In vivo visualization of early microcirculatory changes following ischemia/reperfusion injury in human kidney transplantation

To determine whether microcirculatory changes following ischemia/reperfusion (I/R) may serve as predictors for subsequent graft dysfunction, we used noninvasive orthogonal polarization spectral (OPS) imaging to directly visualize and quantify cortical kidney microcirculation. In a total of 13 combined kidney/pancreas recipients, following reperfusion (5/30 min) microcirculatory parameters such as capillary diameter, functional capillary density (FCD) and red-blood-cell velocity (V(RBC)) of the renal graft were analyzed. From these parameters, a heterogeneity index (HI) and volumetric capillary blood flow (vCBF) were calculated. In addition, the extent of graft injury was determined by daily analysis of serum creatinine, blood urea nitrogen, C-reactive protein and systemic leukocyte count for 7 days post-transplant. At early reperfusion, a heterogeneous perfusion pattern with oscillating flow and scattered microvascular thrombosis of peritubular capillaries, resembling a 'no reflow', was observed. FCD was constant throughout the entire reperfusion period, whereas HI, capillary diameters, V(RBC) and vCBF increased. The latter showed a significant positive correlation with creatinine changes between days 1 and 3. So far our finding of a positive correlation of early microvascular changes (vCBF) and clinical parameters (creatinine) indicate a possible therapeutic implication of OPS imaging to predict early I/R-induced renal graft dysfunction.     

Leukocyte-depleted reperfusion of transplanted human hearts prevents ultrastructural evidence of reperfusion injury.

The present study examines whether leukocyte depletion can prevent postreperfusion ultrastructural injury in transplanted human hearts. Thirty-two patients undergoing orthotopic cardiac transplantation were randomized to receive either enriched, warm, whole blood (Group I; n = 16) or enriched, warm, leukocyte-depleted blood (Group II; n = 16) reperfusion. Donor hearts were arrested with 1 liter of 4 degrees C crystalloid cardioplegia and topically cooled. RV endomyocardial biopsies taken at end-ischemia and following reperfusion were assessed in a blinded fashion and graded according to injury (1 = minimal to 4 = severe). The mean ischemic time (Group I = 142 min, Group II = 153 min) was similar in the two groups. End-ischemic biopsies showed mild-moderate interstitial edema and mild capillary endothelial swelling in both groups with similar injury scores (Group 1 = 1.3 +/- 0.09 (means +/- SEM), Group 2 = 1.25 +/- 0.08). Postreperfusion biopsies in Group I showed nuclear chromatin clumping, moderate mitochondrial swelling, marked capillary endothelial swelling, and marked interstitial edema with a grade of 2.6 +/- 0.14 (P less than 0.001, paired t test). In contrast, postreperfusion biopsies in Group II showed minimal changes with a grade of 1.33 +/- 0.09, P less than 0.0001 in comparison to Group I Leukocyte-depleted reperfusion of human transplanted hearts prevents ultrastructural injury. This may allow safe extension of the ischemic period and result in improved graft function.     

Seatbelt injury resulting in functional loss of a transplanted kidney

The transplanted kidney, lying heterotopically in the iliac fossa, is especially vulnerable to damage from blunt trauma, particularly compression by vehicle seatbelt. We present a case wherein a functioning renal allograft lying in the right iliac fossa was severely injured by seatbelt compression, resulting in significant functional compromise and eventual loss. The patient later underwent successful retransplantation with a second living donor kidney. Management of injured renal transplant recipients requires appreciation of mechanisms likely to cause damage to the graft, as well as familiarity with available treatment options, both surgical and nonsurgical. As functional life spans of renal allografts improve, this type of injury will most likely be encountered with increasing frequency.     

移植肝再灌注损伤的发生机制

目的：介绍有关移植肝再灌注损伤发生机制的研究动向,方法：复习有关文献并进行综述性报告。结果：移植肝冷保存后的再灌注损伤的发生机制主要有：（1）内皮细胞损伤和Kupffer细胞激活,导致一系列细胞因子的产生,引起移植肝损伤,并引发全身炎症反应综合征。（2）白细胞,血小板与肝血窦壁的粘附而损害肝细胞,并可阻塞肝血窦造成“无复流”现象;（3）pH值的变化,再灌注后移植肝的代谢恢复正常后,组织内pH值的改变可引起肝细胞损伤,并可造成线粒体的肿胀,使肝细胞的功能降低,（4）复氧损伤,主要与白细胞释放活性氧（ROS）有关,结论：移植肝再灌注损伤是多种因素综合作用的结果,在再灌注前后提高肝细胞和内皮细胞的活性,抑制Kupffer细胞的激活,减少ROS及肿瘤坏死因子（TNF）的产生将是今后预防移植肝再灌注损伤研究的关键。     

Immunohistochemical evidence of activated lectin pathway in kidney allografts with peritubular capillary C4d deposition.

BACKGROUND: Complement 4d (C4d) deposition in the peritubular capillary (PTC) in the kidney allograft is a useful diagnostic marker for humoral rejection. C4d is produced not only by the classical pathway but also by the lectin pathway of the complement activation cascade. We have recently reported the in situ role of the later phase of the complement cascade in renal allografts with C4d deposition; however, the initial process prior to C4d deposition is yet to be resolved. METHODS: To clarify the early phases of the complement activation cascade, we evaluated the deposition of initial proteins of the above two pathways; IgG, IgM, mannose-binding lectin (MBL), H-ficolin, L-ficolin, MBL-associated serine protease (MASP)-1 and MASP-2 in kidney allografts with PTC C4d deposition. RESULTS: Sixty kidney allograft specimens were divided into two groups on the basis of the presence of C4d deposition in PTC. The C4d-positive group (n = 18) included nine ABO-identical and nine ABO-incompatible cases, and the C4d-negative group (n = 42) had 34 ABO-identical and eight ABO-compatible (but not identical) cases. In the C4d-positive group, 16 of 18 cases showed diffuse H-ficolin and IgM deposition in PTC. In contrast, H-ficolin and IgM were not detected in PTC in the C4d-negative group. Other initial proteins were not detected in all cases. CONCLUSIONS: Our study suggested for the first time that the lectin pathway activated by H-ficolin may be involved in C4d deposition on PTC in the kidney allograft.     

Superoxide anion as a marker of ischemia-reperfusion injury of the transplanted kidney

Reactive oxygen species (ROS) are considered to be important factors involved in the pathophysiology of renal ischemia-reperfusion injury. ROS-induced alterations of proteins, carbohydrates, DNA, and lipid membranes lead to cell and organ dysfunction. Several antioxidant defense mechanisms exist to prevent or limit oxidant injury. Cellular Cu-Zn superoxide dismutase, catalase, and cellular glutathione peroxidase (cGSH-Px) are enzyme ROS scavengers, implicated in the protection against kidney damage resulting from ischemia-reperfusion injury. Reduced glutathione, a cosubstrate of cGSH-Px, have been shown to display a reductive properties without the contribution of enzymes. We examined superoxide anion (O(2)(-)) production by neutrophils, without and with stimulation using opsonized zymosan, in the whole blood of renal transplant patients before and after (5 and 15 minutes) reperfusion. The mean O(2)(-) concentration after reperfusion was statistically significantly higher than that before reperfusion.     

Percutaneous reanastomosis of a transplanted kidney

A case of a successful percutaneous reanastomosis of a transplanted kidney is reported. The kidney had already been operated on several times. The kidney-ureter anastomosis was occluded. Using a combination of ureteroscopy and the percutaneous technique, the old anastomosis was bypassed and a new one was made.     

Glutamine donor pretreatment in rat kidney transplants with severe preservation reperfusion injury

BACKGROUND: Glutamine (GLN) has been shown to confer cytoprotection by enhancing endogenous heat shock protein (HSP) expression. We hypothesized that GLN donor pretreatment protects rat renal grafts against severe preservation reperfusion injury (PRI). MATERIALS AND METHODS: GLN (0.75 g/kg) or saline was administered i.p. to male donor rats 24 h and 6 h before donor nephrectomy. Kidneys (n = 6/group) were cold-stored in UW solution for 40 h and transplanted into bilaterally nephrectomized syngeneic recipients. Grafts were removed after 24 h. Renal HSP 70 expression was determined by Western blotting. Graft function was assessed by serum creatinine. Renal cross sections were microscopically examined for acute tubular necrosis, apoptosis, tubular proliferation, and macrophage infiltration. RESULTS: GLN donor pretreatment significantly increased intragraft HSP 70 expression. Serum creatinine was not different between groups: 2.6 +/- 0.2 mg/dL (saline) versus 2.7 +/- 0.5 mg/dL (GLN). Both treatment groups showed severe tubular damage with significantly less papillary necrosis in the GLN group (P < 0.05). GLN significantly reduced the number of apoptotic tubular cells in the cortex, medulla, and papilla (P < 0.001 versus saline). Postinjury tubular proliferation, measured by PCNA antigen expression, and intragraft macrophage infiltration was not influenced by GLN. CONCLUSIONS: In rat renal grafts suffering severe PRI pharmacological preconditioning with GLN attenuates early structural damage, especially tubular cell apoptosis. Stimulation of renal HSP 70 expression could be an important mechanism of GLN-induced cytoprotection. Our findings may have implications for the treatment of delayed graft function in recipients of marginal donor kidneys.     

Leukocyte-depleted reperfusion of transplanted human hearts: a randomized, double-blind clinical trial.

Standard methods of myocardial preservation for heart transplantation have generally provided good results. Preservation times beyond 3 hours, however, have been associated with decreased survival. Leukocyte-mediated reperfusion injury is partly responsible for decreased graft function after prolonged graft ischemia. Leukocyte-depleted reperfusion has been shown experimentally to improve cardiac function after cold ischemic arrest. To determine the efficacy and safety of leukocyte-depleted reperfusion, 20 patients were enrolled in a randomized, double-blind clinical trial to be treated with either warm whole blood reperfusion (group I; n = 9) or warm leukocyte-depleted blood reperfusion (group II; n = 11). Reperfusion with leukocyte-depleted blood or whole blood was carried out for 10 minutes, with enriched cardioplegic solution added for the first 3 minutes of reperfusion. The mean donor and recipient age and the ischemic time (142 versus 153 minutes) were not significantly different between the two groups. Coronary sinus release of creatinine phosphokinase-MB 5 minutes after reperfusion was significantly less in group II (1.65 EU/min) than in group I (3.83 units/min; p = 0.05). Thromboxane B2 release was also significantly less (p = 0.05) in group II (33.6 pg/min) than in group I (67.0 pg/min). All hearts functioned adequately in both groups. The duration of inotropic support was shorter in group II than in group I, but the difference was not statistically significant. Postoperative hemodynamics, rejection episodes, and infectious complications were also not significantly different between groups in a mean follow-up of 9 months. Mean ejection fraction 1 month after operation was 65% in both groups. One early death occurred at 66 days secondary to infection; two late deaths occurred in group II, both from rejection. Leukocyte-depleted reperfusion is safe and easily applied in the operating room. Furthermore, leukocyte-depleted reperfusion decreases biochemical evidence of reperfusion injury. Although not influencing postoperative cardiac function when the ischemic time is short, less than 3 hours, leukocyte-depleted reperfusion may prevent significant reperfusion injury and improve posttransplantation graft function when ischemic times are long. Safe extension of the ischemic time would expand the donor pool and allow for better crossmatching.     

Ischemia of a transplanted kidney and hyperlactatemia

The authors report four cases of patients presenting with hyperlactatemia following renal transplantation. The post-transplantation course of three patients who underwent renal transplantation was complicated by occult haemorrhage. Excessive blood loss was not evident, the patients were haemodynamically stable and their blood pressure, pulse rare and filling pressure (central venous pressure) were unremarkable. Late examinations revealed an early increase in arterial lactate concentrations a non-aniograp acidosis or lactic acidaemia occurred. Surgical decompression was carried on in all patients. An increase in the intraabdominal pressure might have caused renal impairment in the absence of haemodynamic disturbance, and retroperitoneal haematoma a change in the distribution of intrarenal blood flow. Another patient developed a partial renal venous thrombosis associated with hyperlactatemia. During this re-operation, a renal lactate production was measured. The renal cortex is a site of lactate clearance. Impaired renal perfusion should result in decreased lactate clearance and when the kidney is hypoperfused a lactate production was occur. In the absence of any signs of clinical shock, patient at risk of retroperitoneal haematoma or presenting with oliguria should benefit from lactate measurements, which could help diagnosing severe hypoperfusion of the graft.     

Preconditioning with tin-protoporphyrin IX attenuates ischemia/reperfusion injury in the rat kidney

BACKGROUND: Heme oxygenase (HO)-1 is induced as a unique stress response and leads to a transient resistance against oxidative damage, including ischemia and reperfusion (I/R) injury. In the present study, we examined whether HO-1 induction may confer a protection against I/R injury in the rat kidney. METHODS: Lewis rats were divided into four groups as follows: (1) vehicle group; (2) group treated with ferri-protoporphyrin IX (hemin), an inducer of HO; (3) group treated with low-dose tin-protoporphyrin IX (SnPP), an inhibitor of HO; and (4) group treated with high-dose SnPP. Renal warm ischemia for 60 minutes was performed 24 hours after each treatment. RESULTS: At 24 hours after treatment, hemin induced a significant increase in renal HO activity, but failed to induce HO-1 protein synthesis. Although both low- and high-dose SnPP reduced HO activity, a marked HO-1 expression was observed only in the high-dose SnPP-treated kidney. Hemin exacerbated the renal function after reperfusion, while high-dose SnPP significantly suppressed the intercellular adhesion molecule (ICAM)-1 expression, the infiltration of ED-1-positive macrophages and the expression of activated caspase-3, which resulted in attenuation of apoptotic cell death and ameliorated I/R injury. CONCLUSION: These results suggest that prior induction of HO-1 protein by high-dose SnPP may lead to anti-inflammatory and antiapoptotic effects on warm renal I/R injury independently of its enzyme activity, and that HO enzyme activation may not always act as an antioxidant, especially under I/R-induced oxidative stress.     

C4d deposition and multilayering of peritubular capillary basement membrane in posttransplantation membranous nephropathy indicate its association with antibody-mediated injury

Membranous nephropathy (MN) may develop as recurrence or de novo after transplantation. Recently, autoimmune or alloimmune responses to unspecified glomerular antigens have been considered as a pathogenetic mechanism. To explore the relationship between antibody-mediated injury and posttransplantation MN, we tested C4d positivity using polyclonal antibody in renal allograft biopsy samples diagnosed as posttransplantation MN. A total of 19 cases (16 males and 3 females), including 2 recurrent and 7 de novo forms, were the subject of the study. On light microscopy, stage II was the most common (n = 9). In addition to glomerular capillary immunoglobulin (Ig)G deposits, all but 2 cases having only sclerotic glomeruli were C4d-positive in glomerular capillary walls. Twelve cases were also positive in cortical peritubular capillaries (PTCs): diffuse in 8 cases and focal in 4 cases. Two of 3 cases associated with acute rejection and 3 of 4 cases associated with chronic rejection were PTC C4d-positive. The frequency of C4d positivity in PTCs was significantly higher than that of posttransplantation IgA nephropathy (P = .028). In conclusion, a higher frequency of PTC C4d positivity suggests an involvement of chronic antibody-mediated injury in the evolution of posttransplantation MN.