Complex Assessment of the Functional State of the Urinary System in Preclinical Studies. Part 1. Instrumental and Laboratory Assessment Methods (Review)

Abstract

INTRODUCTION. Functional examination of the urinary system, and particularly the kidneys, is an important challenge in preclinical studies. Currently, there is no generally recognised and detailed approach to drug-induced nephrotoxicity detection in vivo, nor are there clear criteria for its assessment.AIM. This study aimed to analyse and systematise instrumental and laboratory methods for the assessment of urinary system function in laboratory animals and to identify the basic principles for studying drug-induced nephrotoxic effects.DISCUSSION. The study analysed the advantages and limitations of the methods used to study the nephrotoxicity of medicinal products, with considerations for the use of these methods in small and large laboratory animals. The effects of a test substance on the urinary system should first be evaluated using minimally invasive methods. One of these methods is urinalysis. For urinalysis, important considerations include the sampling technique, the volume of the biomaterial, and the turnaround time between urine collection and analysis. Ultrasonography is the most accessible instrumental method in preclinical studies. Ultrasonography can assess organ position, size, structure, and echogenicity and detect abnormalities and changes in real time. Dif ferent method settings are preferred for each species of laboratory animal. Further analysis can include macroscopic examination of organs, measurement of their masses, and microscopic analysis of tissues. Visual assessment should cover the size, colour, and consistency of the ureters, bladder, and kidneys. Nephrotoxicity may manifest as increased apoptosis, vacuolation of renal tubular epithelial cells, epithelial degeneration or dystrophy, oedema, diapedesis-associated haemorrhages, acute tubular and papillary necrosis, necrosis of the Bowman–Schumlansky capsule, casts and crystals in the tubular lumen, glomerulopathy with the corresponding changes, and inflammatory and vascular reactions.CONCLUSIONS. The study analysed and systematised instrumental and laboratory methods for assessing the functional state of the urinary system in preclinical studies. The authors outlined the basic principles for a structured and comprehensive study of the potential nephrotoxicity of novel medicines. The assessment of nephrotoxicity should start with simple and minimally invasive laboratory and instrumental methods, which include general urinalysis and microscopic examination of urine sediment. These methods can detect organ dysfunction that has not yet presented with an associated anatomical lesion. A more in-depth analysis should involve histological and immunohistochemical methods to examine the urinary tissues of laboratory animals.