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Human induced pluripotent stem cell (iPSC) lines are a powerful tool for studying development and disease, but the considerable phenotypic variation between lines makes it challenging to replicate key findings and integrate data across research groups. To address this issue, we sub-cloned candidate human iPSC lines and deeply characterized their genetic properties using whole genome sequencing, their genomic stability upon CRISPR-Cas9-based gene editing, and their phenotypic properties including differentiation to commonly used cell types. These studies identified KOLF2.1J as an all-around well-performing iPSC line. We then shared KOLF2.1J with groups around the world who tested its performance in head-to-head comparisons with their own preferred iPSC lines across a diverse range of differentiation protocols and functional assays. On the strength of these findings, we have made KOLF2.1J and its gene-edited derivative clones readily accessible to promote the standardization required for large-scale collaborative science in the stem cell field.

Summary: Pelizaeus-Merzbacher disease (PMD) is a fatal X-linked disorder caused by loss of myelinating oligodendrocytes and consequent hypomyelination. The underlying cellular and molecular dysfunctions are not fully defined, but therapeutic enhancement of oligodendrocyte survival could restore functional myelination in patients. Here we generated pure, scalable quantities of induced pluripotent stem cell-derived oligodendrocyte progenitor cells (OPCs) from a severe mouse model of PMD, Plp1jimpy. Temporal phenotypic and transcriptomic studies defined an early pathological window characterized by endoplasmic reticulum (ER) stress and cell death as OPCs exit their progenitor state. High-throughput phenotypic screening identified a compound, Ro 25–6981, which modulates the ER stress response and rescues mutant oligodendrocyte survival in jimpy, in vitro and in vivo, and in human PMD oligocortical spheroids. Surprisingly, increasing oligodendrocyte survival did not restore subsequent myelination, revealing a second pathological phase. Collectively, our work shows that PMD oligodendrocyte loss can be rescued pharmacologically and defines a need for multifactorial intervention to restore myelination. : Tesar and colleagues interrogate the severe genetic myelin disorder Pelizaeus-Merzbacher disease (PMD) using iPSC-derived oligodendrocyte progenitor cells (OPCs). Using high-throughput phenotypic screening, they rescue cell death of mutant oligodendrocytes immediately after initiation of differentiation with chemical modulators, including Ro 25–6981. Interestingly oligodendrocyte restoration did not lead to widespread myelination, unmasking a new phase of the disease. Keywords: iPSC disease modeling, high-throughput screening, oligodendrocyte progenitor cells, oligodendrocytes, myelin, Pelizaeus-Merzbacher disease, proteolipid protein 1, endoplasmic reticulum stress, PLP1, rare disease

Regeneration of myelin is mediated by oligodendrocyte progenitor cells (OPCs), an abundant stem cell population in the CNS and the principal source of new myelinating oligodendrocytes. Loss of myelin-producing oligodendrocytes in the central nervous system (CNS) underlies a number of neurological diseases, including multiple sclerosis (MS) and diverse genetic diseases1–3. Using high throughput chemical screening approaches, we and others have identified small molecules that stimulate oligodendrocyte formation from OPCs and functionally enhance remyelination in vivo4–10. Here we show a broad range of these pro-myelinating small molecules function not through their canonical targets but by directly inhibiting CYP51 (cytochrome P450, family 51), TM7SF2, or EBP (emopamil binding protein), a narrow range of enzymes within the cholesterol biosynthesis pathway. Subsequent accumulation of the 8,9-unsaturated sterol substrates of these enzymes is a key mechanistic node that promotes oligodendrocyte formation, as 8,9-unsaturated sterols are effective when supplied to OPCs in purified form while analogous sterols lacking this structural feature have no effect. Collectively, our results define a unifying sterol-based mechanism-of-action for most known small-molecule enhancers of oligodendrocyte formation and highlight specific targets to propel the development of optimal remyelinating therapeutics.

Organoid technologies provide an accessible system to examine cellular composition, interactions, and organization in the developing human brain, but previously have lacked oligodendrocytes, the myelinating glia of the central nervous system. Here we reproducibly generate oligodendrocytes and myelin in human pluripotent stem cell-derived “oligocortical spheroids”. Transcriptional, immunohistochemical, and electron microscopy analyses demonstrate molecular features consistent with maturing oligodendrocytes by 20 weeks in culture, including expression of MYRF, PLP1, and MBP proteins and initial myelin wrapping of axons, with maturation to longitudinal wrapping and compact myelin by 30 weeks. Promyelinating drugs enhance the rate and extent of oligodendrocyte generation and myelination, while oligocortical spheroids generated from patients with a genetic myelin disorder recapitulate human disease phenotypes. Oligocortical spheroids provide a versatile platform to observe and dissect the complex interactions required for myelination of the developing central nervous system and offer new opportunities for disease modeling and therapeutic development in human tissue.

Summary Multiple sclerosis (MS) is an autoimmune disease characterized by attack on oligodendrocytes within the central nervous system (CNS). Despite widespread use of immunomodulatory therapies, patients may still face progressive disability because of failure of myelin regeneration and loss of neurons, suggesting additional cellular pathologies. Here, we describe a general approach for identifying specific cell types in which a disease allele exerts a pathogenic effect. Applying this approach to MS risk loci, we pinpoint likely pathogenic cell types for 70%. In addition to T cell loci, we unexpectedly identified myeloid- and CNS-specific risk loci, including two sites that dysregulate transcriptional pause release in oligodendrocytes. Functional studies demonstrated inhibition of transcriptional elongation is a dominant pathway blocking oligodendrocyte maturation. Furthermore, pause release factors are frequently dysregulated in MS brain tissue. These data implicate cell-intrinsic aberrations outside of the immune system and suggest new avenues for therapeutic development. Video Abstract

Two drugs, miconazole and clobetasol, have functions that modulate differentiation of oligodendrocyte progenitor cells directly, enhance remyelination, and significantly reduce disease severity in mouse models of multiple sclerosis. Multiple sclerosis is characterized by an autoimmune response and failure of remyelination in the brain due to defects in differentiation of myelin-producing cells from oligodendrocyte progenitor cells. Most current treatments target the immune system. Paul Tesar and colleagues screened for compounds that can enhance oligodendrocyte maturation from mouse pluripotent epiblast stem-cell-derived oligodendrocyte progenitors. They found two drugs — miconazole (an antifungal) and clobetasol (a steroid) — that enhance myelin production in vivo in mouse models of multiple sclerosis and enhanced the differentiation of human oligodendrocytes progenitors in vitro. Mechanistically, these compounds appear to target both the immune response and oligodendrocyte progenitor cells. Multiple sclerosis involves an aberrant autoimmune response and progressive failure of remyelination in the central nervous system. Prevention of neural degeneration and subsequent disability requires remyelination through the generation of new oligodendrocytes, but current treatments exclusively target the immune system. Oligodendrocyte progenitor cells are stem cells in the central nervous system and the principal source of myelinating oligodendrocytes1. These cells are abundant in demyelinated regions of patients with multiple sclerosis, yet fail to differentiate, thereby representing a cellular target for pharmacological intervention2. To discover therapeutic compounds for enhancing myelination from endogenous oligodendrocyte progenitor cells, we screened a library of bioactive small molecules on mouse pluripotent epiblast stem-cell-derived oligodendrocyte progenitor cells3,4,5. Here we show seven drugs function at nanomolar doses selectively to enhance the generation of mature oligodendrocytes from progenitor cells in vitro. Two drugs, miconazole and clobetasol, are effective in promoting precocious myelination in organotypic cerebellar slice cultures, and in vivo in early postnatal mouse pups. Systemic delivery of each of the two drugs significantly increases the number of new oligodendrocytes and enhances remyelination in a lysolecithin-induced mouse model of focal demyelination. Administering each of the two drugs at the peak of disease in an experimental autoimmune encephalomyelitis mouse model of chronic progressive multiple sclerosis results in striking reversal of disease severity. Immune response assays show that miconazole functions directly as a remyelinating drug with no effect on the immune system, whereas clobetasol is a potent immunosuppressant as well as a remyelinating agent. Mechanistic studies show that miconazole and clobetasol function in oligodendrocyte progenitor cells through mitogen-activated protein kinase and glucocorticoid receptor signalling, respectively. Furthermore, both drugs enhance the generation of human oligodendrocytes from human oligodendrocyte progenitor cells in vitro. Collectively, our results provide a rationale for testing miconazole and clobetasol, or structurally modified derivatives, to enhance remyelination in patients.

This exploratory study of 28 married male dentists and their families was designed to gain an understanding about the stressors that dentists and their spouses experience, the life events and family strains they incur, the behavioral coping patterns they utilize, and their psychosocial characteristics. The study found that although stable dental families did encounter a significant number of stressors arising from both the dental practice and the family, they maintained their sense of balance through strong family coping skills and family resources. The effect of the dentist's office-related stress was directly felt in the family, especially by the spouse. Strong coping patterns resulted when dentists and spouses maintained a balance of time and responsibility, satisfaction in work and family activity, regular communication, sharing of decision making, good physical health, and the inclusion of an active exercise program within multiple demands on their time.

Everyone must accept a certain measure of responsibility for dealing with personal stresses. This article suggests various active, constructive, self-help strategies. It specifically focuses on the advantages of adopting positive attitudes, maintaining a sense of humor, engaging in a variety of activities, identifying and relabeling stresses, and using multiple, active coping techniques. Demonstrating how professional psychologic counseling may help the individual in effectively dealing with personal problems, the article also defines and delineates counseling. It explains why one should seek professional help, tells how to select a counselor, describes the types of counseling available, advises ways to best utilize the counseling process, and discusses the length and costs of treatments.

A small sodium iodide scintillation detector was designed for insertion through a fiberoptic bronchoscope to detect and localize sites of deposition of cobalt-57 bleomycin in lung cancer. The detector was used in 40 diagnostic studies of 34 patients; 21 of the patients had tumors. We compared the sensitivity, specificity, accuracy, and predictive value of the detector to those of plain chest x-ray films and bronchoscopy in detecting tumors. Sensitivity and specificity for the detector were 68 percent and 80 percent, respectively; for bronchoscopy, 72 percent and 100 percent; and for roentgenograms, 80 percent and 53 percent. Sensitivity for the detector and bronchoscopy combined was 92 percent. The detector succeeded in locating nonvisible submucosal and extraluminal tumors, and may contribute to early diagnosis and more accurate staging of lung cancer.