Growth and accelerated differentiation of mesenchymal stem cells on graphene-oxide-coated titanate with dexamethasone on surface of titanium implants.

OBJECTIVE: In this study, the objective is to construct graphene-oxide-coated titanate on titanium foils as drug vehicle to enhance cell proliferation and osteo-differentiation of rat bone mesenchymal stem cells (rBMSCs).

METHODS: Graphene oxide (GO) sheets obtained using the modified Hummer's method and characterized by AFM were coupled with bioactive titanate on Ti implants (GO-Ti) pretreated by alkali, followed by reduction (rGO-Ti). They were characterized by Raman spectroscopy, XPS, SEM, FTIR and contact angle. After dexamethasone (DEX) was loaded onto them (DEX-GO-Ti and DEX-rGO-Ti), cell proliferation of rBMSCs on them was evaluated by CCK-8 and F-actin staining, and differentiation through alkaline phosphatase activity, mRNA expression, and calcium nodules.

RESULTS: The obtained GO sheets were monolayers from AFM. Raman spectra exhibited two prominent peaks at D and G bands, and the I(D)/I(G) ratios increased from 0.96 to 1.68 after reduction. XPS proved the existence of oxygenated functional groups for GO-Ti and the reduction of their intensity for rGO-Ti. From SEM, GO and rGO were evenly coated on nanostructures. DEX-GO-Ti absorbed most amount of DEX and released in a sustained manner. CCK-8 results showed that DEX-GO-Ti showed excellent performance on promoting cell proliferation. RMBSCs on DEX-GO-Ti presented greatly high expression of calcium, proteins and mRNA related to osteogenic differentiation.

SIGNIFICANCE: GO coated titanate nanostructrues on surfaces of Ti foils by a simple self-assembly method, showed excellent vechiles for DEX. The construct promoted proliferation and accelerated osteogenic differentiation of rBMSCs, and would be prosperous for their further applications.