Stem cell adhesion and proliferation on hydrolyzed poly(butylene succinate)/ß-tricalcium phosphate composites.

Although poly(butylene succinate)/ß-tricalcium phosphate (PBSu/TCP) composites are biocompatible and allow the growth and osteogenic differentiation of stem cells, cell attachment and adhesion to the PBSu-based substrates is often limited. To enhance cell adhesion and proliferation, we used a sodium hydroxide (NaOH) hydrolysis technique to generate a different degree of roughness on PBSu/TCP substrates with different PBSu:TCP ratios. The results showed that NaOH hydrolysis increased surface roughness of PBSu/TCP substrates in a concentration-dependent manner. Substrates with higher ratios of TCP:PBSu provided more porous topography after NaOH hydrolysis, with a substrate containing 40 wt % TCP (PBSu/TCP-6040) hydrolyzed with 1.5M NaOH (HPBSu/TCP-6040-1.5) showing the highest degree of roughness. As with the roughness, PBSu/TCP surface hydrophilicity was positively affected by the increasing NaOH concentration and TCP incorporation. Stem cells adhered best on HPBSu/TCP-6040-1.5 with three-dimensionally elongated cell extensions. Moreover, the HPBSu/TCP-6040-1.5 substrate most significantly facilitated stem cell actin cytoskeleton reorganization and vinculin-positive focal adhesion formation when compared with the other substrates tested. HPBSu/TCP-6040-1.5 also demonstrated the greatest increase in cell proliferation when compared with the other substrates studied. In conclusion, the results have shown that among various substrates tested, HPBSu/TCP-6040-1.5 provided the best support for stem cell adhesion and proliferation, suggesting its potential use in bone engineering.

Enhanced osteogenic activity of a poly(butylene succinate)/calcium phosphate composite by simple alkaline hydrolysis.

Bone engineering offers the prospect of alternative therapies for clinically relevant skeletal defects. Poly(butylene succinate) (PBSu) is a biodegradable and biocompatible polyester which may possess some limitations in clinical use due to its hydrophobicity. In order to overcome these limitations and increase the bioactivity, a simple and convenient surface hydrolysis of PBSu, PBSu/hydroxyapatite and PBSu/ß-tricalcium phosphate (TCP) films was performed. The resulting surfaces (i.e., HPBSu, HPBSu/HA and HPBSu/TCP) were tested for their physicochemical property, biocompatibility and osteogenic potency. The results showed that surface hydrolysis significantly increased surface roughness and hydrophilicity of the composites, with the HPBSu/TCP possessing the most pronounced results. All the materials appeared to be biocompatible and supported in vitro growth and osteoblast differentiation of hMSCs, and the alkaline hydrolysis significantly enhanced the hMSC cell proliferation and the osteogenic potency of PBSu/TCP compared with the non-hydrolyzed sample. In conclusion, the HPBSu/TCP possessed better hydrophilicity, biocompatibility and osteogenic potency in vitro, suggesting that this simple and convenient alkaline hydrolysis could be used to augment the biological property of PBSu-based composites for bone engineering in vivo.