Biology subjects

Meyer, J. S.

Publications and source records attributed to Meyer, J. S..

10 recordsLinked to original sources

bioRxiv2026

Brain organoid computing for robotic decision-making

Biomimicry has inspired the evolution of robotics toward greater autonomy, adaptability, and symbiosis with humans and dynamic environments. However, current robotic systems still face major challenges in recapitulating the high-efficiency decision-making capabilities of the human brain under complex and dynamic conditions. Here, we present Brainobot, a biohybrid robotic system that establishes a brain organoid controller as a high-level robotic decision-making layer for closed-loop embodiment. By leveraging brain organoid reservoir computing, Brainobot interacts with dynamic environments by receiving and processing sensory inputs and generating motor actions. As a proof-of-concept demonstration, Brainobot is implemented in a humanoid robotic system to perform real-world tasks, including object grasping and laser chasing. Interestingly, Brainobot exhibits unique features, including cross-task adaptivity, high computing efficiency, and low energy consumption. Thus, our approach may provide insights for advancing robotic embodiment and understanding biological decision-making.

bioengineering↗

bioRxiv2025

Human induced pluripotent stem cell-derived microglia with a CX3CR1-V249I genetic variant exhibit dysfunctional phenotypes and modulate neuronal growth and function

The involvement of microglia in neurodegenerative diseases has drawn increasing attention, as many genetic risk factors are preferentially expressed in microglia. Microglial fractalkine receptor (CX3CR1) signaling regulates many key microglial functions, and the CX3CR1-V249I single nucleotide polymorphism (SNP) has been associated with increased risk for multiple neurodegenerative conditions, including Alzheimers disease, yet its functional consequences in human microglia remain unexplored. In this study, we generated iPSC-derived human microglia-like cells (hMGLs) and found that the CX3CR1-V249I variant increased susceptibility to starvation-induced cell death, reduced amyloid-beta uptake, altered microglial morphology, and impaired migration, with more pronounced effects in homozygous cells. Co-culture with neurons demonstrated that hMGLs with the CX3CR1-V249I variant misregulated neuronal properties, including abnormal neuronal growth as well as an induction of neuronal hyperexcitability. These findings highlight the critical role of CX3CR1 in regulating microglial function and implicate the V249I variant in driving pathogenic microglial states relevant to neurodegeneration.

neuroscience↗

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

Region-specific Brain Targets Drive Circuit Formation and Maturation of Human Retinal Ganglion Cells

Human vision relies on retinal ganglion cells (RGCs), and their connectivity with distinct brain regions enables higher order visual processing. RGCs vary considerably between species, and many model organisms display distinct RGC types and innervation patterns from those in humans. There is thus a need for robust models of human RGC circuit formation that preserves innervation specificity. Here, we developed an in vitro microfluidics eye-to-brain connectivity model using human pluripotent stem cell (hPSC)-derived RGCs to assess brain region-specific connectivity features. We found that cultured human RGCs segregate their dendrites and axons and display axonal features that align with those of their in vivo human RGC counterparts. To identify brain target surrogates, we conducted bioinformatic similarity assessments, which revealed high conservation and lower variability between human LGN and mouse counterparts relative to available thalamocortical organoids. We thus provided region-specific mouse visual targets to assess specificity and activity. We found that human RGC axons terminals differentially connected with distinct mouse retinorecipient brain regions and promoted region-specific neural activity. Increased synapse formation occurred between RGCs and lateral geniculate neurons relative to that with suprachiasmatic nucleus neurons, modeling retina brain connectivity differences. Both retinorecipient partners induced the formation of more synapses relative to non-retinorecipient brain target controls. These results suggest that human RGC innervation properties are preserved in culture systems and that human RGCs can differentially sense and respond to retinorecipient targets to control wiring outcomes. These systems may aid in the discovery of wiring factors for potential therapeutic applications. Significance StatementThis study presents a novel in vitro model to investigate human retinal ganglion cell (RGC) connectivity, using human pluripotent stem cell-derived RGCs and specific mouse brain targets. By modeling eye-to-brain connections in a microfluidics device, we reveal that cultured human RGCs can form selective, region-specific synapses with mouse-derived brain areas like the lateral geniculate nucleus and the suprachiasmatic nucleus. The findings demonstrate that human RGCs retain their innervation specificity presences in culture, mimicking in vivo human connectivity patterns. This model thus provides a powerful tool for understanding the factors controlling human-specific brain wiring, with potential applications in therapies for visual and neurological disorders.

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↗

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↗

bioRxiv2022

Enhanced mitochondrial biogenesis promotes cell survival in human stem cell derived retinal ganglion cells of the central nervous system

Mitochondrial dysfunctions are widely afflicted in central nervous system (CNS) disorders with minimal understanding on how to improve mitochondrial homeostasis to promote neuroprotection. Here we used human stem cell differentiated retinal ganglion cells (hRGCs) of the CNS, which are highly sensitive towards mitochondrial dysfunctions due to their unique structure and function, to identify mechanisms for improving mitochondrial quality control (MQC). We found that hRGCs are efficient in maintaining mitochondrial homeostasis through rapid degradation and biogenesis of mitochondria under acute damage. Using a glaucomatous Optineurin mutant (E50K) stem cell lines, we saw that at basal level mutant hRGCs possess less mitochondrial mass and suffer mitochondrial swelling due to excess ATP production load. Activation of mitochondrial biogenesis through pharmacological inhibition of the Tank binding kinase 1 (TBK1) restored energy homeostasis, mitigated mitochondrial swelling with neuroprotection against acute mitochondrial damage for glaucomatous E50K hRGCs, revealing a novel neuroprotection mechanism.

neuroscience↗

bioRxiv2019

Molecular and Behavioral Effects of Infant Maltreatment across Generations in Rhesus Monkeys

Childhood maltreatment is among the most robust risk factors for subsequent psychiatric and medical disorders, and data in humans and rodents suggest that effects of adverse childhood experiences may be transmitted across generations. Recent indications for biological processes underlying this transfer of experiential effects are intriguing; yet, their relevance in primates is inconclusive due to limitations of current studies. In this study, we bridge research in rodent models and humans with a natural non-human primate model on intergenerational effects of childhood maltreatment. Using a unique, well-controlled, randomized cross-fostering design in rhesus monkeys, we test the influence of ancestral maltreatment on molecular, neuroendocrine and behavioral outcomes in offspring, and show that childhood maltreatment results in transmission of information to the subsequent generation independent of behavioral transmission. We further demonstrate differences in the offspring longitudinal DNA methylation profile of the FKBP5 gene, an important regulator of the hypothalamus-pituitary-adrenal axis in offspring of the maltreatment lineage compared to the control lineage. Finally, we show that differences in FKBP5 methylation have functional effects on molecular, neuroendocrine and behavioral outcomes in offspring of the maltreatment ancestral line, even if the infants were never exposed to maltreatment nor interacted with their exposed ancestors. Although the molecular mechanism underlying our observations remains unknown, our data point to a potential germline-dependent effect. In summary, our data suggest that history of maltreatment in primates can induce molecular and behavioral changes in a subsequent generation independent of behavioral transmission that may influence risk for mental and physical diseases across generations.

neuroscience↗

bioRxiv2018

Differential Susceptibility of Rat Retinal Ganglion Cell Subtypes Following Optic Nerve Crush

Retinal ganglion cells (RGCs) are a heterogeneous group of cells, comprised of numerous subpopulations, that work together to send visual information to the brain. In numerous blinding disorders termed optic neuropathies, RGCs are the main cell type affected leading to degeneration of these cells and eventual loss of vision. Previous studies have identified and characterized RGC subtypes in numerous animal systems, with only a handful of studies demonstrating their differential loss in response to disease and injury. Thus, efforts of the current study utilized an optic nerve crush (ONC) model to characterize the loss of RGCs and disease phenotypes associated with this injury. Additionally, the loss of RGC subtypes including direction selective-, alpha-, and ip-RGCs following ONC was explored. Results of this study demonstrated the differential loss of RGC subtypes with a high susceptibility for loss of alpha- and direction selective-RGCs and the preferential survival of ip-RGCs following ONC and allows for the establishment of additional studies focused on mechanisms and loss of these cells in optic neuropathies. Additionally, these results put important emphasis on the development of therapeutics targeted at the loss of specific subtypes as well as cellular replacement following injury and disease.

neuroscience↗

bioRxiv2018

Astrocytes Regulate the Development and Maturation of Retinal Ganglion Cells Derived from Human Pluripotent Stem Cells

Retinal ganglion cells (RGCs) form the connection between the eye and the brain, with this connectivity disrupted in numerous blinding disorders. Previous studies have demonstrated the ability to derive RGCs from hPSCs; however these cells exhibited some characteristics that indicated a limited state of maturation. Among the many factors known to influence RGC development in the retina, astrocytes are known to play a significant role in their functional maturation. Thus, efforts of the current study examined the functional maturation of hPSC-derived RGCs, including the ability of astrocytes to modulate this developmental timeline. Morphological and functional properties of RGCs were found to increase over time, with astrocytes significantly accelerating the functional maturation of hPSC-derived RGCs. The results of this study are the first of its kind to extensively study the functional and morphological maturation of RGCs in vitro, including the effects of astrocytes upon the maturation of hPSC-derived RGCs.

neuroscience↗