A Bioengineering Approach Towards Retina Regeneration

Currently, there is no cure for blindness. Pharmacology can only slow down the progression of a blinding disease, aiming at minimizing the symptoms. Stem cell regenerative therapy is a novel and very promising approach to overcome blindness. It has shown some potential in the eye but there remain major obstacles to be overcome before it can turn into a clinical reality, namely, the integration and survival of transplanted cells. In this work, we follow a two-pronged approach to address these challenges. Studies of photoreceptor development and degeneration could previously only be performed in vivo, due to the extremely poor survival of isolated photoreceptors in culture. Here, we describe a three-dimensional culture platform that enables isolated mouse postnatal day 11 rod photoreceptor survival and maturation in vitro and investigate its mechanism of action. We show that material stiffness does not affect photoreceptor survival and instead identify hyaluronic acid (HA) as its bioactive component. We investigate the molecular pathways activated by HA on photoreceptors and find that the Wnt, RhoA and mTOR pathways are its downstream effectors. The photoreceptors and the retinal pigmented epithelium (RPE) of the retina have a well-established mutual relationship in development, homeostasis and degeneration. In the second part of this work, we assess whether co-transplanting human embryonic stem cell-derived RPE and mouse postnatal day 11 rod photoreceptors in an HA hydrogel can improve behavioral recovery and cell survival compared to transplanting each cell type alone. We first validate the NaIO3 mouse model, which recapitulates advanced retinal degeneration. We next demonstrate that visual recovery in this model can be achieved only when RPE and photoreceptors are co-transplanted, as evidenced by three different outcome measures. This is accompanied by superior cell survival for both cell types in the co-transplant group. Our findings will guide future research and translation for retinal degenerative diseases.Ph.D

Hydrogel for Simultaneous Tunable Growth Factor Delivery and Enhanced Viability of Encapsulated Cells <i>in Vitro</i>

Poor cell survival <i>in vitro</i> and <i>in vivo</i> is one of the key challenges in tissue engineering. Prosurvival therapeutic proteins, such as insulin-like growth factor-1 (IGF-1), can promote cell viability but require controlled delivery systems due to their short half-lives and rapid clearance. Biocompatible materials are commonly used for drug delivery platforms or to encapsulate cells for increased viability, but few materials have been used for both applications simultaneously. In this work, we present a dual-use platform. A blend of hyaluronan and methylcellulose, known to promote cell survival, was covalently modified with Src homology 3 (SH3)-binding peptides and demonstrated tunable, affinity-based release of the prosurvival fusion protein SH3–IGF-1. The material also significantly increased the viability of retinal pigment epithelium cells under anchorage-independent conditions. This novel platform is applicable to a broad range of cells and protein therapeutics and is a promising drug delivery/cell transplantation strategy to increase the viability of both exogenous and endogenous cells in tissue engineering applications

Lymphangiogenesis-inducing vaccines elicit potent and long-lasting T cell immunity against melanomas

In melanoma, the induction of lymphatic growth (lymphangiogenesis) has long been correlated with metastasis and poor prognosis, but we recently showed it can synergistically enhance cancer immunotherapy and boost T cell immunity. Here, we develop a translational approach for exploiting this “lymphangiogenic potentiation” of immunotherapy in a cancer vaccine using lethally irradiated tumor cells overexpressing vascular endothelial growth factor C (VEGF-C) and topical adjuvants. Our “VEGFC vax” induced extensive local lymphangiogenesis and promoted stronger T cell activation in both the intradermal vaccine site and draining lymph nodes, resulting in higher frequencies of antigen-specific T cells present systemically than control vaccines. In mouse melanoma models, VEGFC vax elicited potent tumor-specific T cell immunity and provided effective tumor control and long-term immunological memory. Together, these data introduce the potential of lymphangiogenesis induction as a novel immunotherapeutic strategy to consider in cancer vaccine design

Activated cGAS/STING signaling elicits endothelial cell senescence in early diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of blindness in working-age adults and remains an important public health issue worldwide. Here we demonstrate that the expression of stimulator of interferon genes (STING) is increased in patients with DR and animal models of diabetic eye disease. STING has been previously shown to regulate cell senescence and inflammation, key contributors to the development and progression of DR. To investigate the mechanism whereby STING contributes to the pathogenesis of DR, diabetes was induced in STING-KO mice and STINGGT (loss-of-function mutation) mice, and molecular alterations and pathological changes in the retina were characterized. We report that retinal endothelial cell senescence, inflammation, and capillary degeneration were all inhibited in STING-KO diabetic mice; these observations were independently corroborated in STINGGT mice. These protective effects resulted from the reduction in TBK1, IRF3, and NF-κB phosphorylation in the absence of STING. Collectively, our results suggest that targeting STING may be an effective therapy for the early prevention and treatment of DR