Surface Functionalization of Orthopedic Titanium Implants with Bone Sialoprotein.
Orthopedic implant failure due to aseptic loosening and mechanical instability remains a major problem in total joint replacement. Improving osseointegration at the bone-implant interface may reduce micromotion and loosening. Bone sialoprotein (BSP) has been shown to enhance bone formation when coated onto titanium femoral implants and in rat calvarial defect models. However, the most appropriate method of BSP coating, the necessary level of BSP coating, and the effect of BSP coating on cell behavior remain largely unknown. In this study, BSP was covalently coupled to titanium surfaces via an aminosilane linker (APTES), and its properties were compared to BSP applied to titanium via physisorption and untreated titanium. Cell functions were examined using primary human osteoblasts (hOBs) and L929 mouse fibroblasts. Gene expression of specific bone turnover markers at the RNA level was detected at different intervals. Cell adhesion to titanium surfaces treated with BSP via physisorption was not significantly different from that of untreated titanium at any time point, whereas BSP application via covalent coupling caused reduced cell adhesion during the first few hours in culture. Cell migration was increased on titanium disks that were treated with higher concentrations of BSP solution, independent of the coating method. During the early phases of hOB proliferation, a suppressive effect of BSP was observed independent of its concentration, particularly when BSP was applied to the titanium surface via physisorption. Although alkaline phosphatase activity was reduced in the BSP-coated titanium groups after 4 days in culture, increased calcium deposition was observed after 21 days. In particular, the gene expression level of RUNX2 was upregulated by BSP. The increase in calcium deposition and the stimulation of cell differentiation induced by BSP highlight its potential as a surface modifier that could enhance the osseointegration of orthopedic implants. Both physisorption and covalent coupling of BSP are similarly effective, feasible methods, although a higher BSP concentration is recommended.
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Andreas
0000-0001-7954-5289
A
Baranowski
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Anja
A
Klein
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Ulrike
U
Ritz
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Angelika
A
Ackermann
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Joris
J
Anthonissen
Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
Kerstin B
KB
Kaufmann
Division of Pediatric Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
Christian
C
Brendel
Platform for Biomaterial Research, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Hermann
H
Götz
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Pol M
PM
Rommens
Department of Orthopedics and Traumatology, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
Alexander
A
Hofmann
D058574:Integrin-Binding Sialoprotein / Q000737:chemistry*; D009985:Orthopedics; D019736:Prostheses and Implants; D013499:Surface Properties; D014025:Titanium
D058574:Integrin-Binding Sialoprotein; D014025:Titanium