Impact of modification of implants for replacement of osteochondral defects on the gene expression of chondrocytes
Abstract
Introduction: Polymers represent materials suitable for replacement of subchondral defects. The aim of this study was to evaluate the impact of superficial modification of cycloolefin copolymer (COC) and COC blend with collagen type II on the viability and gene expression of chondrocytes.
Material and methods: Human chondrocytes were grown in cell culture medium on the surface of COC and COC blend biomaterials. The surface of a half of the materials was plasmatically modified by atoms of nitrogen and oxygen for bond of collagen type II.
The gene expression of matrix metalloproteinases (MMP-1,-3,-13), proinflammatory cytokines (IL-1, TNF-alfa) and apoptotic molecules (BAX, Bcl-2) was evaluated by quantitative Taq-Man PCR after 48 hours of incubation. Viability of chondrocytes was evaluated by MTT test after 2, 4, and 8 days of incubation.
The synthesis of MMPs was measured by ELISA in cell medium after 48 hours of incubation. Results: Chondrocytes cultured on the surface of copolymers plasmatically modified had an average mRNA expression 2.8-fold increased for IL-1 and 8.2-fold increased for MMP-1.
All of tested MMPs were increasingly produced into cell medium by chondrocytes cultured on the plasmatically modified surface of expression of MMPs mRNA. Modified materials, compared to unmodified polymers, decreased viability of chondrocytes according to the length of exposition.
The gene expression of TNF-? and apoptotic molecules by chondrocytes did not differ among tested materials. Conclusion: Cycloolefin copolymers COC and COC blend can represent suitable materials for tissue engineering, but their plasmatic modification can, at least in "in vitro" conditions, decrease viability of chondrocytes and induce their pro-destructive potential.
The advantages and disadvantages of the plasmatic modification of materials for replacement of osteochondral defects may be unveiled by further studies.