Differentiation of human mesenchymal stem cells on plasma-treated polyetheretherketone

Abstract

Polyetheretherketone (PEEK) generally exhibits physical and chemical characteristics that prevent osseointegration. To activate the PEEK surface, we applied oxygen and ammonia plasma treatments. These treatments resulted in surface modifications, leading to changes in nanostructure, contact angle, electrochemical properties and protein adhesion in a plasma power and process gas dependent way. To evaluate the effect of the plasma-induced PEEK modifications on stem cell adhesion and differentiation, adipose tissue-derived mesenchymal stem cells (adMSC) were seeded on PEEK specimens. We demonstrated an increased adhesion, proliferation, and osteogenic differentiation of adMSC in contact to plasma-treated PEEK. In dependency on the process gas (oxygen or ammonia) and plasma power (between 10 and 200 W for 5 min), varying degrees of osteogenic differentiation were induced. When adMSC were grown on 10 and 50 W oxygen and ammonia plasma-treated PEEK substrates they exhibited a doubled mineralization degree relative to the original PEEK. Thus plasma treatment of PEEK specimens induced changes in surface chemistry and topography and supported osteogenic differentiation of adMSC in vitro. Therefore plasma treated PEEK holds perspective for contributing to osseointegration of dental and orthopedic load-bearing PEEK implants in vivo.

Current Strategies to Improve the Bioactivity of PEEK

“…Animal testing results proved that this nanopatterned PEEK etched by oxygen plasma exhibited potential osteoinductivity in vivo . Waser-Althaus [33] applied the O 2 /Ar or NH 4 plasma to treat the PEEK surface. They demonstrated an increased adhesion, proliferation, and osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (adMSC) on plasma-treated PEEK, and a doubled mineralization degree on 50 W plasma-treated PEEK relative to the 10 W was observed, indicating the osteogenic differentiation was dependent on the plasma power.…”

Tailoring surface nanostructures on polyaryletherketones for load-bearing implants

“…Therefore, the differentiated curves of cooling are presented in A and D, respectively, and of the subsequent heating in C and F. These differentiated curves clearly demonstrate that the characteristic temperatures (melting temperature, cold crystallization temperature, glass transition temperature) are not affected for both plasma-treated PEKK and PEEK films. (25), PEKK films to be applied in cell and animal experiments should be plasma-treated with a power of 25 W.…”

“…These commercially available PEKK films are only available with a nominal thickness of 60 μm, whereas PEEK films are offered with nominal thicknesses of 6, 12, 25, 50, 100, 200, and 300 μm. Our study is based on 100 μm-thick PEEK films because of the available data from previous research activities (23,25).…”

“…The density and size of the nanostructures can be tailored by the choice of the process gas, the plasma power, and the duration of the plasma treatment. Very recently, it has been demonstrated (25,26) that adipose tissue-derived mesenchymal stem cells seeded on plasmatreated PEEK films show an increased adhesion, a higher degree of proliferation, and an improved osteogenic differentiation compared to untreated films. When these cells were grown on films treated with 10 and 50 W oxygen and ammonia plasmas for a duration of 5 min, they exhibited a doubled mineralization degree relative to the untreated PEEK.…”

“…In this communication, we apply the methodology developed (23,25) for both PEEK and PEKK films to present a detailed comparison of the two polymer biomaterials.…”