Biology subjects

Thomasy, S. M.

Publications and source records attributed to Thomasy, S. M..

6 recordsLinked to original sources

bioRxiv2026

A Translational Reference for Green Autofluorescence Imaging in the Rhesus Macaque Eye using the OcuMet Beacon

PurposeTo evaluate associations between green autofluorescence (GAF) and structural and functional measures relevant to retinal and optic neuropathies, and to establish normative GAF values across the optic nerve head (ONH), macula, and papillofoveal bundle (PFB) in rhesus macaques. MethodsEighty-two macaques with normal ONH morphology by spectral-domain optical coherence tomography (SD-OCT) were included with a mean {+/-} SD age of 12.76 {+/-} 7.18 (range 0.11-29.39) years. The GAF images were acquired in the ONH, macula and PFB with the OcuMet Beacon. In a subset of macaques (n=19), pattern electroretinogram (PERG) and photopic full-field ERG including the photopic negative response (PhNR) were recorded. ResultsThe GAF significantly increased with age in the ONH, macula and PFB. After adjusting by age, there were no sex differences, but IOP showed a positive association with macular GAF. At the ONH, higher GAF correlated with thinner retinal nerve fiber layer, inner and outer segment complex, and total retinal thickness. In the macula, inner nuclear layer thickness was positively associated with GAF, whereas outer plexiform layer and inner and outer segment complex were inversely associated. The PERG amplitudes inversely tracked ONH GAF. ConclusionsGAF rises with age and IOP, couples to retinal structure, and at the ONH, aligns with inner-retinal functional indices. This study provides a regional reference for GAF in rhesus macaques. Translational RelevanceNormative GAF data in healthy rhesus macaques provide a framework for interpreting this noninvasive signal in translational studies of retinal and optic nerve disease.

physiology↗

bioRxiv2026

Ocular Safety and Efficacy of AAV-mediated Tyrosinase Gene Augmentation in a Nonhuman Primate Model

PurposeOculocutaneous albinism type 1 (OCA1) is an inherited disorder caused by tyrosinase (TYR) gene mutations. Affected individuals experience visual impairment and severe photosensitivity from ocular hypomelanosis, with no current treatments. We evaluated the safety and efficacy of a TYR-encoding adeno-associated virus (AAV) vector in healthy rhesus macaques as a potential OCA1 treatment. MethodsA novel AAV2-based capsid (ATX002) was packaged with the human VMD2 promoter and TYR (hTYR) fused with mGreenLantern (mGL). Two adult rhesus macaques were injected with ATX002-hVMD2-hTYR-mGL subretinally (OD) and intravitreally (OS). Safety and efficacy were assessed via comprehensive ophthalmic examination, fundus photography, spectral-domain optical coherence tomography (SD-OCT), and full-field electroretinography at baseline and defined timepoints up to 12 weeks post-injection, followed by post-mortem immunohistochemistry (IHC). ResultsBoth subretinal doses induced localized hypermelanosis by 3 weeks post-injection, which persisted through the study endpoint and was accompanied by measurable thickening of the retinal pigment epithelium (RPE) on SD-OCT. Histological IHC confirmed successful RPE transduction via robust mGL fluorescence, corroborating in vivo findings by revealing localized RPE hyperplasia and transgene-expressing cells adjacent to regions of de novo hypermelanosis. Intravitreal delivery did not induce any changes to the RPE. Transient uveitis was observed but successfully managed with anti-inflammatory treatment. ConclusionsSubretinal AAV-TYR delivery is a safe and effective approach with the potential to induce RPE pigmentation. These findings support the use of AAV-TYR gene therapy for OCA1, demonstrating efficacy and a manageable safety profile in a large-animal model, and provide a critical bridge toward human clinical translation.

bioengineering↗

bioRxiv2026

Quantitative imaging of corneal endothelial development reveals dynamic but resilient monolayer

The formation of functional corneal endothelial cells during development requires tight coordination between tissue-scale growth and cell-scale organization, yet how these processes are integrated in three dimensions remains poorly understood. Here, we combine high-resolution confocal imaging with quantitative analysis to reconstruct the morphogenesis of the chick corneal endothelium across embryonic development. Using a pipeline integrating 3D nuclear segmentation, Voronoi-based topological mapping, and spatial statistics, we link macroscopic globe expansion to single-cell geometry and lattice organization. We identify a multiphasic relationship between tissue growth and cell density, driven by temporal decoupling of organ expansion and proliferation. During early development, rapid globe expansion induces cellular stretching and spatial heterogeneity, followed by a phase of density accumulation and geometric refinement. Despite these dynamic conditions, the endothelial sheet maintains a robust monolayer architecture with minimal z-axis stratification. Quantitative topological analysis reveals that hexagonal packing is preserved from early stages and progressively refined through reduction of area variability and spatial clustering. Nearest-neighbor and Clark-Evans analyses demonstrate a transition from localized clustering to a more uniform spatial distribution, consistent with increasing packing regularity. Transient out-of-plane deviations coincide with key mechanical transitions, suggesting a role for 3D remodeling in accommodating mechanical stress. Concomitantly, junctional and cytoskeletal organization undergo progressive maturation. N-cadherin is established early at cell-cell interfaces, while Zonula Occludens-1 (ZO-1) transitions from diffuse localization to apically enriched tight junctions aligned with cortical actin. In parallel, microtubule organization becomes increasingly polarized to the apical domain, coinciding with the emergence of primary cilia. Together, these changes reflect coordinated establishment of epithelial polarity, barrier function, and mechanical stability. Overall, our study provides a multiscale, imaging-driven framework for understanding how epithelial tissues achieve and maintain geometric order under mechanical strain, establishing the corneal endothelium as an exemplar for linking developmental mechanics, 3D architecture, and epithelial topology. Summary StatementUsing 3D imaging and quantitative analysis, this work reveals how corneal endothelial cells stay organized and form a regular pattern during growth, despite ongoing changes in tissue size and shape.

developmental biology↗

bioRxiv2026

TAZ (Wwtr1) deficiency leads to ER stress and mitochondrial dysfunction in a mouse model of Fuchs' endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) impacts over 300 million individuals worldwide with corneal transplantation as the primary treatment. There is a dire need to establish non-surgical alternatives which are dependent on mouse models. Transcriptional co-activator with PDZ-binding motif (TAZ, encoded by Wwtr1) is a mechanotransducer implicated in maintaining homeostasis of corneal endothelial cells (CEnC). Wwtr1-/- (TAZ KO) mice serve as an animal model for late-onset FECD. We combined single-cell transcriptomics, transmission electron microscopy, and immunofluorescence staining to elucidate the mechanisms driving pathogenesis in young (2-month-old) and geriatric (11-month-old) mice. A progressive stress response was observed in TAZ KOs defined by endoplasmic reticulum (ER) stress, mitochondrial structural and functional abnormalities, and impaired Na+/K+ ATPase localization. These changes were accompanied by an altered expression of genes involved in extracellular matrix (ECM) organization, oxidative phosphorylation, macroautophagy and response to oxidative stress. Additionally, we noted age-related differences in cellular response with young TAZ KO CEnCs upregulating macroautophagy and downregulating ECM organization while geriatric TAZ KO CEnCs downregulated macroautophagy, and ECM organization. Both TAZ KO groups downregulated response to oxidative stress and cell-substrate adhesion. Together, these findings establish a mechanistic link between disrupted mechanotransduction and organelle stress in CEnC degeneration, further elaborating on potential mechanisms driving FECD pathogenesis. This positions TAZ KO mice as a translational platform for evaluating non-surgical therapeutic strategies targeting FECD. Significance statementFuchs endothelial corneal dystrophy (FECD) is a common, age-related cause of vision loss involving a depletion of corneal endothelial cells (CEnC) that necessitates corneal transplantation. Understanding why corneal endothelial cells progressively fail in this disease is essential for developing non-surgical therapies. Using transcriptomics, electron microscopy and immunofluorescence staining, we demonstrate that loss of the mechanotransducer TAZ disrupts cellular homeostasis by inducing endoplasmic reticulum stress, mitochondrial dysfunction and improper extracellular matrix and functional protein organization in CEnCs. By linking altered mechanotransduction to organelle stress and endothelial cell loss, these findings provide insight into fundamental disease mechanisms and identify pathways that may be targeted to preserve corneal endothelial function in FECD.

pathology↗

bioRxiv2021

Retinal organoids derived from rhesus macaque iPSCs undergo accelerated differentiation compared to human stem cells

PurposeTo compare the timing and efficiency of the development of non-human primate (NHP) derived retinal organoids in comparison to those derived from human embryonic stem cells. MethodsHuman embryonic stem cells (hESCs) and induced-pluripotent stem cells (rhiPSCs) derived from non-human primates (Macaca mulatta) were differentiated into retinal organoids by using an established differentiation protocol. Briefly, embryoid bodies were formed from pluripotent stem cells and induced into a neural lineage with neural induction media with the addition of BMP4. Thereafter, self-formation of optic vesicles was allowed to form in a 2D culture in retinal differentiation media (RDM). Optic vesicles were then manually harvested and cultured in suspension in 3D-RDM media until analysis. Differences in the timing of differentiation and efficiency of retinal organoid development were assessed by light microscopy, electron microscopy, immunocytochemistry, and single-cell transcriptomics. ResultsGeneration of retinal organoids was achieved from both human and several NHP pluripotent stem cells lines. All rhiPSC lines resulted in retinal differentiation with the formation of optic vesicle-like structures similar to what has been observed in hESC retinal organoids. NHP retinal organoids had laminated structure and were composed of mature retinal cell types including cone and rod photoreceptors. Single cell RNA sequencing was conducted at two time points, which allowed identification of cell types and characterization of developmental trajectory in the developing organoid. Important differences between rhesus and human cells were measured regarding the timing and efficiency of retinal organoid differentiation. While the culture of NHP-derived iPSCs is relatively difficult compared to human stem cells, the generation of retinal organoids is feasible and may be less time consuming due to an intrinsically faster timing of retinal differentiation. ConclusionsRetinal organoids produced from iPSCs derived from Rhesus monkey using established protocols differentiate through the stages of organoid development faster than those derived from human stem cells. The production of NHP retinal organoids may be advantageous to reduce experimental time and cost for basic biology studies in retinogenesis as well as for preclinical trials in NHPs studying retinal allograft transplantation.

cell biology↗

bioRxiv2020

Host immune responses after suprachoroidal delivery of AAV8 in nonhuman primate eyes

The suprachoroid is a potential space located between the sclera and choroid of the eye which provides a novel route for ocular drug or viral vector delivery. Suprachoroidal injection of AAV8 using transscleral microneedles enables widespread transgene expression in eyes of nonhuman primates, but may cause intraocular inflammation. We characterized the host humoral and cellular immune responses after suprachoroidal delivery of AAV8 expressing green fluorescent protein (GFP) in rhesus macaques, and found that it can induce a mild chorioretinitis that resolves after systemic corticosteroid administration, with recovery of photoreceptor morphology but persistent immune cell infiltration after 3 months. Suprachoroidal AAV8 triggered B-cell and T-cell responses against GFP, but only mild antibody responses to the viral capsid as compared to intravitreal injections of the same vector and dose. Systemic biodistribution studies showed lower AAV8 levels in liver and spleen after suprachoroidal injection compared with intravitreal delivery. Our findings suggest that suprachoroidal AAV8 primarily triggers host immune responses to GFP, likely due to sustained transgene expression in scleral fibroblasts outside the blood-retinal barrier, but elicits less humoral immune reactivity to the viral capsid than intravitreal delivery due to lower egress into systemic circulation. Thus, suprachoroidal AAV delivery of human transgenes may have significant translational potential for retinal gene therapy.

genetics↗