POLYMERIC MICELLES AS A NOVEL APPROACH IN THE PREVENTION OF RETINAL SCARRING

Ph.DDOCTOR OF PHILOSOPHY (SOM

PCL-Based Thermogelling Polymer: Molecular Weight Effects on Its Suitability as Vitreous Tamponade

10.1021/acsabm.0c01266ACS Applied Bio Materials3129043-905

Dysfunctional autophagy, proteostasis, and mitochondria as a prelude to age-related macular degeneration

Retinal pigment epithelial (RPE) cell dysfunction is a key driving force of AMD. RPE cells form a metabolic interface between photoreceptors and choriocapillaris, performing essential functions for retinal homeostasis. Through their multiple functions, RPE cells are constantly exposed to oxidative stress, which leads to the accumulation of damaged proteins, lipids, nucleic acids, and cellular organelles, including mitochondria. As miniature chemical engines of the cell, self-replicating mitochondria are heavily implicated in the aging process through a variety of mechanisms. In the eye, mitochondrial dysfunction is strongly associated with several diseases, including age-related macular degeneration (AMD), which is a leading cause of irreversible vision loss in millions of people globally. Aged mitochondria exhibit decreased rates of oxidative phosphorylation, increased reactive oxygen species (ROS) generation, and increased numbers of mitochondrial DNA mutations. Mitochondrial bioenergetics and autophagy decline during aging because of insufficient free radical scavenger systems, the impairment of DNA repair mechanisms, and reductions in mitochondrial turnover. Recent research has uncovered a much more complex role of mitochondrial function and cytosolic protein translation and proteostasis in AMD pathogenesis. The coupling of autophagy and mitochondrial apoptosis modulates the proteostasis and aging processes. This review aims to summarise and provide a perspective on (i) the current evidence of autophagy, proteostasis, and mitochondrial dysfunction in dry AMD; (ii) current in vitro and in vivo disease models relevant to assessing mitochondrial dysfunction in AMD, and their utility in drug screening; and (iii) ongoing clinical trials targeting mitochondrial dysfunction for AMD therapeutics.Ministry of Education (MOE)Published versionThis research was funded by Ministry of Education (MOE) for its MOE Academic Research Fund Tier 3 (STEM) [MOET32020-0001]

Customized strategies for high-yield purification of retinal pigment epithelial cells differentiated from different stem cell sources

Retinal pigment epithelial (RPE) cell dysfunction and death are characteristics of age-related macular degeneration. A promising therapeutic option is RPE cell transplantation. Development of clinical grade stem-cell derived RPE requires efficient in vitro differentiation and purification methods. Enzymatic purification of RPE relies on the relative adherence of RPE and non-RPE cells to the culture plate. However, morphology and adherence of non-RPE cells differ for different stem cell sources. In cases whereby the non-RPE adhered as strongly as RPE cells to the culture plate, enzymatic method of purification is unsuitable. Thus, we hypothesized the need to customize purification strategies for RPE derived from different stem cell sources. We systematically compared five different RPE purification methods, including manual, enzymatic, flow cytometry-based sorting or combinations thereof for parameters including cell throughput, yield, purity and functionality. Flow cytometry-based approach was suitable for RPE isolation from heterogeneous cultures with highly adherent non-RPE cells, albeit with lower yield. Although all five purification methods generated pure and functional RPE, there were significant differences in yield and processing times. Based on the high purity of the resulting RPE and relatively short processing time, we conclude that a combination of enzymatic and manual purification is ideal for clinical applications.Ministry of Education (MOE)National Research Foundation (NRF)Published versionThis study was supported by National Research Foundation (NRF), Singapore, under its Competitive Research Program (CRP) [NRF-CRP21-2018-0008] and Ministry of Education (MOE) for its MOE Academic Research Fund Tier 3 (STEM) [MOET32020-0001]

Electrospun Pectin-Polyhydroxybutyrate Nanofibers for Retinal Tissue Engineering

10.1021/acsomega.7b01604ACS OMEGA2128959-896

Surgical Transplantation of Human RPE Stem Cell-Derived RPE Monolayers into Non-Human Primates with Immunosuppression

10.1016/j.stemcr.2020.12.007Stem Cell Reports162237-25

Multi-species single-cell transcriptomic analysis of ocular compartment regulons

10.1038/s41467-021-25968-8Nature Communications121567

Sustained delivery of anti-VEGFs from thermogel depots inhibits angiogenesis without the need for multiple injections

10.1039/c9bm01049aBIOMATERIALS SCIENCE7114603-461

Electrospun Pectin-Polyhydroxybutyrate Nanofibers for Retinal Tissue Engineering

Natural polysaccharide pectin has for the first time been grafted with polyhydroxybutyrate (PHB) via ring-opening polymerization of β-butyrolactone. This copolymer, pectin-polyhydroxybutyrate (pec-PHB), was blended with PHB in various proportions and electrospun to produce nanofibers that exhibited uniform and bead-free nanostructures, suggesting the miscibility of PHB and pec-PHB. These nanofiber blends exhibited reduced fiber diameters from 499 to 336–426 nm and water contact angles from 123.8 to 88.2° on incorporation of pec-PHB. They also displayed 39–335% enhancement of elongation at break relative to pristine PHB nanofibers. pec-PHB nanofibers were found to be noncytotoxic and biocompatible. Human retinal pigmented epithelium (ARPE-19) cells were seeded onto pristine PHB and pec-PHB nanofibers as scaffold and showed good proliferation. Higher proportions of pec-PHB (pec-PHB10 and pec-PHB20) yielded higher densities of cells with similar characteristics to normal RPE cells. We propose, therefore, that nanofibers of pec-PHB have significant potential as retinal tissue engineering scaffold materials

cGMP-grade human iPSC-derived retinal photoreceptor precursor cells rescue cone photoreceptor damage in non-human primates

10.1186/s13287-021-02539-8STEM CELL RESEARCH & THERAPY121CompletedComplete