| Summary: | 博士 === 國立臺灣大學 === 醫學工程學研究所 === 94 === In this study, the behavior of embryonic rat cortical neural stem cells on biomedical polymer substrates, poly-(ethylene-co-vinyl alcohol) (EVAL), polyvinyl alcohol (PVA), and lysine-alanine sequential (LAS) were explored. However, the behavior of neural stem cells in vitro are mediated by three major factors: (1) soluble factors in the medium, (2) cell-cell interactions, and (3) culture substrates. Hence, by means of altering the interactions of these three factors, the behavior of cortical neural stem cells was manipulated on these substrates.
Chapter one introduces the backgrounds of stem cells, central nervous system (CNS), neural stem cells from CNS, the factors regulated the behavior of neural stem cells, immunocytochemistry for neural stem cells, biomedical polymer substrates, and application of neural stem cells.
Chapter two investigates the behavior of neural stem cells on PVA and EVAL membranes in the presence of the mitogenic effect of basic fibroblast growth factor (bFGF) in the serum-free medium. It was found that EVAL and PVA membranes exerted different influences on the fate of neural stem cells. The behavior of neural stem cells on the EVAL membrane was independent of cell density at the single-cell level. Conversely, the development of cell clusters was in a density-dependent manner on the EVAL membrane. Neurospheres continuously proliferated under high-density culture condition, but differentiated into neurons and astrocytes under low-density culture condition. Therefore, it is reasonable to assume that biomaterials may stimulate or inhibit the proliferation and differentiation of neural stem cells.
Chapter three explores the phenotypic potential of cortical neural stem cells by inducing differentiation on LAS polymer substrates at neurosphere-level. The results provided evidences that LAS could improve better process growth of neurospheres than poly-D-lysine could. The results also suggested that the behavior, proliferation, and differentiation of neural stem cells on LAS substrates is responsible for the effects of seeding density and serum proteins. It was found that forming-neurospheres cells cultured on LAS substrates adopted different strategies to communicate with adjacent neurospheres
Chapter four investigates the influence of fetal bovine serum (FBS) adsorbed to EVAL and PVA substrates (coated FBS) and fetal bovine serum present in the culture medium (soluble FBS) on the behavior of cortical neural stem cells at neurosphere level. The results of this study suggest that besides substrates, coated and soluble serum proteins have their unique effect on the morphological differentiation and fate determination of neural stem cells.
Chapter five explores the effects of cell-cell and cell-substrate interactions on developmental potential of neural stem cells at neurosphere level in the presence of nerve growth factors (NGF) on tissue culture polystyrene (TCPS), poly-D-lysine (PDL), and EVAL substrates. The results also suggested that, in combination with NGF, EVAL substrates could induce process fasciculation of differentiated forming-neurosphere cells under serum free conditions. The results also provided evidence that EVAL can be a potent controller of cell interactions involving cell-cell and cell-substrate contacts. We proposed that, in combination with nerve growth factors, EVAL substrates could induce neurite fasciculation of embryonic rat cortical neural stem cells under serum free conditions.
Chapter six concludes the contribution of this study and suggested that the present study provides evidence that the plasticity of multipotential neural stem cells is versatile and is dependent on the complex environmental conditions.
|
|---|
