The relationship between renal warm ischemia time and glomerular loss. An experimental study in a pig model

A Novel Cooling Device for Kidney Transplant Surgery

Background: Prolonged warm ischemia time (WIT) in kidney transplantation is associated with numerous adverse outcomes including delayed graft function and decreased patient and graft survival. Circumventing WIT lies in maintaining renal hypothermia and efficiently performing the vascular anastomosis during this portion of the procedure. Although numerous methods of intra-operative renal cooling have been proposed, most suffer from practical limitations, and none have been widely adopted. Herein we describe a novel device specifically designed to maintain renal hypothermia during kidney transplant surgery.Methods: Aluminum tubing was organized in a serpentine pattern to create a malleable, form-fitting cooling jacket to manipulate renal allografts during transplant surgery. Adult porcine kidneys were used to test the device with 4°C saline as coolant. Kidneys were placed at 24°C; surface and core temperatures were monitored using implanted thermocouples. Anastomosis of porcine kidney vessels to GORE-TEX® vascular grafts in an ex-vivo operative field was performed to assess the functionality of the device.Results: The device maintained surface and core graft temperatures of ≤5°C after 60 minutes of WIT. Furthermore, the device provided hands-free retraction and support for the allograft. We found that ex-vivo anastomosis testing was enhanced by the presence of the cooling jacket.Conclusions: This proof-of-concept study demonstrated that our novel device is a practical tool for renal transplantation and can maintain sufficiently cool graft temperatures to mitigate WIT in an ex-vivo setting. This device is the first of its kind and has the potential to improve kidney transplant outcomes by eliminating WIT during graft implantation.

Does treatment with dutasteride or finasteride has impact on renal morphology? Experimental study

PURPOSE

To investigate whether renal modifications occur following treatment with dutasteride or finasteride.

METHODS

Twenty-four male rats were divided into three groups: control (that received distilled water), dutasteride (0.5 mg/kg/day), and finasteride (5 mg/kg/day) groups. All administrations were given by gavage for 40 consecutive days. After inducing euthanasia, blood was collected for urea and creatinine analyses, and both the kidneys were collected for stereological analyses of kidney morphology.

RESULTS

Serum urea and creatinine levels were increased in both the finasteride and the dutasteride groups compared with those in the control group. In addition, kidney weight, kidney volume, cortical volume, glomerular volumetric density, and mean glomerular volume were reduced in both treatment groups. Finally, the number of glomeruli per kidney was reduced by 26.8% in the finasteride group and by 51.6% in the dutasteride group compared with that in the control group.

CONCLUSIONS

The 5-ARIs finasteride and dutasteride promoted morphological and functional damages in rat kidneys. In addition, rats in the dutasteride group showed more severe renal modifications than those in the finasteride group.

Changes of renal histopathology and the role of Nrf2/HO-1 in asphyxial cardiac arrest model in rats

PURPOSE

To investigate the role of Nrf2/HO-1 in renal histopathological ailments time-dependently in asphyxial cardiac arrest (CA) rat model.

METHODS

Eighty-eight Sprague Dawley male rats were divided into five groups of eight rats each. Asphyxial CA was induced in all the experimental rats except for the sham group. The rats were sacrificed at 6 hours, 12 hours, one day and two days post-CA. Serum blood urea nitrogen (BUN), creatinine (Crtn) and malondialdehyde from the renal tissues were evaluated. Hematoxylin and eosin and periodic acid-Schiff staining were done to evaluate the renal histopathological changes in the renal cortex. Furthermore, Nrf2/HO-1 immunohistochemistry (ihc) and western blot analysis were performed after CA.

RESULTS

The survival rate of rats decreased in a time-dependent manner: 66.6% at 6 hours, 50% at 12 hours, 38.1% in one day, and 25.8% in two days. BUN and serum Crtn markedly increased in CA-operated groups. Histopathological ailments of the renal cortical tissues increased significantly from 6 hours until two days post-CA. Furthermore, Nrf2/HO-1 expression level significantly increased at 6 hours, 12 hours, and one day.

CONCLUSIONS

The survival rate decreased time-dependently, and Nrf/HO-1 expression increased from 6 hours with the peak times at 12 hours, and one day post-CA.

Quercetin as a nephroprotector after warm ischemia: histomorphometric evaluation in a rodent model

Purpose:

To quantitatively evaluate the possible long-term protective effects of quercetin during renal warm ischemia.

Materials and Methods:

Male rats were allocated into 4 groups: sham (S), sham quercetin (SQ), ischemia (I), and ischemia quercetin (IQ). Groups SQ and IQ received quercetin (50mg/kg) before and after surgery. Groups I and IQ had their left renal vessels clamped for 60 minutes. All animals were euthanized four weeks after the procedure, and serum urea and creatinine levels were measured. Renal weight and volume, cortex-non-cortex area ratio (C-NC), cortical volume (CV), glomerular volumetric density (Vv[glom]), volume-weighted glomerular volume (VWGV) and number of glomeruli per kidney (N[glom]) were evaluated by stereological methods. Results were considered statistically significant when p <0.05.

Results:

Serum urea levels in group I increased by 10.4% in relation to group S, but no differences were observed among the other groups. The C-NC of group I was lower than those of all other groups, and group IQ had similar results to sham groups. The Vv[glom] and N[glom] of group I were lower than those of group S (33.7% and 28.3%, respectively) and group IQ had no significant difference compared to the S group.

Conclusions:

Quercetin was effective as a nephroprotective agent in preventing the glomerular loss observed when the kidney was subjected to warm ischemia. This suggests that this flavonoid may be used preventively in kidney surgery, when warm ischemia is necessary, such as partial nephrectomy.

Prevention of Chronic Rejection of Marginal Kidney Graft by Using a Hydrogen Gas-Containing Preservation Solution and Adequate Immunosuppression in a Miniature Pig Model

In clinical kidney transplantation, the marginal kidney donors are known to develop chronic allograft rejection more frequently than living kidney donors. In our previous study, we have reported that the hydrogen gas-containing organ preservation solution prevented the development of acute injuries in the kidney of the donor after cardiac death by using preclinical miniature pig model. In the present study, we verified the impact of hydrogen gas treatment in transplantation with the optimal immunosuppressive protocol based on human clinical setting by using the miniature pig model. Marginal kidney processed by hydrogen gas-containing preservation solution has been engrafted for long-term (longer than 100 days). A few cases showed chronic rejection reaction; however, most were found to be free of chronic rejection such as graft tissue fibrosis or renal vasculitis. We concluded that marginal kidney graft from donor after cardiac death is an acceptable model for chronic rejection and that if the transplantation is carried out using a strict immunosuppressive protocol, chronic rejection may be alleviated even with the marginal kidney.

Renal salvage using stent graft placement after acute renal artery occlusion with prolonged ischemic time

Purpose

To describe a patient with acute renal artery occlusion who underwent successful revascularization procedure after experiencing a protracted ischemic period, which resulted in successful retrieval of renal function.

Case report

A 58-year-old male with a history of left renal artery stenosis and stent graft placement presented with symptoms of chest pain, shortness of breath, and flank pain. The patient was admitted to the Intensive Care Unit with the diagnosis of multiorgan failure and subsequent anuria that led to the initiation of hemodialysis. Computed tomography angiography demonstrated an aortic occlusion along with bilateral proximal renal artery occlusion with reconstitution of the mid to distal renal arteries via collateralization. The patient underwent angioplasty with bilateral renal artery stent-graft placement and successful revascularization of proximal renal arteries. Post-operatively, his renal function and urine output improved, and the patient was able to be weaned off hemodialysis along with the benefit of concurrent amelioration of his renovascular hypertension.

Conclusion

For select patients with renal artery occlusion, revascularization of the renal arteries may result in dialysis independence and stabilization of renovascular hypertension, despite prolonged time of ischemia.

Anatomical background of ovine kidney for use as animal model: analysis of arterial segmentation, proportional volume of each segment and arterial injury after cranial pole partial nephrectomy

OBJECTIVE

To study the arterial segments of ovine kidney, present a proportional volume analysis of each kidney arterial segment, and analyze arterial injuries caused by simulated partial nephrectomy of cranial pole.

MATERIALS AND METHODS

Forty-eight ovine kidneys injected with polyester resin into the renal arteries and collecting system were used in this study. Eighteen kidneys were used to study the arterial segments and the proportional volume of each renal segment. Other 30 kidneys were submitted to superior pole resection at a distance of 1.0cm, 0.5cm, or exactly at the cranial hilar edge, just before the resin hardening. These endocasts were used to evaluate the arterial injuries caused by these different resection planes.

RESULTS

Ovine renal artery divided into two (ventral and dorsal) or three segmental arteries. Dorsal segment presented higher proportional volume than ventral segment. For kidneys with three segments, the third segment was on the caudal region (caudo-ventral or caudo-dorsal segment) and presented the lowest proportional volume. None of the resected kidneys (at 1.0, 0.5 or at the cranial hilar edge) presented injury of arterial branches that irrigate non-resected region.

CONCLUSION

The segmental distribution of renal artery, the proportional volume of each segment and arterial injuries after cranial pole resection in ovine kidneys are different from what is observed in human kidneys. Meanwhile, ovine kidneys show a primary segmental division on anterior and posterior, as in humans, but different from swine. These anatomical characteristics should be considered when using ovine as animal models for renal experimental and/or training procedures.

Histomorphometric and biochemical data of rat kidney submitted to warm ischemia associated with resveratrol treatment

The data presented here come from the article "Histomorphometric evaluation of the rat kidney submitted to warm ischemia and the protective effect of resveratrol" [1]. Rats of Wistar lineage (n = 39; 9 weeks of age) were obtained and apportioned into 4 groups at random. Both groups Sham (S) and Sham Resveratrol (SR) were submitted to open laparotomy and dissection of the left renal pedicle, the same as groups Ischemia (I) and Ischemia Resveratrol (IR), being the last two also submitted to 1 h left warm renal ischemia. SR and IR were treated with 30 mg/kg of resveratrol intraperitoneally 1 h before the surgical procedure, while S and I received saline injections. Rats were killed a month after surgery by anesthetic overdose. A blood sample was collected by cardiac puncture for determination of serum urea and creatinine serum by biochemical analysis at automated enzymatic method. Kidneys were weighted, Sherle´s method was used for measurement of their volume and then both were fixated in buffered formalin for 48 h. Cortex-non-cortex areas ratio (C-NC) was assessed by Cavalieri's method using a stereoscope. The product of multiplying the renal volume by the C-NC is the cortical volume (CV). Left kidneys fragments were processed for histology resulting in slides that were stained with haematoxylin and eosin. For histomorphometric analyses, 25 random cortical fields were photographed at 200x magnification using a camera attached to a light microscope. The estimation of glomerular volumetric density (Vv [Glom]), indication of proportional volume occupied by glomeruli in the cortex, was performed by the point-counting method. The point-sampled intercepts method was used to estimate the volume-weighted mean glomerular volume (VWGV). Total number of glomeruli per kidney (N [Glom]) estimation was achieved through the formula CVxVv [Glom]/VWGV. All the data were tabulated in spreadsheets. The quantitative results were compared by one-way ANOVA with Tukey's post-test using GraphPad Prism software. All results were considered significant when the value of p <0.05.

Histomorphometric evaluation of the rat kidney submitted to warm ischemia and the protective effect of resveratrol

BACKGROUND

The objective of this study is to quantitatively evaluate the protective effects of resveratrol for using during renal warm ischemia.

METHODS

Rats were allocated into 4 groups: Sham, Sham Resveratrol, Ischemia, Ischemia Resveratrol. Sham Resveratrol and Ischemia Resveratrol received resveratrol before surgery. Ischemia and Ischemia Resveratrol had renal vessels clamped. Animals were euthanized four weeks after. Serum urea and creatinine were measured. Renal weight and volume, cortex-non-cortex areas ratio, cortical volume, glomerular volumetric density, volume-weighted mean glomerular volume and number of glomeruli per kidney were evaluated.

RESULTS

Serum urea in Ischemia increased by 10.4% compared to Sham and no differences were observed among Ischemia Resveratrol and sham groups. The glomerular volumetric density and number of glomeruli of Ischemia were lower than Sham but Ischemia Resveratrol had no difference compared to sham groups.

CONCLUSIONS

Preoperative administration of resveratrol has renoprotective effects, preventing the glomerular number reduction observed in warm ischemia.

Volume and Shape Assessment of Renal Radiofrequency Ablation Lesion

OBJECTIVE

To evaluate the microscopic characteristics and quantify the volume of a radiofrequency ablation (RFA) lesion.

METHODS

Ten male pigs were submitted to laparoscopic RFA. An RFA needle was introduced in the lower pole of the left kidney to create a lesion expected to be a sphere of 2.0 cm diameter. The animals were followed up for 21 days. Kidneys were weighed and the volume was assessed using Scherle's method. Cavalieri's principle was used to assess the RFA volume, and sphericity was calculated to assess RFA lesion. One sample t test was used to compare RFA volume with the volume of a sphere of 2.0 cm diameter, and sphericity to hypothetical values of a sphere and an icosahedron. Fragments of RFA region were histologically evaluated.

RESULTS

Three animals developed postoperative complications and were excluded from the analyses. There was no difference in the mean weight and volume between right and left kidneys following RFA. The mean total volume of RFA injury was 3.44 cm³. There was no difference in the RFA volume in comparison with hypothetical volumes of a sphere and an icosahedron of 2.0 cm diameter. Sphericity of the RFA injury was not similar with a sphere; however, it was similar to an icosahedron. Histology revealed areas of coagulation necrosis, fibrosis, and inflammatory mononuclear infiltration. Areas with normal tissue were also observed.

CONCLUSION

The volume of injury caused by RFA was as expected and its shape was comparable with an icosahedron. Microscopic evaluation revealed areas of normal-appearing tissue.