Cell-based assays can be a useful tool for predicting the biocompatibility of different materials used for medical implants. Assessing the proteome of the cells involved in transplant integration, including osteoblasts, can provide important information about which processes are influenced by modifications to surface features, e.g., cellular attachment, proliferation, or differentiation, and how each of these integral processes can be optimised to increase the chances of successful integration. In a study by Merker and colleagues in Material Science & Engineering C researchers examined the response of osteoblasts to titanium implants coated with diamond nanocrystals with and without oxygen- or amino-terminated surfaces. The label-free analysis of the LC-MS/MS data showed over 2000 unique proteins, with representation from many biologically relevant Gene Ontology (GO) categories being significantly affected by the various surface modifications.
How was PEAKS used?
Peaks Studio 6.0 was used to assess LC-MS/MS data including data refinement, de novo sequencing, database search, label-free quantification, and SPIDER Homology Search. Heat maps generated in PEAKS Studio were used to identify proteins that were deferentially expressed across the treatment groups. Data exported from PEAKS was compatible with downstream analysis with various bioinformatic tools.
Merker D, Handzhiyski Y, Merz R, Kopnarski M, Reithmaier JP, Popov C, Apostolova MD. Influence of surface termination of ultrananocrystalline diamond films coated on titanium on response of human osteoblast cells: A proteome study. Mater Sci Eng C Mater Biol Appl. 2021 Sep;128:112289. doi:10.1016/j.msec.2021.112289. Epub 2021 Jul 1. PMID: 34474840.
Abstract
Successful osseointegration, i.e. the fully functional connection of patient’s bone and artificial implant depends on the response of the cells to the direct contact with the surface of the implant. The surface properties of the implant which trigger cell responses leading to its integration into the surrounding bone can be tailored by surface modifications or coating with thin layers. One potential material for such applications is ultrananocrystalline diamond (UNCD). It combines the exceptional mechanical properties of diamond with good biocompatibility and possibility of coating as thin uniform films on different substrates of biological interest. In the current work we firstly deposited UNCD films on titanium-coated substrates and applied oxygen or ammonia plasma to modify their surface properties. The as-grown and modified UNCD exhibited relatively smooth surfaces with topography dominated by rounded features. The modifications induced oxygen- or amino-terminated surfaces with increased hydrophilicity. In addition, the UNCD coatings exhibited very low coefficient of friction when diamond was used as a counterpart. As-grown and modified UNCD samples were applied to study the responses of human osteoblast MG63 cells triggered by surfaces with various terminations assessed by proteomic analysis. The results revealed that the coating of Ti with UNCD as well as the plasma modifications resulting in O- or NH2-terminated UNCD induced upregulation of proteins specific for cytoskeleton, cell membrane, and extracellular matrix (ECM) involved in the cell-ECM-surface interactions. Proteins from each of these groups, namely, vimentin, cadherin and fibronectin were further studied immunocytochemically and the results confirmed their increased abundance leading to improved cell-to-surface adhesion and cell-to-cell interactions. These findings demonstrate the potential of implant coating with UNCD and its surface modifications for better osseointegration and bone formation.