Biomechanics is often overlooked by biologists, and human or veterinary practitioners, except for those closely working with musculoskeletal disorders. However, mechanical forces are fundamental in tissue development, and morphogenesis is regulated through fluid flow mechanisms and cellular contractility. Furthermore, tissues are submitted to stresses and strains that require intrinsic suitable mechanical properties to protect against damage. Damage can be primary, i.e. caused by a trauma or section, but it can also develop from a tentative correction of a primary lesion, during healing or in response to the application of a foreign material-structure. Materials, whether the native tissues or biomaterials used in the clinics, display different mechanical behaviors that ultimately decide their fate in the body, by locally determining tissue acceptance and reaction to external loads. A hierarchical organization of tissues is considered critical to their function with complex interactions occurring at the molecular level where mechanical forces trigger biochemical and electrical potential changes.
Likewise, the clinical success of implants and their longevity depend on the interplay between the biomaterial, its structural design and its physical and chemical characteristics, and the local microenvironment - which is again profoundly dependent on its biomechanics. Here, optimizing the mechanical properties and the function of an implant including its fixation or tribological behavior are critical to optimize the biological response to the device. Failure to do so may result in non-physiological micromovements at the interface or increased wear and particle generation. While increased micromotion may affect cell response by causing changes on the pattern of mechanical cell stimulation, with effects on the cytoskeleton and microtubule network and gene expression, the presence of wear particles may trigger an inflammatory response that can drive corrosion processes in metallic implants.
Cells in living organisms are characterized by a redox state that drives a set of oxygen and nitrogen dependent metabolic reactions, which results in the synthesis of energy in the form of adenosine triphosphate (ATP), required for the occurrence of various cellular functions. Besides the ATP role in cell metabolism, oxygen and nitrogen participate in the unwanted production of reactive oxygen species (ROS, including oxygen free radicals) and reactive nitrogen species (RNS). Increasing levels of both reactive species are deleterious and trigger significant cell damage. When ROS/RNS oxidant production exceeds the antioxidant capacity in living cells, a state of oxidative stress is achieved. Oxidative stress has been implicated in numerous neurodegenerative, cardiovascular and oncological diseases and impact on the cellular biomechanics is not adequately understood. Additionally, ROS participates in immune cell recruitment and thus, in tissue inflammation and the healing processes. It is now widely recognized that redox reactions are paramount in determining implant success and durability, in a mutual relationship in which biology influences biomaterial degradation and corrosion and these affect the biological system. Oxidative/nitrosative stress (OS/NS) is now accepted as a key player in biomaterial behavior after implantation. Whether OS/NS derives from the local acute inflammation or triggers a chronic inflammatory condition, it plays a role in regeneration and healing for certain. Excessive OS/NS or inflammation at the site of implant application may compromise healing and tissue regeneration. Finally, it is noteworthy that reactive species play important roles in cellular signaling mechanisms in response to external stimuli, including those derived from mechanical stimuli. Oxidative stress phenomena triggered by influencing biomechanical factors may predispose to the pathogenesis of other diseases, such a coronary disease, glaucoma and osteoarthritis.
In this Research Topic we aim to explore and elucidate key interactions between the biomechanical environment and oxidative stress. Researchers are welcome to submit their contributions on the following sub-topics:
• Biomechanical factors as triggers for oxidative stress
• Effects of the mechanical environment on healing, biocompatibility and biofunctionality
• Effects of mechanical forces on the local oxidative stress
• Influence of redox imbalance on biomaterial degradation and corrosion and strategies to improve or mitigate biomaterials degradation and corrosion
• Oxidation effects on biomaterial mechanical properties
Articles may be submitted in the form of Original Research articles, Reviews, Mini-Reviews, Case Reports and Short-Communication.
Important Note: All submissions/contributions to this Research Topic must be in line with the scope of the journal/section they are submitted to. While authors are encouraged to draw from other disciplines to enrich their papers where relevant, they must ensure papers fall within the scope of the journal/section, as expressed in its mission statement.
We would like to acknowledge
Dr. Joana Reis as the Co-ordinator for this Research Topic and her contribution to the collection.
Drs. Kanagaraj and Simoes hold patents related to implants. All other Topic Editors declare no competing interests with regard to the Research Topic subject.