LIF signaling regulates outer radial glial to interneuron fate during human cortical development

Radial glial (RG) development is essential for cerebral cortex growth and organization. In humans, the outer radial glia (oRG) subtype is expanded and gives rise to diverse neurons and glia. However, the mechanisms regulating oRG differentiation are unclear. oRG cells express leukemia-inhibitory factor (LIF) receptors during neurogenesis, and consistent with a role in stem cell self-renewal, LIF perturbation impacts oRG proliferation in cortical tissue and organoids. Surprisingly, LIF treatment also increases the production of inhibitory interneurons (INs) in cortical cultures. Comparative transcriptomic analysis identifies that the enhanced IN population resembles INs produced in the caudal ganglionic eminence. To evaluate whether INs could arise from oRGs, we isolated primary oRG cells and cultured them with LIF. We observed the production of INs from oRG cells and an increase in IN abundance following LIF treatment. Our observations suggest that LIF signaling regulates the capacity of oRG cells to generate INs.

Assembloid CRISPR screens reveal impact of disease genes in human neurodevelopment

The assembly of cortical circuits involves the generation and migration of interneurons from the ventral to the dorsal forebrain1-3, which has been challenging to study at inaccessible stages of late gestation and early postnatal human development4. Autism spectrum disorder and other neurodevelopmental disorders (NDDs) have been associated with abnormal cortical interneuron development5, but which of these NDD genes affect interneuron generation and migration, and how they mediate these effects remains unknown. We previously developed a platform to study interneuron development and migration in subpallial organoids and forebrain assembloids6. Here we integrate assembloids with CRISPR screening to investigate the involvement of 425 NDD genes in human interneuron development. The first screen aimed at interneuron generation revealed 13 candidate genes, including CSDE1 and SMAD4. We subsequently conducted an interneuron migration screen in more than 1,000 forebrain assembloids that identified 33 candidate genes, including cytoskeleton-related genes and the endoplasmic reticulum-related gene LNPK. We discovered that, during interneuron migration, the endoplasmic reticulum is displaced along the leading neuronal branch before nuclear translocation. LNPK deletion interfered with this endoplasmic reticulum displacement and resulted in abnormal migration. These results highlight the power of this CRISPR-assembloid platform to systematically map NDD genes onto human development and reveal disease mechanisms.

Calcium and activity-dependent signaling in the developing cerebral cortex

Calcium influx can be stimulated by various intra- and extracellular signals to set coordinated gene expression programs into motion. As such, the precise regulation of intracellular calcium represents a nexus between environmental cues and intrinsic genetic programs. Mounting genetic evidence points to a role for the deregulation of intracellular calcium signaling in neuropsychiatric disorders of developmental origin. These findings have prompted renewed enthusiasm for understanding the roles of calcium during normal and dysfunctional prenatal development. In this Review, we describe the fundamental mechanisms through which calcium is spatiotemporally regulated and directs early neurodevelopmental events. We also discuss unanswered questions about intracellular calcium regulation during the emergence of neurodevelopmental disease, and provide evidence that disruption of cell-specific calcium homeostasis and/or redeployment of developmental calcium signaling mechanisms may contribute to adult neurological disorders. We propose that understanding the normal developmental events that build the nervous system will rely on gaining insights into cell type-specific calcium signaling mechanisms. Such an understanding will enable therapeutic strategies targeting calcium-dependent mechanisms to mitigate disease.

Novastan (brand of argatroban): a small-molecule, direct thrombin inhibitor

Because of the unsatisfactory options available for safe and effective antithrombotic therapy, recent, intense research and development efforts have focused on direct, or site-directed, thrombin inhibitors. Argatroban is a small-molecule, reversible, direct thrombin inhibitor selective for the catalytic site of the thrombin molecule. Argatroban's molecular properties (small molecule; fast, selective, and reversible inhibition of the thrombin catalytic site; and similar in vitro potency for inhibiting both clot-bound and soluble thrombin) offer the potential for significant antithrombotic efficacy with minimal systemic anticoagulant effects. Its clinical pharmacologic properties offer the potential for minimal risk of bleeding, very rapid achievement of therapeutic antithrombotic efficacy, predictable dose response, and rapid restoration of the hemostatic systems to baseline on termination of intravenous infusion. The intravenous agent Novastan (brand of argatroban) is currently approved for clinical use in Japan for the treatment of peripheral arterial occlusive disease. Novastan is in advanced clinical development in North and South America for several indications, including (1) anticoagulant/antithrombotic therapy in heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia, and thrombosis syndrome (HITTS); and (2) adjunctive therapy to thrombolytic agents in acute myocardial infarction. Results from these trials are projected to be available by early 1997.

Results of a national survey on anticoagulation for PTCA

In order to assess the current practice patterns in the United States for anticoagulation during PTCA, a survey was sent to the ACC membership. A total of 377 surveys from physicians performing PTCA were tabulated; 5 (1.3%) respondents performed < 20 PTCAs/year, 128 (34.0%) performed 20-75 PTCAs/year, 141 (37.4%) performed 75-150 PTCAs/year, 98 (26.0%) performed > 150 PTCAs/year and 5 (1.3%) did not report their volume. Seventy-eight (20.7%) were at university hospitals 153 (40.6%) were at other teaching hospitals, 142 (37.7%) were at non-teaching hospitals and 4 (1.1%) did not report their institutional affiliation. A total of 76.8% of respondents routinely started with a 10,000 U bolus of heparin, while only 3.2% of respondents used only a weight-adjusted heparin bolus. Fifty-nine percent of respondents routinely used intra-procedure heparin infusions, usually 1000 U/hr. Anticoagulation monitoring was used by 92.6% of respondents during PTCA, almost always activated clotting times (ACTs). Of the 335 physicians who used ACTs to guide heparin therapy during PTCA, 59.1% used the Hemochron device, 16.7% used the HemoTec device, and 24.2% did not know which machine they used. Lower volume operators and operators at non-teaching hospitals were more likely not to know the type of ACT machine used. Post-procedure heparin infusions (usually titrated to an aPTT > 2 x control) were used by 70.3% of respondents. Lower volume operators were more likely to use post-procedure heparin infusions. Thus, heparin therapy for PTCA continues to be largely empiric, although the vast majority of cardiologists surveyed use ACT-guided heparin therapy for the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)