The relationship between the mechanical properties and cell behaviour on PLGA and PCL scaffolds for bladder tissue engineering.

Previous work on 2D synthetic films showed growth of human bladder stromal cells was enhanced on materials with lower moduli that mimic the elastic properties of native tissue. This study developed 3D synthetic foam scaffolds for soft tissue engineering by emulsion freeze-drying. Foams of poly(lactide-co-glycolide) (PLGA) and poly(epsilon-caprolactone) (PCL) were extensively characterised using scanning electron microscopy, mercury porosimetry, dynamic mechanical analysis, degradation analysis, size exclusion chromatography and differential scanning calorimetry. Foams of 85-88% porosity and 35 microm pore diameter were selected for further study; the storage modulus of PCL foams was around half that of PLGA (2 MPa vs 4 MPa) and closer to the reported value for native bladder tissue. Urinary tract stromal cells showed a 4.4 and 2.4-fold higher attachment and rate of growth, respectively, on PCL scaffolds, as assessed by a modified 3-[4,5-dimethyl(thiazol-2yl)-3,5-diphery] tetrazolium bromide assay. A greater contractile force was exerted by cells seeded in PLGA than on PCL scaffolds, raising the possibility that the reduced rate of proliferation of cells on PLGA scaffolds may reflect differentiation into a contractile phenotype. This study has generated PCL foam scaffolds with properties that may be pertinent to the tissue engineering of the bladder and other soft tissues.