Featured Article: In vitro development ofpersonalized cartilage microtissues uncovers an individualized differentiation capacity ofhuman chondrocytes

摘要

Personalized features in the treatment of knee injuries and articular replacement therapies play an important role in modern life with increasing demand. Therefore, cell-based therapeutic approaches for the regeneration of traumatic defects of cartilage tissue were developed. However, great variations in the quality of repair tissue or therapeutic outcome were observed. The aim of the study was to capture and visualize individual differentiation capacities of chondrocytes derived from different donors with regard to a possible personal regeneration capacity using a cell-based therapy. The redifferentiation potential of monolayer cultured cells was analyzed in a scaffold-free three-dimensional tissue model. Furthermore, stimulating options using cartilage maturation factors such as L-ascorbic acid and transforming growth factor beta 2 (TGF-β2) on this process were of special interest. Cells and tissues were analyzed via histological and immunohistochemical methods. Gene expression was measured by quantitative real-time polymerase chain reaction. In monolayer culture, cells from all donors showed an almost identical differentiation profile. In contrast, the differentiation state of cartilage-like three-dimensional microtissues revealed clear differences with respect to individual donors. Analyses at the protein and mRNA levels showed high variations regarding cartilage-typical matrix components (e.g. proteoglycans,collagen type II) and intracellular proteins (e.g. S100). Interestingly, only donorchondrocytes with a basic tendency to re-differentiate in a three-dimensional environmentwere able to increase this tissue-specific maturation when exposed to L-ascorbic acidand/or TGF-β2. Our approach revealed clear-cut possibilities for classification ofindividual donors into responders or non-responders. On the basis of these results anin vitro platform could be designed to discriminateresponders from non-responders. This in vitrothree-dimensional test system may be a suitable basis to establish a “personalizeddiagnostic tool” with the opportunity to assess the capacity of expanded chondrocytes torespond to an autologous cell-based therapy.Impact statementA challenge in cell-based cartilage regeneration therapies is the identification of a“personalized diagnostic tool” to predict the chondrogenic potency of cells frompatients who are going to be treated with autologous cells.Comparing the phenotype of isolated chondrocytes from different donors in vitro revealed an individual cartilage-specificdifferentiation capacity. These personalized features are not detectable in vitro until the monolayer cells have the possibility torearrange in 3D tissues.Cells from articular cartilage in monolayer culture may not be a suitable basis todiscriminate responders from non-responders with respect to a personalized cell-basedtherapy to treat cartilage defects. A more physiological 3D (micro-)environment enablethe cells to present their individual differentiation capacity.The here described microtissue model might be the basis for an in vitro platform to predict the therapeutic outcome of autologouscell-based cartilage repair and/or a suitable tool to identify early biomarkers toclassify the patients.