In vitro bone tissue engineering on patterned biodegradable polyester blends

Kenar, Halime
This study aimed at guiding osteoblast cells on biodegradable polymer carriers with well-defined surface microtopography and chemistry, and investigating the effect of cell alignment on osteoblast phenotype expression. A blend of two different polyesters, one being natural in origin (PHBV) and the other synthetic (P(L/DL)LA), was used to form a film with parallel macro- (250 um wide) or microgrooves (27 jam wide) on its surface, by solvent casting on patterned templates. The micropatterned Si template was produced by photolithography, while the Teflon macropatterned template was lathe cut. Fibrinogen (Fb) was adsorbed or immobilized via epichlorohydrin spacer/crosslinker on the film surfaces to enhance cell attachment by increasing the surface hydrophilicity and by providing RGD amino acid sequence for integrin binding. Surface hydrophilicity was assessed by water contact angle measurements. Adsorption of Fb caused an increase in hydrophilicity, while the opposite was achieved with its covalent immobilization. Fb was homogeneously immobilized throughout the whole micropatterned film surface with amount of 153.1 + 42.4 g Fb/cm, determined with the Bradford assay, while it was adsorbed within the grooves of the micropattern. Surface characteristics of the films were studied with Scanning Electron (SEM) and Light microscopy. Osteoblast cells derived from rat bone marrow were seeded on the polymeric films with different surface topography and chemistry and were grown for one and three weeks. Osteoblast proliferation on the films was determined with Cell Titer 96 T Non-Radioactive Cell Proliferation (MTS) test. Alkaline Phosphatase (ALP) assay and tetracycline labelling of mineralized matrix were carried out to determine osteoblast phenotype expression on different surfaces. SEM and fluorescence microscopy were used to evaluate the cell alignment. Osteoblasts on the micropatterned films with adsorbed Fb aligned along the groove axis with a mean deviation angle of 13.1°, while on the unpatterned films deviation from horizontal axis was 63.2° and cells were randomly distributed. Cell alignment did not affect cell proliferation. However, the highest ALP specific activity and the most homogeneous mineral distribution were obtained on the Fb adsorbed micropatterned films.
Citation Formats
H. Kenar, “In vitro bone tissue engineering on patterned biodegradable polyester blends,” M.S. - Master of Science, Middle East Technical University, 2003.