Novel Polypyrrole-Coated Polylactide Scaffolds Enhance Adipose Stem Cell Proliferation and Early Osteogenic Differentiation

An electrically conductive polypyrrole (PPy) doped with a bioactive agent is an emerging functional biomaterial for tissue engineering. We therefore used chondroitin sulfate (CS)-doped PPy coating to modify initially electrically insulating polylactide resulting in novel osteogenic scaffolds. In situ chemical oxidative polymerization was used to obtain electrically conductive PPy coating on poly-96L/4D-lactide (PLA) nonwoven scaffolds. The coated scaffolds were characterized and their electrical conductivity was evaluated in hydrolysis. The ability of the coated and conductive scaffolds to enhance proliferation and osteogenic differentiation of human adipose stem cells (hASCs) under electrical stimulation (ES) in three-dimensional (3D) geometry was compared to the noncoated PLA scaffolds. Electrical conductivity of PPy-coated PLA scaffolds (PLA-PPy) was evident at the beginning of hydrolysis, but decreased during the first week of incubation due to de-doping. PLA-PPy scaffolds enhanced hASC proliferation significantly compared to the plain PLA scaffolds at 7 and 14 days. Furthermore, the alkaline phosphatase (ALP) activity of the hASCs was generally higher in PLA-PPy seeded scaffolds, but due to patient variation, no statistical significance could be determined. ES did not have a significant effect on hASCs. This study highlights the potential of novel PPy-coated PLA scaffolds in bone tissue engineering.