Matching Human Unilateral AKI, a Reverse Translational Approach to Investigate Kidney Recovery after Ischemia

Abstract

BackgroundThe duration of renal ischemia that is associated with (or leads to) renal injury in patients is uncertain, and a reverse translational research approach has been proposed to improve animal models of AKI to facilitate clinical translatability. We developed a two murine models of unilateral renal ischemia to match a recently published human study that investigated renal injury after unilateral renal ischemia during partial nephrectomy.MethodsEight 10-week-old C57BL/6 male mice underwent left UiAKI or sham procedure, with or without intra-operative ice packs. Functional, histological, and biomarker outcomes were followed at 2, 6 and 24 hours, or 14 or 28 days later. The 14 and 28 day cohorts were duplicated such that contralateral nephrectomy could be performed 3 days prior to sacrifice with functional measurements obtained to isolate the glomerular filtration rate of the injured kidney.ResultsThe short-term outcomes correlated with the human study findings with urine and serum biomarkers of injury peaking around 24 hours and then normalizing, and reassuring immediate histological outcomes. Functional and histological outcomes at the later time-points (14 and 28 days) demonstrate an increase in fibrosis markers, and a reduction in glomerular filtration rate in the injured kidney, corresponding to the duration of ischemia, while serum and urine biomarkers remained reassuring.ConclusionsOur findings suggest that clinically available biomarkers of renal function are falsely reassuring against long-term injury following UiAKI, and that the duration of ischemia correlates with impaired function and increased fibrosis.

Acute Kidney Injury Results in Long-Term Diastolic Dysfunction That Is Prevented by Histone Deacetylase Inhibition

“…Imaging software (Image J) was used to calculate the percent area of polarization. Immunohistochemistry for collagen type 3 was performed following standard protocols using goat anti-type III collagen antibody (Cat # 1330-01, Southern Biotech, Birmingham, Alabama [1:100]), followed by rabbit antigoat horseradish peroxidase (Ref # P0449, Dako, Carpinteria, California [1:200]) and analyzed as described previously ( 29 ). Both kidneys were analyzed for PSR and collagen 3, and the average was used for analysis.…”

“…Kidneys were homogenized and analyzed using 1× RIPA buffer (Cell Signaling Technology, Danvers, Massachusetts) with either α-smooth muscle actin (SMA) primary antibody (ab32575, Abcam, Cambridge, United Kingdom, 1:5000) or KIM-1 Primary antibody (Cat#: AF1817, R and D Systems, Minneapolis, Minnesota, 1:1000) as previously described ( 29 ). Blots were normalized using the Revert Total Protein Stain (Cat # 926-11010, Licor, Lincoln, Nebraska) as a loading control and performed following the manufacturer’s instructions.…”

RNA-Seq identifies condition-specific biological signatures of ischemia-reperfusion injury in the human kidney

“…For instance, serum creatinine level may not completely reflect the loss of kidney function during early stages [9]. Further, considering the ethical and regulatory obstacles related to human clinical studies, many studies on AKI have been conducted as observational or treatment research using murine animals [10][11][12][13]. These animal models of AKI mostly include young male mice with normal kidney functions that are evidently different from the actual clinical condition in human patients [14].…”

The sympathetic nervous system in acute kidney injury

“…64 A single-centre study in 30 paediatric patients (1-6 years old) who underwent cardiac surgery reported lower GFR and higher AKI incidence based on serum creatinine measurements obtained 5 minutes and 2 hours after weaning from cardiopulmonary bypass. [66][67][68] Their use in studies on the role of sympathetic activation may improve translatability of experimental data. In contrast to experimental renal IR studies where conditions can be well standardized, the effects of sympatholytics may have been blurred by the complexity of clinical scenarios and factors such as patient age, genetic diversity, associated chronic diseases and diverse co-medications.…”

“…3 Currently, reverse translational approaches are taken to better match animal models of renal IR to clinical situations that cause AKI. [66][67][68] Their use in studies on the role of sympathetic activation may improve translatability of experimental data.…”