Hemodynamics in pig-to-baboon heterotopic thoracic cardiac xenotransplantation: Recovery from perioperative cardiac xenograft dysfunction and impairment by cardiac overgrowth.

INTRODUCTION: Orthotopic cardiac xenotransplantation has seen notable improvement, leading to the first compassionate use in 2022. However, it remains challenging to define the clinical application of cardiac xenotransplantation, including the back-up strategy in case of xenograft failure. In this regard, the heterotopic thoracic technique could be an alternative to the orthotopic procedure. We present hemodynamic data of heterotopic thoracic pig-to-baboon transplantation experiments, focusing on perioperative xenograft dysfunction and xenograft overgrowth. METHODS: We used 17 genetically modified piglets as donors for heterotopic thoracic xenogeneic cardiac transplantation into captive-bred baboons. In all animals, pressure probes were implanted in the graft's left ventricle and the recipient's ascending aorta and hemodynamic data (graft pressure, aortic pressure and recipient's heart rate) were recorded continuously. RESULTS: Aortic pressures and heart rates of the recipients' hearts were postoperatively stable in all experiments. After reperfusion, three grafts presented with low left ventricular pressure indicating perioperative cardiac dysfunction (PCXD). These animals recovered from PCXD within 48 h under support of the recipient's heart and there was no difference in survival compared to the other 14 ones. After 48 h, graft pressure increased up to 200 mmHg in all 17 animals with two different time-patterns. This led to a progressive gradient between graft and aortic pressure. With increasing gradient, the grafts stopped contributing to cardiac output. Grafts showed a marked weight increase from implantation to explantation. CONCLUSION: The heterotopic thoracic cardiac xenotransplantation technique is a possible method to overcome PCXD in early clinical trials and an experimental tool to get a better understanding of PCXD. The peculiar hemodynamic situation of increasing graft pressure but missing graft's output indicates outflow tract obstruction due to cardiac overgrowth. The heterotopic thoracic technique should be successful when using current strategies of immunosuppression, organ preservation and donor pigs with smaller body and organ size.

Evaluation of an alternative heterotopic transplantation model for ovarian tissue to test pharmaceuticals improvements for fertility restoration.

BACKGROUND: Ovarian tissue cryopreservation and transplantation (OTCTP) is currently the main option available to preserve fertility in prepubertal patients undergoing aggressive cancer therapy treatments. However, a major limitation of OTCTP is follicle loss after transplantation. The mouse is a model of choice for studying ovarian function and follicle development after ovarian tissue grafting in vivo. In these mouse models, ovarian tissue or ovaries can be transplanted to different sites. Our aim was to evaluate a new alternative to heterotopic transplantation models that could be useful to test pharmaceutical improvement for ovarian grafts after OTCTP. METHODS: Slow frozen murine whole ovaries were transplanted into the mouse ears (between the external ear skin layer and the cartilage). Ovarian transplants were recovered after 3, 14 or 21 days. Grafts were analyzed by immunohistochemistry and follicle density analyses were performed. RESULTS: An increase of ovarian vascularization (CD31 and Dextran-FITC positive staining), as well as cellular proliferation (Ki67 staining) were observed 3 weeks after transplantation in comparison to 3 days. Fibrosis density, evaluated after Van Gieson staining, decreased 3 weeks after transplantation. Furthermore, transplantation of cryopreserved ovaries into ovariectomized mice favored follicle activation compared to transplantation into non-ovariectomized mice. CONCLUSION: The present study indicates that surgical tissue insertion in the highly vascularized murine ear is an effective model for ovarian grafting. This model could be helpful in research to test pharmaceutical strategies to improve the function and survival of cryopreserved and transplanted ovarian tissue.

Neovaginoplasty Using Nile Tilapia Fish Skin as a New Biologic Graft in Patients with Mayer-Rokitansky-Küster-Hauser Syndrome.

Mayer-Rokitansky-Küster-Hauser syndrome is the second most common cause of primary amenorrhea, trailing only to gonadal dysgenesis. Neovaginoplasty is an appropriate treatment option for patients who have failed dilation therapy. Several biomaterials have been used in this procedure, including peritoneum, amnion, skin grafts, and myocutaneous flaps. Nile Tilapia Fish Skin has noninfectious microbiota, morphologic structure comparable to human skin, and high in vivo bioresorption. In addition, it showed good outcomes when used as a xenograft for burn treatment. Thus, we suggest it as a new biologic graft for vaginal agenesis management. In this descriptive study, neovaginoplasty using Nile Tilapia Fish Skin offered 3 patients an anatomic and functional neovagina via a simple method with potential long-term effectiveness. When postsurgical dilation was performed correctly, a vaginal length greater than 6 cm was maintained at 180 days follow-up. Histologic and immunohistochemical analyses revealed the presence of stratified squamous epithelium with high expression of cytokeratins and fibroblast growth factor, matching the characteristics of normal adult vaginal tissue. We believe that further studies will show Nile Tilapia Fish Skin to be a relevant option in the therapeutic arsenal of Mayer-Rokitansky-Küster-Hauser syndrome.

A case report and follow-up of the first live birth after heterotopic transplantation of cryopreserved ovarian tissue in Eastern Europe.

BACKGROUND: Ovarian insufficiency is a major concern for long-term cancer survivors. Although semen freezing is well established to preserve male fertility, the possibilities to secure post-cancer female fertility are mostly limited to oocyte or embryo freezing. These methods require time-consuming ovarian stimulation with or without in vitro fertilization (IVF) that evidently delays cancer therapy. Ovarian tissue cryopreservation and subsequent thawed tissue autotransplantation are considered the most promising alternative strategy for restoring the fertility of oncology patients, which has not yet received the full clinical acceptance. Therefore, all successful cases are needed to prove its reliability and safety. CASE PRESENTATION: Here we report a single case in Estonia, where a 28-year-old woman with malignant breast neoplasm had ovarian cortex cryopreserved before commencing gonadotoxic chemo- and radiotherapy. Two years after cancer therapy, the patient underwent heterotopic ovarian tissue transplantation into the lateral pelvic wall. The folliculogenesis was stimulated in the transplanted tissue by exogenous follicle-stimulating hormone and oocytes were collected under ultrasound guidance for IVF and embryo transfer. The healthy boy was born after full-term gestation in 2014, first in Eastern Europe. CONCLUSION: Despite many countries have reported the first implementation of the ovarian tissue freezing and transplantation protocols, the data is still limited on the effectiveness of heterotopic ovarian transplant techniques. Thus, all case reports of heterotopic ovarian tissue transplantation and long-term follow-ups to describe the children's health are valuable source of clinical experience.

A highly reproducible cervical cuff technique for rat-to-mouse heterotopic heart xenotransplantation.

Xenotransplantation is an effective way to solve the problem of donor shortage in clinical transplantation. However, clinical use of xenotransplantation is currently limited due to immunological challenges such as acute vascular rejection and cell-mediated rejection. To finally surpass this immunological barrier, more preclinical research is needed into the molecular mechanisms of rejection and the possible effects of new immunosuppressants. Our aim was to create a refined, highly reproducible protocol to establish the most suitable rat-to-mouse heterotopic heart transplantation model using the cuff technique.

Encouraging experience using multi-transgenic xenografts in a pig-to-baboon cardiac xenotransplantation model.

BACKGROUND: Innovations in transgenic technology have facilitated improved xenograft survival. Additional gene expression appears to be necessary to overcome the remaining immune and biologic incompatibilities. We report for the first time the novel use of six-gene modifications within a pig-to-baboon cardiac xenotransplantation model. METHODS: Baboons (8-15 kg) underwent heterotopic cardiac transplantation using xenografts obtained from genetically engineered pigs. Along with previously described modifications (GTKO, hCD46), additional expression of human transgenes for thromboregulation (endothelial protein C receptor, tissue factor pathway inhibitor, thrombomodulin), complement inhibition (decay accelerating factor), and cellular immune suppression (hCD39, hCD47) was used. Immunosuppression consisted of targeted T-cell and B-cell depletion and conventional anti-rejection agents. RESULTS: Heterotopic cardiac transplantations were performed without complication. Flow cytometry and immunohistochemistry on donor biopsies confirmed transgenic phenotype. In contrast to the prior three-gene generation, significant coagulopathy or consumptive thrombocytopenia has not been observed in the six-gene cohort. As a result, these recipients have experienced decreased bleeding-related complications. Pro-inflammatory responses also appear to be mitigated based on cytokine analysis. Baboons survived the critical 30-day post-operative period when mortality has historically been highest, with no evidence of graft rejection. CONCLUSIONS: The inclusion of additional human genes in genetically engineered pigs appears to confer superior xenograft outcomes. Introduction of these genes has not been associated with adverse outcomes. This multifactorial approach to genetic engineering furthers the prospect of long-term cardiac xenograft survival and subsequent clinical application.

A Comparison between splenic fossa and subhepatic fossa auxiliary partial heterotopic liver transplantation in a porcine model.

To test the alternative possible locations for the placement of a liver graft and the relevant surgical technique issues, we developed a porcine model of auxiliary partial heterotopic liver transplantation (APHLT) and evaluated the difference between 2 styles of liver transplantation, either subhepatic fossa or splenic fossa APHLT, by comparing survival and biochemical indexes. Thirty-eight miniature pigs were randomly divided into 2 groups. A left hemihepatic graft without the middle hepatic vein (HV) was procured from the living donor. In group A (n = 9), an 8 mm diameter polytetrafluoroethylene (PTFE) graft approximately 2.5 cm long was connected to the left HV while another PTFE graft of the same size was connected to the left portal vein (PV). The liver graft was implanted in the right subhepatic fossa following splenectomy and right nephrectomy. In group B (n = 10), a PTFE graft of the same size was connected to the left HV while the liver graft was implanted in the splenic fossa following splenectomy and left nephrectomy. Survival rate and complications were observed at 2 weeks after transplantation. Data were collected from 5 animals in group A and 6 animals in group B that survived longer than 2 weeks. The liver function and renal function of the recipients returned to normal at 1 week after surgery in both groups. Eighty-eight percent (14/16) of the PTFE grafts remained patent at 2 weeks after surgery, but 44% of the PTFE grafts (7/16) developed mural thrombus. No significant differences in the survival rate and biochemistry were found between the 2 groups. In conclusion, the splenic fossa APHLT can achieve beneficial outcomes similar to the subhepatic fossa APHLT in miniature pigs, although it also has a high morbidity rate due to hepatic artery thrombosis, PV thrombosis, and PTEF graft mural thrombus formation. Liver Transplantation 22 812-821 2016 AASLD.

Experimental Study on the In-Vivo Heterotopic Transplantation of Aortic Valved Homografts after De-Endothelialization.

BACKGROUND AND AIM OF THE STUDY: The study aims were to monitor the changes in tissue morphology, calcium content and CD40 expression in the in-vivo heterotopic transplantation of aortic valved homografts after de-endothelialization, and to seek better methods for preventing calcification and degeneration of the homograft valves. METHODS: Adult, healthy, inbred male Chinese rabbits were used as donors, and inbred adult female New Zealand White rabbits as recipients for the heterotopic transplantation of aortic valved homografts with abdominal aorta. Controls received aortic valved homografts without treatment, while the de-endothelialization group received aortic valved homografts after de-endothelialization. For the cryopreservation group, aortic valved homografts were treated with 10% dimethyl sulfoxide and cryopreserved in liquid nitrogen for 60 days. Recipients were randomly allocated to three groups (n = 20 per group). Grafts were removed after two, four, eight and 12 weeks of surgery and observed with light microscopy. Calcium concentrations were monitored using flame atomic absorption, and CD40 expressions with immunohistochemistry. RESULTS: At two weeks after transplantation, the calcium contents of the fresh, de-endothelialization and cryopreservation groups were similar (p >0.05). The calcium content at four, eight and 12 weeks in the fresh and cryopreservation groups was significantly higher than that in the de-endothelialization group (p <0.01), while at two, four and eight weeks after transplantation, CD40 expression in the fresh and cryopreservation groups was significantly different from that in the de-endothelialization group (p <0.01). CONCLUSION:The calcium content in valve homografts was found to correlate with immune rejection. De-endothelialization could reduce immune rejection reactions and prevent calcification of aortic homograft valve.

Development of a Vascularized Heterotopic Neonatal Rat Heart Transplantation Model.

BACKGROUND/PURPOSE: Rodent adult-to-adult heterotopic heart transplantation is a well-established animal model, and the detailed surgical technique with several modifications has been previously described. In immature donor organ transplantation, however, the surgical technique needs to be revised given the smaller size and fragility of the donor graft. Here, we report our surgical technique for heterotopic abdominal (AHTx) and femoral (FHTx) neonatal rat heart transplantation based on an experience of over 300 cases. METHODS: Heterotopic heart transplantation was conducted in syngeneic Lewis rats. Neonatal rats (postnatal day 2-4) served as donors. AHTx was performed by utilizing the conventional adult-to-adult transplant method with specific modifications for optimal aortotomy and venous anastomosis. In the FHTx, the donor heart was vascularized by connecting the donor's aorta and pulmonary artery to the recipient's right femoral artery and vein, respectively, in an end-to-end manner. A specifically fashioned butterfly-shaped rubber sheet was used to align the target vessels properly. The transplanted graft was visually assessed for its viability and was accepted as a technical success when the viability met specific criteria. Successfully transplanted grafts were subject to further postoperative evaluation. Forty cases (AHTx and FHTx; n = 20 each) were compared regarding perioperative parameters and outcomes. RESULTS: Both models were technically feasible (success rate: AHTx 75% vs. FHTx 70%) by refining the conventional heterotopic transplant technique. Injury to the fragile donor aorta and congestion of the graft due to suboptimal venous connection were predominant causes of failure, leading to refractory bleeding and poor graft viability. Although the FHTx required significantly longer operation time and graft ischemic time, the in situ graft viabilities were comparable. The FHTx provided better postoperative monitoring as it enabled daily graft palpation and better echocardiographic visualization. CONCLUSIONS: We describe detailed surgical techniques for AHTx and FHTx while addressing neonatal donor-specific issues. Following our recommendations potentially reduces the learning curve to achieve reliable and reproducible results with these challenging animal models.

Hemodynamic Assessment of a Murine Heterotopic Biventricularly Loaded Cardiac Transplant in vivo Model.

BACKGROUND: Heterotopic heart transplantation (HHT) in rodent animal models represents an important technique enabling studies on organ transplantation immunology and pharmaceutical development. Recent investigations used nonworking HHT designs, with the left ventricle (LV) bypassed in the anastomosis system. In spite of their principal success, the lack of orthogonal ventricular filling leads to myocardial atrophy. However, when focusing on the cellular and molecular mechanisms involved in the in vivo remodeling of the myocardium or cell-based cardiovascular implants, a nonworking model is suboptimal as it lacks the native-analogous hemodynamic and metabolic situation. Here we present the hemodynamic and electrical assessment of a biventricularly loaded murine HHT method without the need for a combined heart-lung transplantation approach. METHODS: Heterotopic transplantations (n = 13) were performed on C57BL/6J-(H-2b) inbred mice (n = 13 donors, n = 13 recipients) by creating end-to-side anastomoses between the donors' cranial vena cava (CrVC) and the recipients' abdominal caudal vena cava (CVC), between the donors' ascending aorta and the recipients' abdominal aorta (aAo), and between the grafts' pulmonary trunk and the left atrium. After transplantation, a hemodynamic assessment using echocardiography (including 2D speckle tracking analysis) and electrocardiography was performed. RESULTS: The loaded HHT procedure in the mice was performed with an overall success rate of 61%. In 3 of the remaining 5 cases, only atrial function was restored. The median duration of the entire surgical procedure for the recipient animal was 190 (IQR 180-250) min. The mean heart rate in the loaded HHT group was 355 ± 6 bpm in comparison to the control group with an in situ heart rate of 418 ± 61 bpm. A native-like closing and opening pattern of the aortic and mitral valves (visible on both 2D and M-mode images) was observed, confirming a native-analogous loading of the LV. Pulsed-wave Doppler provided visualization of the flow across the region of anastomoses between the pulmonary trunk and the left atrium, reaching a mean maximum velocity of 382 ± 12 mm/s. Exemplary 2D speckle tracking analysis of the LV free wall and interventricular septum revealed some differences in vector directions in one animal when compared to the orthotopic native heart, indicating an asynchronous movement of the LV. CONCLUSIONS: These results demonstrate the technical (micro)surgical feasibility of a fully loaded HHT procedure in the murine model without using a combined heart-lung transplantation approach. The acute hemodynamic performance of the HHT grafts approximated the native orthotopic situation. This model may open up new options for the investigation of cellular and molecular questions in the murine cardiovascular in vivo system in the near future.

Heterotopic Vascularized Joint Transfer in Mutilating Hand Injuries.

BACKGROUND: In cases of mutilating hand injuries, the primary goal is recovery of prehensile function. This is particularly true in the case of joints, which are extremely difficult to replace or reconstruct adequately when damaged. Heterotopic vascularized joint transfer is indicated when salvageable joints are available for transfer to a more functionally optimal position on the hand. MATERIALS AND METHODS: Seven cases of mutilating hand injuries treated with heterotopic vascularized joint transfers from 2003 to 2012 were retrospectively identified. All patients sustained severe metacarpophalangeal joint (MPJ) or proximal interphalangeal joint (PIPJ) damage that threatened recovery of optimal hand function. All patients were men, with an average age of 34.7 years. Operative, perioperative, and postoperative details including final active range of motion were collected and analyzed. RESULTS: Seven joints were taken from nonsalvageable amputated digits: 4 from the amputated parts, and 3 from the proximal stumps. Five joints were transferred as free flaps requiring microvascular anastomosis, and 2 were transferred on neurovascular pedicles. One joint was lost due to vasospasm. Average active range of motion was 68.3° for homojoint transfers (MPJ to MPJ, PIPJ to PIPJ), and 35° for heterojoint transfers. All but 1 patient were able to achieve tripod pinch; the remaining patient achieved only side-to-side pinch. CONCLUSIONS: Heterotopic vascularized joint transfer is a useful technique to consider in cases of mutilating hand injuries. Improved recovery of prehensile function can be achieved with thoughtful design and execution, followed by proper patient education and rehabilitation.

An Extraperitoneal Technique for Murine Heterotopic Cardiac Transplantation.

The mouse heterotopic cardiac transplantation model has been used extensively by investigators in the field of organ transplantation to study the rejection process, test new antirejection treatments, tolerance induction protocols or to understand basic immunological principles. Due to its extensive use, any small refinement of the technique would have a major impact on replacement, reduction and refinement (commonly known as the 3Rs). Here, we describe a novel approach to refine this model. The donor aorta and pulmonary artery are anastomosed peripherally to the femoral artery and vein of the recipient, respectively. The technical success rate is comparable to the conventional abdominal site, but it avoids a laparotomy and handling of the bowels making it less invasive method. As a result, recipients recover faster and require less postoperative analgesia. It is a major refinement under one of the 3Rs and would represent an advance in animal welfare in scientific research.

Islet xenotransplantation: what is the optimal age of the islet-source pig?

BACKGROUND: The need for pig islet xenotransplantation in patients with type 1 diabetes is compelling; however, the ideal age at which islets should be isolated from the donor pig remains uncertain. Pig islet transplantation in primates, as a valuable pre-clinical model, has been explored using adult, neonatal, fetal pig islets, and also pancreatic primordia from pig embryos as beta cell donors. Neonatal pig islets have some advantages over adult and fetal islets, but the optimal age within the first month of life at which neonatal islets should be isolated and transplanted is as yet unclear. METHODS: In an attempt to answer this question, we carried out a literature search, but limited the search primarily to evidence in the clinically-relevant pig-to-non-human primate model. RESULTS: We identified surprisingly few studies in this model directed to this topic. Even in pig-to-rodent models, there were few definitive data. CONCLUSION: From the few data available to us, we conclude that pancreatectomy and islet isolation from neonatal pigs may have advantages over adult pigs and that isolation during the first week of life may have minor advantages over later weeks.

Pharmacological strategies for protection of extrahepatic islet transplantation.

The safety and effectiveness of islet transplantation has been proven through world-wide trials. However, acute and chronic islet loss has hindered the ultimate objective of becoming a widely used treatment option for type 1 diabetes. A large islet loss is attributed, in part, to the liver being a less-than-optimal site for transplantation. Over half of the transplanted islets are destroyed shortly after transplantation due to direct exposure to blood and non-specific inflammation. Successfully engrafted islets are continuously exposed to the liver micro-environment, a unique immune system, low oxygen tension, toxins and high glucose, which is toxic to islets, leading to premature islet dysfunction/death. Investigations have continued to search for alternate sites to transplant islets that provide a better environment for prolonged function and survival. This article gathers courses and conditions that lead to islet loss, from organ procurement through islet transplantation, with special emphasis on hypoxia, oxidative stress, and antigen non-specific inflammation, and reviews strategies using pharmacological agents that have shown effectiveness in protecting islets, including a new treatment approach utilizing siRNA. Pharmacological agents that support islet survival and promote ß-cell proliferation are also included. Treatment of donor pancreata and/or islets with these agents should increase the effectiveness of islets transplanted into extrahepatic sites. Furthermore, the development of methods designed to release these agents over an extended period, will further increase their efficacy. This requires the combined efforts of both islet transplant biologists and bioengineers.

Revisiting the role of heterotopic ovarian transplantation: futility or fertility.

Scepticism hovers over the future of heterotopic transplantation of cryopreserved human ovarian tissue, as its clinical efficacy and practicability for fertility preservation is still debatable. Despite its limitations, the potential advantages and roles of heterotopic transplantation should not be ignored. Indeed, restoration of ovarian function after heterotopic transplantation of cryopreserved ovarian tissue has been consistently demonstrated in humans. There are many unknowns with this technology, such as the optimal heterotopic site, environmental factors and oocyte quality. Hence, it will require further investigations before making a final verdict. Until then, rather than being considered prematurely as a futile technology, heterotopic ovarian transplantation should be viewed positively, with potential roles for restoration of ovarian function and fertility.

A modified heterotopic auxiliary living donor liver transplantation: report of a case.

Liver transplantation is regarded as an effective treatment for Wilson's disease (WD), and recently has been shown to improve not only hepatic but also neurologic manifestations. Conventional auxiliary liver transplantation for WD is orthotopic liver transplantation and heterotopic liver transplantation. But the conventional procedure could not avoid the problem of space, functional competition, hemodynamic variation. Here we report a case of heterotopic auxiliary living-donor liver transplantation (HALDLT) to treat WD. We modified the operation to have a splenectomy, implant graft into the splenic fossa. The patient recovered well after the transplantation and has been symptom-free during a 5-year follow-up. This modified operation is more safe and simple. HALDLT might be an effective treatment for WD patients with splenomegaly.

Dorsal plus ventral oral mucosal graft bulbar urethroplasty.

Traditionally, anastomotic procedures with transection and urethral excision are suggested for short bulbar strictures, while longer strictures are treated by patch graft urethroplasty preferably using the buccal mucosa as gold-standard material due to its histological characteristics. However, anastomotic urethroplasties may cause sexual complications related to vascular damage of the spongiosum following the urethral section or to excessive urethral shortening. On the other hand, one-sided graft procedures, using either dorsal or ventral graft location, could be insufficient in providing a lumen of adequate width in strictures with a particularly narrow area. The double buccal graft urethroplasty is a new technique that aims to obtain a sufficient "two-sided" augmentation of the urethra avoiding its transection and preserving the urethral plate. In this chapter we discuss the rationale for utilizing our procedure. In addition, the surgical technique is described in detail.

Heterotopic abdominal heart transplantation in rats for functional studies of ventricular unloading.

INTRODUCTION: Chronic changes in mechanical load regulate long-term cardiac function. Chronic overload of the ventricle results in myocardial failure. Clinical use of ventricular assist devices shows that chronic reduction in load has a number of different consequences on the myocardium, including beneficial reverse remodeling as well as undesired remodeling (e.g., myocardial atrophy and fibrosis, both of which could have negative functional implications). The complex response to mechanical unloading necessitates reproducible animal models of mechanical unloading for use in the laboratory. This article aims to describe the operative technique of two animal models of mechanical unloading in detail, to enable the reproducible use of these animal models. METHODS: In 1964, Abbott et al first described the heterotopic abdominal heart transplantation technique as a means to study the biology of transplanted cardiac grafts. This involves an aorto-aortic anastomosis and a pulmonary artery to inferior vena cava anastomosis. In this model, the left ventricle is virtually completely volume unloaded, receiving only thebesian venous return, and substantially but not entirely pressure unloaded. In this report we describe two refined techniques for mechanical unloading of healthy or failing hearts based on experience with over 500 operations. RESULTS: We describe an operative technique, including cardioprotective strategies, that provides a model of mechanical unloading with no immunological rejection and allows measurements of parameters of myocardial structure and function for many months. We describe a refined technique that achieves a lesser degree of left ventricular volume unloading, involving transplantation of both heart and lungs via a single aorto-aortic anastomosis. CONCLUSIONS: This article is the first to describe these two techniques in sufficient detail to enable novices to attempt and understand these operations and the differences between them. The technique we describe provides an effective and reproducible model of complete and partial mechanical unloading.

[Establishment of a novel abdominal heart transplantation model of mice].

This paper is aimed to establish a novel abdominal heart transplantation model in mice and to generalize the experience of the successful cases. The thoracic inferior vena cava instead of pulmonary artery was employed to reconstruct the outflow tract of the graft heart (in the new method group, 82 cases). Meanwhile, in other 47 cases as the control group, traditional anastomosis was used between pulmonary artery of the graft and vena cava of the recipient. The recipient surgery time, vena cava-vena cava anastomosis time, graft cold ischemia time and graft re-beating time were (41.5 +/- 1. 5) min, (8.4 +/- 0.6) min, (32.3 +/- 0.4) min and (1.5 +/- 0.2) min respectively. All the above data were statistically superior to those in the traditional method group (P < 0.001 or P < 0.05). The survival rate of 100 d post surgery in the new method group was 93. 9%. Meanwhile, the cardiac tissue remained almost normal examined by HE and Picro-sirus red staining. Therefore, the novel model can facilitate the anastomosis of the outflow tract in recipient operation in mouse heart transplantation model.

Modified Heterotopic Abdominal Heart Transplantation and a Novel Aortic Regurgitation Model in Rats.

Over the past 50 years, many researchers have reported heterotopic abdominal heart transplantation in mice and rats, with some variations in the surgical technique. Modifying the transplantation procedure to strengthen the myocardial protection could prolong the ischemia time while preserving the donor's cardiac function. This technique's key points are as follows: transecting the donor's abdominal aorta before harvesting to unload the donor's heart; perfusing the donor's coronary arteries with a cold cardioplegic solution; and topical cooling of the donor's heart during the anastomosis procedure. Consequently, since this procedure prolongs the acceptable ischemia time, beginners can easily perform it and achieve a high success rate. Moreover, a new aortic regurgitation (AR) model was established in this work using a technique different from the existing one, which is created by inserting a catheter from the right carotid artery and puncturing the native aortic valve under continuous echocardiographic guidance. A heterotopic abdominal heart transplantation was performed using the novel AR model. In the protocol, after the donor's heart is harvested, a stiff guidewire is inserted into the donor's brachiocephalic artery and advanced toward the aortic root. The aortic valve is punctured by pushing the guidewire further even after the resistance is felt, thus inducing AR. It is easier to damage the aortic valve using this method than with the procedure described in the conventional AR model. Additionally, this novel AR model does not contribute to the recipient's circulation; therefore, this method is expected to produce a more severe AR model than the conventional procedure.