Biology subjects

Lavekar, S. S.

Publications and source records attributed to Lavekar, S. S..

5 recordsLinked to original sources

bioRxiv2025

A human pluripotent stem cell tri-culture platform to elucidate microglial regulation of retinal ganglion cells in neuroinflammation

Optic neuropathies, including glaucoma, are characterized by the progressive degeneration of retinal ganglion cells (RGCs), ultimately leading to irreversible vision loss. Increasing evidence implicates microglia, the resident immune cells of the central nervous system, as key modulators of RGC health and disease progression. However, the precise mechanisms by which microglia influence RGCs remain poorly understood, particularly in the human context. In this study, we established human pluripotent stem cell (hPSC)-derived co-culture systems incorporating microglia, astrocytes, and RGCs to explore how microglia shape RGC growth and maturation under physiological conditions. We first examined the impact of homeostatic microglia on RGCs in both co-culture and tri-culture systems, revealing distinct influences of cell types in co-culture compared to when they were grown individually. We then modeled inflammatory states by activating microglia with lipopolysaccharide (LPS) and evaluated their effects on RGCs both directly and in the context of astrocyte co-culture. This stepwise, reductionist approach enabled us to dissect the cellular interactions driving RGC vulnerability in inflammatory conditions relevant to optic neuropathies. Our findings provide new insight into the complex neuroimmune landscape that underlies RGC degeneration and identify key pathways that may serve as therapeutic targets across a range of optic nerve diseases.

neuroscience↗

bioRxiv2025

Modeling human retinal ganglion cell axonal outgrowth, development, and pathology using pluripotent stem cell-based microfluidic platforms

Retinal ganglion cells (RGCs) are highly compartmentalized cells, with long axons serving as the sole connection between the eye and the brain. RGC degeneration in injury and/or disease also occurs in a compartmentalized manner, with distinct injury responses in axonal and somatodendritic compartments. Thus, the goal of this study was to establish a novel microfluidic-based platform for the analysis of RGC compartmentalization in health and disease states. Human pluripotent stem cell (hPSC)-derived RGCs were seeded into microfluidics, enabling the recruitment and isolation of axons apart from the somatodendritic compartment. Initial studies explored axonal outgrowth and compartmentalization of axons and dendrites. We then compared the differential response of RGCs differentiated from hPSCs carrying the OPTN(E50K) glaucoma mutation with isogenic control RGCs in their respective axonal and somatodendritic compartments, followed by analysis of axonal transport. Further, we explored the axonal transcriptome via RNA-seq, focusing on disease-related axonal differences. Finally, we established models to uniquely orient astrocytes along the axonal compartment combined with modulation of astrocyte reactivity as a pathological feature of neurodegeneration. Overall, RGC culture within microfluidic chips allowed enhanced cell growth and maturation, including long-distance axonal projections and proper compartmentalization, while patient-specific RGCs exhibited axonal outgrowth deficits as well as decreased rate of axonal transport. Finally, the induction of astrocyte reactivity uniquely along the proximal region of RGC axons led to the onset of neurodegenerative phenotypes in RGCs. These results represent the first study to effectively recapitulate the highly compartmentalized properties of hPSC-derived RGCs in healthy and disease states, providing a more physiologically relevant in vitro model for neuronal development and degeneration.

neuroscience↗

bioRxiv2024

Human Astrocytes Synchronize Neural Organoid Networks

Biological neural networks exhibit synchronized activity within and across interconnected regions of the central nervous system. Understanding how these coordinated networks are established and maintained may reveal therapeutic targets for neurodegeneration and neuromodulation. Here, we tested the influence of astrocytes upon synchronous network activity using human pluripotent stem cell-derived bioengineered neural organoids. This study revealed that astrocytes significantly increase activity within individual organoids and across long distances among numerous rapidly merged organoids via influencing synapses and bioenergetics. Treatment of amyloid protein inhibited synchronous activity during neurodegeneration, yet this can be rescued by propagating activity from neighboring networks. Altogether, this study identifies critical contributions of human astrocytes to biological neural networks and delivers a rapid, reproducible, and scalable model to investigate long-range functional communication of the nervous system in healthy and disease states.

neuroscience↗

bioRxiv2023

Autophagy Disruption Reduces mTORC1 Activation Leading to Retinal Ganglion Cell Neurodegeneration Associated with Glaucoma

Autophagy dysfunction has been associated with several neurodegenerative diseases including glaucoma, characterized by the degeneration of retinal ganglion cells (RGCs). However, the mechanisms by which autophagy dysfunction promotes RGC damage remain unclear. Here, we hypothesized that perturbation of the autophagy pathway results in increased autophagic demand, thereby downregulating signaling through mammalian target of rapamycin complex 1 (mTORC1), a negative regulator of autophagy, contributing to the degeneration of RGCs. We identified an impairment of autophagic-lysosomal degradation and decreased mTORC1 signaling via activation of the stress sensor adenosine monophosphate-activated protein kinase (AMPK), along with subsequent neurodegeneration in RGCs differentiated from human pluripotent stem cells (hPSCs) with a glaucoma-associated variant of Optineurin (OPTN-E50K). Similarly, the microbead occlusion model of glaucoma resulting in ocular hypertension also exhibited autophagy disruption and mTORC1 downregulation. Pharmacological inhibition of mTORC1 in hPSC-derived RGCs recapitulated disease-related neurodegenerative phenotypes in otherwise healthy RGCs, while the mTOR-independent induction of autophagy reduced protein accumulation and restored neurite outgrowth in diseased OPTN-E50K RGCs. Taken together, these results highlight an important balance between autophagy and mTORC1 signaling essential for RGC homeostasis, while disruption to these pathways contributes to neurodegenerative features in glaucoma, providing a potential therapeutic target to prevent neurodegeneration.

neuroscience↗

bioRxiv2019

Retinal ganglion cells harboring the OPTN(E50K) glaucoma mutation exhibit neurodegenerative phenotypes when derived from hPSC-derived three dimensional retinal organoids

Retinal ganglion cells (RGCs) serve as the primary connection between the eye and the brain, with this connection disrupted in glaucoma. Numerous cellular mechanisms have been associated with glaucomatous neurodegeneration, and useful models of glaucoma allow for the precise analysis of degenerative phenotypes. Human pluripotent stem cells (hPSCs) serve as powerful tools for studying human neurodegenerative diseases, particularly cellular mechanisms underlying degeneration. Thus, efforts were initially focused upon the use of hPSCs with an E50K mutation in the Optineurin (OPTN) gene. CRISPR/Cas9 gene editing was used to introduce the OPTN(E50K) mutation into existing lines of hPSCs, as well as the generation of isogenic control lines from OPTN(E50K) patient-derived hPSC lines. OPTN(E50K) RGCs exhibited numerous neurodegenerative deficits, including neurite retraction, autophagy dysfunction, apoptosis, and increased excitability. The results of this study provide an extensive analysis of the OPTN(E50K) mutation in hPSC-derived RGCs, with the opportunity to develop novel treatments for glaucoma.

neuroscience↗