FUNCTIONALIZATION OF CARBON NANOTUBES FOR MESENCHYMAL STEM CELL-ASSISTED PHOTOTHERMAL THERAPY

Carbon nanotubes were first cut and functionalized with a newly developed reaction involving autoclaving and sonication in hydrogen peroxide. The functionalized nanotubes were characterized and evaluated for aqueous solubility. Studies which relate reaction conditions to final carbon nanotube length were conducted. Hydroxyl groups present on the carbon nanotubes served as a platform for a series of addition reactions, with the objective of conjugating streptavidin and fluorescent markers onto the carbon nanotubes. The modified nanotubes were attached onto the surface of biotinylated mesenchymal stem cells, creating a novel, tumor-homing delivery system for photothermal anticancer agents.

BIOCHEMICAL AND CELLULAR MECHANISMS OF RETINA AND RETINAL PIGMENT EPITHELIUM APOPTOSIS

Oxidative stress, intense light exposure and oxygen imbalances such as hypoxic or hyperoxic conditions perturb mitochondria, nuclear function and further lead to cellular damage of retina and retinal pigment epithelial (RPE) cells. Our major aim is to understand the various biochemical and proteomic events that occur during the progression of retina and RPE cell death. The comprehensive objectives of this dissertation are to understand the functional aspects of protein expression, posttranslational modifications, protein or lipid binding changes, phenotypic, morphological alterations and their regulation during the retina and RPE apoptosis under oxidative stress. The entire study is divided into four chapters Chapter 1 contains introduction and background on apoptotic signaling in retina and RPE cells. In chapter 2, we demonstrated that the oxidative stress biomarker prohibitin shuttles between mitochondria and nucleus as an anti-apoptotic molecule and acts as a transcriptional regulator by altering its lipid binding affinity and by posttranslational modifications during oxidative damage to the retina and RPE. In chapter 3, we demonstrated that oxidative and photo-oxidative stress induced nitric oxide regulates the RPE apoptosis by altering serine/threonine protein phosphatase 2A (PP2A) catalytic subunit, vimentin phosphorylation and Bcl xL expression regulation in the RPE cells in vitro. In chapter 4, we further analyzed the differential expression of prohibitin in the retina and RPE during oxidative stress, diabetic retinopathy (DR) and age-related macular degeneration (AMD) condition. Our analysis of postmortem retinas reveals that prohibitin is significantly increased in aged and AMD retina, and decreased in retinas of human diabetic retinopathy and RPE of AMD. Our study demonstrates that prohibitin levels determine the apoptotic signaling in the retina and RPE during retinal degenerative disease progression.