Enhanced degradation and bioactivity in polysiloxane-based shape memory polymer (SMP) scaffolds

Abstract

“Self-fitting” shape memory polymer (SMP) scaffolds based on poly(ε-caprolactone) diacrylate (PCL-DA) have the potential to improve healing of irregular bone defects due to their capacity to fill complex geometries and to intrinsically support human mesenchymal stem cell (h-MSC) mediated osteogenesis. In prior work, the incorporation of polydimethylsiloxane dimethacrylate (PDMS-DMA) resulted in PCL/PDMS SMP scaffolds that successfully induced in vitro mineralization and accelerated degradation, the latter stemming from phase separation effects. Herein, analogous scaffolds were created with a more hydrophilic polysiloxane, polymethylhydrosiloxane dimethacrylate (PMHS-DMA). When compared to analogous PCL/PDMS scaffolds, the resulting PCL/PMHS scaffolds exhibited desirably faster rates of in vitro degradation and mineralization. In vitro analyses on RGDS [Arg-Gly-Asp-Ser]-modified PCL/PMHS confirmed their capacity to intrinsically support h-MSC bone marker expression with similar specificity and potency as RGDS-containing PCL scaffolds. However, cellular spreading was reduced on RGDS-modified PCL/PMHS scaffolds versus PCL and analogous PCL/PDMS scaffolds due to a decrease in surface-available cell adhesive peptide.