Titanium particles inhibit bone marrow mesenchymal stem cell osteogenic differentiation through the MAPK signaling pathway

Abstract

Metallic implants have great application in clinical orthopedics. Implants wear out in vivo due to long-term mechanical loading. The formation of wear debris is one of the long-term complications of prosthesis. In the case of artificial joint replacement in particular, aseptic loosening is the most common reason for secondary revision surgery. Previous studies suggested that wear debris caused aseptic loosening mainly by promoting osteolysis around the prosthesis. In this study, titanium particles, the most commonly used particles in clinical practice, were selected to simulate wear debris and explore the influence of titanium particles on osteogenic differentiation of mesenchymal stem cells. Our results show that titanium particles can significantly inhibit osteogenic differentiation in a dose-dependent manner. While engaged in preliminary exploration of the underlying mechanisms, we found that titanium particles significantly affect phosphorylation of ERK1/2, a key component of MAPK signaling. This suggests that the MAPK signaling pathway is involved in the inhibition of osteogenic differentiation by titanium particles.

Keywords: MAPK pathway; Ti particles; mesenchymal stem cell; osteogenic differentiation.

Fig. 1

Model diagram of this study. (A) Schematic illustration of particles generated by wear of the prosthesis in vivo. (B) Ti particles inhibit osteogenic differentiation through MAPK pathway.

Fig. 2

Characterization of Ti particles. (A) SEM images of Ti particles. Scale bar: 2 μm (left); 200 nm (right). (B) The elemental composition of Ti particles.

Fig. 3

Biocompatibility of Ti particles. (A) Microscopic image of Ti particles and cell co‐culture. Scale bar: 5 μm. (B) Viability of rat mesenchymal stem cells (rMSCs) quantified by CCK‐8 assay. (C) Live/dead staining of rMSCs cultured with Ti particles after 48‐h incubation. Live cells were stained as green and dead cells were stained as red. Scale bar: 200 μm. Data are presented as mean values ± standard deviation; n = 3; Student's t‐tests (*P < 0.05, **P < 0.01).

Fig. 4

Ti particles inhibit osteogenic differentiation of rat mesenchymal stem cells (rMSC). (A, B) Alkaline phosphatase (ALP) staining and ALP activity analysis were performed to evaluate the expression of ALP in rMSCs after co‐culture with Ti particles for 3 and 7 days. (C) Osteogenic marker genes were detected to assess the level of cell differentiation by qPCR. (D) Runx2, ERK1/2, and p‐ERK1/2 were determined by western blot. Data are presented as mean values ± standard deviation; n = 3; Student's t‐tests (*P < 0.05, **P < 0.01, ***P < 0.001).