The effect of porous structure on the cell proliferation, tissue ingrowth and angiogenic properties of poly(glycerol sebacate urethane) scaffolds

Novel, porous, biodegradable biomaterials which support tissue integration and angiogenesis and which have elastomeric properties are needed to repair and replace soft tissues in dynamic environments. In this study poly(glycerol sebacate urethane) (PGSU) scaffolds with different porous structures were fabricated using freeze-drying by varying the polymer concentration of the freeze-drying solution, during which the polymer was further crosslinked. The effect of the porous structure on the physical properties, cell proliferation, tissue ingrowth and angiogenic properties was investigated. By increasing the polymer concentration in the freeze-drying solution from 5 w/v% to 10 w/v% and 15 w/v%, the porosity and pore size of the scaffold decreased, resulting in porosities ranging between 88 – 96% and pore sizes 6.4–28.2 μm. The mechanical properties increased with the polymer concentration, with ultimate tensile strength and Young's modulus between 0.05 – 0.86 MPa and 0.05–0.65 MPa respectively and negligible loss of tensile strength after 100 cycles of loading. Enzymatic degradation over 28 days demonstrated linear degradation kinetics with mass loss between 19.1 – 52.3%. All PGSU scaffolds provided a viable environment for cell attachment, in which cell metabolic activity increased over time indicating cell proliferation. The cells adhered to PGSU scaffolds produced and deposited high quantities of collagen, reaching 7.5% of the sample's dry mass after 14 days culture for the scaffold with the highest porosity. Additionally, the scaffolds with the polymer concentration of 5 w/v% implanted onto the chick chorioallantoic membrane supported rapid tissue ingrowth and new blood vessel formation within the porous scaffold. These results demonstrate that PGSU scaffolds have potential for use in many areas of soft tissue engineering.