Connective tissue regeneration: therapeutical strategies for cartilage and bone repair

Osteoarthritis (OA) is the most common arthropathy and a leading cause of pain and disabilities worldwide (Dieppe et al., 2005). This condition entails progressive cartilage breakdown, osteophyte formation, subchondral bone alterations and synovial inflammation, leading to the loss of function of the whole joint (Zeddou, 2019). Recent estimates, updated in 2017, revealed that globally OA affected more than 300 million people, mostly in occidental countries, representing a burden of western societies and a disabling condition at personal level. However, despite its prevalence and importance, even economically, the molecular mechanisms underneath this pathology are still under deep investigation. Most importantly, the lack of knowledge about its complex background reflects into the absence of proper and efficient treatment of OA. For these reasons, the aim of this chapter was to investigate as deeply as possible the molecular mechanisms of OA in order to propose novel therapeutical agents that might be applicable in the field of regenerative medicine. Unlike the poor articular cartilage repair, bone regeneration is a highly orchestrated and efficient process, which comprises whole bone renewal and adaptation to newly physical conditions. However, there are some clinical conditions associated with defective bone healing, which requires new management strategies without the complications associated with the standard treatments (bone grafts). To date, there has been an exquisite improvement in the field of tissue engineering, with the proposal of a variety of bioactive and biomimetic materials as well as the application of tunable physical non-invasive strategies to modulate the dynamic process of bone regeneration. The bone section of this thesis will focus on two different regenerative strategies to improve defective bone healing: biodegradable synthetic polymers and the role of electromagnetic fields in directing new bone formation.