Surgical technique in the rat model of kidney transplantation

Today successful kidney transplantation procedures, techniques and immunosuppression protocols are a consequence of extensive research on animal models. During every transplantation surgery there are two crucial points for the success of the entire procedure: vascular (arterial end venous) and ureteral or ureterovesical anastomosis. Renal artery and vein of the donor kidney can be anastomosed end-to-side to the abdominal aorta and vena cava of the recipient (heterotopic transplantation), or end-to-end to the remains of renal artery and vain of the recipient (orthotopic transplantation) after nephrectomy. The ureter can be anastomosed also end-to-end or we can connect it directly to the urinary bladder (ureterocystoneostomy). The aim of this study was to elucidate which technique has better results according to: animal survival, reperfusion and perfusion of the transplanted kidney, elimination of the urine from the transplanted kidney and procedure costs. The study included 240 (120 donors and 120 recipients) male Wistar rats (3 months old; weight 250-300 g Our results are clearly showing that the end-to-end vascular anastomosis, and Paquins ureterovesical anastomosis have better results in transplanted rat kidneys survival and urine drainage compared to end-to-side vascular anastomosis and end-to-end ureteral anastomosis. Based on our experience we can conclude that described methods of end-to-end vascular anastomosis and Paquins ureterovesical anastomosis are less technically demanding and have a shorter learning curve. Therefore, we can recommend the use of described methods in kidney transplantation related researches.     

A Modified Method for Heterotopic Mouse Heart Transplantion

Mice are often used as heart transplant donors and recipients in studies of transplant immunology due to the wide range of transgenic mice and reagents available. A difficulty is presented due to the small size of the animal and the considerable technical challenges of the microsurgery involved in heart transplantation. In particular, a high rate of technical failure early after transplantation may result from recipient death and post-operative complications such as hind limb paralysis or a non-beating heart. Here, the complete technique for heterotopic mouse heart transplantation is demonstrated, involving harvesting the donor heart and its subsequent implantation into a recipient mouse. The donor heart is harvested immediately following in situ perfusion with cold heparinized saline and transection of the ascending aorta and pulmonary artery. The recipient operation involves preparation of the abdominal aorta and inferior vena cava (IVC), followed by end-to-side anastomosis of the donor aorta with the recipient aorta using a single running 10-0 microsuture and a similar anastomosis of the donor pulmonary artery with the recipient IVC. Following the operation the animal is injected with 0.6 ml normal saline subcutaneously and allowed to recover on a 37 °C heating pad. The results from 227 mouse heart transplants are summarized with a success rate at 48 hr of 86.8%. Of the 13.2% failures within 48 hr, 5 (2.2%) experienced hind limb paralysis, 10 (4.4%) had a non-beating heart due to graft ischemic injury and/or thrombosis, while 15 (6.6%) died within 48 hr.     

Mouse Models for Graft Arteriosclerosis

Graft arteriosclerois (GA), also called allograft vasculopathy, is a pathologic lesion that develops over months to years in transplanted organs characterized by diffuse, circumferential stenosis of the entire graft vascular tree. The most critical component of GA pathogenesis is the proliferation of smooth muscle-like cells within the intima. When a human coronary artery segment is interposed into the infra-renal aortae of immunodeficient mice, the intimas could be expand in response to adoptively transferred human T cells allogeneic to the artery donor or exogenous human IFN-γ in the absence of human T cells. Interposition of a mouse aorta from one strain into another mouse strain recipient is limited as a model for chronic rejection in humans because the acute cell-mediated rejection response in this mouse model completely eliminates all donor-derived vascular cells from the graft within two-three weeks. We have recently developed two new mouse models to circumvent these problems. The first model involves interposition of a vessel segment from a male mouse into a female recipient of the same inbred strain (C57BL/6J). Graft rejection in this case is directed only against minor histocompatibility antigens encoded by the Y chromosome (present in the male but not the female) and the rejection response that ensues is sufficiently indolent to preserve donor-derived smooth muscle cells for several weeks. The second model involves interposing an artery segment from a wild type C57BL/6J mouse donor into a host mouse of the same strain and gender that lacks the receptor for IFN-γ followed by administration of mouse IFN-γ (delivered via infection of the mouse liver with an adenoviral vector. There is no rejection in this case as both donor and recipient mice are of the same strain and gender but donor smooth muscle cells proliferate in response to the cytokine while host-derived cells, lacking receptor for this cytokine, are unresponsive. By backcrossing additional genetic changes into the vessel donor, both models can be used to assess the effect of specific genes on GA progression. Here, we describe detailed protocols for our mouse GA models.     

A Method for Murine Islet Isolation and Subcapsular Kidney Transplantation

Since the early pioneering work of Ballinger and Reckard demonstrating that transplantation of islets of Langerhans into diabetic rodents could normalize their blood glucose levels, islet transplantation has been proposed to be a potential treatment for type 1 diabetes ^1,2. More recently, advances in human islet transplantation have further strengthened this view ^1,3. However, two major limitations prevent islet transplantation from being a widespread clinical reality: (a) the requirement for large numbers of islets per patient, which severely reduces the number of potential recipients, and (b) the need for heavy immunosuppression, which significantly affects the pediatric population of patients due to their vulnerability to long-term immunosuppression. Strategies that can overcome these limitations have the potential to enhance the therapeutic utility of islet transplantation.Islet transplantation under the mouse kidney capsule is a widely accepted model to investigate various strategies to improve islet transplantation. This experiment requires the isolation of high quality islets and implantation of islets to the diabetic recipients. Both procedures require surgical steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol. We also briefly discuss different transplantation models: syngeneic, allogeneic, syngeneic autoimmune, and allogeneic autoimmune.     

Orthotopic Kidney Transplantation in Mice: Technique Using Cuff for Renal Vein Anastomosis

Mouse renal transplantation is a technically challenging procedure. Although the first kidney transplants in mice were performed over 34 years ago and refined some years later, the classical techniques of mouse renal transplantation required clamping both vena cava and aorta simultaneously and carry out suture anastomoses of the renal artery and vein in a heterotopic position. In our laboratory, we have successfully developed mouse orthotopic kidney transplantation for the first time, using a rapid “cuffed” renal vein technique for vessel anastomosis, wherein the donor’s renal vein was inserted through an intravenous catheter, folded back and tied. During grafting, the cuffed renal vein was directly inserted into the recipient’s renal vein without the need for the clamping vena cava and suturing of renal vein. This technique allowed for the exact transplantation of the kidney into the original position, compared to the classical technique, and has significantly shortened the clamping time due to a quicker and precise anastomosis of renal vein as described. This also allowed for a quicker recovery of the lower extremity activity, reduction in myoglobinuria with resultant kidney graft survival of 88.9%. Thus we believe that the cuffed renal vein technique simplifies microvascular anastomoses and affords important additional benefits.     

Computational model for simulation of vascular adaptation following vascular access surgery in haemodialysis patients

An important number of surgical procedures for creation of vascular access (VA) in haemodialysis patients still results in non-adequate increase in blood flow (non-maturation). The rise in blood flow in arteriovenous shunts depends on vascular remodelling. Computational tools to predict the outcome of VA surgery would be important in this clinical context. The aim of our investigation was then to develop a 0D/1D computational model of arm vasculature able to simulate vessel wall remodelling and related changes in blood flow. We assumed that blood vessel remodelling is driven by peak wall shear stress. The model was calibrated with previously reported values of radial artery diameter and blood flow after end-to-end distal fistula creation. Good agreement was obtained between predicted changes in VA flow and in arterial diameter after surgery and corresponding measured values. The use of this computational model may allow accurate vascular surgery planning and ameliorate VA surgery outcomes.     

小鼠异位心脏移植模型的改良

目的探讨小鼠心脏移植模型的建立与改良。方法供体采用BLAB／c小鼠,受体采用C57小鼠。用24GACuff管法套扎供心肺动脉与颈外静脉,用自制Cuff管套扎供心升主动脉与颈总动脉。结果供心冷缺血时间少于15min,手术时间大大缩短,成功率明显提高。结论改进后的模型显著降低了手术难度,可用于移植免疫的各种研究。     

Computer assisted image analysis to assess colonization of recipient seminiferous tubules by spermatogonial stem cells from transgenic donor mice

Transplantation of spermatogonial stem cells from fertile, transgenic donor mice to the testes of infertile recipients provides a unique system to study the biology of spermatogonial stem cells. To facilitate the investigation of treatment effects on colonization efficiency an analysis system was needed to quantify colonization of recipient mouse seminiferous tubules by donor stem cell‐derived spermatogenesis. In this study, a computer‐assisted morphometry system was developed and validated to analyze large numbers of samples. Donor spermatogenesis in recipient testes is identified by blue staining of donor‐derived spermatogenic cells expressing the E. coli lacZ structural gene. Images of seminiferous tubules from recipient testes collected three months after spermatogonial transplantation are captured, and stained seminiferous tubules containing donor‐derived spermatogenesis are selected for measurement based on their color by color thresholding. Colonization is measured as number, area, and length of stained tubules. Interactive, operator‐controlled color selection and sample preparation accounted for less than 10% variability for all collected parameters. Using this system, the relationship between number of transplanted cells and colonization efficiency was investigated. Transplantation of 10⁴ cells per testis only rarely resulted in colonization, whereas after transplantation of 10⁵ and 10⁶ cells per testis the extent of donor‐derived spermatogenesis was directly related to the number of transplanted donor cells. It appears that about 10% of transplanted spermatogonial stem cells result in colony formation in the recipient testis. The present study establishes a rapid, repeatable, semi‐interactive morphometry system to investigate treatment effects on colonization efficiency after spermatogonial transplantation in the mouse. Mol. Reprod. Dev. 53:142–148, 1999. © 1999 Wiley‐Liss, Inc.     

A triangular cutting arteriotomy scissors facilitating end-to-side anastomoses.

A new microsurgical triangular cutting scissors facilitating end-to-side anastomoses has been developed. The instrument removes oval pieces of tissue from the vascular wall with a single cut. This has several advantages over conventional double cuts with straight microscissors. Preferential use of end-to-side anastomoses has been advocated by several authors, one of the main reasons for this being preservation of the distal blood flow in the artery used in the recipient bed. It also has been reported that vascular occlusions are less frequent with this type of coupling. Another important indication for end-to-side anastomoses is a significant discrepancy in vessel size. One of the more demanding tasks in making an end-to-side anastomosis is the performance of a perfect arteriotomy. With the aim of facilitating the arteriotomy in end-to-side anastomoses, a new microsurgical instrument has been developed.     

Mouse models with human immunity and their application in biomedical research

Biomedical research in human beings is largely restricted to in vitro studies that lack complexity of a living organism. To overcome this limitation, humanized mouse models are developed based on immunodeficient characteristics of severe combined immunodeficiency (SCID) or recombination activating gene (Rag)^null mice, which can accept xenografts. Peripheral constitution of human immunity in SCID or Rag^null mice has been achieved by transplantation of mature human immune cells, foetal human thymus, bone marrow, liver tissues, lymph nodes or a combination of these, although efficiency needs to be improved. These mouse models with constituted human immunity (defined as humanized mice in the present text) have been widely used to investigate the basic principles of human immunobiology as well as complex pathomechanisms and potential therapies of human diseases. Here, elements of an ideal humanized mouse model are highlighted including genetic and non-genetic modification of recipient mice, transplantation strategies and proposals to improve engraftments. The applications of the humanized mice to study the development and response of human immune cells, human autoimmune diseases, virus infections, transplantation biology and tumour biology are reviewed as well.     

硬膜外导管在大鼠肾移植血管吻合中的应用

目的建立一种手术难度低,成功率高的大鼠肾移植模型。方法 Wistar大鼠作供体,SD大鼠作受体,将供体腔静脉与受体肾静脉端端吻合,供体腹主动脉与受体腹主动脉端侧吻合,供体膀胱瓣与受体膀胱吻合。根据血管吻合时应用硬膜外导管与否,将受体分为有支架组和无支架组两组。结果有支架组共进行肾移植30次,成活26只;无支架组共进行肾移植20次,成活10只。有支架组的成活率86.7%（26/30）较无支架组50.0%（10/20）明显提高（P〈0.05）,血管吻合总时间（22±2）min较无支架组（32±2）min明显缩短（P〈0.05）。结论硬膜外导管应用于大鼠肾移植血管吻合,降低了手术难度,减少了吻合口出血,提高了手术成功率。     

Vascular anastomosis using controlled phase transitions in poloxamer gels

Vascular anastomosis is the cornerstone of vascular, cardiovascular and transplant surgery. Most anastomoses are performed with sutures, which are technically challenging and can lead to failure from intimal hyperplasia and foreign body reaction. Numerous alternatives to sutures have been proposed, but none has proven superior, particularly in small or atherosclerotic vessels. We have developed a new method of sutureless and atraumatic vascular anastomosis that uses US Food and Drug Administration (FDA)-approved thermoreversible tri-block polymers to temporarily maintain an open lumen for precise approximation with commercially available glues. We performed end-to-end anastomoses five times more rapidly than we performed hand-sewn controls, and vessels that were too small (<1.0 mm) to sew were successfully reconstructed with this sutureless approach. Imaging of reconstructed rat aorta confirmed equivalent patency, flow and burst strength, and histological analysis demonstrated decreased inflammation and fibrosis at up to 2 years after the procedure. This new technology has potential for improving efficiency and outcomes in the surgical treatment of cardiovascular disease.     

Bipolar anastomosis technique with removable instruments: an easy, fast, and reliable technique for vascular anastomosis

The interrupted suture technique is most commonly used for microsurgical vascular anastomosis. For several reasons (e.g., exposure of suture material to blood, time needed), many attempts have been made to find other solutions. This article describes a new means of performing a microsurgical vascular anastomosis. The aim of this study was to show the feasibility and possible advantages of this new technique. The basic components at work here are a modified cuff and electrically generated heat used to unite the vessel walls. In this way, both endothelial layers are adapted without manipulating the inside of the vessel or leaving behind foreign matter. Various energy/coagulation time settings were used to perform arterial anastomoses (n = 42) in an isogeneic abdominal aorta interposition model in the rat. The quality of anastomosis was evaluated at days 1, 10, 21, and 120. Immediately after the welding process all anastomoses (n = 42) were patent. No stenosis was found at any observation time. Anastomosis time ranged from 3 to 18 minutes (average, 11 minutes). This new technique permits a vascular anastomosis to be performed easily and reliably with a high patency rate. With this technique, the authors are convinced that a skilled surgeon can create a high-quality anastomosis in a fraction of the time needed to sew an anastomosis.     

Endothelial primary cilia inhibit atherosclerosis

Primary cilia are microtubule‐based structures present on most mammalian cells that are important for intercellular signaling. Cilia are present on a subset of endothelial cells where they project into the vessel lumen and are implicated as mechanical sensors of blood flow. To test the in vivo role of endothelial cilia, we conditionally deleted Ift88, a gene required for ciliogenesis, in endothelial cells of mice. We found that endothelial primary cilia were dispensable for mammalian vascular development. Cilia were not uniformly distributed in the mouse aorta, but were enriched at vascular branch points and sites of high curvature. These same sites are predisposed to the development of atherosclerotic plaques, prompting us to investigate whether cilia participate in atherosclerosis. Removing endothelial cilia increased atherosclerosis in Apoe^?/? mice fed a high‐fat, high‐cholesterol diet, indicating that cilia protect against atherosclerosis. Removing endothelial cilia increased inflammatory gene expression and decreased eNOS activity, indicating that endothelial cilia inhibit pro‐atherosclerotic signaling in the aorta.     

3-Dimensional Resin Casting and Imaging of Mouse Portal Vein or Intrahepatic Bile Duct System

In organs, the correct architecture of vascular and ductal structures is indispensable for proper physiological function, and the formation and maintenance of these structures is a highly regulated process. The analysis of these complex, 3-dimensional structures has greatly depended on either 2-dimensional examination in section or on dye injection studies. These techniques, however, are not able to provide a complete and quantifiable representation of the ductal or vascular structures they are intended to elucidate. Alternatively, the nature of 3-dimensional plastic resin casts generates a permanent snapshot of the system and is a novel and widely useful technique for visualizing and quantifying 3-dimensional structures and networks.A crucial advantage of the resin casting system is the ability to determine the intact and connected, or communicating, structure of a blood vessel or duct. The structure of vascular and ductal networks are crucial for organ function, and this technique has the potential to aid study of vascular and ductal networks in several ways. Resin casting may be used to analyze normal morphology and functional architecture of a luminal structure, identify developmental morphogenetic changes, and uncover morphological differences in tissue architecture between normal and disease states. Previous work has utilized resin casting to study, for example, architectural and functional defects within the mouse intrahepatic bile duct system that were not reflected in 2-dimensional analysis of the structure^1,2, alterations in brain vasculature of a Alzheimer''s disease mouse model³, portal vein abnormalities in portal hypertensive and cirrhotic mice⁴, developmental steps in rat lymphatic maturation between immature and adult lungs⁵, immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury⁶.Here we present a method of generating a 3-dimensional resin cast of a mouse vascular or ductal network, focusing specifically on the portal vein and intrahepatic bile duct. These casts can be visualized by clearing or macerating the tissue and can then be analyzed. This technique can be applied to virtually any vascular or ductal system and would be directly applicable to any study inquiring into the development, function, maintenance, or injury of a 3-dimensional ductal or vascular structure.     

A histologic comparison of experimental microarterial end-in-end (sleeve) and end-to-end anastomoses

Twenty-five microvascular end-in-end and 21 end-to-end anastomoses were performed on the central arteries (diameters 0.8 to 1.2 mm) of rabbit ears. The appearance of longitudinal specimens taken after intervals of 1 to 2 hours and 1, 3, 7, 14, 30, and 90 days was studied microscopically. Between 1 to 2 hours and 14 days, all end-in-end anastamoses showed considerable narrowing of the telescoped segment, and platelets had accumulated at the sleeved vessel end. The vascular walls of the telescoped segment were thickened distally, and the internal elastic laminas were folded in the lingitudinal direction due to contraction. Extensive loss of endothelium was observed both around sutures and distally in the telescoped segments. The stenosis initially noted in telescoped vessels gradually decreased due to atrophy of the medial layers in the double vascular walls. Following the organization of the platelet aggregates, subsequent endothelialization was completed between 7 and 14 days. After 2 weeks, neointimal hyperplasia was frequently found at the sleeved vessel end. In the early postoperative period, platelets covered exposed subendothelial structures and sealed defects in the vessel walls of all end-to-end anastomoses. During the first few postoperative weeks, the medial layers disintegrated and were replaced by increasing fibrosis. Reendothelialization was completed between 7 and 14 days, whereafter gradual intimal hyperplasia became significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vascular Balloon Injury and Intraluminal Administration in Rat Carotid Artery

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and cellular mechanisms involved in vascular smooth muscle dedifferentiation, neointima formation and vascular remodeling. Male Sprague-Dawley rats are the most frequently employed animals for this model. Female rats are not preferred as female hormones are protective against vascular diseases and thus introduce a variation into this procedure. The left carotid is typically injured with the right carotid serving as a negative control. Left carotid injury is caused by the inflated balloon that denudes the endothelium and distends the vessel wall. Following injury, potential therapeutic strategies such as the use of pharmacological compounds and either gene or shRNA transfer can be evaluated. Typically for gene or shRNA transfer, the injured section of the vessel lumen is locally transduced for 30 min with viral particles encoding either a protein or shRNA for delivery and expression in the injured vessel wall. Neointimal thickening representing proliferative vascular smooth muscle cells usually peaks at 2 weeks after injury. Vessels are mostly harvested at this time point for cellular and molecular analysis of cell signaling pathways as well as gene and protein expression. Vessels can also be harvested at earlier time points to determine the onset of expression and/or activation of a specific protein or pathway, depending on the experimental aims intended. Vessels can be characterized and evaluated using histological staining, immunohistochemistry, protein/mRNA assays, and activity assays. The intact right carotid artery from the same animal is an ideal internal control. Injury-induced changes in molecular and cellular parameters can be evaluated by comparing the injured artery to the internal right control artery. Likewise, therapeutic modalities can be evaluated by comparing the injured and treated artery to the control injured only artery.     

The peritoneum as a natural scaffold for vascular regeneration

Objective

The peritoneum has the same developmental origin as blood vessels, is highly reactive and poorly thrombogenic. We hypothesize that parietal peritoneum can sustain development and regeneration of new vessels.

Methods and Results

The study comprised two experimental approaches. First, to test surgical feasibility and efficacy of the peritoneal vascular autograft, we set up an autologous transplantation procedure in pigs, where a tubularized parietal peritoneal graft was covered with a metal mesh and anastomosed end-to-end in the infrarenal aorta. Second, to dissect the contribution of graft vs host cells to the newly developed vessel wall, we performed human-to-rat peritoneal patch grafting in the abdominal aorta and examined the origin of endothelial and smooth muscle cells. In pig experiments, the graft remodeled to an apparently normal blood vessel, without thrombosis. Histology confirmed arterialization of the graft with complete endothelial coverage and neointimal hyperplasia in the absence of erosion, inflammation or thrombosis. In rats, immunostaining for human mitochondri revealed that endothelial cells and smooth muscle cells rarely were of human origin. Remodeling of the graft was mainly attributable to local cells with no clear evidence of c-kit+ endothelial progenitor cells or c-kit+ resident perivascular progenitor cells.

Conclusions

The parietal peritoneum can be feasibly used as a scaffold to sustain the regeneration of blood vessels, which appears to occur through the contribution of host-derived resident mature cells.     

Busulfan as a Myelosuppressive Agent for Generating Stable High-level Bone Marrow Chimerism in Mice

Bone marrow transplantation (BMT) is often used to replace the bone marrow (BM) compartment of recipient mice with BM cells expressing a distinct biomarker isolated from donor mice. This technique allows for identification of donor-derived hematopoietic cells within the recipient mice, and can be used to isolate and characterize donor cells using various biochemical techniques. BMT typically relies on myeloablative conditioning with total body irradiation to generate niche space within the BM compartment of recipient mice for donor cell engraftment. The protocol we describe here uses myelosuppressive conditioning with the chemotherapeutic agent busulfan. Unlike irradiation, which requires the use of specialized facilities, busulfan conditioning is performed using intraperitoneal injections of 20 mg/kg busulfan until a total dose of 60-100 mg/kg has been administered. Moreover, myeloablative irradiation can have toxic side effects and requires successful engraftment of donor cells for survival of recipient mice. In contrast, busulfan conditioning using these doses is generally well tolerated and mice survive without donor cell support. Donor BM cells are isolated from the femurs and tibiae of mice ubiquitously expressing green fluorescent protein (GFP), and injected into the lateral tail vein of conditioned recipient mice. BM chimerism is estimated by quantifying the number of GFP+ cells within the peripheral blood following BMT. Levels of chimerism >80% are typically observed in the peripheral blood 3-4 weeks post-transplant and remain established for at least 1 year. As with irradiation, conditioning with busulfan and BMT allows for the accumulation of donor BM-derived cells within the central nervous system (CNS), particularly in mouse models of neurodegeneration. This busulfan-mediated CNS accumulation may be more physiological than total body irradiation, as the busulfan treatment is less toxic and CNS inflammation appears to be less extensive. We hypothesize that these cells can be genetically engineered to deliver therapeutics to the CNS.