Fetal nephrotoxicity

Generating Kidney from Stem Cells

Human kidney tissue can now be generated via the directed differentiation of human pluripotent stem cells. This advance is anticipated to facilitate the modeling of human kidney diseases, provide platforms for nephrotoxicity screening, enable cellular therapy, and potentially generate tissue for renal replacement. All such applications will rely upon the accuracy and reliability of the model and the capacity for stem cell-derived kidney tissue to recapitulate both normal and diseased states. In this review, we discuss the models available, how well they recapitulate the human kidney, and how far we are from application of these cells for use in cellular therapies.

North American opossum Didelphis virginiana as a fetal nephrotoxicity model: histologic and ultrastructural assessment of uranyl nitrate (UN)-induced damage

We have used our opossum model of fetal nephrotoxicity to investigate uranyl nitrate-induced morphologic changes in the developing kidney. The present study establishes a renal dose response curve for the uranyl nitrate (UN). We find that pups treated with nonlethal doses of UN do not demonstrate growth retardation compared to saline-treated controls. The kidneys of UN-treated pups are heavier than the control animals, an effect less apparent the longer the pups are followed. A low dose of 60 mg/kg of UN administered to small pups causes slight histologic derangement but nevertheless more change than the same dose administered to larger more mature pups. Using a dose of 100 mg/kg of UN that effectively causes nonfatal renal disruption, we examined the kidneys from 4 to 42 days following injection. We find that tubular dilation and epithelial necrosis starts soon after treatment (day 4) and reaches its maximum during the second and third week (11 and 22 days). Architectural restoration appears complete by the end of the third week. By electron microscopy, UN induces sequential structural damage with loss of proximal tubule brush border, epithelial necrosis with intact basement membranes and regeneration at 4, 11, and 22 days. Residual tubular mitochondrial damage is present at 42 days in spite of histologically normal tubules. No apparent lesions are seen in glomeruli. Fibroblastic interstitial proliferation in UN-treated kidneys at 11 days is not followed by appreciable fibrosis when assessed at 22 and 42 days. As the structural changes caused by 100 mg/ml UN administration in fetal opossum kidneys are reversible, this is a useful model to study the molecular mediators responsible for this form of renal damage and repair.

Review of microscopic studies on the fetal and neonatal kidney

The developing mammalian kidney has been studied by light microscopic, electron microscopic, immunohistochemical, and autoradiographic techniques. The microscopic studies have been conducted on in vivo samples and in vitro samples. The cellular biology and molecular biology of the developmental steps have been clarified, but more investigations are needed. Information has also been collected concerning the influence of the environment on the microscopic development of the kidney.