Biology subjects

Han, I. C.

Publications and source records attributed to Han, I. C..

3 recordsLinked to original sources

bioRxiv2025

Production of clinical grade patient iPSC-derived 3D retinal organoids containing transplantable photoreceptor cells

Neurodegenerative conditions that affect the retina are currently the leading cause of incurable blindness in the developed world. Although gene and drug therapies are being developed to slow disease progression in some cases, restorative cell replacement approaches are needed for patients with significant vision impairment due to retinal degeneration. While a variety of different cell types have been evaluated in the context of retinal cell replacement, induced pluripotent stem cells (iPSCs), which can be generated and delivered as an autologous therapeutic, are in many ways the most attractive donor cell source currently available. Like embryonic stem cells, iPSCs must be differentiated into the target therapeutic cell type prior to transplantation. For instance, for patients with retinitis pigmentosa who have primary photoreceptor cell disease, photoreceptor cell derivation and enrichment are required prior to transplantation. Although other effective retinal differentiation protocols exist, they are often not fully compatible with clinical manufacturing. In this study, we report development of a xeno-free 3D retinal differentiation protocol based on the most robust adherent/non-adherent 3D differentiation strategies published to date. In addition, we demonstrate that while iPSC reprogramming efficiency is enhanced under reduced oxygen tension (i.e., 5%), efficient embryoid body and subsequent retinal organoid production require standard oxygen levels (i.e., 21%). Finally, we show that photoreceptor precursor cells obtained from 3D retinal organoids derived using the developed protocol under current good manufacturing practices (cGMP) survive in the subretinal space of dystrophic Pde6b-null rats for 1-month post-transplantation and form new synaptic connections with host bipolar neurons.

neuroscience↗

bioRxiv2024

Development of self-healing hydrogels to support choroidal endothelial cell transplantation for the treatment of early age related macular degeneration

In retinal diseases such as age-related macular degeneration (AMD) and choroideremia, a key pathophysiologic step is loss of endothelial cells of the choriocapillaris, the dense vascular bed required for maintaining health and function of the retina. As such, repopulation of choroidal vasculature early in the disease process may halt disease progression. Prior studies have shown that injection of donor cells in suspension results in significant cellular efflux and poor cell survival. As such, the goal of this study was to develop a hydrogel system designed to support CEC transplantation. A library of hydrogels was synthesized using laminin (i.e., LN111, LN121, and LN421), carboxy methyl chitosan, and oxidized dextran via reversible Schiff base chemistry. Each of the developed hydrogels was readily injectable into the suprachoroidal space, with excellent gelation, mechanical, and degradation properties. Laminin-based hydrogels were compatible with immortalized CEC survival in vitro, and suprachoroidal injection of LN111 and LN121 containing gels were well-tolerated in an in vivo rat model, whereas LN421 containing gels caused significant chorioretinal inflammation. Hydrogels were detected in the suprachoroidal space of immunosuppressed rats at 1-week post-injection and were completely resorbed by 1-month post-injection. There were significantly more CECs retained in immunosuppressed rats that received cell laden hydrogels than those that received unsupported cell suspensions (i.e., CECs only). These findings pave the way for future CEC replacement studies in animal models of choroidal cell loss toward the development of future therapies. Statement of significanceAge related macular degeneration (AMD) is a leading cause of untreatable blindness in the industrial world. A key pathologic step in AMD is loss of the choriocapillaris endothelial cells, which provide vascular support to the overlying retina, including the light-sensing photoreceptors. We believe that choroidal cell replacement early in disease may prevent retinal cell death and subsequent vision loss. In this study, we present a strategy for repopulating the choriocapillaris using choroidal endothelial cell laden hydrogels. Specifically, we demonstrate the synthesis and characterization of 3 different laminin-based hydrogel systems. LN111 and LN121 hydrogels were found to increase retention of choroidal endothelial cells following suprachoroidal transplantation. These findings pave the way for future cell replacement studies in animal models of choroidal cell dropout.

bioengineering↗

bioRxiv2023

GENE EXPRESSION WITHIN A HUMAN CHOROIDAL NEOVASCULAR MEMBRANE USING SPATIAL TRANSCRIPTOMICS

Macular neovascularization is a relatively common and potentially visually devastating complication of age-related macular degeneration. In macular neovascularization, pathologic angiogenesis can originate from either the choroid or the retina, but we have limited understanding of how different cell types become dysregulated in this dynamic process. In this study, we performed spatial RNA sequencing on a human donor eye with macular neovascularization as well as a healthy control donor. We identified genes enriched within the area of macular neovascularization and used deconvolution algorithms to predict the originating cell type of these dysregulated genes. Within the area of neovascularization, endothelial cells were predicted to increase expression of genes related to Rho family GTPase signaling and integrin signaling. Likewise, VEGF and TGFB1 were identified as potential upstream regulators that could drive the observed gene expression changes produced by endothelial and retinal pigment epithelium cells in the macular neovascularization donor. These spatial gene expression profiles were compared to previous single-cell gene expression experiments in human age-related macular degeneration as well as a model of laser-induced neovascularization in mice. As a secondary aim, we also investigated spatial gene expression patterns within the macular neural retina and between the macular and peripheral choroid. We recapitulated previously described regional-specific gene expression patterns across both tissues. Overall, this study spatially analyzes gene expression across the retina, retinal pigment epithelium, and choroid in health and describes a set of candidate molecules that become dysregulated in macular neovascularization.

genomics↗