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Background: Diffuse Midline Glioma H3K27-altered (DMG) is an extremely aggressive and lethal childhood brain cancer that grows within the midline structure of the brain. Current treatment options are only palliative, making DMG in desperate need for therapeutic breakthroughs. One of the major challenges limiting the study of DMG is the lack of reliable preclinical models. In-vivo mouse models are expensive and technically challenging and in-vitro cell culture models lack the essential components of tumor microenvironment (TME) needed to recapitulate the complex biology of these tumors. Scalable human planar neural organoids (PNOs) with multi-cellular make-up can serve as a cost effective and reliable model system to capture DMG biology and allow effective species matched drug testing in-vitro. Methods: Using 3 separate DMG patient derived xenograft (PDX) cell lines, we spatially profiled a novel scalable human iPSC-derived PNO system containing neurons, functional astrocytes and microglia using the NanoString GeoMx spatial transcriptomics system. Results: We found that all three cell lines interact with and integrate into the human PNOs, demonstrating favorable growth conditions in a complex co-culture. Across spatially resolved regions of interest (ROI’s) tumor cells individually interact with microglia and astrocytes and transcriptomic profiling of these mixed cell ROI’s shows differences in the genetic signatures of both the normal cells (microglia/astrocytes) and the tumor cells. When compared to biopsies obtained directly from DMG patients, DMG cells within PNOs correlate strongly at both transcriptomic and proteomic levels. The multi-cellular PNOs also enabled drug target bystander toxicity screening not possible in a traditional tumor cell only monoculture. Conclusion: This study provides a proof-of-concept for scalable PNO modeling for DMG and underscores the translational relevance of this model system.

Background and Objectives: Recent studies have identified variants in the kinesin family member 5A (KIF5A) gene that predispose to amyotrophic lateral sclerosis (ALS). These ALS-linked KIF5A variants lead to the exclusion of exon 27, resulting in the production of a mutated protein with an altered C-terminal region (KIF5A ΔExon27). Through whole genome sequencing, we identified a novel KIF5A intronic variant, rs1057522322 (c.2993-6C > A; chr12:57582596C > A, GRCh38.p14), in a family segregating ALS. Our goal is to investigate the effect of this variant on exon 27 splicing and to assess its functional consequences on KIF5A-mediated cargo transport. Methods: Induced pluripotent stem cells (iPSCs) were generated from siblings with and without the c.2993-6C > A variant. RT-PCR was performed on RNA extracted from iPSC-derived neurons to assess exon 27 splicing. Functional studies were conducted on iPSC-derived motor neurons (MNs). Results: RT-PCR confirmed that the c.2993-6C > A variant induced exon 27 skipping in KIF5A. Immunofluorescent staining showed that KIF5A ΔExon27 abolished the axonal interaction with splicing factor proline- and glutamine-rich, a cargo specifically transported by KIF5A. Under stress conditions, MNs carrying the c.2993-6C > A variant exhibited TDP-43 proteinopathy. Discussion: KIF5A intronic variant c.2993-6C > A could be a risk factor for ALS. KIF5A ΔExon27 impairs KIF5A-mediated cargo transport and contributes to ALS pathogenesis in a TDP-43–dependent manner.

Chronic neuroinflammation plays a key role in the progression of Alzheimer’s disease (AD), and the cytosolic calcium-dependent phospholipase A2 (cPLA2) enzyme is a critical mediator of inflammatory lipid signaling pathways. Here we investigate the therapeutic potential of novel cPLA2 inhibitors in modulating neuroinflammation in AD. By leveraging the giga-scale V-SYNTHES2 virtual screening in on-demand chemical space and conducting two rounds of optimization for potency and selectivity, we have identified BRI-50460, achieving an IC50 of 0.88 nM in cellular assays that measure cPLA2-mediated arachidonic acid release. In vivo studies revealed favorable brain-to-plasma ratios, highlighting the ability of BRI-50460 to penetrate the central nervous system, modulating neuroinflammatory pathways, and restoring lipid homeostasis. In astrocytes and neurons derived from human induced pluripotent stem cells, BRI-50460 mitigates the effects of amyloid beta 42 oligomers on cPLA2 activation, tau hyperphosphorylation, and synaptic loss. Our results support that small molecule inhibitors of cPLA2 can modulate the downstream inflammatory signaling, offering a promising therapeutic strategy for neurodegenerative diseases.