The two faces of metal ions: From implants rejection to tissue repair/regeneration

Abstract

The paradigm of metallic ions as exclusive toxic agents is changing. During the last 60 years, knowledge about toxicological and immunological reactions to metal particles and ions has advanced considerably. Hip prostheses, namely metal-on-metal bearings, have prompted studies about excessive and prolonged exposure to prosthetic debris. In that context, the interactions of metal particles and ions with cells and tissues are mostly harmful, inducing immune responses that lead to osteolysis and implant failure. However, in the last decade, new strategies to promote immunomodulation and healing have emerged based on the unique properties of metallic ions. The atom-size and charge enable ions to interact with key macromolecules (e.g. proteins, nucleic acids) that affect cellular function. Moreover, these agents are inexpensive, stable and can be integrated in biomaterials, which may open new avenues for a novel generation of medical devices. Herein, orthopedic devices are discussed as models for adverse responses to metal ions, and debated together with the potential to use metal ions-based therapies, thus bridging the gap between unmet clinical needs and cutting-edge research. In summary, this review addresses the two "faces" of metallic ions, from pathological responses to innovative research strategies that use metal ions for regenerative medicine.

Mechanical properties, corrosion, and biocompatibility of Mg‐Zr‐Sr‐Dy alloys for biodegradable implant applications

“…Specifically, Mg1Zr2Sr2.08Dy exhibited a lower corrosion rate in SBF, and it also showed relatively higher cell viability compared with the other Mg alloys. This is in agreement with a report that the release rate of the metallic ions greatly affects the biosafety of an implant material …”

Effect of cobalt ions on the interaction between macrophages and titanium

“…Co is considered as a toxic agent in most studies but might in sub‐toxic concentrations promote angiogenesis as suggested in a review by Vasconcelos et al50 In the present study, neither Co nor Cr addition impaired cell viability as compared with Ti alone. This is supported by a previous study where Co not affected the viability of THP‐1 cells in concentrations up to 200 µM 31.…”

ZnO quantum dots modified bioactive glass nanoparticles with pH-sensitive release of Zn ions, fluorescence, antibacterial and osteogenic properties

“…Alternatively, materials containing therapeutic ions are drawing attention regarding effective use in bone a Institute of Biomaterials, Department of Materials Science and Engineering, regeneration, as these materials can release therapeutic ions and thus lead to positive biological responses depending on the type and amount of released ions. 7,8 Among a large number of ions with therapeutic effects, zinc (Zn), being an important element of alkaline phosphatase (ALP) and a key mediator of bone matrix mineralization, 9 plays a significant role in bone formation. 10,11 Additionally, Zn ions show antibacterial effects, being therefore beneficial for the inhibition of infection.…”