Vasculogenesis in kidney organoids upon transplantation.

Human induced pluripotent stem cell-derived kidney organoids have potential for disease modeling and to be developed into clinically transplantable auxiliary tissue. However, they lack a functional vasculature, and the sparse endogenous endothelial cells (ECs) are lost upon prolonged culture in vitro, limiting maturation and applicability. Here, we use intracoelomic transplantation in chicken embryos followed by single-cell RNA sequencing and advanced imaging platforms to induce and study vasculogenesis in kidney organoids. We show expansion of human organoid-derived ECs that reorganize into perfused capillaries and form a chimeric vascular network with host-derived blood vessels. Ligand-receptor analysis infers extensive potential interactions of human ECs with perivascular cells upon transplantation, enabling vessel wall stabilization. Perfused glomeruli display maturation and morphogenesis to capillary loop stage. Our findings demonstrate the beneficial effect of vascularization on not only epithelial cell types, but also the mesenchymal compartment, inducing the expansion of ´on target´ perivascular stromal cells, which in turn are required for further maturation and stabilization of the neo-vasculature. The here described vasculogenic capacity of kidney organoids will have to be deployed to achieve meaningful glomerular maturation and kidney morphogenesis in vitro.

Hedgehog-GLI signaling in Foxd1-positive stromal cells promotes murine nephrogenesis via TGFß signaling.

Normal kidney function depends on the proper development of the nephron: the functional unit of the kidney. Reciprocal signaling interactions between the stroma and nephron progenitor compartment have been proposed to control nephron development. Here, we show that removal of hedgehog intracellular effector smoothened (Smo-deficient mutants) in the cortical stroma results in an abnormal renal capsule, and an expanded nephron progenitor domain with an accompanying decrease in nephron number via a block in epithelialization. We show that stromal-hedgehog-Smo signaling acts through a GLI3 repressor. Whole-kidney RNA sequencing and analysis of FACS-isolated stromal cells identified impaired TGFß2 signaling in Smo-deficient mutants. We show that neutralization and knockdown of TGFß2 in explants inhibited nephrogenesis. In addition, we demonstrate that concurrent deletion of Tgfbr2 in stromal and nephrogenic cells in vivo results in decreased nephron formation and an expanded nephrogenic precursor domain similar to that observed in Smo-deficient mutant mice. Together, our data suggest a mechanism whereby a stromal hedgehog-TGFß2 signaling axis acts to control nephrogenesis.

A curious case of growth failure and hypercalcemia: Questions.

BACKGROUND: Sarcoidosis is a multisystem granulomatous disease of unknown etiology that rarely presents in childhood. Here, we report a case of pediatric sarcoidosis presenting with renal failure and hypercalcemia. CASE DIAGNOSIS/TREATMENT: A previously well 14-year-old Caucasian boy was admitted to the Hospital for Sick Children, Canada, for hypertension and renal failure following work-up by his family physician for initial concerns of growth failure. On admission, his weight was 35 kg (<3rd percentile), his height was 148 cm (≪3rd percentile), and his blood pressure was 154/116 mmHg (>99th percentile for height). Laboratory findings showed elevated creatinine (218 µmol/L), hypercalcemia (3.21 mmol/L), and normocytic anemia (hemoglobin 105 g/L). His further assessment showed a urinary concentrating defect with hypercalciuria (calcium/creatinine 1.76 mmol/mmol) and nephrocalcinosis on ultrasound. His eye examination showed uveitis with conjunctival biopsy remarkable for granulomas, which led to pursuit of a diagnosis of possible sarcoidosis. Angiotensin-converting enzyme was found to be high at 96 U/L, and he had a renal biopsy that was consistent with interstitial nephritis with granulomas. Treatment was started with prednisone leading to resolution of his hypercalcemia but persistence of his mild chronic kidney disease. CONCLUSIONS: This case represents an atypical presentation of a rare pediatric disease and highlights the spectrum of renal manifestations and treatment options in sarcoidosis.

A curious case of growth failure and hypercalcemia: Answers.

BACKGROUND: Sarcoidosis is a multisystem granulomatous disease of unknown etiology that rarely presents in childhood. Here, we report a case of pediatric sarcoidosis, presenting with renal failure and hypercalcemia. CASE DIAGNOSIS/TREATMENT: A previously well 14-year-old Caucasian boy was admitted to the Hospital for Sick Children, Canada, for hypertension and renal failure following work-up by his family physician for initial concerns of growth failure. On admission, his weight was 35 kg (<3rd percentile), his height was 148 cm (<<3rd percentile), and his blood pressure was 154/116 mmHg (>99th percentile for height). Laboratory findings showed elevated creatinine (218 umol/L), hypercalcemia (3.21 mmol/L), and normocytic anemia (hemoglobin 105 g/L). His further assessment showed a urinary concentrating defect with hypercalciuria (calcium/creatinine 1.76 mmol/mmol) and nephrocalcinosis on ultrasound. His eye examination showed uveitis with conjunctival biopsy remarkable for granulomas, which led to pursuit of a diagnosis of possible sarcoidosis. Angiotensin Angiotensin-converting enzyme was found to be high at 96 U/L, and he had a renal biopsy that was consistent with interstitial nephritis with granulomas. Treatment was started with prednisone leading to resolution of his hypercalcemia but persistence of his mild chronic kidney disease. CONCLUSIONS: This case represents an atypical presentation of a rare pediatric disease and highlights the spectrum of renal manifestations and treatment options in sarcoidosis.

Adult height in short children born SGA treated with growth hormone and gonadotropin releasing hormone analog: results of a randomized, dose-response GH trial.

CONTEXT: GH treatment is effective in improving height in short children born small for gestational age (SGA). GH is thought to have limited effect when started during adolescence. OBJECTIVE: The aim of this study was to investigate GH treatment efficacy in short SGA children when treatment was started during adolescence; to assess whether GH 2 mg/m(2) · d during puberty improves adult height (AH) compared with 1 mg/m(2) · d; and to assess whether an additional 2-yr postponement of puberty by GnRH analog (GnRHa) improves AH in children who are short at the start of puberty (<140 cm), with a poor AH expectation. PATIENTS AND DESIGN: In this longitudinal, randomized, dose-response GH trial, we included 121 short SGA children (60 boys) at least 8 yr of age. We performed intention-to-treat analyses on all children and uncensored case analyses on 84 children who reached AH. Besides, we evaluated growth during 2 yr of combined GH/GnRHa and subsequent GH treatment until AH in a subgroup of 40 pubertal children with a height of less than 140 cm at the start. RESULTS: Short SGA children started treatment at a median age of 11.2 yr, when 46% had already started puberty. Median height increased from -2.9 at start to -1.7 sd score (SDS) at AH (P < 0.001). Treatment with GH 2 vs. 1 mg/m(2) · d during puberty resulted in significantly better AH (P = 0.001), also after correction for gender, age at start, height SDS at start, treatment years before puberty, and target height SDS. AH was similar in children who started puberty at less than 140 cm and received GH/GnRHa, compared with children who started puberty greater than 140 cm and received GH only (P = 0.795). CONCLUSION: When started in adolescence, GH treatment significantly improves AH in short SGA children, particularly with GH 2 mg/m(2) · d during puberty. When SGA children are short at the start of puberty, they can benefit from combined GH/GnRHa treatment.

Evidence for an increasing presence of Echinococcus multilocularis in foxes in The Netherlands.

Echinococcus multilocularis, a tapeworm causing alveolar echinococcosis which is considered a serious zoonosis known to affect humans, appears to be expanding its geographical range in Europe. We studied the emergence of the parasite in the European westernmost edge of its geographical distribution, based on two consecutive parasitological examinations of red foxes (Vulpes vulpes) sampled between 1996 and 2003 in The Netherlands. The average worm count increased from 2.6 worms per fox in the first surveillance to 16.6 worms per fox in the second. Using a mathematical model for a spatially spreading parasite, we found a strong indication that the parasite population is increasing in number and is spreading northward at the speed of 2.7 km per year. The reproduction number (R0), reflecting the parasite's transmission process, is estimated from the surveillance data and it is likely to be more than 1 but not exceeding a value of 4. We analysed a parasite control strategy by estimating the critical fox density for parasite elimination. We conclude that E. multilocularis is an emerging parasite in The Netherlands and thus in the western part of Europe. Control will be very difficult given the current high fox population density.