Biology subjects

Galvan, P.

Publications and source records attributed to Galvan, P..

3 recordsLinked to original sources

bioRxiv2026

Allele-specific correction of dominant Best vitelliform macular dystrophy in patient-derived retinal pigment epithelium

Autosomal dominant Best vitelliform macular dystrophy (BVMD) caused by variants in the BEST1 gene is characterized by dysfunction of the macular retinal pigment epithelium (RPE) and secondary degeneration of the photoreceptors. There are currently no approved treatments for BVMD, and owing to its dominant nature, there remains uncertainty regarding the utility of traditional gene augmentation. Here we evaluated whether a dominant pathogenic BEST1 allele can be corrected by base editing in differentiated RPE cells. We identified a patient with a likely pathogenic BEST1 c.851A>G (p. Tyr284Cys) variant that was amenable to cytidine base editing. After establishing patient-derived induced pluripotent stem cells (iPSCs), we corrected the pathogenic variant in the iPSCs to obtain corrected iPSCs with the same genetic background. Corrected iPSC-derived RPE exhibited normalized monolayer appearance, improved barrier integrity, reduced cell death, and restored RPE-specific transcriptome. We then used a dual adeno-associated virus (AAV) split-intein system to deliver a CRISPR-associated protein 9 cytidine base editor (SpCas9-CBE) to BEST1 c.851A>G mutant RPE monolayers and achieved editing of the pathogenic allele with a maximum efficiency of 13.42 {+/-} 3.64% (mean {+/-} SD). Together, these results demonstrate progress towards allele-specific base editing in a dominantly inherited retinal disorder.

neuroscience↗

bioRxiv2026

Context-dependent tonic signaling shapes the performance and manufacturability of a 4-1BB- based HER2 CAR-T cell therapy

The development of clinically effective CAR-T cell therapies for solid tumors requires careful optimization of receptor design, functional fitness, and manufacturability. While advancing low-affinity HER2-targeting CAR-T cells toward clinical application, we found that the candidate with the strongest in vivo antitumor activity--comprising a CD8 hinge and transmembrane region and a 4-1BB co-stimulatory domain--exhibited measurable tonic signaling. This basal antigen-independent signaling, likely driven by high CAR surface expression, was associated with increased apoptosis and reduced ex vivo expansion under research-grade manufacturing conditions. Modification of the transmembrane domain reduced CAR surface expression but did not alleviate tonic signaling and instead impaired antitumor activity. By contrast, transient pharmacologic inhibition of CAR signaling with dasatinib rescued expansion and reduced apoptosis in small-scale research cultures. Notably, these tonic-signaling-associated defects were largely absent during large-scale, GMP-compliant manufacturing, which enabled robust CAR-T cell expansion without additional benefit from dasatinib supplementation. Together, these findings show that tonic signaling is not inherently detrimental to CAR-T cell performance and that its functional consequences are highly dependent on manufacturing context. Our study underscores the importance of evaluating CAR candidates within clinically relevant production platforms and supports the advancement of this 4-1BB-based HER2-specific CAR-T cell product toward clinical testing.

immunology↗

bioRxiv2026

mGluR6 coordinates cone terminal targeting and synaptic layer assembly during human retinal development

The metabotropic glutamate receptor 6 (mGluR6), encoded by GRM6, is a core component of the ON-bipolar signaling cascade in the retina, but its role in human retinal development remains unclear. Here, we used temporally controlled CRISPR-based genetic ablation in human induced pluripotent stem cell-derived retinal organoids to define the developmental functions of mGluR6. Unexpectedly, we found that mGluR6 is expressed not only in depolarizing ON-bipolar cells but also transiently in cone photoreceptors during human retinal development, a pattern not observed in the mouse retina. Early loss of GRM6 prior to synaptogenesis disrupted cone pedicle architecture, leading to mislocalization of synaptic proteins including Bassoon, ELFN2, and TRPM1, and ultimately resulting in widening or duplication of the outer plexiform layer (OPL). In contrast, deletion after synapse formation did not alter OPL synapses or morphology, revealing a temporally restricted requirement for mGluR6 during circuit assembly. These findings uncover a previously unrecognized role for mGluR6 in coordinating cone terminal targeting and synaptic layer assembly during human retinal development and highlight the power of temporally controlled genetic manipulation in organoid systems to reveal species-specific mechanisms of neural circuit formation.

neuroscience↗