Human Embryonic Stem Cell-Derived Wilson's Disease Model for Screening Drug Efficacy.

Human pluripotent stem cells (hPSCs) including human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) have been extensively studied as an alternative cellular model for recapitulating phenotypic and pathophysiologic characters of human diseases. Particularly, hiPSCs generated from the genetic disease somatic cells could provide a good cellular model to screen potential drugs for treating human genetic disorders. However, the patient-derived cellular model has a limitation when the patient samples bearing genetic mutations are difficult to obtain due to their rarity. Thus, in this study, we explored the potential use of hPSC-derived Wilson's disease model generated without a patient sample to provide an alternative approach for modeling human genetic disease by applying gene editing technology. Wilson's disease hPSCs were generated by introducing a R778L mutation in the ATP7B gene (c.2333G>T) using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system into wildtype hESCs. Established Wilson's disease hESCs were further differentiated into hepatocyte-like cells (HLCs) and analyzed for disease phenotypes and responses against therapeutic agent treatment. R778L mutation in the ATP7B gene was successfully introduced into wildtype hESCs, and the introduction of the mutation neither altered the self-renewal ability of hESCs nor the differentiation capability into HLCs. However, R778L mutation-introduced HLCs exhibited higher vulnerability against excessive copper supplementation than wildtype HLCs. Finally, the applicability of the R778L mutation introduced HLCs in drug screening was further demonstrated using therapeutic agents against the Wilson's diseases. Therefore, the established model in this study could effectively mimic the Wilson's disease without patient's somatic cells and could provide a reliable alternative model for studying and drug screening of Wilson's disease.

Characterization of the Subventricular-Thalamo-Cortical Circuit in the NP-C Mouse Brain, and New Insights Regarding Treatment.

Gliosis in Niemann-Pick type C (NP-C) disease is characterized by marked changes in microglia and astrocytes. However, the gliosis onset and progression in NP-C has not been systematically studied, nor has the mechanism underlying this finding. Here, we found early gliosis in the subventricular zone (SVZ) of NP-C mice. Neural progenitor damage by Npc1 mutation suppressed vascular endothelial growth factor (VEGF) expression and further induced microglia activation followed by astrogliosis. Interestingly, excessive astrogliosis in the SVZ induced neural progenitor retention and/or migration into thalamus via astrocyte-derived VEGF, resulting in acceleration of thalamic and cortical gliosis through thalamo-cortical pathways. Transplantation of VEGF-overexpressing neural stem cells into the SVZ improved whole-brain pathology of NP-C mice. Overall, our data provide a new pathological perspective on NP-C neural pathology, revealing abnormalities in the subventricular-thalamo-cortical circuit of NP-C mouse brain and highlighting the importance of the SVZ microenvironment as a therapeutic target for NP-C disease.

Long-term clinical outcome and the identification of homozygous CYP27B1 gene mutations in a patient with vitamin D hydroxylation-deficient rickets type 1A.

Vitamin D hydroxylation-deficient rickets type 1A (VDDR1A) is an autosomal recessively-inherited disorder caused by mutations in CYP27B1 encoding the 1α-hydroxylase enzyme. We report on a female patient with VDDR1A who presented with hypocalcemic seizure at the age of 13 months. The typical clinical and biochemical features of VDDR1A were found, such as hypocalcemia, increased alkaline phosphatase, secondary hyperparathyroidism and normal 25-hydroxyvitamin D3 (25(OH)D3). Radiographic images of the wrist showed metaphyseal widening with cupping and fraying of the ulna and distal radius, suggesting rickets. A mutation analysis of the CYP27B1 gene identified a homozygous mutation of c.589+1G>A in the splice donor site in intron 3, which was known to be pathogenic. Since that time, the patient has been under calcitriol and calcium treatment, with normal growth and development. During the follow-up period, she did not develop genu valgum, scoliosis, or nephrocalcinosis.

Diverse genetic aetiologies and clinical outcomes of paediatric hypoparathyroidism.

CONTEXT: Hypoparathyroidism is characterized by hypocalcaemia, hyperphosphataemia, and low or inappropriately normal parathyroid hormone (PTH) levels. Idiopathic or genetic drivers are the predominant causes of hypoparathyroidism in paediatric-age patients. OBJECTIVE: This study investigated the aetiology and clinical course of primary hypoparathyroidism in infancy and childhood. SUBJECTS AND MEASUREMENTS: This study included 37 patients (23 males, 14 females) with primary hypoparathyroidism diagnosed prior to 18 years of age. We analysed aetiologies, initial presentation, age at diagnosis, endocrine and radiological findings, and outcomes. RESULTS: The median age at presentation was 1·7 months (range 1 day-17 years), and the mean follow-up duration was 7·0 ± 5·3 years (range 0·5-16·8 years). Our cohort included 22 cases (59·5%) of 22q11·2 microdeletion syndrome. Other aetiologies included hypoparathyroidism-deafness-renal dysplasia syndrome (5/37, 13·5%) and one patient each with autoimmune polyglandular syndrome type 1, Kearns-Sayre syndrome and Kenny-Caffey syndrome. The remaining 7 (18·9%) patients were classified as idiopathic hypoparathyroidism cases. Among the 15 patients who underwent brain imaging, 5 (33·3%) had basal ganglia calcification. Among the 26 patients examined by renal imaging, 5 (19·2%) had either nephrocalcinosis or a renal stone. After 11 months of calcium or calcitriol supplementation, 16 patients (43·2%) discontinued medication. The final PTH levels were significantly higher in patients with transient hypoparathyroidism than those with permanent hypoparathyroidism. CONCLUSIONS: Identification of the genetic aetiologies of hypoparathyroidism makes it possible to predict patient outcomes and provide appropriate genetic counselling. Long-term treatment with calcium and calcitriol necessitates monitoring for renal complications.