Standardized Colon Ascendens Stent Peritonitis in Rats - a Simple, Feasible Animal Model to Induce Septic Acute Kidney Injury

Summary

Acute kidney injury (AKI) is a severe complication in critically ill patients and is related with an increased mortality. Here, we present a reliable and reproducible in vivo model to mimic AKI under inflammatory conditions that might contribute towards understanding the pathogenesis of septic AKI.

Abstract

AKI in septic patients is associated with increased mortality and poor outcome despite major efforts to refine the understanding of its pathophysiology. Here, an in vivo model is presented that combines a standardized septic focus to induce AKI and an intensive care (ICU) setup to provide an advanced hemodynamic monitoring and therapy comparable in human sepsis. Sepsis is induced by standardized colon ascendens stent peritonitis (sCASP). AKI is investigated functionally by measurement of blood and urine samples as well as histologically by evaluation of histopathological scores. Furthermore, the advanced hemodynamic monitoring and the possibility of repetitive blood gas sampling enable a differentiated analysis of severity of induced sepsis.

The sCASP method is a standardized, reliable and reproducible method to induce septic AKI. The intensive care setup, continuous hemodynamic and gas exchange monitoring, low mortality rate as well as the opportunity of detailed analyses of kidney function and impairments are advantages of this setup. Therefore, the described method may serve as a new standard for experimental investigations of septic AKI.

Introduction

Sepsis still remains the leading cause of death on non-cardiac intensive care units (ICU) with mortality rates of ≈ 30 - 50%^1,2,3. A hallmark of severe sepsis and septic shock is the acute kidney injury that causes a further increase of mortality rate when it is associated with distant organ dysfunction such as cardiac and respiratory failure^4,5,6. The overall incidence of AKI in ICU patients varies from 20 to 50%⁷. Despite the pivotal role of AKI regard....

Protocol

All animal procedures were approved by the Laboratory Animal Care and Use Committee of the District of Unterfranken, Germany and carried out according to the Declaration of Helsinki.

1. Surgical preparation and installation of invasive monitoring and continuous medication

1. Anesthetize Sprague-Dawley rats using isoflurane delivered by precision vaporizer at a concentration and flow rate approved by local institution’s animal research oversight body and/or veterinary team. Confirm adequate depth of .......

Discussion

The pathophysiology of septic AKI still remains unknown in its complexity. Clinical research and trials in patients will not enable gains of new insights with respect to histopathology changes, microcirculation disturbances or drug interactions on cellular levels¹⁵. It has been postulated previously that there is a need for improved and new animal models to investigate acute kidney injury associated with sepsis¹⁹. Therefore, we established a new animal model for septic AKI .......

Materials

Name	Company	Catalog Number	Comments
Sprague-Dawley rats	Janvier Labs, France
Isoflurane CP	cp-pharma, Burgdorf, Germany
polyethylen catheter PE 10; 30m	A. Hartenstein, Wuerzburg, Germany		0.58x0.96 mm
Swivel (375/D/20)	Instech, Plymouth Meeting, PA, USA		(375/D/20)
plastic button tethers	Instech, Plymouth Meeting, PA, USA		LW105S
Perfusor	B. Braun; Melsungen, Germany		Perfusor fm
suction catheter ch. 10	B.Braun Melsungen AG, Germany		suction catheter typy „Ideal“; ch. 10
suture	Syneture; USA		Surgipro; Monofilament Polypropylen 4-0
suture	Ethicon; Scotland		Prolene; Polypropylen 5-0
14G-i.v. catheter	BD Insynte; BD Vialon; Madrid; Spain		14GA i.v. catheter
cotton buds	NOBA Verbandmittel Danz GmbH u Co KG; Wetter; Germany
rodent respirator	Hugo Sachs Elektronik KG, Germany		rodent respirator, Type:7025
Midazolam	Ratiopharm, Germany		Midazolam
Thermodilutioncatheter	ADInstruments, Spechbach, Germany
p-Aminohippuric acid	Sigma-Aldrich; St. Louis; USA		p-Aminohippuric acid sodium salt; A3759-25G
Inulin	Sigma-Aldrich; St. Louis; USA		Inulin-FITC; F3272-1G
Formaldehyde	Otto Fischar GmbH & CoKG; Saarbrücken, Germany		Formaldehyde 3.5%
Cyclopentan	Merck; Darmstadt; Germany		Uvasol: 2-Methylbutan
alcohol based scrub	Schülke & Mayr GmbH, Norderstedt; Germany		kodan Tinktur forte; 45g 2-Propanol, 10g 1-Propanol per 100g
povidone iodine solution	B.Braun Melsungen AG, Germany		Braunol, 7.5g Povidone Iodine per 100g