Biodegradable poly (ester-urethane) scaffolds for bone tissue engineering

Kızıltay, Aysel
During last decade, polyurethanes (PUs) which are able to degrade into harmless molecules upon implantation have received a significant level of attention as a biomaterial in tissue engineering applications. Many studies are focused especially on development of PUs based on amino acid derivatives; however, there are only few applications of amino acid based PUs in tissue engineering. In this study, a biocompatible and biodegradable thermoplastic poly(ester-urethane) (PEU) based on L-lysine diisocyanate (LDI) and polycaprolactone diol (PCL) was synthesized and used for the preparation of two dimensional (2D) films and three dimensional (3D) scaffolds. The resulting polymer was casted as 2D films for full characterization purpose and it was found that it is highly elastic with modulus of elasticity ~12 MPa. Surfaces of 2Ds were modified via micropatterning and fibrinogen coating to check the material-cell interaction. The 3D scaffolds were obtained by salt leaching and rapid prototyping (bioplotting) techniques. The 3D scaffolds had various pore size and porosity with different mechanical strength. The bioplotted scaffolds had uniform pore size of ~450 µm and exhibited higher compressive modulus (~4.7 MPa) compared to those obtained by salt leaching (~147 kPa). Salt leached 3D scaffolds had inhomogenous pore size distribution in the range of 5 µm - 350 µm and demonstrated greatest degradation profile compared to 2D films and 3D bioplotted samples under enzymatic condition. Rat bone marrow stem cells (BMSCs) were used to investigate the biocompatibility of the polymer and suitability of fabricated scaffolds for osteogenesis. Presence of micropatterns on 2D matrices did not show any influence on osteoblastic function, but presence of fibrinogen enhanced cell attachment and proliferation. All of the fabricated 3D PEU matrices supported proliferation, osteoblastic differentiation and extracellular matrix (ECM) deposition with highest osteoblastic activity on bioplotted scaffolds which confirmed by von Kossa staining and EDX analysis. The results indicated that the synthesized PEU based scaffolds were able to induce osteoblastic differentiation and mineralization of BMSC and therefore these scaffolds can be good candidates to be used in bone tissue engineering
Citation Formats
A. Kızıltay, “Biodegradable poly (ester-urethane) scaffolds for bone tissue engineering,” Ph.D. - Doctoral Program, Middle East Technical University, 2011.