Hyperfiltration-mediated Injury in the Remaining Kidney of a Transplant Donor

Relationship between new-onset proteinuria and the volume of the non-donated kidney before and after donation in living kidney donors

INTRODUCTION

Some living kidney donors (LKDs) experience proteinuria after donation. Based on several studies, preoperative non-donated side kidney volume (pre-KV) and postoperative percentage change in preserved kidney hypertrophy (%PKH) are associated with proteinuria. This study explored the association of the combination of pre-KV and %PKH with new-onset proteinuria.

METHODS

This single-center, retrospective, observational study included eligible LKDs who underwent donor nephrectomy between January 2008 and July 2022 (N = 195). Among those, LKDs in whom KV and either urinary protein or albumin were obtained both pre-donation and 1 year post-donation were finally included (N = 70). The LKDs were assigned to four groups according to the mean body surface area-adjusted pre-KV and %PKH, and their association with the occurrence of proteinuria or albuminuria was investigated.

RESULTS

Among the 70 LKDs, mean age was 59.8 ± 7.9 years, and 50 (71.4%) were females. The mean preoperative estimated glomerular filtration rate, %PKH, and pre-KV was 78.0 ± 13.6 mL/min/1.73 m2, 20.3 ± 7.0%, and 161.4 ± 24.1 cm3/1.73 m2, respectively. During the 2.4 year follow-up period, there was no significant difference in the occurrence of proteinuria among the four groups (log-rank test, P = 0.111). However, after adjustment, the large pre-KV and small %PKH group had a significantly higher hazard ratio (HR) for proteinuria than the small pre-KV and large %PKH groups (adjusted HR 3.12, 95% confidence interval: 1.09-8.91, P = 0.033).

CONCLUSIONS

Proteinuria is more likely to occur postoperatively in LKDs whose kidneys are already enlarged before donation and cannot appropriately hypertrophy.

U-shaped association between hemoglobin levels and albuminuria in US adults: a cross-sectional study

PURPOSE

This study aimed to explore the correlation between hemoglobin levels and albuminuria in US adults.

METHODS

This cross-sectional investigation analyzed the National Health and Nutrition Examination Survey (NHANES) information from 2011 to 2020. Data on hemoglobin, albuminuria, and other variables were collected from all participants. The logistic-regression analyses and smoothed curves were used to substantiate the research objectives.

RESULTS

The average age of the 8,868 participants was 49.5 ± 17.3 years, and 49.3% were men. The prevalence of albuminuria was 12.1%. After adjusting for potential variables in the logistic-regression analysis models, hemoglobin (per 1 g/dL increase) was inversely associated with the presence of albuminuria (odds ratio [OR], 0.92; 95% confidence interval [95%CI], 0.87-0.97). Compared with participants in quartile 3 (Q3, 14.1-15.0 g/dL) for hemoglobin levels, those in the lowest quartile 1 (Q1, 6.1-13.0 g/dL) and highest quartile 4 (Q4, 15.1-19.6 g/dL) had adjusted ORs for albuminuria of 1.48 (95% CI, 1.19-1.85) and 1.11 (95% CI, 0.9-1.38), respectively. Our observations indicated a U-shaped association between hemoglobin levels and albuminuria, with a point of inflection at approximately 15.5 g/dL. The effect sizes and CIs below and above this point were 0.853 (95% CI, 0.798-0.912) and 1.377 (95% CI, 1.055-1.797), respectively.

CONCLUSION

This study indicates that the presence of albuminuria is linked to both low and high hemoglobin levels in US adults. The management of hemoglobin may benefit kidney health.

The Development of a Predictive Model for Postoperative Renal Function in Living Kidney-Transplant Donors

Background/Objectives: The accurate prediction of postoperative renal function (post-RF) in living kidney donors is essential for optimizing donor safety and long-term health. After nephrectomy, renal function can be significantly altered, owing to the functional adaptation of the remaining kidney; however, the extent of this has not been investigated. This study aimed to examine how various donor factors affect functional adaptation after nephrectomy, and to develop a new predictive model. Methods: In total, 310 patients who underwent donor nephrectomy were included. Preoperative split renal function (pre-SRF) of the remaining kidney was measured. Post-RF was measured 1 month after surgery. The functional adaptation rate was calculated from the difference between pre-SRF and post-RF. Multiple regression analysis was performed to develop a predictive formula for post-RF, incorporating donor age and pre-SRF. Results: The median age of the donors was 60 years, and 38.7% were men. The median pre-SRF was 36.4 mL/min/1.73 m2. The median functional adaptation rate was 26.8%, with donor age, pre-SRF, and a history of hyperuricemia (HUA) being significant predictors of the functional adaptation rate. The equation for post-RF was established as 0.94 × pre-SRF - 0.12 × age + 18.87 mL/min/1.73 m2. The estimated post-RF showed a high coefficient of determination (R2 = 0.76), with a mean bias of -0.01 mL/min/1.73 m2. Conclusions: Donor age, pre-SRF, and HUA are key predictors of renal functional adaptation after nephrectomy. The developed formula accurately estimates post-RF, supporting clinical decision-making and donor counseling for living kidney donations.

Re-Evaluating the Transplant Glomerulopathy Lesion-Beyond Donor-Specific Antibodies

There have been significant advances in short-term outcomes in renal transplantation. However, longer-term graft survival has improved only minimally. After the first post-transplant year, it has been estimated that chronic allograft damage is responsible for 5% of graft loss per year. Transplant glomerulopathy (TG), a unique morphologic lesion, is reported to accompany progressive chronic allograft dysfunction in many cases. While not constituting a specific etiologic diagnosis, TG is primarily considered as a histologic manifestation of ongoing allo-immune damage from donor-specific anti-HLA alloantibodies (DSA). In this review article, we re-evaluate the existing literature on TG, with particular emphasis on the role of non-HLA-antibodies and complement-mediated injury, cell-mediated immune mechanisms, and early podocyte stress in the pathogenesis of Transplant Glomerulopathy.

Longitudinal Trajectories of Estimated Glomerular Filtration Rate in a European Population of Living Kidney Donors

A living donor (LD) kidney transplant is the best treatment for kidney failure, but LDs safety is paramount. We sought to evaluate our LDs cohort's longitudinal changes in estimated glomerular filtration rate (eGFR). We retrospectively studied 320 LDs submitted to nephrectomy between 1998 and 2020. The primary outcome was the eGFR change until 15 years (y) post-donation. Subgroup analysis considered distinct donor characteristics and kidney function reduction rate (%KFRR) post-donation [-(eGFR6 months(M)-eGFRpre-donation)/eGFRpre-donation*100]. Donors had a mean age of 47.3 ± 10.5 years, 71% female. Overall, LDs presented an average eGFR change 6 M onward of +0.35 mL/min/1.73 m2/year. The period with the highest increase was 6 M-2 Y, with a mean eGFR change of +0.85L/min/1.73 m2/year. Recovery plateaued at 10 years. Normal weight donors presented significantly better recovery of eGFR +0.59 mL/min/1.73 m2/year, compared to obese donors -0.18L/min/1.73 m2/year (p = 0.020). Noteworthy, these results only hold for the first 5 years. The subgroup with a lower KFRR (<26.2%) had a significantly higher decrease in eGFR overall of -0.21 mL/min/1.73 m2/year compared to the groups with higher KFRR (p < 0.001). These differences only hold for 6 M-2 Y. Moreover, an eGFR<50 mL/min/1.73 m2 was a rare event, with ≤5% prevalence in the 2-15 Y span, correlating with eGFR pre-donation. Our data show that eGFR recovery is significant and may last until 10 years post-donation. However, some subgroups presented more ominous kidney function trajectories.

Urinary beta-2 microglobulin increases whereas TIMP-2 and IGFBP7 decline after unilateral nephrectomy in healthy kidney donors

Early kidney injury may be detected by urinary markers, such as beta-2 microglobulin (B2M), tissue inhibitor of metalloproteinases-2 (TIMP-2), insulin-like growth factor-binding protein 7 (IGFBP7), kidney injury molecule-1 (KIM-1) and/or neutrophil gelatinase-associated lipocalin (NGAL). Of these biomarkers information on pathophysiology and reference ranges in both healthy and diseased populations are scarce. Differences in urinary levels of B2M, TIMP-2, IGFBP7, KIM-1 and NGAL were compared 24 h before and after nephrectomy in 38 living kidney donors from the REnal Protection Against Ischaemia-Reperfusion in transplantation study. Linear regression was used to assess the relation between baseline biomarker concentration and kidney function 1 year after nephrectomy. Median levels of urinary creatinine and creatinine standardized B2M, TIMP-2, IGFBP7, KIM-1, NGAL, and albumin 24 h before nephrectomy in donors were 9.4 mmol/L, 14 μg/mmol, 16 pmol/mmol, 99 pmol/mmol, 63 ng/mmol, 1390 ng/mmol and 0.7 mg/mmol, with median differences 24 h after nephrectomy of - 0.9, + 1906, - 7.1, - 38.3, - 6.9, + 2378 and + 1.2, respectively. The change of donor eGFR after 12 months per SD increment at baseline of B2M, TIMP-2, IGFBP7, KIM-1 and NGAL was: - 1.1, - 2.3, - 0.7, - 1.6 and - 2.8, respectively. Urinary TIMP-2 and IGFBP7 excretion halved after nephrectomy, similar to urinary creatinine, suggesting these markers predominantly reflect glomerular filtration. B2M and NGAL excretion increased significantly, similar to albumin, indicating decreased proximal tubular reabsorption following nephrectomy. KIM-1 did not change considerably after nephrectomy. Even though none of these biomarkers showed a strong relation with long-term donor eGFR, these results provide valuable insight into the pathophysiology of these urinary biomarkers.

SGLT2 inhibitors in diabetic and non-diabetic kidney transplant recipients: current knowledge and expectations

The beneficial effect of sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been shown recently in numerous randomized controlled trials (RCT) and systematic reviews. According to KDIGO guidelines, SGLT2i currently represent a first choice for diabetic patients with chronic kidney disease (CKD). In addition, a recent meta-analysis of 13 large led by the 'SGLT2 inhibitor Meta-Analysis Cardio-Renal Trialists' Consortium' (SMART-C) provided solid evidence of SGLT2i beneficial effects in CKD or in patients with heart failure, with and without diabetes. Collectively, the patients treated with SGLT2i had a decreased risk of CKD progression, acute kidney injury (AKI), end-stage kidney disease (ESKD) or death from heart failure. Whether these cardio-renal benefits should be extrapolated to kidney transplant recipients (KTR) needs to be assessed in further studies. In this article, we report recent data accumulated so far in the literature, looking at the efficacy and safety of SGLT2i in diabetic and non-diabetic KTR. We found encouraging data regarding the use of SGLT2i in KTR with diabetes. These agents appeared to be safe, and they reduced body weight and blood pressure in this group of patients. Potential effects on kidney graft function and survival are yet to be investigated.

Glomerular hyperfiltration: part 2-clinical significance in children

Glomerular hyperfiltration (GHF) is a phenomenon that can occur in various clinical conditions affecting the kidneys such as sickle cell disease, diabetes mellitus, autosomal dominant polycystic kidney disease, and solitary functioning kidney. Yet, the pathophysiological mechanisms vary from one disease to another and are not well understood. More so, it has been demonstrated that GHF may occur at the single-nephron in some clinical conditions while in others at the whole-kidney level. In this review, we explore the pathophysiological mechanisms of GHF in relation to various clinical conditions in the pediatric population. In addition, we discuss the role and mechanism of action of important factors such as gender, low birth weight, and race in the pathogenesis of GHF. Finally, in this current review, we further highlight the consequences of GHF in the progression of kidney disease.

Long-term outcomes of acute kidney injury in children

PURPOSE OF REVIEW

Acute kidney injury (AKI) affects up to 35% of all critically ill children and is associated with substantial short-term morbidity and mortality. However, the link between paediatric AKI and long-term adverse outcomes remains incompletely understood. This review highlights the most recent clinical data supporting the role of paediatric AKI as a risk factor for long-term kidney and cardiovascular consequences. In addition, it stresses the need for long-term surveillance of paediatric AKI survivors.

RECENT FINDINGS

Recent large-scale studies have led to an increasing understanding that paediatric AKI is a significant risk factor for adverse outcomes such as hypertension, cardiovascular disease and chronic kidney disease (CKD) over time. These long-term sequelae of paediatric AKI are most often observed in vulnerable populations, such as critically ill children, paediatric cardiac surgery patients, children who suffer from severe infections and paediatric cancer patients.

SUMMARY

A growing body of research has shown that paediatric AKI is associated with long-term adverse outcomes such as CKD, hypertension and cardiovascular disease. Although therapeutic pathways tailored to individual paediatric AKI patients are yet to be validated, we provide a framework to guide monitoring and prevention in children at the highest risk for developing long-term kidney dysfunction.

Paradigm shift in lifestyle modification for solitary kidney after donor nephrectomy

PURPOSE OF REVIEW

Living donor kidney transplantation potentially leads to long-term complications including chronic kidney disease, end-stage kidney disease, elevated blood pressure, and pregnancy-associated hypertension. Given living donors generally do not have underlying medical conditions, lifestyle modifications, particularly dietary interventions may prevent those complications and improve their health outcomes.

RECENT FINDINGS

Glomerular hyperfiltration occurs as physiologic adaptation during an initial postdonor nephrectomy period. In the long-term, these adaptations may become pathologic consequences resulting from hyperfiltration-mediated kidney injury and ultimately secondary focal segmental glomerulosclerosis in the solitary kidney. Dietary interventions to slow a decline in kidney function include low protein intake of <0.8 g/kg/day and low sodium consumption of 2-4 g/day as well as certain health dietary patterns. There is no evidence regarding the quantity and quality of protein that can be recommended for living kidney donors and the same for sodium. Plant Dominant (PLADO) diets, Dietary Approaches to Stop Hypertension (DASH), Mediterranean, and vegetarian diets may be favorable for living kidney donors with solitary kidney but the evidence is still lacking.

SUMMARY

Although dietary interventions may provide benefits and kidney health for living kidney donors, further studies including clinical trials are required to incorporate them into clinical practice guidelines.

Novel insights in classic versus relative glomerular hyperfiltration and implications on pharmacotherapy

PURPOSE OF REVIEW

Glomerular filtration rate (GFR) assessment and its estimation (eGFR) is a long-lasting challenge in medicine and public health. Current eGFR formulae are indexed for standardized body surface area (BSA) of 1.73 m2, ignoring persons and populations wherein the ratio of BSA or metabolic rate to nephron number might be different, due to increased BSA, increased metabolic rate or reduced nephron number. These equations are based on creatinine, cystatin C or a combination of the two, which adds another confounder to eGFR assessment. Unusually high GFR values, also known as renal hyperfiltration, have not been well defined under these equations.

RECENT FINDINGS

Special conditions such as solitary kidney in kidney donors, high dietary protein intake, obesity and diabetes are often associated with renal hyperfiltration and amenable to errors in GFR estimation. In all hyperfiltration types, there is an increased intraglomerular pressure that can be physiologic, but its persistence over time is detrimental to glomerulus leading to progressive glomerular damage and renal fibrosis. Hyperfiltration might be underdiagnosed due to BSA standardization embedded in the formula. Hence, timely intervention is delayed. Reducing intraglomerular pressure in diabetes can be achieved by SGLT2 inhibitors or low protein diet to reverse the glomerulopathy process.

SUMMARY

Accurate identification of glomerular hyperfiltration as a pre-CKD condition needs accurate estimation of GFR in the above normal range should establish a threshold for timely intervention.

Prostanoid receptors in hyperfiltration-mediated glomerular injury: Novel agonists and antagonists reveal opposing roles for EP2 and EP4 receptors

Increased fluid-flow shear stress (FFSS) contributes to hyperfiltration-induced podocyte and glomerular injury resulting in progression of chronic kidney disease (CKD). We reported that increased FFSS in vitro and in vivo upregulates PGE2 receptor EP2 (but not EP4 expression), COX2-PGE₂ -EP2 axis, and EP2-linked Akt-GSK3β-β-catenin signaling pathway in podocytes. To understand and use the disparities between PGE2 receptors, specific agonists, and antagonists of EP2 and EP4 were used to assess phosphorylation of Akt, GSK3β and β-catenin in podocytes using Western blotting, glomerular filtration barrier function using in vitro albumin permeability (P_alb ) assay, and mitigation of hyperfiltration-induced injury in unilaterally nephrectomized (UNX) mice at 1 and 6 months. Results show an increase in P_alb by PGE₂ , EP2 agonist (EP2^AGO ) and EP4 antagonist (EP4^ANT ), but not by EP2 antagonist (EP2^ANT ) or EP4 agonist (EP4^AGO ). Pretreatment with EP2^ANT blocked the effect of PGE₂ or EP2^AGO on P_alb . Modulation of EP2 and EP4 also induced opposite effects on phosphorylation of Akt and β-Catenin. Individual agonists or antagonists of EP2 or EP4 did not induce significant improvement in albuminuria in UNX mice. However, treatment with a combination EP2^ANT  + EP4^AGO for 1 or 6 months caused a robust decrease in albuminuria. EP2^ANT  + EP4^AGO combination did not impact adaptive hypertrophy or increased serum creatinine. Observed differences between expression of EP2 and EP4 on the glomerular barrier highlight these receptors as potential targets for intervention. Safe and effective mitigating effect of EP2^ANT  + EP4^AGO presents a novel opportunity to delay the progression of hyperfiltration-associated CKD as seen in transplant donors.

Cancer risk in living kidney donors

Living kidney donors are screened for transmissible diseases including cancer. Outcomes following donation are excellent, but concern exists regarding development of chronic kidney disease, and cancer risk is unknown. We used linked transplant and cancer registry data to identify incident cancers among 84,357 kidney donors in the United States (1995-2017). We compared risk with the general population using standardized incidence ratios (SIRs). For selected cancers, we used Poisson regression to compare donors with 47,451 Adventist Health Study 2 (AHS-2) participants, who typically have healthy lifestyles. During follow-up, 2843 cancers were diagnosed in donors, representing an overall deficit (SIR 0.79, 95%CI 0.76-0.82). None of 46 specified cancer sites occurred in excess relative to the general population, and 15 showed significant deficits (SIR < 1.00). Compared with AHS-2 participants, donors had similar incidence of liver cancer, melanoma, breast cancer, and non-Hodgkin lymphoma but, starting 7 years after donation, elevated incidence of colorectal cancer (adjusted incidence rate ratio 2.07, 95%CI 1.54-2.79) and kidney cancer (2.97, 1.58-5.58, accounting for the presence of a single kidney in donors). Elevated kidney cancer incidence may reflect adverse processes in donors' remaining kidney. Nonetheless, cancer risk is lower than in the general population, suggesting that enhanced screening is unnecessary.

Glomerular hyperfiltration

Circulating blood is filtered across the glomerular barrier to form an ultrafiltrate of plasma in the Bowman's space. The volume of glomerular filtration adjusted by time is defined as the glomerular filtration rate (GFR), and the total GFR is the sum of all single-nephron GFRs. Thus, when the single-nephron GFR is increased in the context of a normal number of functioning nephrons, single glomerular hyperfiltration results in 'absolute' hyperfiltration in the kidney. 'Absolute' hyperfiltration can occur in healthy people after high protein intake, during pregnancy and in patients with diabetes, obesity or autosomal-dominant polycystic kidney disease. When the number of functioning nephrons is reduced, single-nephron glomerular hyperfiltration can result in a GFR that is within or below the normal range. This 'relative' hyperfiltration can occur in patients with a congenitally reduced nephron number or with an acquired reduction in nephron mass consequent to surgery or kidney disease. Improved understanding of the mechanisms that underlie 'absolute' and 'relative' glomerular hyperfiltration in different clinical settings, and of whether and how the single-nephron haemodynamic and related biomechanical forces that underlie glomerular hyperfiltration promote glomerular injury, will pave the way toward the development of novel therapeutic interventions that attenuate glomerular hyperfiltration and potentially prevent or limit consequent progressive kidney injury and loss of function.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

OUP accepted manuscript

Background

Left ventricular hypertrophy and heart failure with preserved ejection fraction (HFpEF) are primary manifestations of the cardiorenal syndrome in patients with chronic kidney disease (CKD). Therapies that improve morbidity and mortality in HFpEF are lacking. Cell-based therapies promote cardiac repair in ischemic and non-ischemic cardiomyopathies. We hypothesized that cell-based therapy ameliorates CKD-induced HFpEF.

Methods and Results

Yorkshire pigs (n = 26) underwent 5/6 embolization-mediated nephrectomy. CKD was confirmed by increased creatinine and decreased glomerular filtration rate (GFR). Mean arterial pressure (MAP) was not different between groups from baseline to 4 weeks. HFpEF was evident at 4 weeks by increased LV mass, relative wall thickening, end-diastolic pressure, and end-diastolic pressure-volume relationship, with no change in ejection fraction (EF). Four weeks post-embolization, allogeneic (allo) bone marrow-derived mesenchymal stem cells (MSC; 1 × 10⁷ cells), allo-kidney-derived stem cells (KSC; 1 × 10⁷ cells), allo-cell combination therapy (ACCT; MSC + KSC; 1:1 ratio; total = 1 × 10⁷ cells), or placebo (Plasma-Lyte) was delivered via intra-renal artery. Eight weeks post-treatment, there was a significant increase in MAP in the placebo group (21.89 ± 6.05 mmHg) compared to the ACCT group. GFR significantly improved in the ACCT group. EF, relative wall thickness, and LV mass did not differ between groups at 12 weeks. EDPVR improved in the ACCT group, indicating decreased ventricular stiffness.

Conclusions

Intra-renal artery allogeneic cell therapy was safe in a CKD swine model manifesting the characteristics of HFpEF. The beneficial effect on renal function and ventricular compliance in the ACCT group supports further research of cell therapy for cardiorenal syndrome.

Alterations in the Mineral Bone Metabolism of Living Kidney Donors After Uni-Nephrectomy: Prospective Observational Study

We investigated the dynamic change of mineral bone metabolism and explored factors associated with the alteration of mineral bone metabolism in the living kidney donors (LKDs) after uni-nephrectomy. One-hundred forty-four prospective LKDs who underwent kidney donation between May 2016 and September 2018 were enrolled. Laboratory evaluation regarding mineral bone metabolism including intact parathyroid hormone (iPTH), renal fractional excretion of phosphate (FEPi), and technetium-99m diethylenetriaminepentaacetate (^99mTc-DTPA) scan was performed predonation and 6 months after donation. We divided donors into two groups, the low ΔFEPi and high ΔFEPi groups, according to the change of FEPi after donation, and investigated significant risk factors associated with high ΔFEPi. At 6 months after uni-nephrectomy, estimated glomerular filtration rate (eGFR) significantly declined by 30.95 ml/min/1.73 m² (p < 0.001), but the measured GFR (mGFR) of the remaining kidney by ^99mTc-DTPA scan showed significant increase. Serum phosphorus decreased (p < 0.001), whereas FEPi (13.34–20.23%, p < 0.001) and serum iPTH (38.70–52.20 pg/ml, p < 0.001) showed significant increase. In the high ΔFEPi group, the proportion of preexisting hypertension (HTN) was higher, the baseline FEPi was lower, and the percent decline in eGFR was greater. Moreover, all of these factors were independently associated with high ΔFEPi upon multivariable logistic regression analysis. LKDs showed a significant change in mineral bone metabolism after uni-nephrectomy, especially when the donors had preexisting HTN, lower baseline FEPi, and showed greater loss of kidney function. Hence, strict monitoring of the mineral bone metabolism parameters and bone health may be required for these donors.

[Renal functional compensation after unilateral radical nephrectomy of renal cell carcinoma]

OBJECTIVE

To investigate factors influencing renal functional compensation(RFC) of the preserved kidney after radical nephrectomy (RN).

METHODS

A total of 286 patients treated with RN in Peking University People's Hospital were retrospectively analyzed. Preoperative body mass index (BMI), systolic blood pressure (SBP), history of smoking, history of chronic diseases and other basic information, as well as preoperative blood biochemistry, urine routine, imaging examination results were recorded. All the patients underwent ^99mtechnetium-diethylenetriamine pentaacetic acid (^99mTc-DTPA) renal scans before operation. The surgical method, pathology and blood creatinine values from 1 month to 60 months after RN were recorded. Preoperative and postoperative estimated glomerular filtration rate (eGFR) was calculated by the chronic kidney disease epidemiology collaboration (CKD-EPI) formula. Renal functional compensation was defined as percent change in eGFR of the preserved kidney after RN compared with the preoperative eGFR. Univariate and multivariate regression analyses were used to identify predictive factors of RFC.

RESULTS

Median age was 61 years and 65.4% of the patients were male. Early stage (T1 or T2) tumors were found in 83.6% of the cases. 18.5% of the patients had preoperative diabetes mellitus, 39.5% had hypertension, 19.2% had a history of smoking, and 27.6% were found to have renal cyst on the contralateral side. In the study, 226 cases underwent laparoscopic radical nephrectomy and 60 cases underwent open radical nephrectomy. Renal clear cell carcinoma was the most common pathological type, accounting for 88.5%. The median tumor maximum diameter was 4.5 cm (0.7-13.5 cm). Median renal function compensation was 27% one month after radical nephrectomy. Functional stability was then observed to 5 years. The results of univariate analysis showed that age, gender, preoperative blood uric acid, preoperative urine protein, contralateral renal cyst, and percentage of split renal function of contralateral kidney were correlated with RFC (P < 0.05). Among them, UA level and split renal function of contralateral kidney were strongly negatively correlated with RFC. The results of multivariate linear regression analysis showed age (P < 0.001), blood uric acid (P < 0.001), urine protein (P=0.002), preoperative eGFR (P < 0.001) and the split renal function of contralateral kidney (P < 0.001) were independent predictors of RFC.

CONCLUSION

The basic examinations, such as blood biochemistry, urine routine and renal scan before RN are of great significance in predicting the compen-satory ability of the preserved kidney after RN, which is supposed to be taken into consideration when making clinical decision.

Maintaining proteostasis under mechanical stress

Cell survival, tissue integrity and organismal health depend on the ability to maintain functional protein networks even under conditions that threaten protein integrity. Protection against such stress conditions involves the adaptation of folding and degradation machineries, which help to preserve the protein network by facilitating the refolding or disposal of damaged proteins. In multicellular organisms, cells are permanently exposed to stress resulting from mechanical forces. Yet, for long time mechanical stress was not recognized as a primary stressor that perturbs protein structure and threatens proteome integrity. The identification and characterization of protein folding and degradation systems, which handle force-unfolded proteins, marks a turning point in this regard. It has become apparent that mechanical stress protection operates during cell differentiation, adhesion and migration and is essential for maintaining tissues such as skeletal muscle, heart and kidney as well as the immune system. Here, we provide an overview of recent advances in our understanding of mechanical stress protection.

A mouse model of prenatal exposure to Interleukin-6 to study the developmental origin of health and disease

Systemic inflammation in pregnant obese women is associated with 1.5- to 2-fold increase in serum Interleukin-6 (IL-6) and newborns with lower kidney/body weight ratio but the role of IL-6 in increased susceptibility to chronic kidney (CKD) in adult progeny is not known. Since IL-6 crosses the placental barrier, we administered recombinant IL-6 (10 pg/g) to pregnant mice starting at mid-gestation yielded newborns with lower body (p < 0.001) and kidney (p < 0.001) weights. Histomorphometry indicated decreased nephrogenic zone width (p = 0.039) with increased numbers of mature glomeruli (p = 0.002) and pre-tubular aggregates (p = 0.041). Accelerated maturation in IL-6 newborns was suggested by early expression of podocyte-specific protein podocin in glomeruli, increased 5-methyl-cytosine (LC–MS analysis for CpG DNA methylation) and altered expression of certain genes of cell-cycle and apoptosis (RT-qPCR array-analysis). Western blotting showed upregulated pJAK2/pSTAT3. Thus, treating dams with IL-6 as a surrogate provides newborns to study effects of maternal systemic inflammation on future susceptibility to CKD in adulthood.

Transcription Factor β-Catenin Plays a Key Role in Fluid Flow Shear Stress-Mediated Glomerular Injury in Solitary Kidney

Increased fluid flow shear stress (FFSS) in solitary kidney alters podocyte function in vivo. FFSS-treated cultured podocytes show upregulated AKT-GSK3β-β-catenin signaling. The present study was undertaken to confirm (i) the activation of β-catenin signaling in podocytes in vivo using unilaterally nephrectomized (UNX) TOPGAL mice with the β-galactosidase reporter gene for β-catenin activation, (ii) β-catenin translocation in FFSS-treated mouse podocytes, and (iii) β-catenin signaling using publicly available data from UNX mice. The UNX of TOPGAL mice resulted in glomerular hypertrophy and increased the mesangial matrix consistent with hemodynamic adaptation. Uninephrectomized TOPGAL mice showed an increased β-galactosidase expression at 4 weeks but not at 12 weeks, as assessed using immunofluorescence microscopy (p < 0.001 at 4 weeks; p = 0.16 at 12 weeks) and X-gal staining (p = 0.008 at 4 weeks; p = 0.65 at 12 weeks). Immunofluorescence microscopy showed a significant increase in phospho-β-catenin (Ser552, p = 0.005) at 4 weeks but not at 12 weeks (p = 0.935) following UNX, and the levels of phospho-β-catenin (Ser675) did not change. In vitro FFSS caused a sustained increase in the nuclear translocation of phospho-β-catenin (Ser552) but not phospho-β-catenin (Ser675) in podocytes. The bioinformatic analysis of the GEO dataset, #GSE53996, also identified β-catenin as a key upstream regulator. We conclude that transcription factor β-catenin mediates FFSS-induced podocyte (glomerular) injury in solitary kidney.

Role of Shear Stress on Renal Proximal Tubular Cells for Nephrotoxicity Assays

Drug-induced nephrotoxicity causes huge morbidity and mortality at massive financial cost. The greatest burden of drug-induced acute kidney injury falls on the proximal tubular cells. To maintain their structure and function, renal proximal tubular cells need the shear stress from tubular fluid flow. Diverse techniques to reintroduce shear stress have been studied in a variety of proximal tubular like cell culture models. These studies often have limited replicates because of the huge cost of equipment and do not report all relevant parameters to allow reproduction and comparison of studies between labs. This review codifies the techniques used to reintroduce shear stress, the cell lines utilized, and the biological outcomes reported. Further, we propose a set of interventions to enhance future cell biology understanding of nephrotoxicity using cell culture models.

Changes in renal function and predictors affecting renal outcome of living kidney donors: a nationwide prospective cohort study

AIM

The safety of donors is an important issue in living donor kidney transplantation. We investigated serial changes in renal function and predictors affecting the renal outcome of living kidney donors.

METHODS

We obtained the data of 456 kidney donors registered to the Korean Organ Transplantation Registry from 2014 to 2016. The estimated glomerular filtration rate (eGFR) changes according to the development of incident chronic kidney disease (CKD) and factors related to CKD were analysed. CKD was defined as an eGFR <60 ml/min/1.73 m² or the presence of proteinuria or albuminuria. The change in eGFR over time was analysed using a linear mixed model.

RESULTS

At 2 years after kidney donation, 21.7% of the donors (99/456) developed CKD. Annual eGFR changes after nephrectomy were 2.2 ml/min/1.73 m² /year in donors without CKD, and - 0.4 ml/min/1.73 m² /year in donors with CKD. Higher systolic blood pressure was associated with higher risk of CKD (odds ratio [OR] 1.322 per 10 mmHg increment, 95% confidence interval [CI] 1.036-1.686, p = .025). Higher pre-donation eGFR (OR 0.906 per 1 ml/min/1.73 m² increment, 95% CI 0.876-0.936, p < .001) and higher ratio of eGFR at discharge to pre-donation (OR 0.603 per 0.1 increment, 95% CI 0.426-0.849, p = .004) were related to lower risk of CKD.

CONCLUSION

Kidney donors without incident CKD at 2 years after donation showed gradual increases in eGFR, whereas donors with CKD had relatively constant eGFR. A low ratio of eGFR at discharge after nephrectomy to baseline was a risk factor of CKD.

Association of Obesity with Cardiovascular Risk Factors and Kidney Disease Outcomes in Primary Proteinuric Glomerulopathies

BACKGROUND/AIMS

Obesity is a known risk factor for cardiovascular disease and contributes to the development and progression of kidney disease. However, the specific influence of obesity on outcomes in primary glomerular disease has not been well characterized.

METHODS

In this prospective cohort study, data were from 541 participants enrolled in the Nephrotic Syndrome Study Network (NEPTUNE), between 2010 and 2019, at 23 sites across North America. Blood pressure, lipids, and kidney disease outcomes including complete proteinuria remission, kidney failure, and chronic kidney disease progression were evaluated. Data were analyzed using linear and logistic regression with generalized estimating equations and time-varying Cox regression with Kaplan-Meier plots.

RESULTS

The prevalence of obesity at baseline was 43.3% (N = 156) in adults and 37.6% (N = 68) in children. In adults, obesity was longitudinally associated with higher systolic BP (β = 6.49, 95% CI: 2.41, 10.56, p = 0.002), dyslipidemia (OR = 1.74, 95% CI: 1.30, 2.32, p < 0.001), triglycerides (β = 41.92, 95% CI: 17.12, 66.71, p = 0.001), and lower HDL (β = -6.92, 95% CI: -9.32, -4.51, p < 0.001). In children, obesity over time was associated with higher systolic BP index (β = 0.04, 95% CI: 0.02, 0.06, p < 0.001) and hypertension (OR = 1.43, 95% CI: 1.04, 1.98, p = 0.03). In both adults and children, obesity was associated with a significantly lower hazard of achieving complete remission of proteinuria (adult HR = 0.80, 95% CI: 0.69, 0.88, p < 0.001; pediatric HR = 0.72, 95% CI: 0.61, 0.84, p < 0.001).

CONCLUSION

Obesity was associated with higher cardiovascular risk and less proteinuria remission from nephrotic syndrome in adults and children with proteinuric glomerulopathies. Weight-loss strategies may forestall cardiovascular disease and progressive kidney function decline in this high-risk patient group.

Contraception in Kidney Disease

Unplanned pregnancies account for a large number of encountered pregnancies. One of the reasons for this is the lack of counseling surrounding contraception and subsequently lack of contraception use. A conversation during a regular CKD office visit of simply asking a woman what her plans are regarding pregnancy can lead to further discussion on timing of pregnancy and contraception and eventually safer outcomes for both the mother and fetus. Individual preference, as well as comorbid conditions, should be taken into account when deciding on optimal contraceptive methods. One must remember that contraception counseling and initiation of contraception should not be wrapped up in a single office visit, and there must be continued follow-up to ensure that the woman is using the contraceptive method correctly to prevent any future unplanned pregnancy.

HbA1c and Aortic Calcification Index as Noninvasive Predictors of Pre-Existing Histopathological Damages in Living Donor Kidney Transplantation

We previously reported that allografts from living donors may have pre-existing histopathological damages, defined as the combination of interstitial fibrosis (ci), tubular atrophy (ct), and arteriolar hyalinosis (ah) scores of ≧1, according to the Banff classification. We examined preoperative characteristics to identify whether the degree of these damages was related to metabolic syndrome-related factors of donors. We conducted a single-center cross-sectional analysis including 183 living kidney donors. Donors were divided into two groups: chronic change (ci + ct ≧ 1 &cap; ah ≧ 1, n = 27) and control (n = 156). Preoperative characteristics, including age, sex, blood pressure, hemoglobin A1c (HbA1c), aortic calcification index (ACI), and psoas muscle index (PMI), were analyzed. Comparing the groups, the baseline estimated glomerular filtration rate was not significantly different; however, we observed a significant difference for ACI (p = 0.009). HbA1c (p = 0.016) and ACI (p = 0.006) were independent risk factors to predict pre-existing histopathological damages, whereas PMI was not. HbA1c correlated with ct scores (p = 0.035), and ACI correlated with ci (p = 0.005), ct (p = 0.021), and ah (p = 0.017). HbA1c and ACI may serve as preoperative markers for identifying pre-existing damages on the kidneys of living donors.

Upregulated proteoglycan-related signaling pathways in fluid flow shear stress-treated podocytes

The ultrafiltrate flow over the major processes and cell body generates fluid flow shear stress (FFSS) on podocytes. Hyperfiltration-associated increase in FFSS can lead to podocyte injury and detachment. Previously, we showed that FFSS-induced upregulation of the cyclooxygenase 2 (COX2)-PGE₂-prostaglandin E receptor 2 (EP2) axis in podocytes activates Akt-glycogen synthase kinase-3β-β-catenin and MAPK/ERK signaling in response to FFSS. Integrative MultiOmics Pathway Resolution (IMPRes) is a new bioinformatic tool that enables simultaneous time-series analysis of more than two groups to identify pathways and molecular connections. In the present study, we used previously characterized COX2 [prostaglandin-endoperoxide synthase 2 (Ptgs2)], EP2 (Ptger2), and β1-catenin (Ctnnb1) as "seed genes" from an array data set of four groups analyzed over a time course. The 3 seed genes shared 7 pathways and 50 genes of 14 pathways and 89 genes identified by IMPRes. A composite of signaling pathways highlighted the temporal molecular connections during mechanotransduction signaling in FFSS-treated podocytes. We investigated the "proteoglycans in cancer" and "galactose metabolism" pathways predicted by IMPRes. A custom-designed PCR array validated 60.7% of the genes predicted by IMPRes analysis, including genes for the above-named pathways. Further validation using Western blot analysis showed increased expression of phosho-Erbb2, phospho-mammalian target of rapamycin (mTOR), CD44, and hexokinase II (Hk2); decreased total Erbb2, galactose mutarotase (Galm), and β-1,4-galactosyltransferase 1 (B4galt1); and unchanged total mTOR and AKT3. These findings corroborate our previously reported results. This study demonstrates the potential of the IMPRes method to identify novel pathways. Identifying the "proteoglycans in cancer" and "galactose metabolism" pathways has generated a lead to study the significance of FFSS-induced glycocalyx remodeling and possible detachment of podocytes from the glomerular matrix.

Long-term compensation of renal function after donor nephrectomy

Background

Living donors are the major source of kidneys in countries with a shortage of deceased donors. Kidney donation after careful donor selection is generally accepted as a safe procedure, but the physiologic consequences after donor nephrectomy are not fully verified. In this study we retrospectively reviewed the renal function of the residual kidney in living donors.

Methods

Post-nephrectomy laboratory data of 1,175 living donors (60.7%) from 1,933 living donors who received uninephrectomy from January 1999 to December 2017 at Yonsei University, Severance Hospital, Korea were retrospectively collected. Post-nephrectomy renal function was monitored by the relative ratio of estimated glomerular filtration rate (e-GFR; pre-nephrectomy e-GFR ratio vs. post-nephrectomy e-GFR) that was calculated by the Modification of Diet in Renal Disease formula.

Results

During 36.3±37.6 months of mean follow-up, two cases (0.17%, 2/1,175) of renal failure developed. The mean e-GFR decreased to 64.3±14.2 mL/min/1.73 m2 immediately after nephrectomy from 99.2±19.9 mL/min/1.73 m2 of the pre-nephrectomy e-GFR. Early decrement of e-GFR was prominent in male and obese donors (body mass index >25 kg/m2, P<0.05). The e-GFR ratio increased according to post-nephrectomy duration, and the mean increment degree of e-GFR ratio after nephrectomy calculated by linear regression analysis was 1.94% per year. Unlike the early decrement of e-GFR ratio after nephrectomy, donor factors such as degree of obesity and donor sex did not affect the late increment of e-GFR ratio after nephrectomy (P>0.05).

Conclusions

Our data showed that long-term compensation of the renal function after nephrectomy occurs independently of preoperative donor characteristics.

The Family Attitudes of Patients With End-Stage Renal Disease Toward Living Kidney Donation in China

BACKGROUND

Organ shortages limit the progress of organ transplantation. The family attitudes of patients with end-stage renal disease (ESRD) play an important role in advocating organ transplantation and donation. The purpose of this study was to analyze the family attitudes of patients with ESRD toward living kidney donation in China. Ethical approval was obtained from the ethics committee of Linyi People's Hospital. This study was performed in compliance with the Declaration of Helsinki.

MATERIALS AND METHODS

This research was performed at 5 third-level hospitals with hemodialysis and nephrology departments, and a small section comes from urology departments. The participants were surveyed from January to November 2018. Attitudes were evaluated using a validated questionnaire concerning the psychosocial aspects of organ donation. The self-administered questionnaire was completed anonymously. Statistical analyses employed t tests and the χ² test.

RESULTS

Regarding living kidney donation, 69.1% (n = 428) of patient families favored it; however, only 30.9% (n = 192) did not support it. A favorable attitude toward living donation was mainly associated with the following variables: 1. the recipient is not more than 50 years old; 2. the recipient is a member of the immediate family; 3. the living donation is from the recipient's family member; 4. the family has previous personal experience with organ transplantation and donation; and 5. the family has a concern about the possibility of needing a transplant within the family unit (P < .05).

CONCLUSIONS

Economic burden and mental stress from long-term dialysis influenced the attitudes and behavioral intentions of the families of patients with ESRD on advocating organ donation. Repeated education and constant advocacy are advised to increase the participation of families of patients with ESRD in organ donation. The results showed favorable attitudes toward living kidney donation among the families of patients with ESRD.

Concerted EP2 and EP4 Receptor Signaling Stimulates Autocrine Prostaglandin E2 Activation in Human Podocytes

Glomerular hyperfiltration is an important mechanism in the development of albuminuria. During hyperfiltration, podocytes are exposed to increased fluid flow shear stress (FFSS) in Bowman’s space. Elevated Prostaglandin E2 (PGE₂) synthesis and upregulated cyclooxygenase 2 (Cox2) are associated with podocyte injury by FFSS. We aimed to elucidate a PGE₂ autocrine/paracrine pathway in human podocytes (hPC). We developed a modified liquid chromatography tandem mass spectrometry (LC/ESI-MS/MS) protocol to quantify cellular PGE₂, 15-keto-PGE₂, and 13,14-dihydro-15-keto-PGE₂ levels. hPC were treated with PGE₂ with or without separate or combined blockade of prostaglandin E receptors (EP), EP2, and EP4. Furthermore, the effect of FFSS on COX2, PTGER2, and PTGER4 expression in hPC was quantified. In hPC, stimulation with PGE₂ led to an EP2- and EP4-dependent increase in cyclic adenosine monophosphate (cAMP) and COX2, and induced cellular PGE₂. PTGER4 was downregulated after PGE₂ stimulation in hPC. In the corresponding LC/ESI-MS/MS in vivo analysis at the tissue level, increased PGE₂ and 15-keto-PGE₂ levels were observed in isolated glomeruli obtained from a well-established rat model with glomerular hyperfiltration, the Munich Wistar Frömter rat. COX2 and PTGER2 were upregulated by FFSS. Our data thus support an autocrine/paracrine COX2/PGE₂ pathway in hPC linked to concerted EP2 and EP4 signaling.

A prospective controlled study of metabolic and physiologic effects of kidney donation suggests that donors retain stable kidney function over the first nine years

While there have been numerous studies of living kidney donors, most have been retrospective without suitable controls and have yielded conflicting results. To clarify this we studied 205 living donor candidates and 203 controls having no medical conditions precluding donation. Before and at six months, one, two, three, six, and nine years after donation we measured iohexol glomerular filtration rate, clinic blood pressure, urine protein excretion and metabolic parameters reported to be affected by kidney function. We measured 24 hour ambulatory blood pressure at three, six, and nine years and at six and nine years blood pressure after treadmill exercise, carotid-femoral pulse wave velocity and arterial elasticity. Between six months and nine years, the mean (95% confidence interval) change in glomerular filtration rate was significantly different among 133 donors 0·02 (-0·16-0·20) mL/min/1·73m²/year versus -1·26 (-1·52--1·00) mL/min/1·73m²/year in 113 healthy controls. Blood pressure, urine protein, urine albumin, glucose, hemoglobin A1c, insulin, and lipoproteins were not different in controls versus donors; but parathyroid hormone, homocysteine and uric acid remained higher at nine years. At six and nine years carotid-femoral pulse wave velocity was not different, but the mean small artery elasticity was significantly lower in 141 donors 6·1 mL/mmHg x100, versus 113 controls 7·1 mL/mmHg x100, and 6·1 mL/mmHg x100 in 137 donors versus 7·6 mL/mmHg x100 in 112 controls at six and nine years, respectively [significant adjusted difference of 1·1 mL/mmHg x100]. Thus, donors remain healthy with stable kidney function for the first nine years, but differences in metabolic and vascular parameters could be harbingers of adverse outcomes requiring future interventions.

Urinary prostaglandin E2 is a biomarker of early adaptive hyperfiltration in solitary functioning kidney

INTRODUCTION

Hyperfiltration is a major contributor to progression of chronic kidney disease (CKD) in diabetes, obesity and in individuals with solitary functioning kidney (SFK). We have proposed hyperfiltration-induced injury as a continuum of overlapping glomerular changes caused by increased biomechanical forces namely, fluid flow shear stress (FFSS) and tensile stress. We have shown that FFSS is elevated in animals with SFK and, it upregulates prostaglandin E₂ (PGE₂), cyclooxygenase-2 and PGE₂ receptor EP2 in cultured podocytes and in uninephrectomized mice. We conceptualized urinary PGE₂ as a biomarker of early effects of hyperfiltration-induced injury preceding microalbuminuria in individuals with SFK. We studied children with SFK to validate our hypothesis.

METHODS

Urine samples from children with SFK and controls were analyzed for PGE₂, albumin (glomerular injury biomarker) and epidermal growth factor (EGF, tubular injury biomarker). Age, gender, and Z-scores for height, weight, BMI, and blood pressure were obtained.

RESULTS

Children with SFK were comparable to controls except for lower BMI Z-scores. The median values were elevated in SFK compared to control for urine PGE₂ [9.1 (n = 57) vs. 5.7 (n = 72), p = 0.009] ng/mgCr and albumin [7.6 (n = 40) vs. 7.0 (n = 41), p = 0.085] μg/mgCr, but not for EGF [20098 (n = 44) vs. 18637 (n = 44), p = 0.746] pg/mgCr. Significant increase in urinary PGE₂ (p = 0.024) and albumin (p = 0.019) but not EGF (p = 0.412) was observed using additional regression modeling. These three urinary analytes were independent of each other.

CONCLUSION

Increased urinary PGE₂ from elevated SNGFR and consequently increased FFSS during early stage of CKD precedes overt microalbuminuria and is a biomarker for early hyperfiltration-induced injury in individuals with SFK.

Kidney regeneration with biomimetic vascular scaffolds based on vascular corrosion casts

We have developed a biomimetic renal vascular scaffold based on a vascular corrosion casting technique. This study evaluated the feasibility of using this novel biomimetic scaffold for kidney regeneration in a rat kidney cortical defect model. Vascular corrosion casts were prepared from normal rat kidneys by perfusion with 10% polycaprolactone (PCL) solution, followed by tissue digestion. The corrosion PCL cast was coated with collagen, and PCL was removed from within the collagen coating, leaving only a hollow collagen-based biomimetic vascular scaffold. The fabricated scaffolds were pre-vascularized with MS1 endothelial cell coating, incorporated into 3D renal constructs, and subsequently implanted either with or without human renal cells in the renal cortex of nude rats. The implanted collagen-based vascular scaffold was easily identified and integrated into native kidney tissue. The biomimetic vascular scaffold coated with endothelial cells (MS1) showed significantly enhanced vascularization, as compared to the uncoated scaffold and hydrogel only groups (P < 0.001). Along with the improved vascularization effects, the MS1-coated scaffolds showed a significant renal cell infiltration from the neighboring host tissue, as compared to the other groups (P < 0.05). Moreover, addition of human renal cells to the MS1-coated scaffold resulted in further enhancement of vascularization and tubular structure regeneration within the implanted constructs. The biomimetic collagen vascular scaffolds coated with endothelial cells are able to enhance vascularization and facilitate the formation of renal tubules after 14 days when combined with human renal cells. This study shows the feasibility of bioengineering vascularized functional renal tissues for kidney regeneration. STATEMENT OF SIGNIFICANCE: Vascularization is one of the major hurdles affecting the survival and integration of implanted three-dimensional tissue constructs in vivo. A novel, biomimetic, collagen-based vascular scaffold that is structurally identical to native kidney tissue was developed and tested. This biomimetic vascularized scaffold system facilitates the development of new vessels and renal cell viability in vivo when implanted in a partial renal defect. The use of this scaffold system could address the challenges associated with vascularization, and may be an ideal treatment strategy for partial augmentation of renal function in patients with chronic kidney disease.