Cystic partially differentiated nephroblastoma in an adult: a case imitating the process of normal nephrogenesis along with corresponding WT1 expression

Cystic partially differentiated nephroblastoma (CPDN) is extremely rare in adults. Only 2 cases have been documented in the English literature. Herein, we present a third case of CPDN with unique morphological and immunohistochemical features. A 45-year-old man had a multicystic right renal mass, with a maximum diameter of 3 cm on magnetic resonance imaging. Being unable to rule out malignancy, partial nephrectomy was performed. The surgically resected specimen contained a multicystic mass, 3 × 3 × 2.5 cm in size, without an expansile solid nodule. Histopathological examination revealed nephroblastomatous elements without identifiable blastema; transition from cap-mesenchyme-like cells to an immature glomerulus was observed and maturing tubules and a glomerulus were present. Despite the lack of a blastema, the diagnosis of CPDN was the most appropriate. Immunohistochemical WT1 expression imitated the pattern of ongoing normal nephrogenesis. Therefore, we believe that the blastema disappeared because of maturation.     

Analysis of structure and gene expression in developing kidneys of male and female rats exposed to low protein diets in utero

A maternal low protein (LP) diet in rodents often results in low nephron endowment and renal pathophysiology in adult life, with outcomes often differing between male and female offspring. Precisely how a maternal LP diet results in low nephron endowment is unknown. We conducted morphological and molecular studies of branching morphogenesis and nephrogenesis to identify mechanisms and timepoints that might give rise to low nephron endowment. Sprague–Dawley rats were fed a normal protein (19.4% protein, NP) or LP (9% protein) diet for 3 weeks prior to mating and throughout gestation. Embryonic day 14.25 (E14.25) kidneys from males and females were either cultured for 2 days after which branching morphogenesis was quantified, or frozen for gene expression analysis. Real-time PCR was used to quantify expression of key nephrogenesis and branching morphogenesis genes at E14.25 and 17.25. At E17.25, nephron number was determined in fixed tissue. There was no effect of either maternal diet or sex on branching morphogenesis. Nephron number at E17.25 was 14% lower in male and female LP offspring than in NP controls. At E14.25 expression levels of genes involved in branching morphogenesis (Gfrα1, Bmp4, Gdnf) and nephrogenesis (Hnf4a, Pax2, Wnt4) were similar in the dietary groups, but significant differences between sexes were identified. At E17.25, expression of Gfrα1, Gdnf, Bmp4, Pax2 and Six2 was lower in LP offspring than NP offspring, in both male and female offspring. These findings provide new insights into how a LP diet leads to low nephron endowment and renal sexual dimorphism.     

Gremlin – a putative pathogenic player in progressive renal disease

Progressive renal fibrosis is the end process of renal injury leading to kidney failure. Current therapies for chronic renal failure aim to slow this process but fail to halt its progression. As the mechanisms involved in glomerulosclerosis and tubulointerstitial fibrosis are unravelled, potential treatments for this growing clinical problem should emerge. Gremlin, a developmental regulator of bone morphogenetic proteins (BMPs), has recently been implicated in processes such as glomerulosclerosis, tubulointerstitial fibrosis and cellular hypertrophy, and may represent a novel therapeutic target in progressive renal diseases.     

Nephrogenesis accompanied by vascularisation in the mouse embryonic metanephros transplanted into the adult kidney for the creation of additional nephrons

SUMMARY: Metanephric kidneys of nude mice were transplanted on embryonic day 12 into an adult kidney of the same strain, and the growth of the implants was analysed histochemically to investigate the ontogenesis, structure and function of the newly developed additional nephrons. By using a light microscope, developing nephrons at various stages were observed in the implants growing in the host kidney 7 days after transplantation. Immature nephrons, comprising the nephrogenic zone, were intensely positive for proliferating cell nuclear antigen (PCNA) immunostaining, but were no longer present 14 days after transplantation. Vascular integration was observed between the host and implant tissues. Electron microscopic observation 14 days after transplantation showed that the afferent arterioles together with juxtaglomerular cells had entered the gtomeruli. All of the cell types were identified in the vascularised glomeruli with erythrocytes. the visceral epithelial cells had differentiated foot processes, whereas the endothelium of the glomerular tufts was rather thick in parts, and most of the epithelial and endothelial basement membranes were not fused. Several parts of the uriniferous tubules, including proximal and distal tubules, could be identified, and it was found that many of them had remained immature. Some proximal tubules with well-developed brush-border microvilli reabsorbed the horseradish peroxidase (HRP) injected into the host inferior vena cava, thus providing evidence of glomerular ultrafiltration in the vascularised implants perfused by the host. These findings indicate that the nephrogenesis in the implants followed a nearly normal developmental route and showed marked vascularisation, which promoted the organogenesis of the implanted metanephros and nephron function.     

Expression of TGF-α, EGF and their common receptor in human fetal kidney

Summary: Transforming growth factor-α (TGF-α) and epidermal growth factor (EGF) are structurally related mitogenic polypeptides. They share the same receptor; EGF receptor. the EGF receptor is widely expressed in human fetal tissues including the kidney, but little is known about the role of TGF-α/EGF/EGF receptor system in human fetal kidney. the expression of TGF-α, EGF and their common receptor was investigated immunohistochemically in the human fetal kidneys. In the cortex, immunoreactivity for TGF-α was found in the differentiating proximal tubules. In contrast, immunoreactivity for EGF was present in the thick ascending limbs of the Henle's loop (TAL) and medullary collecting duct cells (CD). Immunoreactivity for their common receptor was present mainly in the TAL and medullary CD. These data support the assumption that the system of TGF-α, EGF and its receptor has an important role in the proliferation and differentiation of the TAL and medullary CD. the different localization of TGF-α and its receptor may indicate that TGF-α acts through a paracrine mechanism. the co-localization of EGF and its receptor in the TAL and medullary CD suggests that EGF may act as an autocrine growth factor.     

The renin–angiotensin system from conception to old age: the good,the bad and the ugly

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