A Comparative In Vitro Study of Cell Growth on Textile Scaffolds for Tissue Engineering Applications
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Solujen kasvun vertailu tekstiili-skaffoldeilla in vitro kudosteknologisiin sovelluksiin
Biotextiles are fibrous structures created from synthetic or natural materials, which are used as biodegradable temporary scaffolds in tissue engineering. The function of such cell-seeded devices is to heal or replace damaged organs or tissues. Biocompatibility and retention of mechanical properties in the relatively hostile environment is required from the fiber materials. Porosity, pore sizes and pore shapes affect cell coverage and distribution on the scaffolds. Textile manufacturing techniques provide a vast variety of available structures in both small and large scale production. The aim of this thesis was to compare cell viability and distribution on textile scaffolds. For this purpose melt spinning method was used to process poly-L/D-lactide 96/4 (PLDLA 96/4) fibers. A 36-week hydrolytic degradation experiment was conducted for the gamma irradiated fibers to evaluate retention of mechanical properties and changes in crystallinity and thermal properties. Tensile testing method was used for mechanical properties and differential scanning calorimetry (DSC) for the two last mentioned. The fibers were used to manufacture braided, knitted and woven fabrics. Heat sealing and compression at elevated temperature was used to prepare multi-layered scaffolds with approximately 1 mm thickness. Recovery after heat treatment and swelling in cell culture medium was evaluated for the scaffolds. Human urothelial cells (hUCs) and human foreskin fibroblasts (hFFs) were used in the cell culture experiment. Live/Dead analysis and crystal violet staining were used to assess cell viability and distribution. Tensile strength of the PLDLA 96/4 fibers decreased during degradation as did strain at maximum load. Crystallinity increased with a few percent. Glass transition temperature decreased, as was predicted based on previous studies. Unexpectedly, the melting temperature showed a slight increase during degradation. In the recovery and swelling experiments, unwanted changes were not observed. The cell culture experiment demonstrated good biocompatibility for the fibers. After 2 weeks of incubation, the less porous braided and woven scaffolds had the most attached hUC and hFF cells. The large pores of knitted scaffolds remained mostly cell free for both cell types throughout the experiment. The experiments conducted for this thesis demonstrated that PLDLA 96/4 fiber bundles can be processed into biodegradable braided, knitted and woven textile scaffolds. These structures support viability of cells in vitro. The number of attached cells was the largest in braided and woven structures that had significantly smaller pores in comparison to knitted scaffolds.