Macrophage Phenotypes in Degenerative Joint Diseases

Macrophages are plastic cells and depending on their phenotype can contribute to the inflammatory state of tissues. The main objective of this thesis is to explore the involvement of macrophages, in particular the role of their phenotypes, during processes of joint degeneration. The answers of the following questions contribute to the main objective:
• How are macrophages of different phenotypes involved in inflammatory tissue degeneration and degenerative joint disease?
• How can modulation of macrophage phenotypes be applied to control either inflammation or their response to biomaterials?
The work described in this thesis revealed that pro-inflammatory, anti-inflammatory, and tissue repair macrophages each have their own behavior and association with OA development and progression. The studies in this thesis present methods on specifically modulating a macrophage phenotype within tissue with the ultimate goal: suppressing OA progression. These methods can be interpreted as guidelines for selecting the most suitable approach for modulation while taking into account the stage of the disease, the inflammatory state of the tissue, or the type of biomaterial in case of biomaterial based joint tissue regeneration. The knowledge can be applied to use macrophage phenotype modulation as a tool to intervene or suppress processes that contribute to degeneration of joint tissues.