The brainstem is a posterior region of the brain, composed of three parts, midbrain, pons, and medulla oblongata. It is critical in controlling heartbeat, blood pressure, and respiration, all of which are life-sustaining functions, and therefore, damages to or disorders of the brainstem can be lethal. Brain organoids derived from human pluripotent stem cells (hPSCs) recapitulate the course of human brain development and are expected to be useful for medical research on central nervous system disorders. However, existing organoid models are limited in the extent hPSCs recapitulate human brain development and hence are not able to fully elucidate the diseases affecting various components of the brain such as brainstem. Here, we developed a method to generate human brainstem organoids (hBSOs), containing midbrain/hindbrain progenitors, noradrenergic and cholinergic neurons, dopaminergic neurons, and neural crest lineage cells. Single-cell RNA sequence (scRNA-seq) analysis, together with evidence from proteomics and electrophysiology, revealed that the cellular population in these organoids was similar to that of the human brainstem, which raises the possibility of making use of hBSOs in investigating central nervous system disorders affecting brainstem and in efficient drug screenings.

Human stem cell-derived organoids have great potential for modelling physiological and pathological processes. They recapitulate in vitro the organization and function of a respective organ or part of an organ. Human midbrain organoids (hMOs) have been described to contain midbrain-specific dopaminergic neurons that release the neurotransmitter dopamine. However, the human midbrain contains also additional neuronal cell types, which are functionally interacting with each other. Here, we analysed hMOs at high-resolution by means of single-cell RNA sequencing (scRNA-seq), imaging and electrophysiology to unravel cell heterogeneity. Our findings demonstrate that hMOs show essential neuronal functional properties as spontaneous electrophysiological activity of different neuronal subtypes, including dopaminergic, GABAergic, glutamatergic and serotonergic neurons. Recapitulating these in vivo features makes hMOs an excellent tool for in vitro disease phenotyping and drug discovery.

Sporadic Inclusion Body Myositis (sIBM) is a refractory myositis developing in the elderly. Recently, anti-cytosolic 5'-nucleotidase 1A (cN1A) antibodies were reported to be present specifically in sIBM. To assess the clinicopathological features and usefulness of anti-cN1A positivity in muscle specimens, we evaluated a group of Japanese patients with sIBM. Among Japanese patients with myositis who underwent a muscle biopsy from 1991 through 2014 in our hospital, we identified cases of sIBM that met the European Neuromuscular Center (ENMC) criteria. We then analyzed clinical course, pathological findings, and treatment response. Of 282 patients with myositis, 35 (12%) were given a diagnosis of sIBM (24 men and 11 women). The median age at onset was 67 ± 7 (55-81) years, and that at diagnosis was 70 ± 7 years. Remarkably, 5 (14%) patients concurrently had hepatitis C virus (HCV) infection and 4 (11%) had heart disease. Pathologically, we found rimmed vacuoles in 32 (91%) patients and anti-cN1A positivity in perinuclear regions and rimmed vacuoles in 31 (89%) patients. Remarkably, anti-cN1A antibody positivity was significantly higher in sIBM than in polymyositis (30%), dermatomyositis (10%), and morphologically normal cases (0%), suggesting its high specificity for sIBM. Twelve (34%) patients received immunosuppressants, 8 (23%) received prednisone, and 5 (14%) received intravenous immunoglobulins (IVIg). Clinical symptoms transiently improved in 5 patients given prednisone and in 4 patients given IVIg, but these treatments failed to be radical therapies. In our study of Japanese patients with sIBM, anti-cN1A antibody positivity in muscle specimens was highly sensitive and specific pathologically. Therefore, the expression of anticN1A antibody may be greatly useful for the diagnosis of sIBM. Although the concurrent presence of HCV infection and heart disease was notable, other epidemiological characteristics were consistent with the results of previous studies.

Ischemic stroke is one of the most common neurological diseases. However, the impact of ischemic stroke on human cerebral tissue remains largely unknown due to a lack of ischemic human brain samples. In this study, we applied cerebral organoids derived from human induced pluripotent stem cells to evaluate the effect of oxygen-glucose deprivation/reoxygenation (OGD/R). Pathway analysis showed the relationships between vitamin digestion and absorption, fat digestion and absorption, peroxisome proliferator-activated receptor (PPAR) signaling pathway, and complement and coagulation cascades. Combinational verification with transcriptome and gene expression analysis of different cell types revealed fatty acids-related PPAR signaling pathway and pyruvate kinase isoform M2 (PKM2) as key markers of neuronal cells in response to OGD/R. These findings suggest that, although there remain some limitations to be improved, our ischemic stroke model using human cerebral organoids would be a potentially useful tool when combined with other conventional two-dimensional (2D) mono-culture systems.

The brainstem controls heartbeat, blood pressure and respiration, which are life-sustaining functions, therefore, disorders of the brainstem can be lethal. Brain organoids derived from human pluripotent stem cells recapitulate the course of human brain development and are expected to be useful for medical research on central nervous system disorders. However, existing organoid models have limitations, hampering the elucidation of diseases affecting specific components of the brain. . Here, we developed a method to generate human brainstem organoids (hBSOs), containing neural crest stem cells as well as midbrain/hindbrain progenitors, noradrenergic and cholinergic neurons, and dopaminergic neurons, demonstrated by specific electrophysiological signatures. Single-cell RNA sequence analysis, together with proteomics and electrophysiology, revealed that the cellular population in these organoids was similar to that of the human brainstem and neural crest, which raises the possibility of making use of hBSOs in grafting for transplantation, efficient drug screenings and modeling the neural crest diseases. IntroductionThe brainstem is a posterior region of the brain between the deep structures of the cerebral hemispheres. It connects the cerebrum with the spinal cord and is divided into three parts: midbrain, pons and medulla oblongata. They contain multiple nuclei and small fiber tracts widely projecting to the cerebrum cortex, basal ganglia and other parts of the cerebrum. Brainstem functions such as alertness, heartbeat, blood pressure and respiration are considered to be more vital for life than that of the cortex. Therefore, damages to or disorders of brainstem such as infarction, hemorrhage, tumors, or any neurodegenerative diseases may lead to death.Of those, Parkinson's disease (PD) is the most well-known degenerative disease, showing progressive voluntary movement impairments, including rigidity, akinesia, tremor, and postural instability. These symptoms are caused by the loss of dopaminergic neurons at midbrain substantia nigra. In addition, non-motor symptoms, such as autonomic dysfunction, sleep disorder, and depression in PD patients, are thought to be derived from impairments of the serotonergic or noradrenergic system in the brainstem. However, the mechanisms driving these symptoms have yet to be determined. Hence, we need the development of models that can recapitulate the human midbrain and surrounding brainstem to elucidate the process of neural degeneration in this area.Recent progress on protocols for inducing organs in-a-dish (organoids) provides potentials for the modeling of various diseases (Clevers, 2016). Organoids mimic the structure of organs Eura, Matsui, Luginbühl et al.