The role of coenzyme Q10 for preservation of the rat kidney: a model experiment for kidney transplantation.

In an experimental model system for kidney transplantation, the ability of the rat kidney to resynthesize ATP after warm ischemic time and subsequent restoration of renal blood flow was found to determine tissue viability and survival of the animal. The administration of CoQ₁₀ prior to warm ischemia enhanced the rate and extent of ATP resynthesis by reflow following two-hour warm ischemia and this was accompanied by an increase in survival rate of the rats.     

A functional model of the rat kidney

Summary A mathematical model of the nephron was developed by writing a set of material balance equations for the flow of urea, salt and water along the length of the nephron. The geometric proportions have been elaborated in a foregoing study and are taken here as a basis, in particular the model configuration of the collecting duct system. The medullary interstitial solute concentration profiles are taken to increase linearly in outer and inner zone. The several transepithelial fluxes are driven by diffusion, osmosis, solvent drag and active transport. The development of osmotic gradient in the inner medulla is taken here to be caused by active secretion of salt into the descending limb of Henle's loop. The parameters in the flux equations for all parts of the nephron and the concentration values at the end of each tubular section are determined by collecting and averaging the values given in literature and by extrapolating the measurement data.The simulation of the model equations with these averaged parameters resulted in concentration profiles which at the ends of the several tubular sections were consistent with the values observed in experimental investigations.This work was supported by the Deutsche Forschungsgemeinschaft.     

Hemodynamic changes in the kidney in a pediatric rat model of sepsis-induced acute kidney injury

Sepsis is a leading cause of acute kidney injury (AKI) and mortality in children. Understanding the development of pediatric sepsis and its effects on the kidney are critical in uncovering new therapies. The goal of this study was to characterize the development of sepsis-induced AKI in the clinically relevant cecal ligation and puncture (CLP) model of peritonitis in rat pups 17-18 days old. CLP produced severe sepsis demonstrated by time-dependent increase in serum cytokines, NO, markers of multiorgan injury, and renal microcirculatory hypoperfusion. Although blood pressure and heart rate remained unchanged after CLP, renal blood flow (RBF) was decreased 61% by 6 h. Renal microcirculatory analysis showed the number of continuously flowing cortical capillaries decreased significantly from 69 to 48% by 6 h with a 66% decrease in red blood cell velocity and a 57% decline in volumetric flow. The progression of renal microcirculatory hypoperfusion was associated with peritubular capillary leakage and reactive nitrogen species generation. Sham adults had higher mean arterial pressure (118 vs. 69 mmHg), RBF (4.2 vs. 1.1 ml·min(-1)·g(-1)), and peritubular capillary velocity (78% continuous flowing capillaries vs. 69%) compared with pups. CLP produced a greater decrease in renal microcirculation in pups, supporting the notion that adult models may not be the most appropriate for studying pediatric sepsis-induced AKI. Lower RBF and reduced peritubular capillary perfusion in the pup suggest the pediatric kidney may be more susceptible to AKI than would be predicted using adults models.     

Relationship between chimerism and tolerance in a kidney transplantation model

The persistence of donor leukocytes in recipients of organ allografts has been associated with long-term graft acceptance. However, it remains unclear whether this peripheral donor cell microchimerism plays an active role in graft acceptance or is simply a consequence of the maintenance of sufficient immunosuppression to avoid rejection. A model of kidney transplantation between swine leukocyte Ag (SLA)-matched miniature swine, in which tolerance can be established with or without immunosuppressive treatment, has been used to study the correlation between donor leukocyte chimerism and kidney graft acceptance. SLA-identical kidney transplants were performed from animals positive for an allelic pig leukocyte Ag to animals negative for this marker. SLA-identical kidney transplant recipients given a 12-day course of cyclosporine (CyA) (n = 3) became tolerant, showing stable serum creatinine levels (1-2 mg/dl) after cessation of CyA treatment. Donor cell chimerism (0.2-0.7%) was present by FACS in all three animals with peak levels detected at 3 wk. Two control animals receiving SLA-identical kidney grafts without CyA also showed stable serum creatinine levels and became tolerant. However, in neither of these animals could donor leukocytes be detected in the peripheral blood beyond 1 wk following transplantation. In one additional control animal, ureteral obstruction occurred at day 10, and was associated with additional peripheral chimerism, presumably related to inflammation rather than to immune status. These results indicate that the persistence of donor cell chimerism is not a requirement for the maintenance of tolerance to organ allografts in this model.     

A functional model for whole limb transplantation in the rat

To develop a functional model for the study of whole limb transplantation, inbred Lewis rats were used as both donors and recipients. In this model, the recipient biceps femoris muscle was elevated from its distal attachment to preserve part of the adductor function of the limb after surgery. The tibial, peroneal, and sural branches of the sciatic nerve were anastomosed separately to provide faster and more precise functional recovery. For control sensory evaluation, the saphenous branches of the femoral nerve were not reattached. A flat intramedullary pin stabilized with methyl methacrylate was used to rigidly immobilize the femur. The transplanted limbs started bearing weight at 17 to 22 days. Walking on the plantar surface of the hock and adduction of the toes gradually decreased, and the rats developed a normal walking pattern. Sciatic and tibial function indexes, based on walking track analysis, correlated well with clinical observations. In this study, a new model for limb transplantation was developed that provided good and reliable sensory and ambulatory recovery.     

Tolerance induction in composite facial allograft transplantation in the rat model

Clinical application of composite tissue allograft transplants opened discussion on the restoration of facial deformities by allotransplantation. The authors introduce a hemifacial allograft transplant model to investigate the rationale for the development of functional tolerance across the major histocompatibility complex barrier. Eighteen rats in three groups were studied. The composite hemifacial allotransplantations including the ear and scalp were performed between Lewis-Brown Norway (RT1l+n) and Lewis (RT1l) rats and isotransplantations were performed between Lewis rats. Isograft controls (n = 6) and allograft controls (n = 6) did not receive treatment. Allografts in treatment group (n = 6) were treated with cyclosporine A 16 mg/kg/day during the first week; this dose was tapered to 2 mg/kg/day over 4 weeks and maintained at this level thereafter. Functional tolerance to face allografts was evaluated clinically and histologically. Donor-specific chimerism was assessed at days 21 and 63 by flow cytometry. In vitro evaluation of donor-specific tolerance was performed by mixed lymphocyte reaction at day 160 after transplantation. Isograft controls survived indefinitely. All nontreated allografts were rejected within 5 to 7 days after transplantation, as confirmed by histopathologic analysis. Five of six face allografts under the cyclosporine A protocol showed no signs of rejection for up to 240 days and remained alive and under evaluation, whereas one animal showed signs of rejection at day 140. This was reversed by adjustment of the cyclosporine A dose. At day 21 after transplantation, flow cytometric analysis of the donor-specific chimerism showed 1.11 percent of double-positive CD4FITC/RT1Ac-Cy7 and 1.43 percent of double-positive CD8PE/RT1Ac-Cy7 T-cell populations in the peripheral blood of hemiface allotransplant recipients. The chimerism level of double-positive CD4FITC/RT1Ac-Cy7 T cells increased to 3.39 percent, whereas it remained stable for the double-positive CD8PE/RT1Ac-Cy7 T-cell population at day 63 after transplantation (1.00 percent). The mixed lymphocyte reaction assay at day 160 after transplantation revealed donor-specific tolerance to donor (Lewis-Brown Norway) antigens and strong reactivity to the third-party (ACI) alloantigens. In this study, donor-specific chimerism and functional tolerance were induced in hemifacial allograft transplants across the major histocompatibility complex barrier under cyclosporine A monotherapy protocol. This model will allow further studies on tolerance induction protocols.     

Simultaneous orthotopic transplantation of carotid and aorta in the rat by the sleeve technique

Graft vascular disease (GVD) remains the major limitation to long-term survival after solid organ transplantation. Aortic or carotid allografts in rats have been shown to be useful models because similar changes to those observed in man develop within weeks. Both immunological and non-immunological factors influence the process of GVD and a method that could permit rapid multiple arterial allotransplantation in the rat would be of great value. We performed simultaneous orthotopic aortic and carotid allotransplantations in 25 rats. The vessels were anastomosed using a sleeve technique. No immunosuppression was given. The animals were killed at 15, 30, or 60 days and histological analyses of the grafts were performed. The overall survival rate was 80% and the incidence of technical failure was very low. The histopathological aspect revealed typical progressive GVD. In conclusion, we have developed a new model of simultaneous aortic and carotid transplantation in rats. This model, which incorporates a modification of the sleeve anastomosis, is rapid and yields an easy tool to investigate immunological and non-immunological processes driving GVD.     

Establishment of animal model of dual liver transplantation in rat

The animal model of the whole-size and reduced-size liver transplantation in both rat and mouse has been successfully established. Because of the difficulties and complexities in microsurgical technology, the animal model of dual liver transplantation was still not established for twelve years since the first human dual liver transplantation has been made a success. There is an essential need to establish this animal model to lay a basic foundation for clinical practice. To study the physiological and histopathological changes of dual liver transplantation, "Y" type vein from the cross part between vena cava and two iliac of donor and "Y' type prosthesis were employed to recanalize portal vein and the bile duct between dual liver grafts and recipient. The dual right upper lobes about 45-50% of the recipient liver volume were taken as donor, one was orthotopically implanted at its original position, the other was rotated 180° sagitally and heterotopically positioned in the left upper quadrant. Microcirculation parameters, liver function, immunohistochemistry and survival were analyzed to evaluate the function of dual liver grafts. No significant difference in the hepatic microcirculatory flow was found between two grafts in the first 90 minutes after reperfusion. Light and electronic microscope showed the liver architecture was maintained without obvious features of cellular destruction and the continuity of the endothelium was preserved. Only 3 heterotopically positioned graft appeared patchy desquamation of endothelial cell, mitochondrial swelling and hepatocytes cytoplasmic vacuolization. Immunohistochemistry revealed there is no difference in hepatocyte activity and the ability of endothelia to contract and relax after reperfusion between dual grafts. Dual grafts made a rapid amelioration of liver function after reperfusion. 7 rats survived more than 7 days with survival rate of 58.3.%. Using "Y" type vein and bile duct prosthesis, we successfully established a novel rat model of dual right upper liver lobe transplantation.     

Uric acid metabolism of kidney and intestine in a rat model of chronic kidney disease

ABSTRACT

Uric acid (UA) is a potential risk factor of the progression of chronic kidney disease (CKD). Recently, we reported that intestinal UA excretion might be enhanced via upregulation of the ATP-binding cassette transporter G2 (Abcg2) in a 5/6 nephrectomy (Nx) rat model. In the present study, we examined the mRNA and protein expressions of UA transporters, URAT1, GLUT9/URATv1, ABCG2 and NPT4 in the kidney and ileum in the same rat model. Additionally, we investigated the Abcg2 mRNA expression of ileum in hyperuricemic rat model by orally administering oxonic acid. Male Wistar rats were randomly assigned to three groups consisting of Nx group, oxonic acid-treated (Ox) group and sham-operated control group, and sacrificed at 8 weeks. Creatinine and UA were measured and the mRNA expressions of UA transporters in the kidney and intestine were evaluated by a real time PCR. UA transporters in the kidney sections were also examined by immunohistochemistry. Serum creatinine elevated in the Nx group whereas serum UA increased in the Ox group. Both the mRNA expression and the immunohistochemistry of the UA transporters were decreased in the Nx group, suggesting a marginal role in UA elevation in decreased kidney function. In contrast, the mRNA expression of Abcg2 in the ileum significantly increased in the Ox group. These results suggest that the upregulation of Abcg2 mRNA in the ileum triggered by an elevation of serum UA may play a compensatory role in increasing intestinal UA excretion.     

大鼠异位工作型心脏移植模型的建立

目的 建立大鼠腹腔异位工作型心脏移植动物模型.方法 Wistar大鼠30只,将供心主肺动脉与左房吻合,再将供心移植到受体腹部,将升主动脉与供心腹主动脉端侧吻合,使得左心房获得前负荷,成为工作型心脏.结果 成功建立大鼠腹腔异位工作型心脏移植模型,15例成功11例,手术成功率为73%.手术平均时间为(38.8±5.7)min.移植心脏获得长期存活,在28 d后通过超声观察可见供体心脏工作正常.结论 手术的关键是提高供心的摘取技术及受体的血管吻合技术,同时术后给与供心适当的按摩辅助也非常必要.此模型可以更好的用于移植免疫学的研究.     

Vascularized bone allograft transplantation in a genetically defined rat model

A heterotopic subcutaneous model for experimental vascularized bone allograft transplantation has been presented. This model uses genetically defined rats and allows serial assessment of graft viability. The reliability of this model has been proven by successful isograft transplantation. This model was used to study the effect of matching at the major histocompatibility complex on vascularized bone allograft survival. Whereas grafts transplanted across a minor histocompatibility barrier survived until sacrifice, grafts transplanted across a major histocompatibility barrier were victims of an acute rejection process. This study, therefore, showed genetic disparity to be a critical determinant of vascularized bone allograft survival. It indicates that primary vascularized bone allografts are as susceptible to rejection as heart and kidney allografts. For these reasons, it can be anticipated that genetic matching will be important in clinical vascularized bone allograft transplantation. The model used in this study should be useful for obtaining further fundamental immunologic information concerning vascularized bone allograft transplantation.     

Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury

Objective: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury.

Methods and results: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (β-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-μ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney.

Conclusion: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.     

Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury

Objective: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury. Methods and results: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (β-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-μ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney. Conclusion: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.     

Linked suppression across an MHC-mismatched barrier in a miniature swine kidney transplantation model

We have demonstrated previously that a 12-day course of FK506 permits the induction of tolerance to fully MHC-mismatched renal transplants in miniature swine. In the present study, we examined the mechanism of this tolerance by assessing the possibility that the survival of one-haplotype mismatched third-party kidneys might be prolonged via linked suppression. Ten SLA(d/d) miniature swine received fully MHC-mismatched renal allografts from SLA(c/c) donors with 12 days of FK506. Six animals received second SLA(c/c) kidneys without immunosuppression to confirm tolerance. Regulatory mechanisms were assessed by mixed lymphocyte reaction (MLR) and cell-mediated lympholysis coculture assays and ELISA for regulatory cytokines. Linked suppression was investigated by transplanting SLA(a/c) or SLA(a/d) allografts into long-term tolerant recipients without immunosuppression. All recipients showed donor-specific unresponsiveness in standard cell-mediated lympholysis and MLR assays. Tolerant cells prestimulated with donor Ag and then cocultured with naive recipient MHC-matched cells inhibited antidonor responses, confirming the presence of regulatory cells. ELISA and MLR assays showed that TGF-beta2 was involved in mediating the suppression in vitro. SLA(a/d) renal allografts transplanted into tolerant recipients were rejected by postoperative day 8 (median, 7 days; range, 6-8). In contrast, SLA(a/c) allografts showed markedly prolonged survival (median, 52 days; range, 28-78; p = 0.0246), suggesting linked suppression. Animals not challenged with a second donor-matched graft did not manifest linked suppression consistent with in vitro data showing that re-exposure to tolerated Ags is important for generation of regulatory cells. To our knowledge, these data represent the first evidence of linked suppression across fully MHC-mismatched barriers in a large animal model.     

Melatonin prevents oxidative kidney damage in a rat model of thermal injury

Animal models of thermal trauma implicate oxygen radicals as causative agents in local wound response and distant organ injury following burn. This study was designed to determine the effect of melatonin treatment on levels of glutathione (GSH), malondialdehyde (MDA), protein oxidation (PO) and myeloperoxidase (MPO) activity in the kidney tissues of rats with thermal injury. Under ether anaesthesia, shaved dorsum of the rats was exposed to 90 degrees C bath for 10 s to induce burn injury. Rats were decapitated either 3 h or 24 h after burn injury. Melatonin was administered i.p. immediately after burn injury. In the 24-h burn group melatonin injections were repeated for two more occasions. In the sham group the same protocol was applied except that the dorsum was dipped in a 25 degrees C water bath for 10 s. Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, and significant increases in MDA and PO levels, and MPO activity at post-burn 3 and 24 hours. Treatment of rats with melatonin (10 mg/kg) significantly elevated the reduced GSH levels while it decreased MDA and PO levels as well as MPO activity.