Kidney function after partial nephrectomy: current thinking

Effects of grape seed proanthocyanidin B2 pretreatment on oxidative stress and renal tubular epithelial cell apoptosis after renal ischemia reperfusion in mice

PURPOSE

To investigate the effects of grape seed proanthocyanidin B2 (GSPB2) preconditioning on oxidative stress and apoptosis of renal tubular epithelial cells in mice after renal ischemia-reperfusion (RIR).

METHODS

Forty male ICR mice were randomly divided into 4 groups: Group A: mice were treated with right nephrectomy. Group B: right kidney was resected and the left renal vessel was clamped for 45 minutes. Group C: mice were intraperitoneally injected with GSPB2 before RIR established. Group D: mice were intraperitoneally injected with GSPB2 plus brusatol before RIR established. Creatinine and urea nitrogen of mice were determined. Pathological and morphological changes of kidney were checked. Expressions of Nrf-2, HO-1, cleaved-caspase3 were detected by Western-blot.

RESULTS

Compared to Group B, morphology and pathological damages of renal tissue were less serious in Group C. Western-blot showed that expressions of Nrf-2 and HO-1 in Group C were obviously higher than those in Group B. The expression of cleaved-caspase3 in Group C was significantly lower than that in Group B.

CONCLUSION

GSPB2 preconditioning could attenuate renal oxidative stress injury and renal tubular epithelial cell apoptosis by up-regulating expressions of Nrf-2 and HO-1 and down-regulating the expression of cleaved-caspase-3, but the protective effect could be reversed by brusatol.

Exosomes Derived From Mesenchymal Stem Cells Ameliorate Renal Ischemic-Reperfusion Injury Through Inhibiting Inflammation and Cell Apoptosis

This study aimed to investigate the underlying mechanism of mesenchymal stem cells (MSCs) on protection of renal ischemia reperfusion injury (IRI). Exosomes originated from MSCs (MSC-ex) were extracted according to the instructions of Total Exosome Isolation Reagent. Rats were divided into five groups: sham-operated, IRI, MSC, MSC-ex, and MSC-ex + RNAase group. MSCs or MSC-ex were injected via carotid artery. The renal function test and pathological detection were applied to determine the renoprotection of MSC-ex on IRI. Western blotting and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were conducted to examine the levels of apoptosis-related proteins and inflammatory cytokines. Our results revealed that MSC-derived exosomes attenuated renal dysfunction, histologic damage, and decreased apoptosis. The expression levels of inflammatory cytokines, such as interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), and interferon gamma (IFN-γ), were decreased by the MSC-ex treatment. The expression levels of caspase-9, cleaved caspase-3, Bax, and Bcl-2 caused by IR were also inhibited by MSC-ex. MSC-ex + RNAase group shared the similar pattern of changes with IRI group, likely due to the ability of RNA hydrolase to eliminate the function of exosomes. Our results demonstrated that exosomes originating from MSCs have protective effects on IRI via inhibiting cell apoptosis and inflammatory responses. Out findings may provide a new insight into therapeutic mechanism of MSCs on renal IRI.

Evaluation of surgery-related kidney volume loss to predict the outcomes of laparoscopic partial nephrectomy with segmental renal artery clamping

BACKGROUND

Laparoscopic partial nephrectomy (LPN) with segmental renal artery clamping has become an important method to minimize the warm ischemia of the kidney during the surgery. In the present study, we adopted a new model of calculating surgery-related kidney volume loss (SKVL), which was derived from the imaging technology to predict the outcomes of LPN with segmental renal artery clamping.

METHODS

A total of 111 consecutive patients underwent LPN with available pre- and post-operation computed tomography (CT) scanning data were retrospectively analyzed. The SKVL was calculated using the parameter derived from the CT scan. The correlation between the SKVL and the perioperative outcomes as well as the renal function loss was estimated by the logistic regression analyses.

RESULTS

The mean SKVL was 8.99 cm³; kidney volume and tumor volume was 147.48 cm³ and 25.87 cm³, respectively. The SKVL was associated with maximum diameter of tumor (P = 0.001), tumor volume (P < 0.001), intraoperative blood loss (P < 0.001), and the warm ischemia time (P = 0.004), but not associated with the surgery time (P = 0.322) and complications (P = 0.638). Besides, the SKVL was associated with the renal function loss after LPN (P < 0.001). The multivariable logistic regression showed that SKVL was an independent parameter to predict the renal function loss.

CONCLUSIONS

SKVL is a pre-operation parameter derived from the imaging data, which may be used to predict the perioperative outcomes and renal function loss of patients undergoing LPN.

Outcome of kidney function after ischaemic and zero-ischaemic laparoscopic and open nephron-sparing surgery for renal cell cancer

Background

Nephron-sparing surgery (NSS) remains gold standard for the treatment of localised renal cell cancer (RCC), even in case of a normal contralateral kidney. Compared to radical nephrectomy, kidney failure and cardiovascular events are less frequent with NSS. However, the effects of different surgical approaches and of zero ischaemia on the postoperative reduction in renal function remain controversial.

We aimed to investigate the relative short- and long-term changes in estimated glomerular filtration rate (eGFR) after ischaemic or zero-ischaemic open (ONSS) and laparoscopic NSS (LNSS) for RCC, and to analyse prognostic factors for postoperative acute kidney injury (AKI) and chronic kidney disease (CKD) stage ≥3.

Methods

Data of 444 patients (211 LNSS, 233 ONSS), including 57 zero-ischaemic cases, were retrospectively analysed. Multiple regression models were used to predict relative changes in renal function. Natural cubic splines were used to demonstrate the association between ischaemia time (IT) and relative changes in renal function.

Results

IT was identified as significant risk factor for short-term relative changes in eGFR (ß = − 0.27) and development of AKI (OR, 1.02), but no effect was found on long-term relative changes in eGFR. Natural cubic splines revealed that IT had a greater effect on patients with baseline eGFR categories ≥G3 concerning short-term decrease in renal function and development of AKI. Unlike LNSS, ONSS was significantly associated with short-term decrease in renal function (ß = − 13.48) and development of AKI (OR, 3.87). Tumour diameter was associated with long-term decrease in renal function (ß = − 1.76), whereas baseline eGFR was a prognostic factor for both short- (ß = − 0.20) and long-term (ß = − 0.29) relative changes in eGFR and the development of CKD stage ≥3 (OR, 0.89).

Conclusions

IT is a significant risk factor for AKI. The short-term effect of IT is not always linear, and the impact also depends on baseline eGFR. Unlike LNSS, ONSS is associated with the development of AKI. Our findings are helpful for surgical planning, and suggest either the application of a clampless NSS technique or at least the shortest possible IT to reduce the risk of short-time impairment of the renal function, which might prevent AKI, particularly regarding patients with baseline eGFR category ≥G3.

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

Purpose:

To investigate the glomerular number after different warm ischemia times.

Methods:

Thirty two pigs were assigned into four groups. Three groups (G10, G20, and G30) were treated with 10, 20, and 30 minutes of left renal warm ischemia. The sham group underwent the same surgery without renal ischemia. The animals were euthanized after 3 weeks, and the kidneys were collected. Right kidneys were used as controls. The kidney weight, volume, cortical-medullar ratio, glomerular volumetric density, volume-weighted mean glomerular volume, and the total number of glomeruli per kidney were obtained. Serum creatinine levels were assessed pre and postoperatively.

Results:

Serum creatinine levels did not differ among the groups. All parameters were similar for the sham, G10, and G20 groups upon comparison of the right and left organs. The G30 group pigs' left kidneys had lower weight, volume, and cortical-medullar ratio and 24.6% less glomeruli compared to the right kidney. A negative correlation was found between warm ischemia time and glomerular number.

Conclusions:

About one quarter of glomeruli was lost after 30 minutes of renal warm ischemia. No glomeruli loss was detected before 20 minutes of warm ischemia. However, progressive glomerular loss was associated with increasing warm ischemia time.

Robust augmented reality registration method for localization of solid organs' tumors using CT-derived virtual biomechanical model and fluorescent fiducials

BACKGROUND

Augmented reality (AR) is the fusion of computer-generated and real-time images. AR can be used in surgery as a navigation tool, by creating a patient-specific virtual model through 3D software manipulation of DICOM imaging (e.g., CT scan). The virtual model can be superimposed to real-time images enabling transparency visualization of internal anatomy and accurate localization of tumors. However, the 3D model is rigid and does not take into account inner structures' deformations. We present a concept of automated AR registration, while the organs undergo deformation during surgical manipulation, based on finite element modeling (FEM) coupled with optical imaging of fluorescent surface fiducials.

METHODS

Two 10 × 1 mm wires (pseudo-tumors) and six 10 × 0.9 mm fluorescent fiducials were placed in ex vivo porcine kidneys (n = 10). Biomechanical FEM-based models were generated from CT scan. Kidneys were deformed and the shape changes were identified by tracking the fiducials, using a near-infrared optical system. The changes were registered automatically with the virtual model, which was deformed accordingly. Accuracy of prediction of pseudo-tumors' location was evaluated with a CT scan in the deformed status (ground truth). In vivo: fluorescent fiducials were inserted under ultrasound guidance in the kidney of one pig, followed by a CT scan. The FEM-based virtual model was superimposed on laparoscopic images by automatic registration of the fiducials.

RESULTS

Biomechanical models were successfully generated and accurately superimposed on optical images. The mean measured distance between the estimated tumor by biomechanical propagation and the scanned tumor (ground truth) was 0.84 ± 0.42 mm. All fiducials were successfully placed in in vivo kidney and well visualized in near-infrared mode enabling accurate automatic registration of the virtual model on the laparoscopic images.

CONCLUSIONS

Our preliminary experiments showed the potential of a biomechanical model with fluorescent fiducials to propagate the deformation of solid organs' surface to their inner structures including tumors with good accuracy and automatized robust tracking.

"Zero-Ischemia" Laparoscopic-assisted Partial Nephrectomy for the Management of Selected Children With Wilms Tumor Following Neoadjuvant Chemotherapy

OBJECTIVE

To describe the experience and technique of zero-ischemia laparoscopic-assisted partial nephrectomy at The Hospital for Sick Children, as an alternative to the traditional open approach for nephron-sparing surgery (NSS) in selected children with Wilms tumor (WT).

MATERIALS AND METHODS

Patients with diagnosis of WT treated with neoadjuvant chemotherapy and who underwent laparoscopic-assisted NSS at the Hospital for Sick Children from 2012 to 2016 were identified and their charts were reviewed retrospectively. Patients underwent laparoscopic exploration, lymph node sampling, kidney mobilization, vascular control, and adrenal sparing. This was followed by open NSS through a small flank incision; no clamping of the hilum or major renal branches was performed.

RESULTS

Six patients were identified; all patients underwent successful resection. One patient required radical nephrectomy due to inability to safely define negative margins. Tumors ranged in size from 0.9 to 5.6 cm in diameter. Mean operating time was 293 ± 50.2 minutes, with an average duration of pneumoperitoneum of 216 ± 27 minutes. Intraoperative blood loss was negligible. No tumor spillages occurred. Postoperative pathology revealed negative margins in all resected specimens. One case of urine leak occurred postoperatively, which resolved spontaneously. Renal function was preserved in all children. At a mean follow up of 11.5 months, all patients have been recurrence free.

CONCLUSION

The herein presented strategy allows for safe nephron-sparing resection of selected WT with acceptable morbidity, good short-term disease-free survival, and potentially better cosmesis and recovery than traditional open surgery. This preliminary experience suggests that minimally invasive options for NSS in children merit further evaluation.

Spherical cap surface model: A novel method for predicting renal function after partial nephrectomy

OBJECTIVES

To estimate the percent functional volume preservation from preoperative images using a novel method, the spherical cap surface model, and to investigate whether this model can preoperatively predict renal function after partial nephrectomy.

METHODS

A total of 233 patients with renal cell carcinoma who underwent open or laparoscopic partial nephrectomy between January 2011 and December 2013 were included in the present study. The spherical cap surface model was used to calculate the estimated percent functional volume preservation on preoperative computed tomography, and the estimated percent functional volume preservation was multiplied by the preoperative estimated glomerular filtration rate to predict the postoperative estimated glomerular filtration rate. The occurrence of acute kidney injury also served as an outcome. Univariate and multivariate linear regression, and receiver operating characteristic curve analysis were used to test the model.

RESULTS

The estimated percent functional volume preservation calculated by the novel model was significantly associated with both nadir percent estimated glomerular filtration rate preservation and late percent estimated glomerular filtration rate preservation in the multivariate analysis (the P-values were 0.021 and 0.043, respectively). Receiver operating characteristic curve analysis for predicting acute kidney injury after partial nephrectomy showed that volume preservation (P < 0.001) and warm ischemia time (P = 0.040) were both significant. Regarding the ability to predict a significant decrease in late renal function after partial nephrectomy, only volume preservation (P = 0.044) was significant.

CONCLUSIONS

Preservation of functional volume is the primary determinant of functional outcomes after partial nephrectomy. The spherical cap surface model seems to represent a promising tool to predict nadir and late postoperative renal function in patients undergoing partial nephrectomy.

Reconstructive kidney surgery for organ-preserving therapy of renal tumors

Background: The objective of this study was to evaluate differences in various clinical endpoints in patients with reconstructive surgery by renal partial nephrectomy for tumors up to 4 cm compared to tumors larger than 4 cm.

Material and methods: A total of 170 partial renal resection patients that presented malignant tumors were included in the retrospective study. Data was analyzed retrospectively based on internal clinic files, as well as a questionnaire to enhance the follow-up clinical outcomes data obtained. The most important outcomes determined included post-operative renal function, intra- and post-operative complications, local recurrence rate and total survival time.

Results: The local recurrence rate was 6.1% for tumors up to 4 cm in size, compared to 14.9% for tumors that were larger than 4 cm. Compared to results for partial resection of T1a tumors, results for partial resection of tumors larger than 4 cm are worse in terms of post-operative renal function (p=0.007), as well as in terms of a total complications rate (p=0.048). It is important to note that there was not only a higher risk of post-operative bleeding that required transfusions (p=0.012), but also a higher risk of a hypertensive episode during the post-operative period reviewed (p=0.022). In addition, the total survival time for patients presenting tumors of up to 4 cm in size was significantly better (p=0.003).

Conclusion: The results of our retrospective study of 170 patients that underwent partial renal resection after the diagnosis of malignant tumors, is that partial renal resection presents an oncologicaly safe surgical solution with low local recurrence rates. Additionally, partial resection in case of tumors that are larger than 4 cm showed worse post-operative renal function, a higher complications rate and a worse survival rate.

The learning curve and factors affecting warm ischemia time during robot-assisted partial nephrectomy

Introduction:

The learning curve for robotic partial nephrectomy was investigated for an experienced laparoscopic surgeon and factors associated with warm ischemia time (WIT) were assessed.

Materials and Methods:

Between 2007 and 2014, one surgeon completed 171 procedures. Operative time, blood loss, complications and ischemia time were examined to determine the learning curve. The learning curve was defined as the number of procedures needed to reach the targeted goal for WIT, which most recently was 20 min. Statistical analyses including multivariable regression analysis and matching were performed.

Results:

Comparing the first 30 to the last 30 patients, mean ischemia time (23.0–15.2 min, P < 0.01) decreased while tumor size (2.4–3.4 cm, P = 0.02) and nephrometry score (5.9–7.0, P = 0.02) increased. Body mass index (P = 0.87), age (P = 0.38), complication rate (P = 0.16), operating time (P = 0.78) and estimated blood loss (P = 0.98) did not change. Decreases in ischemia time corresponded with revised goals in 2011 and early vascular unclamping with the omission of cortical renorrhaphy in selected patients. A multivariable analysis found nephrometry score, tumor diameter, cortical renorrhaphy and year of surgery to be significant predictors of WIT.

Conclusions:

Adoption of robotic assistance for a surgeon experienced with laparoscopic surgery was associated with low complication rates even during the initial cases of robot-assisted partial nephrectomy. Ischemia time decreased while no significant changes in blood loss, operating time or complications were seen. The largest decrease in ischemia time was associated with adopting evidence-based goals and new techniques, and was not felt to be related to a learning curve.

A Study of Relationship of Atheroembolic Risk Factors with Postoperative Recovery in Renal Function after Partial Nephrectomy in Patients Staged T1-2 Renal Cell Carcinoma during Median 4-Year Follow-up

Purpose

The objective of this study is to evaluate the relationship of atheroembolic risk factors with postoperative recovery of renal function after on-clamp partial nephrectomy (PN) with warm ischemia in patients with staged T1-2 renal cell carcinoma (RCC).

Materials and Methods

A total of 234 patients from 2004 to 2012 were included, and their clinicopathologic and operative parameters, including atheroembolic risk factors were reviewed retrospectively. Renal function, as determined by estimated glomerular filtration rate (eGFR) and measurement of serum creatinine level (Cr) at each scheduled follow-up for a median four years, was compared between the high-risk (HR) group (n=49, ≥ five risk factors) and the low-risk (LR) group (n=185, < five risk factors).

Results

Except for baseline renal function and number of risk factors for atheroembolism, differences in characteristics between groups were comparatively insignificant. At 3 months after the operation, Cr and eGFR differed significantly between the two groups (p < 0.05), but no differences were observed afterward. Significant deterioration from baseline in Cr and eGFR was observed in both groups at 1 month after the operation, with a greater change in the HR group (p < 0.05). From measurement to measurement, significantly faster deterioration in Cr and eGFR was observed in the HR group than in the LR group until 6 months after the operation (Cr: LR, 0.02 mg/dL and HR, 0.13 mg/dL; eGFR: LR, 1.50 mL/min/1.73 m² and HR, 6.38 mL/min/1.73 m²; p < 0.05).

Conclusion

The presence of atheroembolic risk factors may negatively influence postoperative recovery of renal function after PN in patients with localized RCC.

Cystatin C for early detection of acute kidney injury after laparoscopic partial nephrectomy

Introduction and Objectives:

Mortality due to AKI has not changed significantly over the past 50 years. This is due in part to failure to detect early AKI and to initiate appropriate therapeutic measures. There is therefore a need to identify biomarkers that would improve the early detection of AKI. The objective of this study was to assess whether cystatin C levels obtained at specific timepoints during laparoscopic partial nephrectomy (PN) could be early predictors of AKI.

Materials and Methods:

Twenty-five patients underwent laparoscopic PN for organ-confined tumors. All procedures were performed by two surgeons in a single institution. Plasma samples were collected preoperatively, and post-unclamping at 5, 20, 120 min and on the day following surgery. Plasma cystatin C was measured by enzyme-linked immunosorbent assay. Correlation between levels of cystatin C and other parameters of interest were assessed in order to define cystatin C ability to predict AKI and loss of renal function following laparoscopic PN.

Results:

The mean baseline eGFR was 93 ml/min/1.73 m². Warm ischemia time varied between 16 and 44 min. Post-operative day 1 (POD1) cystatin C levels compared to baseline were increased in 13 (52%) of the patients. There was a high correlation between the difference of POD 1 and baseline value, and eGFR in the immediate postoperative period (r = −0.681; P = 0.0002) and at 12-month follow-up (r = −0.460, P = 0.048). However, the variation in cystatin C levels at earlier timepoints were not associated to AKI nor renal function.

Conclusions:

High increase in POD 1 cystatin C levels from baseline may help identify patients with AKI and those at higher risk of chronic kidney disease, following laparoscopic PN.

Can selective arterial clamping with fluorescence imaging preserve kidney function during robotic partial nephrectomy?

OBJECTIVE

To compare renal functional outcomes in robotic partial nephrectomy (RPN) with selective arterial clamping guided by near-infrared fluorescence (NIRF) imaging to a matched cohort of patients who underwent RPN without selective arterial clamping and NIRF imaging.

METHODS

From April 2011 to December 2012, NIRF imaging-enhanced RPN with selective clamping was used in 42 cases. Functional outcomes of successful cases were compared with a cohort of patients, matched by tumor size, preoperative estimated glomerular filtration rate (eGFR), functional kidney status, age, sex, body mass index, and American Society of Anesthesiologists score, who underwent RPN without selective clamping and NIRF imaging.

RESULTS

In matched-pair analysis, selective clamping with NIRF was associated with superior kidney function at discharge, as demonstrated by postoperative eGFR (78.2 vs 68.5 mL/min/1.73 m(2); P = .04), absolute reduction of eGFR (-2.5 vs -14.0 mL/min/1.73 m(2); P <.01), and percent change in eGFR (-1.9% vs -16.8%; P <.01). Similar trends were noted at 3 month follow-up, but these differences became nonsignificant (P[eGFR] = .07; P[absolute reduction of eGFR] = .10; and P[percent change in eGFR] = .07). In the selective clamping group, a total of 4 perioperative complications occurred in 3 patients, all of which were Clavien grade I-III.

CONCLUSION

Use of NIRF imaging was associated with improved short-term renal functional outcomes when compared with RPN without selective arterial clamping and NIRF imaging. With this effect attenuated at later follow-up, randomized prospective studies and long-term assessment of kidney-specific functional outcomes are needed to further assess the benefits of this technology.

[Controversies of partial nephrectomy for renal cell carcinoma : survey in the German-speaking countries]

BACKGROUND

The goal of this study was to evaluate how partial nephrectomy is technically performed in Germany, Austria, and Switzerland.

METHODS

A one-page anonymous questionnaire was designed to evaluate the indication, the technical procedure, and the follow-up of R1 situation after partial nephrectomy. Furthermore, the size of the hospitals and their catchment areas were recorded. The questionnaire was sent to 341 clinics and a statistical analysis was performed.

RESULTS

The response rate was 69 %. Up to 99 % of the clinics also perform partial resection in T1b tumors. Of those responding, 58 % perform this surgery laparoscopically, and 83 % of the surgeries are performed in warm ischemia. For the follow-up, 29 % suggest imaging within the first 6 weeks. According to this survey, maximum care clinics perform laparoscopic nephrectomy more frequently (p = 0.003).

CONCLUSION

The survey of 236 hospitals performing partial nephrectomy shows great variability in the indication, technique, and aftercare of organ-preserving renal tumor surgery. It also shows that a large proportion of tumors >4 cm undergo organ-preserving surgery, many of them minimally invasive. The diverse handling with positive instantaneous section and R1 results suggest the need for further studies concerning long-term follow-up after minimally invasive surgery with R1 situation and renal tumors > T1a.