenged by chemical agent (dextran sodium sulfate, DSS 5%) to induce colitis. Here we also showed the method to induce colitis in mice and evaluate the role of the gene of interest expressed from bone-marrow derived cells. If the gene-of-interest from the bone derived cells plays an important role in the development of the disease (such as colitis), the phenotype of the recipient mice with bone marrow transplantation can be significantly altered. At the end of colitis experiments, the bone marrow derived cells in blood and bone marrow were labeled with antibodies against CD45.1 and CD45.2 and their quantitative ratio of existence could be used to evaluate the success of bone marrow transplantation by flow cytometry. Successful bone marrow transplantation should show a vast majority of donor genotype (in term of CD molecule marker) over recipient genotype in both the bone marrow and blood of recipient mice.

Bone marrow transplantation provides a way to change the genotype of the bone marrow derived cells. If the gene of interest is expressed in both bone marrow derived cells and non-bone marrow derived cells, bone marrow transplantation can change the bone marrow derived cells to a different genotype without changing the non-bone marrow derived cell genotype.

To understand the role of a gene in the development of colitis, we compared the responses of wild-type mice and gene-of-interest deficient knockout mice ...

Murine Full-thickness Skin Transplantation

Murine full-thickness skin transplantation is a well-established in vivo model to study alloimmune response and graft rejection. Despite its limited application to humans, skin transplantation in mice has been widely employed for transplantation research. The procedure is easy to learn and perform, and it does not require delicate microsurgical techniques nor extensive training. Moreover, graft rejection in this model occurs in a very reproducible immunological reaction and is easily monitored by direct inspection and palpation. In addition, secondary skin transplantation with donor-matched or third-party skin grafts can be performed on more complex transplant models as an alternative and uncomplicated method to assess donor-specific tolerance. The complications are low and are in general limited to anesthesia overdose or respiratory distress after the procedure. Graft failure, on the other hand, occurs commonly as a result of poor preparation of the graft, incorrect positioning in the graft bed, or inappropriate placement of the bandage. In this article, we present a protocol for full-thickness skin transplantation in mice and describe the important steps necessary for a successful procedure.

Murine full-thickness skin transplantation is a well-established model to study rejection in an alloimmune setting. Here, we provide a tutorial of each step involved in performing a BALB/c--&#62;C57BL/6 full-thickness skin transplant.

Murine full-thickness skin transplantation is a well-established in vivo model to study alloimmune response and graft rejection. Despite its limited ...

In Vitro and In Vivo Assessment of T, B and Myeloid Cells Suppressive Activity and Humoral Responses from Transplant Recipients

The main concern in transplantation is to achieve specific tolerance through induction of regulatory cells. The understanding of tolerance mechanisms requires reliable models. Here, we describe models of tolerance to cardiac allograft in rat, induced by blockade of costimulation signals or by upregulation of immunoregulatory molecules through gene transfer. Each of these models allowed in vivo generation of regulatory cells such as regulatory T cells (Tregs), regulatory B cells (Bregs) or regulatory myeloid cells (RegMCs). In this manuscript, we describe two complementary protocols that have been used to identify and define in vitro and in vivo regulatory cell activity to determine their responsibility in tolerance induction and maintenance. First, an in vitro suppressive assay allowed rapid identification of cells with suppressive capacity on effector immune responses in a dose dependent manner, and can be used for further analysis such as cytokine measurement or cytotoxicity. Second, the adoptive transfer of cells from a tolerant treated recipient to a newly irradiated grafted recipient, highlighted the tolerogenic properties of these cells in controlling graft directed immune responses and/or converting new regulatory cells (termed infectious tolerance). These methods are not restricted to cells with known phenotypic markers and can be extended to any cell population. Furthermore, donor directed allospecificity of regulatory cells (an important goal in the field) can be assessed by using third party donor cells or graft either in vitro or in vivo. Finally, to determine the specific tolerogenic capacity of these regulatory cells, we provide protocols to assess the humoral anti-donor antibody responses and the capacity of the recipient to develop humoral responses against new or former known antigens. The models of tolerance described can be used to further characterize regulatory cells, to identify new biomarkers, and immunoregulatory molecules, and are adaptable to other transplantation models or autoimmune diseases in rodent or human.

In Vitro and In Vivo Assessment of T, B and Myeloid Cells Suppressive Activity and Humoral Responses from Transplant Recipients

Here, we present a protocol to induce tolerance in transplantation, and assess in vitro and in vivo the suppressive capacity of distinct cell subsets from the recipient and the immune status of the recipient toward donor or exogenous antigens.

The main concern in transplantation is to achieve specific tolerance through induction of regulatory cells. The understanding of tolerance mechanisms ...

Assessment of the Cytotoxic and Immunomodulatory Effects of Substances in Human Precision-cut Lung Slices

Respiratory diseases in their broad diversity need appropriate model systems to understand the underlying mechanisms and enable development of new therapeutics. Additionally, registration of new substances requires appropriate risk assessment with adequate testing systems to avoid the risk of individuals being harmed, for example, in the working environment. Such risk assessments are usually conducted in animal studies. In view of the 3Rs principle and public skepticism against animal experiments, human alternative methods, such as precision-cut lung slices (PCLS), have been evolving. The present paper describes the ex vivo technique of human PCLS to study the immunomodulatory potential of low-molecular-weight substances, such as ammonium hexachloroplatinate (HClPt). Measured endpoints include viability and local respiratory inflammation, marked by altered secretion of cytokines and chemokines. Pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-&#945;), and interleukin 1 alpha (IL-1&#945;) were significantly increased in human PCLS after exposure to a sub-toxic concentration of HClPt. Even though the technique of PCLS has been substantially optimized over the past decades, its applicability for the testing of immunomodulation is still in development. Therefore, the results presented here are preliminary, even though they show the potential of human PCLS as a valuable tool in respiratory research.

In view of the 3Rs principle, respiratory models as alternatives to animal studies are evolving. Especially for risk assessment of respiratory substances, there is a lack of appropriate assays. Here, we describe the use of human precision-cut lung slices for the assessment of airborne substances.

Respiratory diseases in their broad diversity need appropriate model systems to understand the underlying mechanisms and enable development of new ...

An Immunological Model for Heterotopic Heart and Cardiac Muscle Cell Transplantation in Rats

Heterotopic heart transplantation in rats has been a commonly used model for diverse immunological studies for more than 50 years. Several modifications have been reported since the first description in 1964. After 30 years of performing heterotopic heart transplantation in rats, we have developed a simplified surgical approach, which can be easily taught and performed without further surgical training or background.
After dissection of the ascending aorta and the pulmonary artery and ligation of superior and inferior caval and pulmonary veins, the donor heart is harvested and subsequently perfused with ice-cold saline solution supplemented with heparin. After clamping and incising the recipient abdominal vessels, the donor ascending aorta and pulmonary artery are anastomosed to the recipient abdominal aorta and inferior vena cava, respectively, using continuous running sutures.
Depending on different donor-recipient combinations, this model allows analyses of either acute or chronic rejection of allografts. The immunological significance of this model is further enhanced by a novel approach of in-ear injection of vital cardiac muscle cells and subsequent analysis of draining cervical lymphatic tissue.

We describe a model of heterotopic abdominal heart transplantation in rats, implying modifications of current strategies, which lead to a simplified surgical approach. Additionally, we describe a novel rejection model by in-ear injection of vital cardiac muscle cells, allowing further transplant immunological analyses in rats.

Heterotopic heart transplantation in rats has been a commonly used model for diverse immunological studies for more than 50 years. Several modifications ...

Optimization of the Cuff Technique for Murine Heart Transplantation

Murine cardiac transplantation has been performed for more than 40 years. With advancements in microsurgery, certain new techniques have been used to improve surgical efficiency. In our lab, we have optimized the cuff technique with two major steps. First, we used the inner tube technique to insert a temporary inner tube into the external jugular vein and carotid artery blood vessel to facilitate eversion of the vessel over the cuff. Second, we performed complete heterotopic cardiac transplantation through the collaboration of two experienced surgeons. These modifications effectively reduced the operation time to 25 minutes, with a success rate of 95%. In this report, we describe these procedures in detail and provide a supplemental video. We believe that this report on the improved cuff technique will offer practical guidance for murine heterotopic heart transplantation and will enhance the utility of this mouse model for basic research.

We introduce an inner tube approach to the cuff technique for mouse cervical heterotopic heart transplantation to help evert the vessel over the cuff. We found that cooperation between two experienced surgeons markedly shortens the operation time.

Murine cardiac transplantation has been performed for more than 40 years. With advancements in microsurgery, certain new techniques have been used to ...

Visualization of SARS-CoV-2 using Immuno RNA-Fluorescence In Situ Hybridization

This manuscript provides a protocol for in situ hybridization chain reaction (HCR) coupled with immunofluorescence to visualize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in cell line&#160;and three-dimensional (3D) cultures of human airway epithelium. The method allows highly specific and sensitive visualization of viral RNA by relying on HCR initiated by probe localization. Split-initiator probes help amplify the signal by fluorescently labeled amplifiers, resulting in negligible background fluorescence in confocal microscopy. Labeling amplifiers with different fluorescent dyes facilitates the simultaneous recognition of various targets. This, in turn, allows the mapping of the infection in tissues to better understand viral pathogenesis and replication at the single-cell level. Coupling this method with immunofluorescence may facilitate better understanding of host-virus interactions, including alternation of the host epigenome and immune response pathways. Owing to sensitive and specific HCR technology, this protocol can also be used as a diagnostic tool. It is also important to remember that the technique may be modified easily to enable detection of any RNA, including non-coding RNAs and RNA viruses that may emerge in the future.

Here, we describe a simple method that combines RNA fluorescence in situ&#160;hybridization (RNA-FISH) with immunofluorescence to visualize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. This protocol may increase understanding of the molecular characteristics of SARS-CoV-2 RNA-host interactions at a single-cell level.

This manuscript provides a protocol for in situ hybridization chain reaction (HCR) coupled with immunofluorescence to visualize severe acute respiratory ...

Purification and Expansion of Mouse Invariant Natural Killer T Cells for in vitro and in vivo Studies

Invariant Natural Killer T (iNKT) cells are innate-like T Lymphocytes expressing a conserved semi-invariant T cell receptor (TCR) specific for self or microbial lipid antigens presented by the non-polymorphic MHC class I-related molecule CD1d. Preclinical and clinical studies support a role for iNKT cells in cancer, autoimmunity and infectious diseases. iNKT cells are very conserved throughout species and their investigation has been facilitated by mouse models, including CD1d-deficient or iNKT-deficient mice, and the possibility to unequivocally detect them in mice and men with CD1d tetramers or mAbs specific for the semi-invariant TCR. However, iNKT cells are rare and they need to be expanded to reach manageable numbers for any study. Because the generation of primary mouse iNKT cell line in vitro has proven difficult, we have set up a robust protocol to purify and expand splenic iNKT cells from the iV&#945;14-J&#945;18 transgenic mice (iV&#945;14Tg), in which iNKT cells are 30 times more frequent. We show here that primary splenic iV&#945;14Tg iNKT cells can be enriched through an immunomagnetic separation process, yielding about 95-98% pure iNKT cells. The purified iNKT cells are stimulated by anti-CD3/CD28 beads plus IL-2 and IL-7, resulting in 30-fold expansion by day +14 of the culture with 85-99% purity. The expanded iNKT cells can be easily genetically manipulated, providing an invaluable tool to dissect mechanisms of activation and function in vitro and, more importantly, also upon adoptive transfer in vivo.

We describe a rapid and robust protocol to enrich invariant natural killer T (iNKT) cells from mouse spleen and expand them in vitro to suitable numbers for in vitro and in vivo studies.

Invariant Natural Killer T (iNKT) cells are innate-like T Lymphocytes expressing a conserved semi-invariant T cell receptor (TCR) specific for self or ...