Comparison of the osteogenic, adipogenic, chondrogenic and cementogenic differentiation potential of periodontal ligament cells cultured on different biomaterials.

ABSTRACT

It has been shown that the cellular responses such as adhesion, proliferation and differentiation are influenced by the surface properties, such as the topography or the surface energy. However, less is known about the effect of the chemical composition and type of material on the differentiation potential. The objective of the present paper is to compare the differentiation potential of periodontal ligament cells (HPLC) into adipocytes, osteoblasts, chondroblasts and cementoblasts of three type of materials (metals, ceramics and polymers) without using any biological induction media, but keeping the average roughness values within a limited range of 2.0-3.0µm. The samples were produced as discs of 14×2mm; (n=30 for each type of material). Two samples of each type were chosen; stainless-steel 316L and commercially pure titanium for the metallic samples. The polymers were polymethyl methacrylate and high-density polyethylene, and finally for the ceramics; zirconia and dental porcelain were used. The surfaces properties of the samples (wettability, chemical composition and point of zero charge, PZC) were measured in order to correlate them with the biological response. To evaluate the potential of differentiation, human periodontal ligament cells obtained from extracted teeth were used since they are a promising source for periodontal tissue regeneration. Cell proliferation was initially tested to assure non-toxic effects using a viability colorimetric assay. Finally, the differentiation pattern was evaluated using real time reverse transcription quantitative polymerase chain reaction for 5, 10 and 15days without adding any induction medium. The results indicated that the relative expression of genes related to a particular phenotype were different for each surface. However, not clear correlation between the type of material or their surface properties (morphology, chemical composition, wettability or point of zero charge) and the expression pattern could be identified. For example, bone markers were mainly expressed on cpTi and PMMA; one metallic hydrophobic and one polymeric hydrophilic sample which have similar Ra values but presented different topographical features, although both samples have in common a PZC below 7.