The role of computer-aided design and surface chemistry on Cell-scaffold interactions

Abstract: Cell interactions and cell response to three dimensional scaffolds based on poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO)] and poly(L-lactide-co-e-caprolactone) [poly(LLA-co-CL)] wereimprovedstudiedby increasing surface hydrophilicity and by using computer-aided scaffold design.Different amounts of Tween 80 (3, 10, 20 wt%) were mixed with the copolymer and it was found that the water contact angle decreased significantly with the amount of Tween 80.  The contact angle of poly(LLA-co-CL) and poly(LLA-co-DXO) decreased from 85° to 35° and 75° to 17° respectively by using 3 wt% Tween 80.  Samples with 20% Tween 80 had a water contact angle of 15°.  In addition, stiffness decreased when the amount of Tween 80 was increased and thermal properties changed significantly when the amount of Tween 80 was higher than 3 wt%.  Cell response was evaluated using three dimensional scaffolds and homogenous films. It was clear in this study that a high amount of Tween 80 resulting in a very low water contact angle had a toxic effect and negative influence on attachment and spreading of bone marrow stromal cells (hBMSC), while a moderate water contact angle had a positive influence on hBMSC differentiation, with significantly higher expression of Runx2 and osteocalcin.A three-dimensional fiber deposition (3DF) technique was employed to make layer-based scaffolds in a reproducible fashion. The 3DF scaffolds manufactured in this way showed enhanced mechanical properties, with E-modulus ranging from about 3 to 5 MPa in tensile strength and 0,22 to 0,29 MPa in compression tests, compared with scaffolds formed by a salt leaching method which had values of 1 and 0,03 MPa, respectively. Degradation during printing was obvious but the decrease in molecular weight did not influence thermal properties or stability of the 3DF structure.  After 1 and 7 days of in vitro cell culture fluorescence staining and scanning electron microscopy showed homogeneous distribution of human osteoblasts (hOBs) on the scaffolds. The 3DF technique thus appears to be a promising method for fabrication of computer designed scaffolds as the scaffold structure is reproducible and their design can be controlled to achieve tailor made products for clinical applications.