Accordingly with the WP1 main objective of characterizing the early signs of ageing associated to cartilage and joint defects, the DCs involved in the project successfully: 1. obtained valuable insights into underlying disease mechanisms of specific monogenic diseases, namely diastrophic dysplasia (DTD) and spondylo-epimetaphyseal dysplasia with joint laxity type2 (SEMD JL2). The progression of alterations in cartilage and bone during ageing has been reported. A cartilage damage model by means of overloading osteochondral explants with a combination of static compression and shear has been developed and currently is being further optimized and validated. Accordingly, with the WP2 main goal of identifying the early signs of ageing associated to bone defects, the DCs involved in the project successfully characterized in adult and aged mice the skeletal and cellular phenotype of mutant mice carrying a dominant negative mutation in type I collagen (Brtl) and a gain-of-function mutation in FGFR3. Early signs of aging were identified in bone of both models. A bone phenotype has also been identified in a murine model of chondrodysplasia and in a murine and a zebrafish model for myopathy supporting the involvement of other tissues beyond the most affected one in different diseases during aging. In compliance with the WP3 main objective to identify early signs of ageing associated to muscular, cardiac and vascular defects, the DCs involved in the project successfully demonstrated altered vertebrae angles, correlating with stiff spine characteristics, in the col6a1∆ex14 mutant zebrafish. A worsening phenotype was observed in adult fish, leading to severe muscle integrity damage. In a knockout mouse for collagen VI, changes in cardiomiocytes ultrasctructure was observed during aging. A potential pro inflammatory role of extracellular vesicles derived from immortalized Ulrich congenital muscular dystrophy patients was proposed. More than 12 senescence markers in human brain endothelial cells and patient fibroblasts were successfully studied. The phenotypic characterization of a mutant Col4a2 mouse line during ageing was achieved. In accordance with the WP4 main goal to develop new tools to target cellular senescence as a treatment strategy for connective tissue disorders, the DCs involved in the project successfully accomplished already relevant results. The presence of primary cilium defects in immortalized cells derived from UCMD patients was described and was partially rescued by treating the cells with a direct inducer of adenilate cyclase or prostaglandin receptor targeting compounds. Also, the therapeutic potential of EP2 agonists in restoring primary cilia function and modulating senescence in the chondrocyte models was achieved. Defect in primary cilium was also found in presence of COL4 mutations and investigation of cell senescence in these cells supports activation of senescence.
