Engineering porcine arteries: effects of scaffold modification

Techniques have been developed to culture bovine or porcine vascular cells on polyglycolic acid (PGA) scaffolds to form engineered vessels. Previously, it was shown that smooth muscle cells (SMCs) that were in close proximity to PGA remnants after 8 weeks of culture had lower expression of SMC markers of differentiation and were more mitotic compared with SMCs that were distant from polymer residuals. Modifications of PGA were explored as a means to minimize residual polymer fragments after culture. To hasten degradation, polymer was treated with heat, NaOH, or gamma-irradiation. Differential scanning calorimetry, mass and tensile strength degradation, and inherent viscosity were used to assess polymer characteristics. When polymer was maintained in aqueous conditions, tensile strength of treated PGA degraded to zero within 3 weeks for each treatment. Engineered vessel constructs cultured on NaOH and gamma-treated polymer displayed smooth muscle alpha-actin throughout the vessel wall. Scaffold treatment impacted graft morphology, cellular differentiation, and mechanical integrity.