Biology subjects

Wong, W. T.

Publications and source records attributed to Wong, W. T..

3 recordsLinked to original sources

bioRxiv2023

Human iPSC-derived Microglia Cells Integrated into Mouse Retina and Recapitulated Features of Endogenous Microglia Cells

Microglia exhibit both maladaptive and adaptive roles in the pathogenesis of neurodegenerative diseases and have emerged as a cellular target for central nervous system (CNS) disorders, including those affecting the retina. Replacing maladaptive microglia, such as those impacted by aging or over-activation, with exogenous microglia that can enable adaptive functions has been proposed as a potential therapeutic strategy for neurodegenerative diseases. To investigate microglia replacement as an approach for retinal diseases, we first employed a protocol to efficiently generate human-induced pluripotent stem cells (hiPSC)-derived microglia in quantities sufficient for in vivo transplantation. These cells demonstrated expression of microglia-enriched genes and showed typical microglial functions such as LPS-induced responses and phagocytosis. We then performed xenotransplantation of these hiPSC-derived microglia into the subretinal space of adult mice whose endogenous retinal microglia have been pharmacologically depleted. Long-term analysis post-transplantation demonstrated that transplanted hiPSC-derived microglia successfully integrated into the neuroretina as ramified cells, occupying positions previously filled by the endogenous microglia and expressed microglia homeostatic markers such as P2ry12 and Tmem119. Further, these cells were found juxtaposed alongside residual endogenous murine microglia for up to eight months in the retina, indicating their ability to establish a stable homeostatic state in vivo. Following retinal pigment epithelial (RPE) cell injury, transplanted microglia demonstrated responses typical of endogenous microglia, including migration, proliferation, and phagocytosis. Our findings indicate the feasibility of microglial transplantation and integration in the retina and suggest that modulating microglia through replacement may be a therapeutic strategy for treating neurodegenerative retinal diseases.

neuroscience↗

bioRxiv2019

Choroid-resident macrophages maintain local vasculature and RPE integrity and spontaneously regenerate following depletion

The choroid of the eye provides necessary vascular supply to the outer retina across the retinal pigment epithelial (RPE) layer and is a locus of progressive degenerative change in aging and age-related macular degeneration (AMD). Cellular mechanisms that maintain or compromise choroidal vasculature homeostasis are not well understood, complicating therapeutic efforts. We discover here that pharmacological ablation of macrophages normally resident in the adult mouse choroid via blockade of the CSF1 receptor resulted in progressive thinning of the choroid layer and atrophy of the choriocapillaris. Concurrently, choroidal macrophage ablation also induced structural disorganization of the RPE cell layer, downregulation of RPE visual cycle genes, and altered RPE angiogenic factor expression. Suspension of CSF1R blockade following ablation conversely enabled spontaneous regeneration of the choroidal macrophage population, restoring original macrophage distribution and morphological features. Macrophage repopulation significantly ameliorated the ablation-induced changes in RPE structure and angiogenic factor expression and arrested choroidal vascular atrophy. These findings reveal a previously unsuspected trophic function of resident choroidal macrophages in the maintenance of choroidal vasculature and the RPE layer, suggesting that insufficiency of macrophage function may contribute to age- and AMD-associated pathology. Modulating choroidal macrophage support function can constitute a strategy for therapeutic preservation of the choroid and RPE in AMD prevention and treatment. Significance StatementChoroidal atrophy is associated with normal aging and progression in age-related macular degeneration (AMD), a leading cause of blindness. Herein, we identify the choroidal macrophage as a critical player in the homeostatic maintenance of choroid-RPE complex of the eye. Depletion of choroidal macrophages resulted in progressive vascular atrophy, altered structure of retinal pigment epithelial (RPE) cells, and dysregulated RPE expression of visual cycle protein and angiogenic factors, VEGF and PEDF. We discovered that choroidal macrophages can regenerate and repopulate the choroid following depletion, ameliorating RPE alterations and arresting vascular atrophy. Our results suggest that insufficiency of macrophage function may contribute to age- and AMD-associated pathology, and modulation of macrophage support functions may be therapeutically useful in AMD prevention and treatment.

immunology↗

bioRxiv2018

Complement C3- and CR3-dependent microglial clearance protects photoreceptors in retinitis pigmentosa

Complement activation has been implicated as an inflammatory driver of neurodegeneration in retinal and brain pathologies. However, its involvement and influence of photoreceptor degeneration in retinitis pigmentosa (RP), an inherited, largely incurable blinding disease, is unclear. We discover that markedly upregulated retinal expression of multiple complement components coincided spatiotemporally with photoreceptor degeneration in both the rd10 mouse model and in human specimens of RP, with increased complement C3 expression and activation localizing to infiltrating microglia near photoreceptors. Genetic ablation of C3 in the rd10 background resulted in accelerated structural and functional photoreceptor degeneration and altered retinal expression of inflammatory genes. These effects were phenocopied by the genetic deletion of CR3, a microglia-expressed receptor for the C3 activation product C3b, implicating an adaptive microglial-mediation mechanism involving C3-CR3 interaction. Deficiency of either C3 or CR3 resulted in deficient microglial phagocytosis of apoptotic photoreceptors in vivo, as well as increased microglial neurotoxicity to photoreceptors in vitro. These findings demonstrate a novel adaptive role for complement activation in RP that facilitates microglial clearance of apoptotic photoreceptors, without which increased proinflammatory microglial neurotoxicity ensues. These positive contributions of complement via microglial-mediated mechanisms are important in the design of immunomodulatory therapeutic approaches to neurodegeneration.\n\nOne Sentence SummaryComplement activation mediates adaptive neuroprotection for photoreceptors by facilitating C3-CR3 dependent microglial clearance of apoptotic cells.

neuroscience↗