Exogenous Leukemia Inhibitory Factor Stimulates Oligodendrocyte Progenitor Cell Proliferation and Enhances Hippocampal Remyelination

New CNS neurons and glia are generated throughout adulthood from endogenous neural stem and progenitor cells. These progenitors can respond to injury, but their ability to proliferate, migrate, differentiate, and survive is usually insufficient to replace lost cells and restore normal function. Potentiating the progenitor response with exogenous factors is an attractive strategy for the treatment of nervous system injuries and neurodegenerative and demyelinating disorders. Previously, we reported that delivery of leukemia inhibitory factor (LIF) to the CNS stimulates the self-renewal of neural stem cells and the proliferation of parenchymal glial progenitors. Here we identify these parenchymal glia as oligodendrocyte (OL) progenitor cells (OPCs) and show that LIF delivery stimulates their proliferation through the activation of gp130 receptor signaling within these cells. Importantly, this effect of LIF on OPC proliferation can be harnessed to enhance the generation of OLs that express myelin proteins and reform nodes of Ranvier in the context of chronic demyelination in the adult mouse hippocampus. Our findings, considered together with the known beneficial effects of LIF on OL and neuron survival, suggest that LIF has both reparative and protective activities that make it a promising potential therapy for CNS demyelinating disorders and injuries

Unraveling Heterogeneity in X Chromosome Regulation and Transcriptional Heterogeneity in Naïve Human Pluripotent Stem Cells

In the works described below, I investigate and describe heterogeneity in naïve human pluripotent stem cells (hPSCs)—both the heterogeneity exhibited in XCI status and the nearly unexplored transcriptional heterogeneity in these cells. Stem cells are a highly desirable model for studying XCI, as both pluripotency and XCI play out during peri-implantation. By comparing female naïve and primed stem cells, I elucidate the functional differences in their XCI state. Recent studies incorporating single-cell RNA sequencing (scRNA-seq) have demonstrated that transcript-based technologies are insufficiently developed to unequivocally resolve these questions in a human system (Kaur et al., 2020; Mandal et al., 2020; Moreira de Mello et al., 2017; Petropoulos et al., 2016a; Reinius and Sandberg, 2019; Sahakyan et al., 2017). Further studies have instead shown that 3D genomics holds immense promise for studying XCI by interrogating changes to the X chromosomes’ 3D states (Darrow et al., 2016; Giorgetti et al., 2016; Wang et al., 2016b). As such, I have collaborated with the Wang lab to characterize the 3D state of the X chromosome in naïve and primed human pluripotent stem cells. Using a combination of Hi-C and DNA FISH, we analyzed 40 TADs across the X chromosome in multiple naïve and primed hPSC lines. From this, we determined that naïve cells typically exhibit the 3D conformation of active X chromosomes. Naïve X chromosomes generally compartmentalize around the centromere and appear more dispersed than primed X chromosomes on average, which further suggests that naive X chromosomes exist in the active state. The addition of FGF does not seem to have a major effect on the X chromosome conformation in the naïve state either. In naïve hPSCs, transcriptional heterogeneity is an almost completely open question regarding its variation across cell lines, mechanism(s), cultural conditions, and even its effects. However, multiple studies using primed cells, including those published by my lab, have shown that some degree of heterogeneity is present in this culture system. Because naïve cells are a fairly recent discovery—and transgene-free naïve hPSCs are an even more recent innovation—there is ample space in this undeveloped field to leverage single-cell RNA sequencing to conduct a basal characterization of transcriptional heterogeneity in these cells. From this, we found that the cells clustered into two distinct populations, independently of the scRNA-seq method used. We also leveraged previously published scRNA-seq data from the same cell line (performed by another group in a different cultural context) in order to correlate our findings; their data also contained these two populations. Based on the research described here, my colleagues and I have made novel advancements within the field of stem cell biology, implementing novel experimental approaches. Critically, we have found that naïve X chromosomes are not explicitly heterogeneous, finding no evidence of X chromosome inactivation in female naïve hPSCs. From a transcriptional perspective, we conclude that naïve cells demonstrate discrete heterogeneity and form developmentally and functionally distinct populations. This body of work represents one of the first efforts in the field to characterize the heterogeneity of naïve hPSCs at single-cell resolution, both in a 3D genomics and transcriptional context

Reviews

Star Wars, Episode VI: Return of the Jedi. Lucasfilm, 20th Century Fox. Reviewed by Benjamin Urrutia. And God Came In. Lyle W. Dorsett. Reviewed by Nancy-Lou Patterson. Charles Williams, Poet of Theology. Glen Cavaliero. Reviewed by Nancy-Lou Patterson. VII: An Anglo-American Literary Review. Vol. 4. Reviewed by Nancy-Lou Patterson. A Reference Guide. Ruth Tanis Youngberg, Dorothy L. Sayers. Reviewed by Nancy-Lou Patterson

Determining the Health Utility of Urinary Incontinence in Women

Objective The goal of this study was to define the utility of urinary incontinence in women using the Standard Gamble, the gold standard method for determining health state utilities, based on a diagnosis obtained from multichannel urodynamic testing, the gold standard in clinical diagnosis. Background Health state utility values are important in many areas of medical research. The values are used in cost-utility analysis, decision analysis and health related quality of life studies. To date, studies that have estimated the utility of urinary incontinence in women have relied on values from generic health related quality of life questionnaires such as the ED-5Q and Health Utilities Index or from expert opinion. The utility of urinary incontinence in these studies appears to be unintuitivelylow, at 0.71 to 0.82, with perfect health represented by 1.0. The utility of health states that are much more debilitating, for example cancer (0.82), is higher than urinary incontinence. These studies have relied on patient self-diagnosis of incontinence. Additionally, they have considered all types of urinary incontinence together. Intuitively, one would think that quality of life would be affected differently with different types (stress, urge, mixed) and differing severity of incontinence. Methods All adult female patients who underwent urodynamic testing at Brigham and Women’s Hospital were prospectively recruited. Diagnosis of type of incontinence was made by attending physician interpretation of the urodynamic study. No exclusion criteria. Patients completed three validated questionnaires: Sandvik Severity Index - A validated two question symptom specific instrument to evaluate urinary incontinence EQ-5D -A five-domain generic quality of life questionnaire. Answers are converted into a utility value. Visual Analog Scale - Vertical line from 0 (worst imaginable health) to 100 (best imaginable health). Patient rates own perception of health on line. The Standard Gamble technique was used in a standard format to determine each patient’s utility value for their health state. Patient is asked to choose between life in current health state and varying risks of immediate painless death. Gold Standard method to determine patients utility preference for their health state. Results This pilot study of 28 patients demonstrated a significant difference in utility value derived from the Standard Gamble and the generic health-related quality of life instruments. There were 21 patients with stress urinary incontinence, 6 patients with urge urinary incontinence and 1 patient with mixed urinary incontinence. Mean Sandvik score was higher in Urge Incontinence subgroup. Mean Utility from Standard Gamble was lower in Urge Incontinence group. Sandvik scores were moderately correlated with EQ-5D, SG and VAS utilities. Conclusions Utility scores derived from Standard Gamble were significantly higher than those derived from generic health related quality of life instruments. Utility scores derived from EQ-5D and VAS were similar tothose previously reported in the literature. Current utility values over-estimate the degree of bother of urinary incontinence. Researchers should consider using higher utility values for urinary incontinence in future cost utility and quality of life studies

Reviews

The Politics of Fantasy: C.S. Lewis and J.R.R. Tolkien. Lee D. Rossi. Reviewed by David Bratman. Shadowlands: The Story of C.S. Lewis and Joy Davidman. Brian Sibley. Reviewed by Nancy-Lou Patterson. The Silver Trumpet. Owen Barfield. Reviewed by Nancy-Lou Patterson. The Grand Miracle and Other Essays on Theology and Ethics from God in the Dock. C.S. Lewis. Reviewed by Nancy-Lou Patterson. First and Second Things: Essays on Theology and Ethics. C.S. Lewis. Reviewed by Nancy-Lou Patterson. The Art of G.K. Chesterton. Alzina Stone Dale. Reviewed by Nancy-Lou Patterson. The Lord Peter Wimsey Companion. Stephan P. Clarke. Reviewed by Nancy-Lou Patterson. The Great Mouse Detective. A Walt Disney animated film. Reviewed by Benjamin Urrutia

Reviews

J.R.R. Tolkien - Myth, Morality and Religion. Richard L. Purtill. Reviewed by Nancy-Lou Patterson. Love All / Busman\u27s Honeymoon. Dorothy L. Sayers and Muriel St. Clare Byrne. Reviewed by Nancy-Lou Patterson. The Terminator. Direc. by James Cameron. Reviewed by Benjamin Urrutia. Fantasists on Fantasy. Robert H. Boyer and Kenneth J. Zahorski. Reviewed by Mabel Drew

Reviews

Studies in the Literary Imagination. Vol. XIV, No. 2. Fall, 1981. Georgia State University. Ed. by Rayond Carter Sutherland. Reviewed by Nancy-Lou Patterson. The Mists of Avalon. Marion Zimmer Bradley. Reviewed by Benjamin Urrutia. The Harmony Within: The Spiritual Vision of George MacDonald. Rolland Hein. Reviewed by Roderick McGillis. C.S. Lewis and the Church of Rome. Christopher Derrick. Reviewed by Lee Speth. Between Heaven and Hell. Peter Kreeft. Reviewed by Nancy-Lou Patterson