Nanotube surface triggers increased chondrocyte extracellular matrix production

We have altered TiO2 nanotube diameters from 30 to 100 nm by anodization and investigated the in vitro bovine cartilage chondrocyte (BCC) response to the different nanoscale dimensions. The nanotopography of the vertically aligned TiO2 nanotube structures triggered enhanced overall production of extracellular matrix (ECM) components over flat Ti control surfaces without a nanostructure-based surface topography. Initial SEM observations revealed that BCCs produced dense ECM fibrils on nanotubular substrates, which were lacking on flat Ti. Biochemical examination confirmed that glycosaminoglycan (GAG) secretion in the culture media was also up-regulated on nanotube substrates, reaching the highest production on the 70 nm diameter nanotubes with ∼ 100% amplification in GAG secretion over flat Ti. PCR analysis revealed that aggrecan and collagen type II transcription levels were increased on nanotube surfaces with the 70 nm diameter nanotubes exhibiting the highest relative levels of both chondrogenic transcription levels. This study demonstrates that TiO2 nanotube structures in the ∼ 70 nm diameter regime, already being an osseo-integrating biomaterial, have significant and favorable effects on the extracellular matrix production of chondrocytes that could have encouraging implications for material applications in cartilage/bone interface osteochondral treatments utilizing nanotechnology. © 2010 Elsevier B.V. All rights reserved.