Biological responses of human mesenchymal stem cells to titanium wear debris particles

Abstract

Wear debris-induced osteolysis is a major cause of orthopaedic implant aseptic loosening, and various cell types, including macrophages, monocytes, osteoblasts, and osteoclasts, are involved. We recently showed that mesenchymal stem/osteoprogenitor cells (MSCs) are another target, and that endocytosis of titanium (Ti) particles causes reduced MSC proliferation and osteogenic differentiation. Here we investigated the mechanistic aspects of the endocytosis-mediated responses of MSCs to Ti particulates. Dose-dependent effects were observed on cell viability, with doses >300 Ti particles/cell resulting in drastic cell death. To maintain cell viability and analyze particle-induced effects, doses <300 particles/cell were used. Increased production of IL- 8, but not IL-6, was observed in treated MSCs, while levels of TGF-β, IL-1β, and TNF-α were undetectable in treated or control cells, suggesting MSCs as a likely major producer of IL-8 in the periprosthetic zone. Disruptions in cytoskeletal and adherens junction organization were also observed in Ti particles-treated MSCs. However, neither IL-8 and IL-6 treatment nor conditioned medium from Ti particle-treated MSCs failed to affect MSC osteogenic differentiation. Among other Ti particle-induced cytokines, only GM-CSF appeared to mimic the effects of reduced cell viability and osteogenesis. Taken together, these results strongly suggest that MSCs play both responder and initiator roles in mediating the osteolytic effects of the presence of wear debris particles in periprosthetic zones.

NF-κB as a Therapeutic Target in Inflammatory-Associated Bone Diseases

“…Inhibition of NF-κB activity in the MSCs exposed to wear particles mitigated the reduced bone formation (Lin et al, 2015). The paracrine regulators including IL-8, GM-CSF (Haleem-Smith et al, 2012), M-CSF, and RANKL (Pioletti & Kottelat, 2004) are also upregulated in OB or MSC exposed to wear particles, which could further enhance inflammation and the osteolytic process.…”

Chemokines Associated with Pathologic Responses to Orthopedic Implant Debris

“…The roles of chemokines relevant to the context of orthopedic implant debris include pro-inflammatory cytokine production, pyroptosis, apoptosis, angiogenesis, and collagen production, which act together to product aseptic bone resorption around implants. However, mostly macrophages and MSCs have been implicated as the major source of this chemokine in periprosthetic tissues induced by different types of wear particles like titanium, CoCr, and UMHWPE (62, 63). This migration of macrophages and osteoclasts to the sites around implants leads to accelerated osteolysis (64).…”

Gene Expression in Osteolysis: Review on the Identification of Altered Molecular Pathways in Preclinical and Clinical Studies

“…Mouse macrophage cell lines (RAW264.7) were the most used [4,6,27,28,29,30,31,32,33,34,35,36,37], followed by OB precursors derived from mouse calvaria (MC3T3-E1) [27,28,38,39,40,41] and human (Saos-2 and MG-63) [1,42,43] or rat (ROS 17/2.8) [44] osteosarcoma and monocitic (THP-1) [20,45,46] cell lines. In addition, other studies also used primary cells: mouse [28,47] or human [42,48] OBs, mouse or rat bone-marrow-derived macrophages (BMM) [28,49,50,51], human MSCs [39,52], mouse [47] or human [53] FBs and mouse peritoneal macrophages [54]. In one study, mouse calvaria [4] were cultured in toto.…”

“…In one study, mouse calvaria [4] were cultured in toto. Regarding the different wear particles used, Ti [4,6,27,28,29,30,31,32,33,38,39,42,45,50,52,53] was the most employed, followed by PE [20,34,37,43,47,48], PMMA [36,41,51] and Co-Cr alloy [1,40,46]. Three studies compared Ti effects with PMMA [49], zirconia (ZrO 2 ) [54] and aluminia ceramic (CE) [34] and one compared PE and hydroxyapatite (HA) particles [44].…”

“…In addition, one study analyzed osteogenesis and apoptotic pathways with microarray in hMSCs, showing an up-regulation of genes of pro-apoptotic proteins (Bcl-2-associated death promoter (BAD), Cluster of Differentiation 70 (CD70), B-cell lymphoma 2 (BCL2) and a down-regulation of anti-apoptotic and osteogenesis genes, encoding for Cartilage oligomeric matrix protein (COMP), Fibroblast Growth Factor Receptor 2 (FGFR2), Insulin-like growth factor 1 (IGF-1), Bone morphogenetic protein 6 (BMP6), Collagens (COLLs), (sex determining region Y)-box 9 (SOX9) and OPG [52]. …”