Text

theses

In several retinal degenerative disease pathologies, the retinal pigment epithelium (RPE) cell monolayer becomes dysfunctional. This monolayer, along with the underlying Bruch’s membrane, creates a selective barrier for transport into and out of the retina, as well as supports neural retinal cells through the secretion of several key proteins. One such disease in which this dysfunction occurs is dry age-related macular degeneration (AMD). AMD is the leading cause of blindness in developed countries. Currently no treatment exists for dry AMD. Previous studies in animal models using a tissue engineering approach of implanting cells on scaffolds, show promise for the treatment of dry AMD. However, this approach is not without challenges. Two major challenges that must be addressed are RPE cell migration and dedifferentiation and inflammatory response to transplantation. Design and optimization of scaffold cues for the purpose of RPE transplantation remain relatively unexplored, specifically the mechanical properties of the scaffolds. The first aim of this work seeks to isolate the effects of scaffold modulus on RPE cells grown on these scaffolds. This was accomplished through the use of a synthetic polymer scaffold and a short cell adhesion peptide sequence. The results of this study indicated significant differences between cells on different substrate moduli in cell cytoskeleton structure, cellular activity, and expression of inflammatory markers. Further work in this dissertation sought to promote the mature phenotype of RPE cells grown on scaffolds through Activin A supplemented media, scaffold encapsulated Activin A, and covalent bonding of Activin A on the scaffold surface. It was hypothesized that the Activin A chemical cue would provide rescue effects for cells demonstrating dedifferentiated characteristics. The results revealed that for cells on low modulus scaffolds, the mechanical environment was the dominating cue and the Activin A was unable to rescue these cells. However, the Activin A was able to affect cells on high modulus scaffolds. This finding demonstrates that when cultured on scaffolds with an appropriate modulus, exogenous factors, such as Activin A, can affect cell expression, morphology, and activity, while the wrong scaffold modulus can have devastating effects on survival regardless of chemical stimulation. These findings have broad implications on the design and optimization of scaffolds for long term successful RPE transplantation.

ETD_8378

Ph.D.

Includes bibliographical references

by Corina White

doi:10.7282/T3R214JT

ETD doctoral

The author owns the copyright to this work.