Region Specific Brain Organoids to Study Neurodevelopmental Disorders

Region specific brain organoids are brain organoids derived by patterning protocols using extrinsic signals as opposed to cerebral organoids obtained by self-patterning. The main focus of this review is to discuss various region-specific brain organoids developed so far and their application in modeling neurodevelopmental disease. We first discuss the principles of neural axis formation by series of growth factors, such as SHH, WNT, BMP signalings, that are critical to generate various region-specific brain organoids. Then we discuss various neurodevelopmental disorders modeled so far with these region-specific brain organoids, and findings made on mechanism and treatment options for neurodevelopmental disorders (NDD).

Correction to: New Advances in Human X Chromosome Status from a Developmental and Stem Cell Biology

Unfortunately, Acknowledgements section was missing in the originally published article.

New Advances in Human X Chromosome Status from a Developmental and Stem Cell Biology

Recent advances in stem cell biology have dramatically increased the understanding of molecular and cellular mechanism of pluripotency and cell fate determination. Additionally, pluripotent stem cells (PSCs), including embryonic stem cells and induced pluripotent stem cells, arose as essential resources for disease modeling and cellular therapeutics. Despite these advancements, the epigenetic dysregulation in pluripotency such as the imprinting status, and X chromosome dosage compensation, and its consequences on future utility of PSCs yet remain unresolved. In this review, we will focus on the X chromosome regulation in human PSCs (hPSCs). We will introduce the previous findings in the dosage compensation process on mouse model, and make comparison with those of human systems. Particularly, the X chromosome activation status of human preimplantation embryos, and the regulation of the active X chromosome by human specific lincRNA, X Active Coating Transcript (XACT), will be discussed. We will also discuss the recent findings on higher order X chromosome architecture, and abnormal X chromosome status in hPSCs.

In Vivo Roles of a Patient-Derived Induced Pluripotent Stem Cell Line (HD72-iPSC) in the YAC128 Model of Huntington's Disease

Induced pluripotent stem cells (iPSCs) generated from somatic cells of patients can provide immense opportunities to model human diseases, which may lead to develop novel therapeutics. Huntington's disease (HD) is a devastating neurodegenerative genetic disease, with no available therapeutic options at the moment. We recently reported the characteristics of a HD patient-derived iPSC carrying 72 CAG repeats (HD72-iPSC). In this study, we investigated the in vivo roles of HD72-iPSC in the YAC128 transgenic mice, a commonly used HD mouse model carrying 128 CAG repeats. To do this, we transplanted HD72-iPSC-derived neural precursors into the striatum of YAC128 mice bilaterally and observed a significant behavioral improvement in the grafted mice. Interestingly, the transplanted HD72-iPSC-derived neural precursors formed GABAeric neurons efficiently, but no EM48-positive protein aggregates were detected at 12 weeks after transplantation. Taken together, these results indicate no HD pathology was developed from the grafted cells, or no transmission of HD pathology from the host to the graft occurred at 12 weeks post-transplantation.