Biology subjects

Gullapalli, V.

Publications and source records attributed to Gullapalli, V..

3 recordsLinked to original sources

bioRxiv2026

SCIMETAR-seq tracks immunophenotype, demethylation, mutations, and transcriptomes in single cells undergoing HMA therapy

5-azacytidine improves haematopoiesis and delays leukaemic progression in myelodysplastic neoplasms, but responses vary and are complicated by clonal mosaicism and heterogenous demethylation. Using a novel single-cell pipeline ("SCIMETAR-seq"), we found 5-azacytidine induced clonally distinct differentiation responses, with nuclear DNA demethylation occurring primarily in cycling progenitors. Despite the absence of significant nuclear DNA demethylation, quiescent stem cells underwent transcriptional remodelling in vivo, accompanied by 5-azacytidine-induced C*G-to-G*C mutations in mitochondria.

cancer biology↗

bioRxiv2025

A 3D iPSC retina model reveals non-cell-autonomous and non-neuronal mechanism of photoreceptor degeneration in a lysosomal storage disorder.

Disruption of photoreceptor-retinal pigment epithelium (RPE) interface with loss of photoreceptor outer segments (POSs) in the retina is a pathological hallmark of several neurodegenerative and retinal diseases including lysosomal storage disorders like CLN3 disease. However, the retina is a functional composite in vivo; and in vitro stem cell models of retina that enable investigation of the photoreceptor-RPE interface in healthy and diseased retina are lacking. Here, we developed a 3D human pluripotent stem cell (hPSC)-derived retina model to investigate the photoreceptor-RPE interface in healthy and disease tissue. Using this 3D hPSC retina model, we demonstrated that the most common disease causing CLN3 mutation (CLN3{Delta}ex7-8) leads to reduced levels of acid ceramidase (AC) and consequently altered sphingolipid metabolism and signaling and POS loss in CLN3 disease. Consistent with the 3D hPSC retina model, altered sphingolipid metabolism and signaling coincided with POS loss in a large animal model of CLN3 disease, CLN3 miniswine. Therapeutically, recombinant human acid ceramidase (rhAC) targeted both altered sphingolipid metabolism and retina degeneration in the CLN3 hPSC retina model and the CLN3 miniswine eye. These findings demonstrate a proof-of-concept that rhAC can rescue disease phenotype in a large animal model of CLN3 disease and suggest that rhAC could be a therapeutic approach for CLN3 disease. One Sentence SummaryAcid ceramidase deficiency and consequently altered sphingolipid signaling promotes disease phenotype(s) in a lysosomal storage disorder, CLN3 disease.

neuroscience↗

bioRxiv2024

Inner limiting Membrane Peel Extends In vivo Calcium Imaging of Retinal Ganglion Cell Activity Beyond the Fovea in Non-Human Primate

PurposeAdaptive Optics Scanning Light Ophthalmoscopy (AOSLO) paired with intravitreal injection of a viral vector coding for the calcium indicator GCaMP has enabled visualization of neuronal activity in retinal ganglion cells (RGCs) at single cell resolution in the living eye. However, the inner limiting membrane (ILM) restricts viral transduction to the fovea in humans and non-human primates (NHP), hindering both therapeutic intervention and physiological study of the retina. To address this, we explored peeling the ILM before intravitreal injection to expand calcium imaging beyond the fovea in the living primate eye. MethodsFive eyes from Macaca fascicularis (age 3-10; n=3; 2 males, 1 female) underwent vitrectomy and ILM peel centered on the fovea prior to intravitreal delivery of 7m8:SNCG:GCaMP8s. RGC responses to visual flicker were evaluated using AOSLO calcium imaging 1-6 months post intravitreal injection. ResultsCalcium activity was observed in RGCs throughout the ILM peeled area in all eyes, representing a mean 8-fold increase in accessible recording area relative to a representative control eye. RGC responses in the ILM peeled and control eyes were comparable and showed no significant decrease over the 6 months following the procedure. In addition, we demonstrated that activity can be recorded directly from the retinal nerve fiber layer. ConclusionsPeeling the ILM is a viable strategy to expand viral access to the GCL for gene therapies in NHP. Overall, this approach has potential to advance visual neuroscience, including pre-clinical evaluation of retinal function, detection of vision loss, and assessment of therapeutic interventions.

neuroscience↗