Cell-Material Interactions in Complex Microenvironments.

Abstract

Recently, effort has been placed on creating biomaterials that can directly interact biologically with cells and tissue. In this dissertation, mammalian cells are cultured on a variety of engineered microenvironments, designed to elicit a specific cellular response. In Chapter 2, chemical vapor deposition is used to create multi-modal substrates that can co-immobilize two biomolecules at precise ratios. The substrates were characterized, and the biological potency of each of the tethered biomolecules was confirmed by cell culture with the HUVEC and A431 cell lines, respectively. We also demonstrated that a CVD coating created by polymerization of pyridinophane has higher rates of cell adhesion in comparison to traditional Parylene. In Chapter 3, surface-initiated graft polymerization and atom-transfer radical polymerization were used to generate substrates coated with a thin film of poly[2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide] (PMEDSAH). We characterized the proliferation, markers of pluripotency, and morphology of human mesenchymal stem cells (hMSCs) grown on these substrates and compared them to tissue culture polystyrene (TCPS). We found that hMSCs grown on PMEDSAH retain their characteristic markers, but those on grafted PMEDSAH grow at a slower rate than those on TCPS or ATRP PMEDSAH. In Chapter 4 we created bioactuators. Flexible microcylinders spatially selective for cell adhesion were fabricated via electrohydrodynamic co-jetting. Cell selectivity was subsequently demonstrated first with fibroblasts, then neonatal rat cardiomyocytes. We showed that the cardiomyocytes selectively bound to our microcylinders could bend them with a significant amount of force in comparison to other reported bioactuators. Finally, in Chapter 5 we produced microenvironments conducive to forming cell sheets, which will be used as building blocks for higher ordered tissues. PLGA grid scaffolds were generated via electrohydrodynamic co-jetting. We created sheets of fibroblasts and hMSCs by growing them on scaffolds in rotator culture, and characterized sheet development by examining the distribution of extracellular matrix proteins over time. We also created keratinocyte sheets by co-culture with a feeder cell sheet of fibroblasts. In conclusion, we controlled cell behaviors on our engineered microenvironments to obtain desired biological outcomes.